CrazeAnalytix/services/dataProcessor.ts

import { SalesRecord, AdsRecord, TrafficRecord, CombinedKPIs, FilterState, AggregatedData, LineGrowthMetric, ItemGrowthMetric, SeasonalityPoint, YearlySplitData, PivotRow, YearlyData, TimeSeriesData, ComparisonTimeSeriesPoint, ForecastRecord, MonthlyForecastPoint, ProductForecastData, VendorCSVRow, VendorDailyRow } from '../types';
import * as XLSX from 'xlsx';
import Papa from 'papaparse';

/**
 * Parses Vendor CSV and returns mapped VendorDailyRow items.
 */
export const processVendorCSV = (fileOrContent: File | string): Promise<VendorDailyRow[]> => {
    return new Promise((resolve, reject) => {
        const config = {
            header: true,
            skipEmptyLines: true,
            complete: (results: any) => {
                const rows = results.data
                    .filter((row: any) => row['Date'] && row['Market'] && row['ASIN'])
                    .map((row: any) => ({
                        date: row['Date'],
                        market: row['Market'],
                        asin: row['ASIN'],
                        product_title: row['Product Title'] || null,
                        tags: row['Tags'] || null,
                        bsr_top_rank: parseIntSafe(row['Top Level Category (Rank)']),
                        bsr_top_category: row['Top Level Category (Name)'] || null,
                        bsr_detail_rank: parseIntSafe(row['Detail Level Category (Rank)']),
                        bsr_detail_category: row['Detail Level Category (Name)'] || null,
                        avg_rating: parseCurrency(row['Average Rating']), // Uses existing parseCurrency which handles EU/US
                        num_reviews: parseIntSafe(row['Number of Reviews']),
                        buybox_owner: row['Buybox Seller Name'] || null,
                        buybox_price: parseCurrency(row['Buybox Price']),
                        amazon_has_buybox: row['Amazon Has Buybox'] === '1',
                        glance_views: parseIntSafe(row['Glance Views']),
                    }));
                resolve(rows);
            },
            error: (error: any) => {
                reject(error);
            }
        };

        if (typeof fileOrContent === 'string') {
            Papa.parse(fileOrContent, config);
        } else {
            Papa.parse(fileOrContent, config);
        }
    });
};

function parseIntSafe(val: string | undefined | null): number | null {
    if (!val || typeof val !== 'string' || val.trim() === '') return null;
    const cleaned = val.replace(/\./g, '').replace(',', '.').replace(/[^0-9.]/g, '');
    const num = parseInt(cleaned, 10);
    return isNaN(num) ? null : num;
}

// Helper to parse currency values handling both EU (1.234,56) and US/Standard (1,234.56 or 1234.56) formats
const parseCurrency = (value: string): number => {
    if (!value) return 0;

    // Remove currency symbol and whitespace
    let clean = value.replace(/[€$£\s]/g, '').trim();

    // HEURISTIC: 
    // If it contains a comma, we assume it's likely European format (Decimal separator)
    // UNLESS it also contains a dot and the comma is before the dot (e.g. 1,000.50 - US format)
    // But given the context (DE data), comma is usually decimal.

    // Case A: European Format (e.g., "277.179,09" or "50,00" or "263,83")
    if (clean.includes(',') && !clean.includes('.')) {
        // Likely EU decimal without thousands or with thousands implicitly handled
        // e.g. "263,83" -> "263.83"
        clean = clean.replace(',', '.');
        const num = parseFloat(clean);
        return isNaN(num) ? 0 : num;
    }
    else if (clean.includes(',') && clean.includes('.')) {
        // Mixed: 1.234,56 -> EU
        if (clean.indexOf(',') > clean.indexOf('.')) {
            clean = clean.replace(/\./g, '').replace(',', '.');
        } else {
            // 1,234.56 -> US
            clean = clean.replace(/,/g, '');
        }
        const num = parseFloat(clean);
        return isNaN(num) ? 0 : num;
    }

    // Case B: Standard/US Format or Clean Number (e.g. "277179.09" or "1000")
    clean = clean.replace(/,/g, ''); // Remove commas just in case
    const num = parseFloat(clean);

    return isNaN(num) ? 0 : num;
};

const parseUnits = (value: string): number => {
    if (!value) return 0;
    // Remove dots (thousands separators in EU) and commas (thousands in US) just to be safe for integers
    const clean = value.replace(/[\.,]/g, '');
    const num = parseInt(clean, 10);
    return isNaN(num) ? 0 : num;
}

const MONTH_ORDER = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];

// Helper for numeric filtering (e.g. ">5", "10-20")
export const checkNumericConditions = (value: number, filters: string[]): boolean => {
    if (!filters || filters.length === 0) return true;

    return filters.some(f => {
        // Handle specific string labels
        if (f.includes('Out of Stock') || f === 'Out of Stock') return value === 0;
        if (f.includes('In Stock') && !f.includes('Low')) return value > 0;
        if (f.includes('Low Stock')) return value < 10;
        if (f === '< 4 Weeks') return value < 4;
        if (f === '> 4 Weeks') return value >= 4;
        if (f === 'Infinite Cover') return value === 999;

        const input = f.trim().toLowerCase();

        // Range: 10-20
        if (input.includes('-') && !input.startsWith('-')) { // Avoid negative numbers confusion if possible, though simple range usually 10-20
            const parts = input.split('-').map(s => parseFloat(s.trim()));
            if (parts.length === 2 && !isNaN(parts[0]) && !isNaN(parts[1])) {
                return value >= parts[0] && value <= parts[1];
            }
        }

        // Expressions
        if (input.startsWith('<=')) {
            const val = parseFloat(input.substring(2));
            return !isNaN(val) && value <= val;
        }
        if (input.startsWith('>=')) {
            const val = parseFloat(input.substring(2));
            return !isNaN(val) && value >= val;
        }
        if (input.startsWith('<')) {
            const val = parseFloat(input.substring(1));
            return !isNaN(val) && value < val;
        }
        if (input.startsWith('>')) {
            const val = parseFloat(input.substring(1));
            return !isNaN(val) && value > val;
        }

        // Exact Match
        const val = parseFloat(input);
        if (!isNaN(val)) return value === val;

        return false;
    });
};

// Comprehensive Month Mapping (English + Spanish + Short/Full)
const MONTH_MAP: Record<string, string> = {
    // English Short
    'jan': 'Jan', 'feb': 'Feb', 'mar': 'Mar', 'apr': 'Apr', 'may': 'May', 'jun': 'Jun',
    'jul': 'Jul', 'aug': 'Aug', 'sep': 'Sep', 'oct': 'Oct', 'nov': 'Nov', 'dec': 'Dec',
    // Spanish Short
    'ene': 'Jan', 'abr': 'Apr', 'ago': 'Aug', 'dic': 'Dec', 'set': 'Sep',
    // Spanish Full
    'enero': 'Jan', 'febrero': 'Feb', 'marzo': 'Mar', 'abril': 'Apr', 'mayo': 'May', 'junio': 'Jun',
    'julio': 'Jul', 'agosto': 'Aug', 'septiembre': 'Sep', 'octubre': 'Oct', 'noviembre': 'Nov', 'diciembre': 'Dec',
    // English Full
    'january': 'Jan', 'february': 'Feb', 'march': 'Mar', 'april': 'Apr', 'june': 'Jun',
    'july': 'Jul', 'august': 'Aug', 'september': 'Sep', 'october': 'Oct', 'november': 'Nov', 'december': 'Dec'
};

// Robust Month Normalizer
const monthCache: Record<string, string> = {};

const normalizeMonth = (rawMonth: string): string => {
    if (!rawMonth) return '';
    if (monthCache[rawMonth]) return monthCache[rawMonth];

    let m = String(rawMonth).trim().toLowerCase();

    // 0. Check for Excel Serial Date (e.g. 45544 -> Sep)
    // 25569 is the offset days between Excel epoch (1899-12-30) and Unix epoch (1970-01-01)
    // We check if it's a number > 20000 (roughly year 1954+) to avoid confusion with valid days like "31"
    const potentialSerial = parseFloat(m);
    if (!isNaN(potentialSerial) && potentialSerial > 20000) {
        // Convert Excel serial to JS Date
        const date = new Date(Math.round((potentialSerial - 25569) * 86400 * 1000));
        if (!isNaN(date.getTime())) {
            return MONTH_ORDER[date.getMonth()];
        }
    }

    // 1. Direct Map Lookup (Handles "jan", "enero", "sep", etc.)
    if (MONTH_MAP[m]) {
        monthCache[rawMonth] = MONTH_MAP[m];
        return MONTH_MAP[m];
    }

    // 2. Handle numeric months "01", "1", "01-2023"
    // If it's a full date string like "2023-04-01" or "01/04/2023"
    if (m.includes('/') || m.includes('-')) {
        // Try parsing standard date
        const date = new Date(m);
        if (!isNaN(date.getTime())) {
            const monthIdx = date.getMonth();
            const yearShort = date.getFullYear().toString().slice(2);
            return `${MONTH_ORDER[monthIdx]}-${yearShort}`;
        }
    }

    const numMatch = m.match(/^(\d{1,2})([^\d]|$)/);
    if (numMatch) {
        const num = parseInt(numMatch[1]);
        if (num >= 1 && num <= 12) return MONTH_ORDER[num - 1];
    }

    // 3. Fallback: Extract first 3 letters and capitalize
    const alphaMatch = m.match(/([a-zA-Z\u00C0-\u00FF]+)/);
    if (alphaMatch) {
        let alpha = alphaMatch[1];
        if (alpha.length > 3) alpha = alpha.substring(0, 3);
        // Check map again with short version
        if (MONTH_MAP[alpha]) return MONTH_MAP[alpha];

        return alpha.charAt(0).toUpperCase() + alpha.slice(1);
    }

    // Try to grab year from original string to append (e.g. "Apr-23") if strict matching failed
    const yearMatch = rawMonth.match(/(\d{2,4})/);
    if (yearMatch) {
        let y = yearMatch[1];
        if (y.length === 4) y = y.slice(2);
        // This part is likely fallback for Sales Data records
        const letters = m.replace(/[^a-z]/g, '');
        if (letters && MONTH_MAP[letters]) {
            return `${MONTH_MAP[letters]}-${y}`;
        }
    }

    monthCache[rawMonth] = rawMonth;
    return rawMonth; // Return as-is if all else fails
};

// Robust CSV Column Value Extractor
const getColumnValue = (row: any, aliases: (string | RegExp)[]): string => {
    const rowKeys = Object.keys(row);
    const normalizedRowKeys: Record<string, string> = {};

    rowKeys.forEach(k => {
        // Normalize by removing all non-alphanumeric characters for a bulletproof exact match
        // e.g., "ACOS %" -> "acos", "Sales (30d)" -> "sales30d"
        const cleanKey = k.toLowerCase().replace(/[^a-z0-9]/g, '');
        normalizedRowKeys[cleanKey] = k;
    });

    for (const alias of aliases) {
        if (alias instanceof RegExp) {
            // Find the first original key that matches the regex
            const matchedKey = rowKeys.find(k => alias.test(k));
            if (matchedKey) {
                const val = row[matchedKey];
                if (val !== undefined && val !== null) {
                    const strVal = String(val).trim();
                    if (strVal.length > 0) return strVal;
                }
            }
        } else {
            const lookup = alias.toLowerCase().replace(/[^a-z0-9]/g, '');
            if (normalizedRowKeys[lookup]) {
                const actualKey = normalizedRowKeys[lookup];
                const val = row[actualKey];
                if (val !== undefined && val !== null) {
                    const strVal = String(val).trim();
                    if (strVal.length > 0) return strVal;
                }
            }
        }
    }
    return '';
};
// Allowed Customers Whitelist
export const PAN_EU_COUNTRIES = ['Amazon DE', 'Amazon IT', 'Amazon FR', 'Amazon ES'];
const ALLOWED_CUSTOMERS = [...PAN_EU_COUNTRIES, 'Amazon UK', 'Amazon SC'];

const isAllowedCustomer = (customer: string): boolean => {
    if (!customer) return false;
    const normCustomer = customer.trim().toLowerCase();
    return ALLOWED_CUSTOMERS.some(allowed => allowed.toLowerCase() === normCustomer);
};

// --- SALES / SELL OUT MAPPING ---

export const validateSellOutHeaders = (headers: string[]) => {
    const normHeaders = headers.map(h => String(h).trim().toLowerCase());

    const hasYear = normHeaders.includes('year');
    const hasTime = normHeaders.includes('month') || normHeaders.includes('week');
    const hasCustomerRef = normHeaders.includes('customer reference') || normHeaders.includes('asin');
    const hasEan = normHeaders.includes('ean');
    const hasUnits = normHeaders.includes('units');
    const hasAmount = normHeaders.includes('amount_eur') || normHeaders.includes('amount');

    const missing = [];
    if (!hasYear) missing.push('YEAR');
    if (!hasTime) missing.push('MONTH or WEEK');
    if (!hasCustomerRef) missing.push('CUSTOMER REFERENCE');
    if (!hasEan) missing.push('EAN');
    if (!hasUnits) missing.push('UNITS');
    if (!hasAmount) missing.push('AMOUNT_EUR');

    if (missing.length > 0) {
        throw new Error(`Invalid or missing critical columns in Sell-Out Report. Missing: ${missing.join(', ')}`);
    }
};

const mapRowToRecord = (row: any, index: number): SalesRecord => {
    // Add exact matches to the front of getColumnValue arrays
    const customer = getColumnValue(row, ['NEW CUSTOMER', 'COUNTRY', 'Customer', 'Client', 'Account', 'Partner', 'Country', 'Market']) || 'Unknown';
    const yearStr = getColumnValue(row, ['YEAR', 'Year', 'D']);
    // Sanitize year string before parsing (remove commas/dots e.g. "2,023")
    let year = parseInt(yearStr.replace(/[,.]/g, '')) || 0;
    const monthStr = getColumnValue(row, ['MONTH', 'Month', 'Period']);
    const month = normalizeMonth(monthStr);

    // BACKFILL YEAR if missing but present in Month (e.g. "Apr-23")
    if (year === 0 && month.includes('-')) {
        const parts = month.split('-');
        if (parts.length === 2) {
            const yPart = parts[1];
            // assume 20xx for 2 digits
            if (yPart.length === 2) year = 2000 + parseInt(yPart);
            else if (yPart.length === 4) year = parseInt(yPart);
        }
    }

    const weekStr = getColumnValue(row, ['WEEK', 'Week', 'CW', 'Semana', 'KW', 'E']);
    const weekNum = weekStr ? parseInt(weekStr.replace(/cw/i, '').trim(), 10) : NaN;
    const week = isNaN(weekNum) ? undefined : weekNum;
    const line = getColumnValue(row, ['PRODUCT LINE', 'Product Line', 'LINE', 'LICENSE', 'License']) || 'Unassigned';

    const asin = getColumnValue(row, [
        'CUSTOMER REFERENCE', 'AMAZON ASIN', 'ASIN', 'Asin', 'PRODUCT ID', 'ITEM IDENTIFIER', 'ASIN NO.', 'Product ASIN', 'IDENTIFIER'
    ]);

    const sku = getColumnValue(row, ['RAW ARTICLE NO.', 'SKU', 'Sku', 'Item No']);
    const title = getColumnValue(row, ['ARTICLE NAME (Customer)', 'ARTICLE NAME (Craze)', 'Title', 'TITLE', 'Product Title', 'Article Name']);
    const articleName = getColumnValue(row, ['ARTICLE NAME (Craze)', 'ARTICLE NAME (Customer)', 'Article Name', 'ArticleName', 'Title']);

    const unitsRaw = getColumnValue(row, ['UNITS', 'Units', 'Quantity', 'Qty']);
    const sellOutRaw = getColumnValue(row, ['AMOUNT_EUR', 'AMOUNT', 'Sell Out', 'SellOut', 'Revenue', 'Sales', 'Turnover']);

    return {
        id: `row-${index}`,
        customer,
        year,
        month,
        week,
        asin,
        sku,
        title,
        articleName,
        units: parseUnits(unitsRaw),
        sellOut: parseCurrency(sellOutRaw),
        line
    };
};

export const processCSV = (fileOrContent: File | string): Promise<SalesRecord[]> => {
    return new Promise((resolve, reject) => {
        // @ts-ignore
        Papa.parse(fileOrContent, {
            header: true,
            skipEmptyLines: true,
            complete: (results: any) => {
                try {
                    if (results.meta && results.meta.fields) {
                        validateSellOutHeaders(results.meta.fields);
                    } else if (results.data && results.data.length > 0) {
                        validateSellOutHeaders(Object.keys(results.data[0]));
                    }

                    const data: SalesRecord[] = results.data.map((row: any, index: number) => {
                        return mapRowToRecord(row, index);
                    })
                        // Filter: Valid Year > 2023 (exclude incomplete 2023 data) AND Allowed Customer
                        .filter((r: SalesRecord) => r.year > 2023 && isAllowedCustomer(r.customer));

                    resolve(data);
                } catch (err) {
                    reject(err);
                }
            },
            error: (error: any) => reject(error)
        });
    });
};

export const processExcel = async (file: File): Promise<SalesRecord[]> => {
    try {
        const arrayBuffer = await file.arrayBuffer();
        const workbook = XLSX.read(arrayBuffer);
        const firstSheetName = workbook.SheetNames[0];
        const worksheet = workbook.Sheets[firstSheetName];
        const jsonData = XLSX.utils.sheet_to_json(worksheet, { defval: "" });

        if (jsonData.length > 0) {
            validateSellOutHeaders(Object.keys(jsonData[0] as object));
        }

        const data: SalesRecord[] = jsonData.map((row: any, index: number) => {
            return mapRowToRecord(row, index);
        })
            // Filter: Valid Year AND Allowed Customer
            .filter((r: SalesRecord) => r.year > 0 && isAllowedCustomer(r.customer));

        return data;
    } catch (error) {
        console.error("Error processing Excel file:", error);
        throw error;
    }
}

// --- ADS DATA MAPPING ---

const mapCountryToMarketplace = (country: string): string => {
    const c = String(country).toLowerCase().trim();
    if (c.includes('germany') || c.includes('deutschland') || c.includes('de')) return 'Amazon DE';
    if (c.includes('spain') || c.includes('espana') || c.includes('españa') || c.includes('es')) return 'Amazon ES';
    if (c.includes('france') || c.includes('fr')) return 'Amazon FR';
    if (c.includes('italy') || c.includes('italia') || c.includes('it')) return 'Amazon IT';
    if (c.includes('kingdom') || c.includes('uk') || c === 'gb') return 'Amazon UK';
    if (c.includes('netherlands') || c.includes('nederland') || c.includes('holland') || c.includes('nl')) return 'Amazon NL';
    return country.toUpperCase(); // Fallback
};

export const processAdsCSV = (file: File): Promise<AdsRecord[]> => {
    return new Promise((resolve, reject) => {
        // @ts-ignore
        Papa.parse(file, {
            header: true,
            skipEmptyLines: true,
            complete: (results: any) => {
                try {
                    const data: AdsRecord[] = [];
                    const rows = results.data;
                    const len = rows.length;

                    for (let i = 0; i < len; i++) {
                        const row = rows[i];
                        if (!row || Object.keys(row).length < 5) continue;

                        const countryRaw = getColumnValue(row, ['country', 'marketplace', 'portfolio', 'customer', 'kunde']);
                        const weekRaw = getColumnValue(row, ['week', 'woche', 'semana']);
                        const asin = getColumnValue(row, ['asin']);
                        const costRaw = getColumnValue(row, ['cost', 'spend', 'ausgaben', 'gasto', 'coste', /ad\s*spend/i, /^cost$/i, /^spend$/i, /(?<!of\s)cost(?!\s*of)/i]);
                        const clicksRaw = getColumnValue(row, ['clicks', 'klicks', 'clics', /click/i]);
                        const impressionsRaw = getColumnValue(row, ['impressions', 'impresiones', 'imp', /impression/i]);
                        const cpcRaw = getColumnValue(row, ['cpc', 'cost-per-click', 'coste por clic', /cost.*per.*click/i, /cpc/i]);
                        const ctrRaw = getColumnValue(row, ['ctr', 'click-through rate', 'click-through-rate', 'click through rate', /click.*through.*rate/i, /ctr/i]);
                        const acosRaw = getColumnValue(row, ['acos', 'advertising cost of sales', 'aCOS', /cost.*of.*sales/i, /acos/i]);
                        const conversionsRaw = getColumnValue(row, ['conversions', 'konversionen', 'orders', 'pedidos', 'total orders', /order/i, /conversion/i]);
                        const unitsRaw = getColumnValue(row, ['units', 'einheiten', 'unidades', 'units sold', 'total units', /\d+\s*day.*unit/i, /unit.*within.*\d+\s*day/i, /total\s+unit/i, /units?\s*sold/i, /^units?$/i, /unit/i, /einheit/i, /unidad/i]);
                        const salesRaw = getColumnValue(row, ['sales', 'umsatz', 'ventas', 'ad sales', 'total sales', 'sales (30d)', /\d+\s*day.*sale/i, /sale.*within.*\d+\s*day/i, /total\s+sale/i, /attributed.*sale/i, /ad\s+sale/i, /^sales$/i, /(?<!cost of )sale/i, /umsatz/i, /ventas/i]);

                        if (!asin || !countryRaw || weekRaw === undefined || weekRaw === '') continue;

                        const weekMatch = String(weekRaw).match(/\d+/);
                        const weekNum = weekMatch ? parseInt(weekMatch[0], 10) : NaN;
                        if (isNaN(weekNum) || weekNum < 1 || weekNum > 53) continue;

                        // For CSV without sheet names, assume current year
                        const currentYear = new Date().getFullYear();

                        data.push({
                            country: mapCountryToMarketplace(String(countryRaw)),
                            year: currentYear,
                            week: weekNum,
                            asin: String(asin).trim(),
                            cost: parseCurrency(String(costRaw)),
                            clicks: parseUnits(String(clicksRaw)),
                            impressions: parseUnits(String(impressionsRaw)),
                            cpc: parseCurrency(String(cpcRaw)),
                            ctr: parseCurrency(String(ctrRaw)),
                            acos: parseCurrency(String(acosRaw)),
                            conversions: parseUnits(String(conversionsRaw)),
                            attributedUnits30d: parseUnits(String(unitsRaw)),
                            attributedSales30d: parseCurrency(String(salesRaw)),
                        });
                    }
                    resolve(data);
                } catch (err) {
                    reject(err);
                }
            },
            error: (error: any) => reject(error)
        });
    });
};

export const processAdsExcel = async (fileOrBuffer: File | ArrayBuffer): Promise<AdsRecord[]> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });
        const allData: AdsRecord[] = [];

        // Process ALL sheets (e.g., "2025", "2026")
        for (const sheetName of workbook.SheetNames) {
            const year = parseInt(sheetName);
            if (isNaN(year) || year < 2020 || year > 2100) {
                console.warn(`Skipping sheet "${sheetName}" - not a valid year`);
                continue;
            }

            const worksheet = workbook.Sheets[sheetName];
            // Use default format (header mapping) instead of array rows
            const jsonData: any[] = XLSX.utils.sheet_to_json(worksheet, { defval: "" });

            console.log(`Processing sheet ${sheetName}: ${jsonData.length} rows`);

            // Log column headers for first row to diagnose column matching
            if (jsonData.length > 0) {
                console.log(`[Ads Excel] Sheet "${sheetName}" columns: ${Object.keys(jsonData[0]).join(' | ')}`);
            }

            // No need to skip index 0 since headers are mapped as keys automatically
            for (let i = 0; i < jsonData.length; i++) {
                const row = jsonData[i];
                if (!row || Object.keys(row).length < 5) continue;

                const countryRaw = getColumnValue(row, ['country', 'marketplace', 'portfolio', 'customer', 'kunde']);
                const weekRaw = getColumnValue(row, ['week', 'woche', 'semana']);
                const asin = getColumnValue(row, ['asin']);
                const costRaw = getColumnValue(row, ['cost', 'spend', 'ausgaben', 'gasto', 'coste', /ad\s*spend/i, /^cost$/i, /^spend$/i, /(?<!of\s)cost(?!\s*of)/i]);
                const clicksRaw = getColumnValue(row, ['clicks', 'klicks', 'clics', /click/i]);
                const impressionsRaw = getColumnValue(row, ['impressions', 'impresiones', 'imp', /impression/i]);
                const cpcRaw = getColumnValue(row, ['cpc', 'cost-per-click', 'coste por clic', /cost.*per.*click/i, /cpc/i]);
                const ctrRaw = getColumnValue(row, ['ctr', 'click-through rate', 'click-through-rate', 'click through rate', /click.*through.*rate/i, /ctr/i]);
                const acosRaw = getColumnValue(row, ['acos', 'advertising cost of sales', 'aCOS', /cost.*of.*sales/i, /acos/i]);
                const conversionsRaw = getColumnValue(row, ['conversions', 'konversionen', 'orders', 'pedidos', 'total orders', /order/i, /conversion/i]);
                const unitsRaw = getColumnValue(row, ['units', 'einheiten', 'unidades', 'units sold', 'total units', /\d+\s*day.*unit/i, /unit.*within.*\d+\s*day/i, /total\s+unit/i, /units?\s*sold/i, /^units?$/i, /unit/i, /einheit/i, /unidad/i]);
                const salesRaw = getColumnValue(row, ['sales', 'umsatz', 'ventas', 'ad sales', 'total sales', 'sales (30d)', /\d+\s*day.*sale/i, /sale.*within.*\d+\s*day/i, /total\s+sale/i, /attributed.*sale/i, /ad\s+sale/i, /^sales$/i, /(?<!cost of )sale/i, /umsatz/i, /ventas/i]);

                // Skip if missing essential data
                if (!asin || !countryRaw || weekRaw === undefined || weekRaw === '') continue;

                const weekMatch = String(weekRaw).match(/\d+/);
                const weekNum = weekMatch ? parseInt(weekMatch[0], 10) : NaN;
                if (isNaN(weekNum) || weekNum < 1 || weekNum > 53) continue;

                // Log first parsed row per sheet for column match diagnosis
                if (allData.length === 0 || (allData.length > 0 && allData[allData.length - 1]?.year !== year)) {
                    console.log(`[Ads Excel] First row sheet ${year}: costRaw="${costRaw}" salesRaw="${salesRaw}" unitsRaw="${unitsRaw}" acosRaw="${acosRaw}"`);
                }

                allData.push({
                    country: mapCountryToMarketplace(String(countryRaw)),
                    year,
                    week: weekNum,
                    asin: String(asin).trim(),
                    cost: parseCurrency(String(costRaw)),
                    clicks: parseUnits(String(clicksRaw)),
                    impressions: parseUnits(String(impressionsRaw)),
                    cpc: parseCurrency(String(cpcRaw)),
                    ctr: parseCurrency(String(ctrRaw)),
                    acos: parseCurrency(String(acosRaw)),
                    conversions: parseUnits(String(conversionsRaw)),
                    attributedUnits30d: parseUnits(String(unitsRaw)),
                    attributedSales30d: parseCurrency(String(salesRaw)),
                });
            }
        }

        console.log(`Total Ads records loaded: ${allData.length}`);
        return allData;
    } catch (error) {
        console.error("Error processing Ads Excel:", error);
        throw error;
    }
};

// --- TRAFFIC DATA PARSING ---

export const processTrafficExcel = async (fileOrBuffer: File | ArrayBuffer): Promise<TrafficRecord[]> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });
        const allData: TrafficRecord[] = [];

        // Process ALL sheets (e.g., "2025", "2026") - same pattern as processAdsExcel
        for (const sheetName of workbook.SheetNames) {
            const worksheet = workbook.Sheets[sheetName];
            const jsonData: any[][] = XLSX.utils.sheet_to_json(worksheet, { header: 1, defval: "" });

            console.log(`Processing Traffic sheet "${sheetName}": ${jsonData.length} rows`);

            // Detect if sheet name is a valid year (multi-sheet format)
            const sheetYear = parseInt(sheetName);
            const isYearSheet = !isNaN(sheetYear) && sheetYear >= 2020 && sheetYear <= 2100;

            // Auto-detect column layout from header row
            const headerRow = jsonData[0];
            if (!headerRow) continue;

            const headers = headerRow.map((h: any) => String(h).trim().toLowerCase());
            let yearIdx = headers.findIndex((h: string) => h === 'year' || h === 'año');
            let weekIdx = headers.findIndex((h: string) => h === 'week' || h === 'semana');
            let asinIdx = headers.findIndex((h: string) => h === 'asin');
            let countryIdx = headers.findIndex((h: string) => h === 'country' || h === 'país' || h === 'pais' || h === 'marketplace' || h === 'store code');
            let gvIdx = headers.findIndex((h: string) => h.includes('glance') || h === 'gv' || h.includes('page view') || h === 'featured offer page views');

            // Fallback to positional mapping if headers not found
            if (asinIdx === -1 || countryIdx === -1 || gvIdx === -1) {
                if (isYearSheet) {
                    // Year-based sheets: no year column
                    weekIdx = 0; asinIdx = 1; countryIdx = 4; gvIdx = 5; yearIdx = -1;
                } else {
                    // Single sheet with year column
                    yearIdx = 0; weekIdx = 1; asinIdx = 2; countryIdx = 5; gvIdx = 6;
                }
            }

            const minCols = Math.max(asinIdx, countryIdx, gvIdx) + 1;

            for (let i = 1; i < jsonData.length; i++) {
                const row = jsonData[i];
                if (!row || row.length < minCols) continue;

                const yearRaw = isYearSheet ? sheetYear : (yearIdx >= 0 ? row[yearIdx] : undefined);
                const weekRaw = weekIdx >= 0 ? row[weekIdx] : undefined;
                const asin = row[asinIdx];
                const countryRaw = row[countryIdx];
                const gvRaw = row[gvIdx];

                if (!asin || yearRaw === undefined || weekRaw === undefined || !countryRaw) continue;

                const year = typeof yearRaw === 'number' ? yearRaw : parseInt(String(yearRaw));
                const weekMatch = String(weekRaw).match(/\d+/);
                const weekNum = weekMatch ? parseInt(weekMatch[0], 10) : NaN;
                if (isNaN(year) || year < 2020 || year > 2100) continue;
                if (isNaN(weekNum) || weekNum < 1 || weekNum > 53) continue;

                allData.push({
                    country: mapCountryToMarketplace(String(countryRaw)),
                    year,
                    week: weekNum,
                    asin: String(asin).trim().toUpperCase(),
                    glanceViews: parseUnits(String(gvRaw)),
                });
            }
        }

        console.log(`Total Traffic records loaded: ${allData.length}`);
        return allData;
    } catch (error) {
        console.error("Error processing Traffic Excel:", error);
        throw error;
    }
};

// --- DATA MERGING ---

export const mergeSalesAndAdsData = (
    salesData: SalesRecord[],
    adsData: AdsRecord[],
    asinMetadataMap?: Map<string, { sku: string; title: string; line: string }>,
    trafficData?: TrafficRecord[],
    velocityMap?: Map<string, number>
): CombinedKPIs[] => {
    const stringCache: Record<string, string> = {};
    const getNorm = (s: string) => {
        if (!s) return '';
        if (stringCache[s]) return stringCache[s];
        const v = s.trim().toUpperCase();
        stringCache[s] = v;
        return v;
    };

    // Key for both sales and ads: ASIN|Customer|Year|Week
    const createKey = (asin: string, customer: string, year: number, week: number) =>
        `${getNorm(asin)}|${getNorm(customer)}|${year}|${week}`;

    // Build traffic lookup map - Use a more efficient key
    const trafficMap = new Map<string, number>();
    if (trafficData) {
        for (let i = 0; i < trafficData.length; i++) {
            const t = trafficData[i];
            const key = `${getNorm(t.asin)}|${getNorm(t.country)}|${t.year}|${t.week}`;
            trafficMap.set(key, (trafficMap.get(key) || 0) + (t.glanceViews || 0));
        }
    }

    // 1. Initialize metadata lookup map with provided global map if available, otherwise build from current sales
    const asinMetadata = asinMetadataMap || new Map<string, { sku: string; title: string; line: string }>();

    // 2. Aggregate Sales by ASIN|Customer|Year|Week (combine all SKUs)
    const salesMap = new Map<string, {
        sellOut: number;
        units: number;
        sku: string;
        title: string;
        line: string;
        asin: string;
        customer: string;
        year: number;
        week: number;
        month: string;
    }>();

    for (let i = 0; i < salesData.length; i++) {
        const sale = salesData[i];
        const weekNum = sale.week || 0;
        if (weekNum === 0) continue;

        const asinUpper = getNorm(sale.asin);
        const key = `${asinUpper}|${getNorm(sale.customer)}|${sale.year}|${weekNum}`;

        // If no global map provided, build it on the fly
        if (!asinMetadataMap) {
            const existingMeta = asinMetadata.get(asinUpper);
            if (!existingMeta || (sale.title && sale.title.length > (existingMeta.title?.length || 0))) {
                asinMetadata.set(asinUpper, { sku: sale.sku, title: sale.title, line: sale.line });
            }
        }

        const existing = salesMap.get(key);
        if (existing) {
            existing.sellOut += sale.sellOut;
            existing.units += sale.units;
            if (sale.title && sale.title.length > (existing.title?.length || 0)) {
                existing.title = sale.title;
            }
            if (sale.sku && !existing.sku) {
                existing.sku = sale.sku;
            }
        } else {
            salesMap.set(key, {
                sellOut: sale.sellOut,
                units: sale.units,
                sku: sale.sku,
                title: sale.title,
                line: sale.line,
                asin: sale.asin,
                customer: sale.customer,
                year: sale.year,
                week: weekNum,
                month: sale.month
            });
        }
    }

    // 3. Aggregate Ads by ASIN|Customer|Year|Week
    const adsMap = new Map<string, AdsRecord>();
    for (let i = 0; i < adsData.length; i++) {
        const ad = adsData[i];
        const key = `${getNorm(ad.asin)}|${getNorm(ad.country)}|${ad.year}|${ad.week}`;
        const existing = adsMap.get(key);
        if (existing) {
            existing.cost += ad.cost;
            existing.clicks += ad.clicks;
            existing.impressions += ad.impressions;
            existing.attributedSales30d += ad.attributedSales30d;
            existing.attributedUnits30d += ad.attributedUnits30d;
            existing.conversions += ad.conversions;
        } else {
            adsMap.set(key, { ...ad });
        }
    }

    const mergedData: CombinedKPIs[] = [];
    const processedKeys = new Set<string>();

    // 4. Create ONE record per ASIN/Customer/Year/Week from sales
    salesMap.forEach((sale, key) => {
        processedKeys.add(key);
        const ad = adsMap.get(key);

        const adCost = ad?.cost || 0;
        const adClicks = ad?.clicks || 0;
        const adImpressions = ad?.impressions || 0;
        const adSales = ad?.attributedSales30d || 0;
        const adUnits = ad?.attributedUnits30d || 0;

        const salesTotal = sale.sellOut;
        const unitsTotal = sale.units;
        const salesOrganic = Math.max(0, salesTotal - adSales);
        const unitsOrganic = Math.max(0, unitsTotal - adUnits);

        const acos = adSales > 0 ? (adCost / adSales) * 100 : 0;
        const tacos = salesTotal > 0 ? (adCost / salesTotal) * 100 : 0;
        const roas = adCost > 0 ? adSales / adCost : 0;
        const ctr = adImpressions > 0 ? (adClicks / adImpressions) * 100 : 0;
        const cpc = adClicks > 0 ? adCost / adClicks : 0;
        const cvrUnits = adClicks > 0 ? (adUnits / adClicks) * 100 : 0;
        const avgWeeklySales = velocityMap?.get(sale.asin.trim().toUpperCase()) || 0;

        mergedData.push({
            id: `merged-${key}`,
            marketplace: sale.customer,
            customer: sale.customer,
            month: sale.month,
            week: sale.week,
            year: sale.year,
            asin: getNorm(sale.asin),
            title: sale.title,
            line: sale.line,
            sku: sale.sku,
            salesTotal,
            unitsTotal,
            salesAds: adSales,
            unitsAds: adUnits,
            cost: adCost,
            clicks: adClicks,
            impressions: adImpressions,
            conversions: ad?.conversions || 0,
            salesOrganic,
            unitsOrganic,
            paidSalesShare: salesTotal > 0 ? (adSales / salesTotal) * 100 : 0,
            organicSalesShare: salesTotal > 0 ? (salesOrganic / salesTotal) * 100 : 0,
            acos,
            tacos,
            roas,
            ctr,
            cpc,
            cvrUnits,
            glanceViews: trafficMap.get(key) || 0,
            avgWeeklySales
        });
    });

    // 5. Add ads-only records - use provided metadata for line/title
    adsMap.forEach((ad, key) => {
        if (!processedKeys.has(key)) {
            const asin = getNorm(ad.asin);
            const meta = asinMetadata.get(asin);
            const avgWeeklySales = velocityMap?.get(asin) || 0;

            mergedData.push({
                id: `ads-only-${key}`,
                marketplace: ad.country,
                customer: ad.country,
                month: 'N/A',
                week: ad.week,
                year: ad.year,
                asin: asin,
                title: meta?.title || ad.asin,
                line: meta?.line || 'Unassigned',
                sku: meta?.sku || '',
                salesTotal: 0,
                unitsTotal: 0,
                salesAds: ad.attributedSales30d || 0,
                unitsAds: ad.attributedUnits30d || 0,
                cost: ad.cost || 0,
                clicks: ad.clicks || 0,
                impressions: ad.impressions || 0,
                conversions: ad.conversions || 0,
                salesOrganic: 0,
                unitsOrganic: 0,
                paidSalesShare: 0,
                organicSalesShare: 0,
                acos: ad.attributedSales30d > 0 ? (ad.cost / ad.attributedSales30d) * 100 : 0,
                tacos: 0,
                roas: ad.cost > 0 ? ad.attributedSales30d / ad.cost : 0,
                ctr: ad.impressions > 0 ? (ad.clicks / ad.impressions) * 100 : 0,
                cpc: ad.clicks > 0 ? ad.cost / ad.clicks : 0,
                cvrUnits: ad.clicks > 0 ? (ad.attributedUnits30d / ad.clicks) * 100 : 0,
                glanceViews: trafficMap.get(key) || 0,
                avgWeeklySales
            });
        }
    });

    return mergedData;
};



// --- EXISTING HELPERS ---

// Helper to check stock filter
const checkStockFilter = (sku: string, filters: string[], stockMap?: Map<string, number>): boolean => {
    if (!filters || !Array.isArray(filters) || filters.length === 0) return true;
    if (!stockMap) return true;

    // Normalize SKU (remove DE/EN) to match stock map
    const baseSku = sku?.replace(/(DE|EN)$/i, '');
    const stockValue = stockMap.get(baseSku) || 0;

    return checkNumericConditions(stockValue, filters);
};

const checkVendorStockFilter = (asin: string, filters: string[], vendorStockMap?: Map<string, { eu: number; uk: number }>, mode: 'eu' | 'uk' = 'eu'): boolean => {
    if (!filters || !Array.isArray(filters) || filters.length === 0) return true;
    if (!vendorStockMap) return true;

    const data = vendorStockMap.get(asin);
    const stockValue = data ? (mode === 'uk' ? data.uk : data.eu) : 0;

    return checkNumericConditions(stockValue, filters);
};

// Filter Ads Data by Country, Year, Week, ASIN, SKU, and Product Line
export const filterAdsData = (
    adsData: AdsRecord[],
    filters: FilterState,
    asinMetadata?: Map<string, { sku: string; line: string }>,
    stockMap?: Map<string, number>,
    vendorStockMap?: Map<string, { eu: number; uk: number }>,
    top50Mode: 'eu' | 'uk' = 'eu'
): AdsRecord[] => {
    return adsData.filter(ad => {
        const asin = ad.asin.trim().toUpperCase();
        const meta = asinMetadata?.get(asin);

        // Country/Customer match (ads use 'country', sales use 'customer')
        const countryMatch = filters.customer.length === 0
            ? PAN_EU_COUNTRIES.some(c => c.toUpperCase() === ad.country.toUpperCase())
            : filters.customer.some(c => c.toUpperCase() === ad.country.toUpperCase());

        // Year match
        const yearMatch = filters.year.length === 0 ||
            filters.year.includes(ad.year.toString());

        // Week match (filters use "W1", "W2" format)
        const weekStr = `W${ad.week}`;
        const weekMatch = filters.week.length === 0 || filters.week.includes(weekStr);

        // ASIN match
        const asinMatch = filters.asin.length === 0 ||
            filters.asin.some(a => a.toUpperCase() === asin);

        // SKU match (Requires metadata)
        let skuMatch = true;
        if (filters.sku.length > 0) {
            skuMatch = meta ? filters.sku.some(s => s.toUpperCase() === meta.sku.toUpperCase()) : false;
        }

        // Line match (Requires metadata)
        let lineMatch = true;
        if (filters.line.length > 0) {
            lineMatch = meta ? filters.line.includes(meta.line) : false;
        }

        // Stock match
        const stockMatch = checkStockFilter(meta?.sku || '', filters.stock, stockMap);
        const vendorStockMatch = checkVendorStockFilter(asin, filters.vendorStock, vendorStockMap, top50Mode);

        // Bulk Search Logic
        let bulkMatch = true;
        if (filters.bulkSearch && filters.bulkSearch.trim()) {
            const searchTerms = filters.bulkSearch
                .split(/[\s,\n]+/)
                .map(t => t.trim().toUpperCase())
                .filter(t => t.length > 0);

            if (searchTerms.length > 0) {
                const itemAsin = (asin || '').toUpperCase();
                const itemSku = (meta?.sku || '').toUpperCase();
                bulkMatch = searchTerms.some(term =>
                    itemAsin.includes(term) || itemSku.includes(term)
                );
            }
        }

        return countryMatch && yearMatch && weekMatch && asinMatch && skuMatch && lineMatch && stockMatch && vendorStockMatch && bulkMatch;
    });
};

export const filterData = (
    data: SalesRecord[],
    filters: FilterState,
    stockMap?: Map<string, number>,
    vendorStockMap?: Map<string, { eu: number; uk: number }>,
    top50Mode: 'eu' | 'uk' = 'eu'
): SalesRecord[] => {
    let result = data; // Changed from rawData to data

    // 1. Column Filters (Excel-style)
    if (filters.columnFilters) {
        Object.entries(filters.columnFilters).forEach(([key, condition]) => {
            if (!condition) return;

            // Apply selected values filter
            if (condition.selectedValues && condition.selectedValues.length > 0) {
                result = result.filter(r => {
                    const val = String((r as any)[key] || '');
                    return condition.selectedValues?.includes(val);
                });
            }

            // Apply text condition filter
            if (condition.textFilter) {
                const { operator, value } = condition.textFilter;
                const lowerValue = value.toLowerCase();

                result = result.filter(r => {
                    const rowVal = String((r as any)[key] || '').toLowerCase();
                    switch (operator) {
                        case 'equals': return rowVal === lowerValue;
                        case 'notEquals': return rowVal !== lowerValue;
                        case 'contains': return rowVal.includes(lowerValue);
                        case 'notContains': return !rowVal.includes(lowerValue);
                        case 'startsWith': return rowVal.startsWith(lowerValue);
                        case 'notStartsWith': return !rowVal.startsWith(lowerValue);
                        case 'endsWith': return rowVal.endsWith(lowerValue);
                        case 'notEndsWith': return !rowVal.endsWith(lowerValue);
                        default: return true;
                    }
                });
            }
        });
    }

    // 2. Standard Filters
    return result.filter(item => { // Apply remaining filters to the 'result'
        // 1. Month Logic: Handle "Apr-23" matching "Apr" filter
        const recordMonth = item.month; // e.g. "Apr-23"
        const pureMonth = recordMonth.split('-')[0]; // "Apr"

        // 2. Filter Checks
        const customerMatch = filters.customer.length === 0
            ? (PAN_EU_COUNTRIES.includes(item.customer) || item.customer === 'Pan-EU')
            : filters.customer.includes(item.customer);
        const yearMatch = filters.year.length === 0 || filters.year.includes(item.year.toString());

        // Check match against pure month ("Apr") OR full month ("Apr-23") just in case filters evolve
        const monthMatch = filters.month.length === 0 || filters.month.includes(pureMonth) || filters.month.includes(recordMonth);

        const lineMatch = filters.line.length === 0 || filters.line.includes(item.line);
        const asinMatch = filters.asin.length === 0 || filters.asin.includes(item.asin);
        const skuMatch = filters.sku.length === 0 || filters.sku.includes(item.sku);
        const titleMatch = filters.title.length === 0 || filters.title.includes(item.title);

        // Bulk Search Logic
        let bulkMatch = true;
        if (filters.bulkSearch && filters.bulkSearch.trim()) {
            const searchTerms = filters.bulkSearch
                .split(/[\s,\n]+/)
                .map(t => t.trim().toUpperCase())
                .filter(t => t.length > 0);

            if (searchTerms.length > 0) {
                const itemAsin = (item.asin || '').toUpperCase();
                const itemSku = (item.sku || '').toUpperCase();
                bulkMatch = searchTerms.some(term =>
                    itemAsin.includes(term) || itemSku.includes(term)
                );
            }
        }

        // Week Logic: Match "W1", "W2" etc.
        // item.week is a number (e.g. 1), filter uses strings "W1"
        const weekStr = item.week ? `W${item.week}` : '';
        const weekMatch = filters.week.length === 0 || (weekStr !== '' && filters.week.includes(weekStr));

        // Stock match
        const stockMatch = checkStockFilter(item.sku, filters.stock, stockMap);
        const vendorStockMatch = checkVendorStockFilter(item.asin, filters.vendorStock, vendorStockMap, top50Mode);

        return customerMatch && yearMatch && monthMatch && lineMatch && asinMatch && skuMatch && titleMatch && bulkMatch && weekMatch && stockMatch && vendorStockMatch;
    });
};

const calculateSeasonality = (data: SalesRecord[]): { seasonality: SeasonalityPoint[], seasonalityUnits: SeasonalityPoint[], years: string[] } => {
    const seasonalityMap = new Map<string, SeasonalityPoint>();
    const seasonalityUnitsMap = new Map<string, SeasonalityPoint>();
    const yearsSet = new Set<string>();

    // Initialize all months
    MONTH_ORDER.forEach(m => {
        seasonalityMap.set(m, { name: m });
        seasonalityUnitsMap.set(m, { name: m });
    });

    data.forEach(record => {
        const monthName = record.month;
        // Extract year from record.month if it's in Format "Mon-YY", else use record.year
        // record.year is numeric, record.month is "Apr-23".
        const yearStr = record.year.toString();
        yearsSet.add(yearStr);

        // We need to match month name purely (Jan, Feb) for the X Axis, ignoring year
        const pureMonth = monthName.split('-')[0];

        if (seasonalityMap.has(pureMonth)) {
            // Sell Out
            const entrySO = seasonalityMap.get(pureMonth)!;
            const currentValSO = (entrySO[yearStr] as number) || 0;
            entrySO[yearStr] = currentValSO + record.sellOut;

            // Units
            const entryUnits = seasonalityUnitsMap.get(pureMonth)!;
            const currentValUnits = (entryUnits[yearStr] as number) || 0;
            entryUnits[yearStr] = currentValUnits + record.units;
        }
    });

    const seasonality = Array.from(seasonalityMap.values());
    const seasonalityUnits = Array.from(seasonalityUnitsMap.values());
    const years = Array.from(yearsSet).sort();

    return { seasonality, seasonalityUnits, years };
};

const calculateTopLinesSplit = (data: SalesRecord[]): YearlySplitData[] => {
    // 1. Identify Lines by Sell Out (Sort desc)
    const lineTotals = new Map<string, number>();
    data.forEach(item => {
        lineTotals.set(item.line, (lineTotals.get(item.line) || 0) + item.sellOut);
    });

    // Return ALL lines
    const topLines = Array.from(lineTotals.entries())
        .sort((a, b) => b[1] - a[1])
        .map(([line]) => line);

    // 2. Aggregate data by Year
    const resultMap = new Map<string, YearlySplitData>();

    topLines.forEach(line => {
        resultMap.set(line, { name: line });
    });

    data.forEach(item => {
        if (resultMap.has(item.line)) {
            const entry = resultMap.get(item.line)!;
            const keyVal = `${item.year}_value`;
            const keyUnits = `${item.year}_units`;

            entry[keyVal] = ((entry[keyVal] as number) || 0) + item.sellOut;
            entry[keyUnits] = ((entry[keyUnits] as number) || 0) + item.units;
        }
    });

    return Array.from(resultMap.values());
};

const calculateGenericSplit = (data: SalesRecord[], groupField: keyof SalesRecord, valueField: 'sellOut' | 'units', limit?: number): YearlySplitData[] => {
    const totals = new Map<string, number>();
    data.forEach(item => {
        const key = String(item[groupField]);
        totals.set(key, (totals.get(key) || 0) + item[valueField]);
    });

    let sortedKeys = Array.from(totals.entries()).sort((a, b) => b[1] - a[1]).map(e => e[0]);
    if (limit) sortedKeys = sortedKeys.slice(0, limit);
    const keySet = new Set(sortedKeys);

    const resultMap = new Map<string, YearlySplitData>();
    sortedKeys.forEach(k => resultMap.set(k, { name: k }));

    data.forEach(item => {
        const key = String(item[groupField]);
        if (keySet.has(key)) {
            const entry = resultMap.get(key)!;
            const yearKey = item.year.toString();
            entry[yearKey] = ((entry[yearKey] as number) || 0) + item[valueField];
        }
    });

    return Array.from(resultMap.values());
};

// Renamed from calculateMovers
export const calculateLineMovers = (data: SalesRecord[]): { topMovers: LineGrowthMetric[], bottomMovers: LineGrowthMetric[], comparisonPeriods: { current: string, previous: string } } => {
    const lineYearMap = new Map<string, Map<number, { sellOut: number; units: number }>>();
    const allYears = new Set<number>();

    data.forEach(item => {
        if (!lineYearMap.has(item.line)) {
            lineYearMap.set(item.line, new Map());
        }
        const yearMap = lineYearMap.get(item.line)!;
        const current = yearMap.get(item.year) || { sellOut: 0, units: 0 };
        yearMap.set(item.year, {
            sellOut: current.sellOut + item.sellOut,
            units: current.units + item.units
        });
        allYears.add(item.year);
    });

    const sortedYears = Array.from(allYears).sort((a, b) => b - a);

    if (sortedYears.length < 2) {
        return { topMovers: [], bottomMovers: [], comparisonPeriods: { current: 'N/A', previous: 'N/A' } };
    }

    const currentYear = sortedYears[0];
    const prevYear = sortedYears[1];

    const metrics: LineGrowthMetric[] = [];

    lineYearMap.forEach((yearMap, line) => {
        const currData = yearMap.get(currentYear) || { sellOut: 0, units: 0 };
        const prevData = yearMap.get(prevYear) || { sellOut: 0, units: 0 };

        // Sell Out Growth
        let sellOutGrowthValue = 0;
        let sellOutGrowthPercentage = 0;
        if (prevData.sellOut > 0) {
            sellOutGrowthValue = currData.sellOut - prevData.sellOut;
            sellOutGrowthPercentage = (sellOutGrowthValue / prevData.sellOut) * 100;
        } else if (currData.sellOut > 0) {
            sellOutGrowthValue = currData.sellOut;
            sellOutGrowthPercentage = 100;
        } else if (currData.sellOut === 0 && prevData.sellOut > 0) {
            sellOutGrowthValue = -prevData.sellOut;
            sellOutGrowthPercentage = -100;
        }

        // Unit Growth
        let unitsGrowthValue = 0;
        let unitsGrowthPercentage = 0;
        if (prevData.units > 0) {
            unitsGrowthValue = currData.units - prevData.units;
            unitsGrowthPercentage = (unitsGrowthValue / prevData.units) * 100;
        } else if (currData.units > 0) {
            unitsGrowthValue = currData.units;
            unitsGrowthPercentage = 100;
        } else if (currData.units === 0 && prevData.units > 0) {
            unitsGrowthValue = -prevData.units;
            unitsGrowthPercentage = -100;
        }

        if (currData.sellOut > 0 || prevData.sellOut > 0) {
            metrics.push({
                line,
                currentYearSellOut: currData.sellOut,
                previousYearSellOut: prevData.sellOut,
                sellOutGrowthValue,
                sellOutGrowthPercentage,
                currentYearUnits: currData.units,
                previousYearUnits: prevData.units,
                unitsGrowthValue,
                unitsGrowthPercentage
            });
        }
    });

    const topMovers = metrics
        .filter(m => m.sellOutGrowthValue > 0)
        .sort((a, b) => b.sellOutGrowthValue - a.sellOutGrowthValue);

    const bottomMovers = metrics
        .filter(m => m.sellOutGrowthValue < 0)
        .sort((a, b) => a.sellOutGrowthValue - b.sellOutGrowthValue);

    return {
        topMovers,
        bottomMovers,
        comparisonPeriods: { current: currentYear.toString(), previous: prevYear.toString() }
    };
};


const createItemKey = (record: SalesRecord) => {
    // A robust key combining all identifiers
    return `${record.sku || 'NO_SKU'}||${record.asin || 'NO_ASIN'}||${record.title || 'NO_TITLE'}`;
}

export const calculateItemMovers = (
    currentFilteredData: SalesRecord[],
    selectedCustomerFromPage: string | null,
    currentComparisonYearFromPage: number | null
): { topMovers: ItemGrowthMetric[], bottomMovers: ItemGrowthMetric[], comparisonPeriods: { current: string, previous: string } } => {

    let dataToProcess = currentFilteredData;

    // Apply customer filter if selected on the Top Movers page
    if (selectedCustomerFromPage) {
        dataToProcess = dataToProcess.filter(item => item.customer === selectedCustomerFromPage);
    }

    if (dataToProcess.length === 0) {
        return { topMovers: [], bottomMovers: [], comparisonPeriods: { current: 'N/A', previous: 'N/A' } };
    }

    // Map to store item data aggregated by year
    const itemYearMap = new Map<string, Map<number, { sellOut: number; units: number, sku: string, asin: string, title: string, line: string }>>();
    const allYearsInFilteredData = new Set<number>();

    dataToProcess.forEach(item => {
        const itemKey = createItemKey(item);
        if (!itemYearMap.has(itemKey)) {
            itemYearMap.set(itemKey, new Map());
        }
        const yearMap = itemYearMap.get(itemKey)!;
        const current = yearMap.get(item.year) || { sellOut: 0, units: 0, sku: item.sku, asin: item.asin, title: item.title, line: item.line };
        yearMap.set(item.year, {
            sellOut: current.sellOut + item.sellOut,
            units: current.units + item.units,
            sku: item.sku,
            asin: item.asin,
            title: item.title,
            line: item.line
        });
        allYearsInFilteredData.add(item.year);
    });

    const sortedYearsInFilteredData = Array.from(allYearsInFilteredData).sort((a, b) => b - a); // Descending (most recent first)

    let currentYear: number;
    let prevYear: number;

    if (currentComparisonYearFromPage) {
        // If a specific comparison year is provided by the user on the Top Movers page
        currentYear = currentComparisonYearFromPage;
        const currentYearIndex = sortedYearsInFilteredData.indexOf(currentYear);
        if (currentYearIndex === -1 || currentYearIndex === sortedYearsInFilteredData.length - 1) {
            // Specified year not found in filtered data or it's the oldest year (no previous year for comparison)
            return { topMovers: [], bottomMovers: [], comparisonPeriods: { current: currentYear.toString(), previous: 'N/A' } };
        }
        prevYear = sortedYearsInFilteredData[currentYearIndex + 1]; // The year directly before the currentComparisonYear
    } else {
        // Default to the two most recent years from the *filtered data* if no specific year is chosen
        if (sortedYearsInFilteredData.length < 2) {
            return { topMovers: [], bottomMovers: [], comparisonPeriods: { current: 'N/A', previous: 'N/A' } };
        }
        currentYear = sortedYearsInFilteredData[0]; // Most recent
        prevYear = sortedYearsInFilteredData[1];   // Second most recent
    }

    const metrics: ItemGrowthMetric[] = [];

    itemYearMap.forEach((yearMap) => {
        const currData = yearMap.get(currentYear) || { sellOut: 0, units: 0, sku: '', asin: '', title: '', line: '' };
        const prevData = yearMap.get(prevYear) || { sellOut: 0, units: 0, sku: '', asin: '', title: '', line: '' };

        // Only include items that had some activity in at least one of the comparison years
        if ((currData.sellOut === 0 && currData.units === 0) && (prevData.sellOut === 0 && prevData.units === 0)) {
            return;
        }

        // Use metadata from current year, if not available use previous (for sku/asin/title/line)
        const itemMeta = currData.sku ? currData : prevData;


        // Sell Out Growth
        let sellOutGrowthValue = currData.sellOut - prevData.sellOut;
        let sellOutGrowthPercentage = 0;
        if (prevData.sellOut !== 0) {
            sellOutGrowthPercentage = (sellOutGrowthValue / prevData.sellOut) * 100;
        } else if (currData.sellOut > 0) {
            sellOutGrowthPercentage = 100; // Growth from zero
        } else if (currData.sellOut === 0 && prevData.sellOut > 0) {
            sellOutGrowthPercentage = -100; // Decline to zero
        }

        // Unit Growth
        let unitsGrowthValue = currData.units - prevData.units;
        let unitsGrowthPercentage = 0;
        if (prevData.units !== 0) {
            unitsGrowthPercentage = (unitsGrowthValue / prevData.units) * 100;
        } else if (currData.units > 0) {
            unitsGrowthPercentage = 100; // Growth from zero
        } else if (currData.units === 0 && prevData.units > 0) {
            unitsGrowthPercentage = -100; // Decline to zero
        }

        metrics.push({
            sku: itemMeta.sku,
            asin: itemMeta.asin,
            title: itemMeta.title,
            line: itemMeta.line,
            currentYearSellOut: currData.sellOut,
            previousYearSellOut: prevData.sellOut,
            sellOutGrowthValue,
            sellOutGrowthPercentage,
            currentYearUnits: currData.units,
            previousYearUnits: prevData.units,
            unitsGrowthValue,
            unitsGrowthPercentage
        });
    });

    const topMovers = metrics
        .sort((a, b) => b.unitsGrowthValue - a.unitsGrowthValue) // Sort by unitsGrowthValue
        .slice(0, 20); // Top 20 Gainers

    const bottomMovers = metrics
        .sort((a, b) => a.unitsGrowthValue - b.unitsGrowthValue) // Sort by unitsGrowthValue
        .slice(0, 20); // Top 20 Losers

    return {
        topMovers,
        bottomMovers,
        comparisonPeriods: { current: currentYear.toString(), previous: prevYear.toString() }
    };
};


export const aggregateData = (data: SalesRecord[]): AggregatedData => {
    const totalSellOut = data.reduce((acc, curr) => acc + curr.sellOut, 0);
    const totalUnits = data.reduce((acc, curr) => acc + curr.units, 0);

    const totalsByYear: Record<string, { sellOut: number; units: number }> = {};
    data.forEach(item => {
        const y = item.year.toString();
        if (!totalsByYear[y]) totalsByYear[y] = { sellOut: 0, units: 0 };
        totalsByYear[y].sellOut += item.sellOut;
        totalsByYear[y].units += item.units;
    });

    const lineMap = new Map<string, { value: number; units: number }>();
    data.forEach(item => {
        const current = lineMap.get(item.line) || { value: 0, units: 0 };
        lineMap.set(item.line, {
            value: current.value + item.sellOut,
            units: current.units + item.units
        });
    });
    const byLine = Array.from(lineMap.entries())
        .map(([name, data]) => ({ name, value: data.value, units: data.units }))
        .sort((a, b) => b.value - a.value);

    const customerMap = new Map<string, number>();
    data.forEach(item => {
        customerMap.set(item.customer, (customerMap.get(item.customer) || 0) + item.sellOut);
    });
    const byCustomer = Array.from(customerMap.entries())
        .map(([name, value]) => ({ name, value }))
        .sort((a, b) => b.value - a.value);

    const { seasonality, seasonalityUnits, years } = calculateSeasonality(data);
    const { topMovers, bottomMovers, comparisonPeriods } = calculateLineMovers(data); // Use calculateLineMovers
    const topLinesSplit = calculateTopLinesSplit(data);
    const byCustomerSplit = calculateGenericSplit(data, 'customer', 'sellOut');
    const byLineOverviewSplit = calculateGenericSplit(data, 'line', 'units', 10);

    return {
        totalSellOut,
        totalUnits,
        totalsByYear,
        byLine,
        byCustomer,
        seasonality,
        seasonalityUnits,
        availableYears: years,
        topMovers,
        bottomMovers,
        comparisonPeriods,
        topLinesSplit,
        byCustomerSplit,
        byLineOverviewSplit
    };
};

/**
 * Groups Pan-EU countries (Amazon DE, IT, FR, ES) into a single "Pan-EU" customer
 * when no customer filter is applied. This provides a consolidated view of European
 * markets while keeping UK and SC separate.
 * 
 * @param data - Array of sales records
 * @param hasCustomerFilter - Whether a customer filter is currently applied
 * @returns Processed data with Pan-EU grouping applied if appropriate
 */
export const applyPanEUGrouping = (
    data: SalesRecord[],
    hasCustomerFilter: boolean
): SalesRecord[] => {
    // If customer filter is applied, don't group - show selected countries as-is
    if (hasCustomerFilter) {
        return data;
    }

    // Replace Pan-EU country names with "Pan-EU" for grouping
    return data.map(record => {
        if (PAN_EU_COUNTRIES.includes(record.customer)) {
            return { ...record, customer: 'Pan-EU' };
        }
        return record;
    });
};

export const getUniqueValues = (data: SalesRecord[], field: keyof SalesRecord): string[] => {
    const values = new Set(data.map(item => String(item[field])));
    return Array.from(values).sort();
};

export const pivotSalesData = (data: any[], dimensions: string[] = ['title', 'customer', 'line', 'sku']): { rows: PivotRow[], years: string[] } => {
    // 1. Determine all years present in the data for columns
    const yearsSet = new Set(data.map(d => d.year));
    const years = Array.from(yearsSet).sort((a, b) => b - a).map(String);

    const map = new Map<string, PivotRow>();

    data.forEach(record => {
        // Group by Dynamic Dimensions
        // Use a fallback for 'customer' dimension as some records use 'marketplace'
        const keyParts = new Array(dimensions.length);
        for (let i = 0; i < dimensions.length; i++) {
            const dim = dimensions[i];
            let val = '';
            if (dim === 'customer') val = String(record.customer || record.marketplace || '');
            else val = String(record[dim] || '');

            // Normalize ASIN and SKU in keys to fold duplicates
            if (dim === 'asin' || dim === 'sku' || dim === 'customer') {
                keyParts[i] = val.trim().toUpperCase();
            } else {
                keyParts[i] = val;
            }
        }
        const key = keyParts.join('||');

        if (!map.has(key)) {
            map.set(key, {
                id: key,
                customer: record.customer || record.marketplace || '',
                line: record.line || '',
                title: record.title || '',
                articleName: record.articleName || '',
                sku: record.sku || '',
                asin: record.asin || '',
                // Initialize 12 months with empty year maps
                months: Array(12).fill(null).map((_, i) => ({
                    monthIndex: i,
                    byYear: {}
                })),
                totalsByYear: {},
                adsByYear: {}
            });
        }

        const row = map.get(key)!;
        const monthRaw = record.month || '';
        const monthPart = monthRaw.split('-')[0]; // Handle "Apr-23" -> "Apr"
        const monthIdx = MONTH_ORDER.indexOf(monthPart);
        const yearStr = record.year.toString();

        // 1. Update Row Totals for Year
        if (!row.totalsByYear[yearStr]) {
            row.totalsByYear[yearStr] = { sellOut: 0, units: 0 };
        }
        row.totalsByYear[yearStr].sellOut += (record.sellOut || record.salesTotal || 0);
        row.totalsByYear[yearStr].units += (record.units || record.unitsTotal || 0);

        // 2. Update Ads Data (if present in the record)
        if (record.cost !== undefined || record.salesAds !== undefined) {
            if (!row.adsByYear) row.adsByYear = {};
            if (!row.adsByYear[yearStr]) {
                row.adsByYear[yearStr] = { adSpend: 0, attributedSales: 0, acos: 0, tacos: 0 };
            }
            row.adsByYear[yearStr].adSpend += (record.cost || 0);
            row.adsByYear[yearStr].attributedSales += (record.salesAds || 0);

            // Recalculate ACOS/TACOS at the aggregated level
            const ads = row.adsByYear[yearStr];
            const sales = row.totalsByYear[yearStr].sellOut;
            ads.acos = ads.attributedSales > 0 ? (ads.adSpend / ads.attributedSales) * 100 : 0;
            ads.tacos = sales > 0 ? (ads.adSpend / sales) * 100 : 0;
        }

        // 3. Update Monthly Data
        if (monthIdx !== -1) {
            const m = row.months[monthIdx];
            if (!m.byYear[yearStr]) {
                m.byYear[yearStr] = { sellOut: 0, units: 0 };
            }
            m.byYear[yearStr].sellOut += (record.sellOut || record.salesTotal || 0);
            m.byYear[yearStr].units += (record.units || record.unitsTotal || 0);
        }
    });

    return {
        rows: Array.from(map.values()),
        years
    };
};

export const generateXLSX = (rows: PivotRow[], dimensions: string[], years: string[]) => {
    // Flatten PivotRows into Excel-friendly objects
    const flatData = rows.map(row => {
        const flatRow: any = {};

        // Always ensure ASIN and SKU are exported as foundational identifiers
        flatRow['ASIN'] = row.asin || '-';
        flatRow['SKU'] = row.sku || '-';

        // Add User Selected Dimension Columns
        dimensions.forEach(dim => {
            if (dim.toLowerCase() === 'asin' || dim.toLowerCase() === 'sku') return; // Skip if already explicitly set

            let header = dim;
            if (dim === 'line') header = 'Product Line';
            if (dim === 'title') header = 'Title';
            if (dim === 'customer') header = 'Customer';

            flatRow[header] = row[dim as keyof PivotRow];
        });

        // Add Yearly Totals
        years.forEach(year => {
            const data = row.totalsByYear[year];
            flatRow[`Total Sell Out ${year}`] = data?.sellOut || 0;
            flatRow[`Total Units ${year}`] = data?.units || 0;
        });

        // Add Monthly Data
        row.months.forEach(m => {
            const monthName = MONTH_ORDER[m.monthIndex];
            years.forEach(year => {
                const data = m.byYear[year];
                flatRow[`${monthName} ${year} Sell Out`] = data?.sellOut || 0;
                flatRow[`${monthName} ${year} Units`] = data?.units || 0;
            });
        });

        return flatRow;
    });

    const ws = XLSX.utils.json_to_sheet(flatData);
    const wb = XLSX.utils.book_new();
    XLSX.utils.book_append_sheet(wb, ws, 'Business Data');
    XLSX.writeFile(wb, `Business_Data_Export_${new Date().toISOString().slice(0, 10)}.xlsx`);
};

export const generateItemMoversXLSX = (
    data: ItemGrowthMetric[],
    periods: { current: string; previous: string },
    type: 'Gainers' | 'Losers'
) => {
    const flatData = data.map(item => ({
        SKU: item.sku || '-',
        ASIN: item.asin || '-',
        'Product Title': item.title || '-',
        'Product Line': item.line || '-',
        [`Sell Out ${periods.previous}`]: item.previousYearSellOut,
        [`Sell Out ${periods.current}`]: item.currentYearSellOut,
        'SO Diff': item.sellOutGrowthValue,
        'SO Growth %': Number(item.sellOutGrowthPercentage.toFixed(2)),
        [`Units ${periods.previous}`]: item.previousYearUnits,
        [`Units ${periods.current}`]: item.currentYearUnits,
        'Units Diff': item.unitsGrowthValue,
        'Units Growth %': Number(item.unitsGrowthPercentage.toFixed(2)),
    }));

    const ws = XLSX.utils.json_to_sheet(flatData);
    const wb = XLSX.utils.book_new();
    XLSX.utils.book_append_sheet(wb, ws, type);
    XLSX.writeFile(wb, `${type}_${periods.current}_vs_${periods.previous}_${new Date().toISOString().split('T')[0]}.xlsx`);
};


export const aggregateForTimeSeries = (data: SalesRecord[]): TimeSeriesData[] => {
    const map = new Map<string, { sellOut: number; units: number }>();
    const recordsWithWeek = data.filter(r => r.week != null && r.year != null && r.week >= 1 && r.week <= 53);

    if (recordsWithWeek.length === 0) return []; // No weekly data to process

    recordsWithWeek.forEach(record => {
        // Create a sortable key YYYY-WW
        const weekStr = record.week!.toString().padStart(2, '0');
        const key = `${record.year}-${weekStr}`;

        const current = map.get(key) || { sellOut: 0, units: 0 };
        // Support both SalesRecord (sellOut/units) and CombinedKPIs (salesTotal/unitsTotal)
        current.sellOut += (record as any).sellOut ?? (record as any).salesTotal ?? 0;
        current.units += (record as any).units ?? (record as any).unitsTotal ?? 0;
        map.set(key, current);
    });

    // Convert map to array and sort chronologically
    return Array.from(map.entries())
        .sort((a, b) => a[0].localeCompare(b[0]))
        .map(([key, values]) => {
            const [year, weekNum] = key.split('-');
            const yearShort = year.substring(2);

            return {
                name: `W${weekNum} '${yearShort}`,
                sellOut: values.sellOut,
                units: values.units
            };
        });
};

export const aggregateForComparisonTimeSeries = (data: SalesRecord[]): ComparisonTimeSeriesPoint[] => {
    const map = new Map<number, { [key: string]: number }>(); // Key is week number
    const years = Array.from(new Set(data.map(d => d.year)));

    // Initialize map for all 53 possible weeks to ensure a consistent X-axis
    for (let i = 1; i <= 53; i++) {
        const initialWeekData: { [key: string]: number } = {};
        years.forEach(year => {
            initialWeekData[`${year}_sellOut`] = 0;
            initialWeekData[`${year}_units`] = 0;
        });
        map.set(i, initialWeekData);
    }

    data.forEach(record => {
        if (record.week != null && record.year != null && record.week >= 1 && record.week <= 53) {
            const weekData = map.get(record.week)!;

            const sellOutKey = `${record.year}_sellOut`;
            const unitsKey = `${record.year}_units`;

            // Support both SalesRecord (sellOut/units) and CombinedKPIs (salesTotal/unitsTotal)
            const sellOut = (record as any).sellOut ?? (record as any).salesTotal ?? 0;
            const units = (record as any).units ?? (record as any).unitsTotal ?? 0;

            weekData[sellOutKey] = (weekData[sellOutKey] || 0) + sellOut;
            weekData[unitsKey] = (weekData[unitsKey] || 0) + units;

            map.set(record.week, weekData);
        }
    });

    // Convert map to array, filter out weeks with no data across all years, and sort
    return Array.from(map.entries())
        .map(([week, values]) => ({
            week,
            name: `W${week}`,
            ...values,
        }))
        .filter(d => {
            // Check if there is any non-zero value for this week
            return Object.values(d).some(val => typeof val === 'number' && val > 0);
        })
        .sort((a, b) => a.week - b.week);
};
export interface WeeklyPivotRow {
    id: string;
    sku: string;
    title: string;
    asin: string;
    line: string;
    customer: string;
    unitsByWeek: { [weekKey: string]: number }; // Key: "YYYY-WW"
    spendByWeek: { [weekKey: string]: number }; // Key: "YYYY-WW" (Ads Cost)
    revenueByWeek: { [weekKey: string]: number }; // Key: "YYYY-WW" (Sell-out)
    gvByWeek: { [weekKey: string]: number }; // Key: "YYYY-WW"
}

export const pivotWeeklySalesData = (data: CombinedKPIs[]): {
    rows: WeeklyPivotRow[],
    weeks: string[]
} => {
    const weekKeysSet = new Set<string>();
    const map = new Map<string, WeeklyPivotRow>();

    // Cache week keys to avoid repeated string formatting
    // Key: year|week, Value: YYYY-WW
    const weekCache = new Map<string, string>();

    const getWeekKey = (year: number, week: number) => {
        const cacheKey = `${year}|${week}`;
        let k = weekCache.get(cacheKey);
        if (!k) {
            k = `${year}-${String(week).padStart(2, '0')}`;
            weekCache.set(cacheKey, k);
        }
        return k;
    };

    const len = data.length;
    for (let i = 0; i < len; i++) {
        const record = data[i];
        if (!record.week) continue;

        const weekKey = getWeekKey(record.year, record.week);
        weekKeysSet.add(weekKey);

        const recordAsin = (record.asin || '').trim().toUpperCase();
        const recordSku = (record.sku || '').trim().toUpperCase();
        const key = recordAsin || recordSku || `${record.title}-${record.line}`;
        if (!key) continue;

        let row = map.get(key);
        if (!row) {
            row = {
                id: key,
                sku: record.sku || '',
                title: record.title || '',
                asin: record.asin || '',
                line: record.line || '',
                customer: record.customer || record.marketplace || '',
                unitsByWeek: {},
                spendByWeek: {},
                revenueByWeek: {},
                gvByWeek: {}
            };
            map.set(key, row);
        }

        row.unitsByWeek[weekKey] = (row.unitsByWeek[weekKey] || 0) + (record.unitsTotal || 0);
        row.spendByWeek[weekKey] = (row.spendByWeek[weekKey] || 0) + (record.cost || 0);
        row.revenueByWeek[weekKey] = (row.revenueByWeek[weekKey] || 0) + (record.salesTotal || 0);
        row.gvByWeek[weekKey] = (row.gvByWeek[weekKey] || 0) + (record.glanceViews || 0);
    }

    const sortedWeeks = Array.from(weekKeysSet).sort((a, b) => b.localeCompare(a));

    return {
        rows: Array.from(map.values()),
        weeks: sortedWeeks
    };
};

export const processForecastExcel = async (fileOrBuffer: File | ArrayBuffer): Promise<ForecastRecord[]> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });
        const sheetName = workbook.SheetNames[0];
        const worksheet = workbook.Sheets[sheetName];
        const jsonData: any[] = XLSX.utils.sheet_to_json(worksheet, { defval: "" });

        return jsonData.map(row => ({
            asin: String(row['ASIN'] || row['asin'] || '').trim().toUpperCase(),
            annualForecast: parseUnits(String(row['Forecast 2026'] || row['forecast 2026'] || '0')),
            sku: row['SKU'] || row['sku'] || undefined,
            title: row['Title'] || row['title'] || row['Article Name'] || undefined,
            line: row['Product Line'] || row['line'] || row['ProductLine'] || undefined
        })).filter(r => r.asin && r.annualForecast > 0);
    } catch (error) {
        console.error("Error processing Forecast Excel:", error);
        throw error;
    }
};

export const calculateForecastViewData = (
    rawData: SalesRecord[],
    forecastData: ForecastRecord[],
    asinMetadata: Map<string, { sku: string; title: string; line: string }>,
    filters?: FilterState,
    velocityMap?: Map<string, number>,
    referenceData?: SalesRecord[] // NEW: Full dataset for global seasonality context
): ProductForecastData[] => {
    // Use referenceData if provided (for global weights), otherwise fallback to rawData
    const seasonalitySource = referenceData || rawData;
    const historicalData = seasonalitySource.filter(r => r.year < 2026);

    // IMPORTANT: Actuals for 2026 must be strictly scoped to the forecast region
    // to avoid mixing UK stats into Pan-EU or vice-versa.
    const isForecastUKMode = filters?.customer?.includes('Amazon UK');
    const data2026 = rawData.filter(r => {
        if (r.year !== 2026) return false;
        if (isForecastUKMode) {
            return r.customer === 'Amazon UK';
        } else {
            // In Pan-EU mode, explicitly exclude UK units even if they are in the dataset
            return r.customer !== 'Amazon UK';
        }
    });

    // Calculate Seasonality weights for 2025
    const getWeightsInfo = (records: SalesRecord[]): { weights: number[]; monthsCount: number } | null => {
        const weights = new Array(12).fill(0);
        let total = 0;
        const seenMonths = new Set<string>();

        records.forEach(r => {
            const m = r.month.split('-')[0];
            const idx = MONTH_ORDER.indexOf(m);
            if (idx !== -1 && r.units > 0) {
                weights[idx] += r.units;
                total += r.units;
                seenMonths.add(m);
            }
        });

        // If ASIN has any 2025 sales, we trust its specific seasonality.
        // Return null ONLY if there's no data at all for this ASIN in 2025.
        if (total === 0) return null;

        return {
            weights: weights.map(w => w / total),
            monthsCount: seenMonths.size
        };
    };

    // 1. Determine Global/Default Weights
    const panEuHistoricalData = historicalData.filter(r => PAN_EU_COUNTRIES.includes(r.customer));
    // For Global Weights, we do NOT return null on sparse data (we accept whatever we have for the whole catalog)
    // We recreate a simple version of getWeights that doesn't return null for the global set
    const getGlobalWeightsInner = (records: SalesRecord[]) => {
        const weights = new Array(12).fill(0);
        let total = 0;
        const seenMonths = new Set<string>();

        records.forEach(r => {
            const m = r.month.split('-')[0];
            const idx = MONTH_ORDER.indexOf(m);
            if (idx !== -1) {
                weights[idx] += r.units;
                total += r.units;
                if (r.units > 0) seenMonths.add(m);
            }
        });

        // SAFETY NET: Even for Global Weights, if the reference file (2025 Sales) 
        // has fewer than 4 months of data (e.g. user only uploaded Jan 2025),
        // we should NOT assume 100% seasonality in those months. Fallback to flat.
        if (total === 0 || seenMonths.size < 4) {
            return new Array(12).fill(1 / 12);
        }

        return weights.map(w => w / total);
    };

    const panEuWeights = getGlobalWeightsInner(panEuHistoricalData);

    // Check if we are in UK-only mode
    const isUkOnly = filters?.customer?.includes('Amazon UK') && filters.customer.length === 1;

    const getHybridWeights = (paEuRecords: SalesRecord[], ukRecords: SalesRecord[]) => {
        // Use Inner helper to ensure we always get weights for global subsets
        const peWeights = getGlobalWeightsInner(paEuRecords);
        const ukWeights = getGlobalWeightsInner(ukRecords);

        // Blend: Jan-Aug from Pan-EU, Sep-Dec from UK
        const hybrid = new Array(12).fill(0);
        const hasUkHistory = ukRecords.length > 0;

        for (let i = 0; i < 12; i++) {
            if (i < 8) { // Jan-Aug
                hybrid[i] = peWeights[i];
            } else { // Sep-Dec
                hybrid[i] = hasUkHistory ? ukWeights[i] : peWeights[i];
            }
        }

        // Normalize
        const sum = hybrid.reduce((a, b) => a + b, 0);
        return sum > 0 ? hybrid.map(w => w / sum) : peWeights;
    };

    const globalWeights = isUkOnly
        ? getHybridWeights(panEuHistoricalData, historicalData.filter(r => r.customer === 'Amazon UK'))
        : panEuWeights;

    // Map historical data by ASIN for quick access
    const dataByAsinHistorical = new Map<string, SalesRecord[]>();
    historicalData.forEach(r => {
        const key = r.asin.trim().toUpperCase();
        if (!dataByAsinHistorical.has(key)) dataByAsinHistorical.set(key, []);
        dataByAsinHistorical.get(key)!.push(r);
    });

    // Map 2026 actual sales by ASIN and Month
    const actuals2026 = new Map<string, Map<string, number>>();
    data2026.forEach(r => {
        const key = r.asin.trim().toUpperCase();
        const m = r.month.split('-')[0];
        if (!actuals2026.has(key)) actuals2026.set(key, new Map());
        const monthMap = actuals2026.get(key)!;
        monthMap.set(m, (monthMap.get(m) || 0) + r.units);
    });

    // 1b. Determine Line-Level Weights (NEW STRATEGY)
    const lineWeightsMap = new Map<string, number[]>();
    const linesMap = new Map<string, SalesRecord[]>();

    historicalData.forEach(r => {
        if (!r.line) return;
        if (!linesMap.has(r.line)) linesMap.set(r.line, []);
        linesMap.get(r.line)!.push(r);
    });

    linesMap.forEach((records, line) => {
        // We use the same getWeightsInfo logic but for the whole line
        const info = getWeightsInfo(records);
        if (info) {
            lineWeightsMap.set(line, info.weights);
        } else {
            // Fallback for line if it has data but odd distribution? 
            // Actually getWeightsInfo returns null only if total=0.
            // If we have records but 0 units total, we skip map set, so it will fall to global.
        }
    });

    return forecastData.map(fc => {
        const identifier = fc.asin.toUpperCase();
        const meta = asinMetadata.get(identifier);

        // Resolve Line: Try meta first, then forecast file
        const resolvedLine = meta?.line || fc.line || "Unassigned";

        const avgWeeklySales = velocityMap?.get(identifier) || 0;

        // 2. Determine weights for this ASIN
        const productHistoricalRecords = dataByAsinHistorical.get(identifier) || [];

        // LAYERED FALLBACK STRATEGY:
        // Level 1: Product's own history (Most accurate)
        // Level 2: Product Line's history (Good for new items in known category e.g. Advent Calendars)
        // Level 3: Global/Pan-EU history (Generic fallback)

        const lineWeights = lineWeightsMap.get(resolvedLine);
        const baselineWeights = lineWeights || globalWeights;

        let finalWeights = baselineWeights;

        if (productHistoricalRecords.length > 0) {
            const historyToUse = isUkOnly
                ? productHistoricalRecords.filter(r => r.customer === 'Amazon UK')
                : productHistoricalRecords;

            const info = getWeightsInfo(historyToUse);
            if (info) {
                // Adaptive Blending (Bayesian Shrinkage):
                // We blend local seasonality with baseline (Line or Global) based on data density.
                const trustFactor = (info.monthsCount / 12) * 0.85;
                finalWeights = info.weights.map((w, i) => (w * trustFactor) + (baselineWeights[i] * (1 - trustFactor)));
            }
        }

        // 3. Build monthly points and aggregate
        const monthlyData: Record<string, MonthlyForecastPoint> = {};
        let totalActualUnits = 0;
        let totalForecastUnits = 0;

        MONTH_ORDER.forEach((m, idx) => {
            const forecastUnits = Math.round(fc.annualForecast * finalWeights[idx]);
            const actualUnits = actuals2026.get(identifier)?.get(m) || 0;

            monthlyData[m] = {
                month: m,
                forecastUnits,
                actualUnits,
                units: actualUnits // Added for chart compatibility
            } as any;

            totalActualUnits += actualUnits;
            totalForecastUnits += forecastUnits;
        });

        const accuracy = totalForecastUnits > 0
            ? Math.max(0, Math.min(100, Math.round((1 - Math.abs(totalActualUnits - totalForecastUnits) / totalForecastUnits) * 100)))
            : (totalActualUnits === 0 ? 100 : 0);

        return {
            asin: identifier,
            sku: meta?.sku || fc.sku || identifier,
            title: meta?.title || fc.title || identifier,
            line: meta?.line || fc.line || "Unassigned",
            annualForecast: fc.annualForecast,
            actualUnits: totalActualUnits,
            forecastUnits: totalForecastUnits,
            accuracy: Math.max(0, accuracy),
            avgWeeklySales,
            monthlyData
        };
    });
};

export const processVendorStockExcel = async (fileOrBuffer: File | ArrayBuffer): Promise<Map<string, { eu: number; uk: number }>> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });
        const sheetName = workbook.SheetNames[0];
        const worksheet = workbook.Sheets[sheetName];
        const jsonData: any[][] = XLSX.utils.sheet_to_json(worksheet, { header: 1 });

        const vendorStockMap = new Map<string, { eu: number; uk: number }>();

        // Find header row (it contains "ASIN")
        let headerRowIndex = -1;
        for (let i = 0; i < Math.min(jsonData.length, 20); i++) {
            if (jsonData[i] && (jsonData[i].includes('ASIN') || jsonData[i].includes('asin'))) {
                headerRowIndex = i;
                break;
            }
        }

        if (headerRowIndex === -1) {
            // Fallback: look for ASIN in first row if not found in header scan
            if (jsonData[0] && (jsonData[0].includes('ASIN') || jsonData[0].includes('asin'))) headerRowIndex = 0;
            else {
                console.warn("Could not find header row in Vendor Stock Excel");
                return vendorStockMap;
            }
        }

        const headers: any[] = jsonData[headerRowIndex];
        const asinIdx = headers.findIndex(h => String(h || '').toUpperCase() === 'ASIN');

        // Enhanced marketplace detection - includes 'Store code' for PANEU reports
        const marketplaceIdx = headers.findIndex(h => {
            const sh = String(h || '').toUpperCase();
            return sh === 'MARKETPLACE' || sh === 'COUNTRY' || sh === 'COUNTRY/REGION' ||
                sh === 'STORE CODE' || sh === 'STORE';
        });

        // REFINED SEARCH STRATEGY for Stock column:
        // Priority 1: Look specifically for "Sellable On Hand Units" (most accurate for current inventory)
        let finalStockIdx = headers.findIndex(h => {
            const sh = String(h || '').toUpperCase();
            return sh === 'SELLABLE ON HAND UNITS';
        });

        // Priority 2: Look for columns with "SELLABLE" AND "UNITS" (but not necessarily exact match)
        if (finalStockIdx === -1) {
            finalStockIdx = headers.findIndex(h => {
                const sh = String(h || '').toUpperCase();
                return sh.includes('SELLABLE') && sh.includes('UNITS') &&
                    !sh.includes('UNSELLABLE') && !sh.includes('AGED');
            });
        }

        // Priority 3: Look for "On Hand Units" variations
        if (finalStockIdx === -1) {
            finalStockIdx = headers.findIndex(h => {
                const sh = String(h || '').toUpperCase();
                return sh.includes('ON HAND') && sh.includes('UNITS') &&
                    !sh.includes('UNSELLABLE');
            });
        }

        // Priority 4: Fallback to generic stock column search (but avoid monetary columns)
        if (finalStockIdx === -1) {
            finalStockIdx = headers.findIndex(h => {
                const sh = String(h || '').toUpperCase();
                // Exclude columns that are clearly wrong
                if (sh.includes('COST') || sh.includes('VALUE') || sh.includes('AMOUNT') ||
                    sh.includes('PRICE') || sh.includes('RECEIVED') || sh.includes('UNFILLED') ||
                    sh.includes('AGED') || sh.includes('UNSELLABLE')) {
                    return false;
                }
                return sh.includes('STOCK') || sh.includes('AVAILABILITY') ||
                    (sh.includes('UNITS') && sh.includes('SELLABLE'));
            });
        }

        // Final sanity check for indexes, fallback to defaults if headers.findIndex returned -1
        const finalAsinIdx = asinIdx !== -1 ? asinIdx : 0;
        const finalMarketplaceIdx = marketplaceIdx !== -1 ? marketplaceIdx : 3;
        finalStockIdx = finalStockIdx !== -1 ? finalStockIdx : 15;

        console.log(`[VendorStock] Selected Stock Column: "${headers[finalStockIdx]}" (Index: ${finalStockIdx})`);
        console.log(`[VendorStock] Marketplace Column: "${headers[finalMarketplaceIdx]}" (Index: ${finalMarketplaceIdx})`);

        for (let i = headerRowIndex + 1; i < jsonData.length; i++) {
            const row = jsonData[i];
            if (!row || row.length <= Math.max(finalAsinIdx, finalMarketplaceIdx, finalStockIdx)) continue;

            const asin = String(row[finalAsinIdx] || '').trim().toUpperCase();
            if (!asin) continue;

            const marketplace = String(row[finalMarketplaceIdx] || '').trim().toLowerCase();
            const stockValue = parseUnits(String(row[finalStockIdx] || '0'));

            if (!vendorStockMap.has(asin)) {
                vendorStockMap.set(asin, { eu: 0, uk: 0 });
            }

            const current = vendorStockMap.get(asin)!;

            // Map to UK or EU
            if (marketplace.includes('uk') || marketplace.includes('kingdom') || marketplace === 'gb' || marketplace === 'united kingdom') {
                current.uk += stockValue;
            } else if (marketplace) {
                // Assume everything else with a marketplace is Pan-EU (DE, IT, FR, ES)
                current.eu += stockValue;
            }
        }

        return vendorStockMap;
    } catch (error) {
        console.error("Error processing Vendor Stock Excel:", error);
        throw error;
    }
};

/**
 * Process UK Inventory Excel file from Amazon Vendor Central.
 * This file contains ONLY UK inventory, so all stock goes to the 'uk' property.
 * It merges with an existing vendorStockMap to combine PANEU + UK data.
 */
export const processUKInventoryExcel = async (
    fileOrBuffer: File | ArrayBuffer,
    existingMap?: Map<string, { eu: number; uk: number }>
): Promise<Map<string, { eu: number; uk: number }>> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });
        const sheetName = workbook.SheetNames[0];
        const worksheet = workbook.Sheets[sheetName];
        const jsonData: any[][] = XLSX.utils.sheet_to_json(worksheet, { header: 1 });

        // Start with existing map or create new one
        const vendorStockMap = existingMap || new Map<string, { eu: number; uk: number }>();

        // Find header row (it contains "ASIN")
        let headerRowIndex = -1;
        for (let i = 0; i < Math.min(jsonData.length, 20); i++) {
            if (jsonData[i] && (jsonData[i].includes('ASIN') || jsonData[i].includes('asin'))) {
                headerRowIndex = i;
                break;
            }
        }

        if (headerRowIndex === -1) {
            console.warn("[UK Inventory] Could not find header row");
            return vendorStockMap;
        }

        const headers: any[] = jsonData[headerRowIndex];
        const asinIdx = headers.findIndex(h => String(h || '').toUpperCase() === 'ASIN');

        // Find "Sellable On Hand Units" column (same logic as PANEU)
        let stockIdx = headers.findIndex(h => String(h || '').toUpperCase() === 'SELLABLE ON HAND UNITS');

        if (stockIdx === -1) {
            stockIdx = headers.findIndex(h => {
                const sh = String(h || '').toUpperCase();
                return sh.includes('SELLABLE') && sh.includes('UNITS') &&
                    !sh.includes('UNSELLABLE') && !sh.includes('AGED');
            });
        }

        // Fallback to default index if not found
        const finalAsinIdx = asinIdx !== -1 ? asinIdx : 0;
        const finalStockIdx = stockIdx !== -1 ? stockIdx : 14; // UK file has it at index 14

        console.log(`[UK Inventory] ASIN Column: "${headers[finalAsinIdx]}" (Index: ${finalAsinIdx})`);
        console.log(`[UK Inventory] Stock Column: "${headers[finalStockIdx]}" (Index: ${finalStockIdx})`);

        let ukCount = 0;
        for (let i = headerRowIndex + 1; i < jsonData.length; i++) {
            const row = jsonData[i];
            if (!row || row.length <= Math.max(finalAsinIdx, finalStockIdx)) continue;

            const asin = String(row[finalAsinIdx] || '').trim().toUpperCase();
            if (!asin) continue;

            const stockValue = parseUnits(String(row[finalStockIdx] || '0'));

            if (!vendorStockMap.has(asin)) {
                vendorStockMap.set(asin, { eu: 0, uk: 0 });
            }

            const current = vendorStockMap.get(asin)!;
            current.uk += stockValue;
            ukCount++;
        }

        console.log(`[UK Inventory] Processed ${ukCount} UK stock entries`);
        return vendorStockMap;
    } catch (error) {
        console.error("Error processing UK Inventory Excel:", error);
        throw error;
    }
};

export const calculateVelocityMap = (data: SalesRecord[]): Map<string, number> => {
    // 4-Week Average Sales Calculation
    const validYears = data.map(r => r.year).filter(y => y > 0);
    if (validYears.length === 0) return new Map();

    const latestYear = Math.max(...validYears);
    const yearData = data.filter(r => r.year === latestYear);
    const latestWeek = yearData.length > 0 ? Math.max(...yearData.map(r => r.week).filter(w => w !== undefined) as number[]) : 0;

    const last4WeeksKeys = new Set<string>();
    for (let i = 0; i < 4; i++) {
        let w = latestWeek - i;
        let y = latestYear;
        if (w <= 0) {
            w = 52 + w;
            y = latestYear - 1;
        }
        last4WeeksKeys.add(`${y}|${w}`);
    }

    const asin4WeekSales = new Map<string, number>();
    data.forEach(r => {
        if (r.week === undefined) return;
        if (last4WeeksKeys.has(`${r.year}|${r.week}`)) {
            const key = r.asin.trim().toUpperCase();
            asin4WeekSales.set(key, (asin4WeekSales.get(key) || 0) + r.units);
        }
    });

    const velocityMap = new Map<string, number>();
    asin4WeekSales.forEach((total, asin) => {
        velocityMap.set(asin, total / 4);
    });

    return velocityMap;
};

export const processStockExcel = async (fileOrBuffer: File | ArrayBuffer): Promise<Map<string, number>> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });
        const sheetName = workbook.SheetNames[0];
        const worksheet = workbook.Sheets[sheetName];
        const jsonData: any[][] = XLSX.utils.sheet_to_json(worksheet, { header: 1 });

        const stockMap = new Map<string, number>();

        // Skip headers (index 0)
        for (let i = 1; i < jsonData.length; i++) {
            const row = jsonData[i];
            const rawSku = String(row[0] || '').trim();
            if (!rawSku) continue;

            // Normalize SKU: Remove trailing EN or DE
            const normalizedSku = rawSku.replace(/(DE|EN)$/i, '');

            // User requested Column I which is index 8 (After Assembly Orders GMBH)
            const stockValue = Number(row[8] || 0);

            if (!isNaN(stockValue)) {
                const current = stockMap.get(normalizedSku) || 0;
                stockMap.set(normalizedSku, current + stockValue);
            }
        }

        return stockMap;
    } catch (error) {
        console.error("Error processing Stock Excel:", error);
        throw error;
    }
};

const BB_SHEET_CONFIG: { sheet: string; country: string }[] = [
    { sheet: 'BB_FR', country: 'FR' },
    { sheet: 'BB_UK', country: 'UK' },
    { sheet: 'BB_DE', country: 'DE' },
    { sheet: 'BB_IT', country: 'IT' },
    { sheet: 'BB_ES', country: 'ES' },
];

export const processBuyBoxExcel = async (fileOrBuffer: File | ArrayBuffer): Promise<Map<string, { countries: string[]; reasons: Record<string, string> }>> => {
    try {
        const arrayBuffer = fileOrBuffer instanceof File
            ? await fileOrBuffer.arrayBuffer()
            : fileOrBuffer;
        const workbook = XLSX.read(arrayBuffer, { type: 'array' });

        // Map: ASIN -> { countries: [], reasons: {} }
        const buyBoxMap = new Map<string, { countries: string[]; reasons: Record<string, string> }>();

        // Log available sheets for debugging
        console.log('[BuyBox] Available sheets:', workbook.SheetNames.join(', '));

        for (const config of BB_SHEET_CONFIG) {
            // Find sheet case-insensitively and with flexible separators (BB_ES, BB-ES, BB ES, ES BB)
            const sheetName = workbook.SheetNames.find(name => {
                const n = name.toUpperCase().replace(/[-_ ]/g, '');
                const target = config.sheet.toUpperCase().replace(/[-_ ]/g, '');
                const country = config.country.toUpperCase();
                // Match if:
                // 1. Exact pattern (BB_ES)
                // 2. Just the country code (ES)
                // 3. Contains 'BB' and the country code
                // 4. Special cases for Spain (SPAIN, ESPAÑA)
                return n === target ||
                    n === country ||
                    (n.includes('BB') && n.includes(country)) ||
                    (country === 'ES' && (n.includes('SPAIN') || n.includes('ESPAÑA') || n.includes('ESPANA')));
            });

            if (!sheetName) {
                console.warn(`[BuyBox] Sheet matching ${config.sheet} not found, skipping...`);
                continue;
            }

            const worksheet = workbook.Sheets[sheetName];
            const jsonData: any[][] = XLSX.utils.sheet_to_json(worksheet, { header: 1 });
            if (jsonData.length === 0) continue;

            // Find the header row (first row with ASIN or similar)
            let headerRowIdx = 0;
            let headers: any[] = jsonData[0] || [];
            for (let r = 0; r < Math.min(jsonData.length, 10); r++) {
                const rowData = jsonData[r];
                if (!rowData) continue;
                const isHeader = rowData.some(cell => {
                    const s = String(cell || '').toUpperCase().trim();
                    return s === 'ASIN' || s.includes('AMAZON ASIN') || s.includes('PRODUCT ID') || s.includes('SKU');
                });
                if (isHeader) {
                    headerRowIdx = r;
                    headers = rowData;
                    break;
                }
            }

            const asinIdx = headers.findIndex(h => {
                const s = String(h || '').toUpperCase().trim();
                return s === 'ASIN' || s.includes('AMAZON ASIN') || s.includes('CHILD ASIN') || s.includes('IDENTIFIER') || s.includes('PRODUCT ID') || s.includes('SKU');
            });
            let finalAsinIdx = asinIdx !== -1 ? asinIdx : 1; // Default to Col B if not found

            // Dynamically find the "Issue Type" or "Reason" column
            let reasonIdx = headers.findIndex(h => {
                const s = String(h || '').toUpperCase();
                return s.includes('ISSUE TYPE') || s.includes('REASON') || s.includes('BUY BOX STATUS') || s.includes('LBB REASON') || s.includes('ESTADO BB') || s.includes('COMENTARIO') || s.includes('MOTIVO') || s.includes('CAUSA') || s.includes('OBSERVACIONES') || s.includes('DETALLES') || s.includes('JUSTIFICACIÓN') || s.includes('SITUACIÓN') || s.includes('STATUS');
            });

            // If still not found, check for exact matches of common Spanish headers
            if (reasonIdx === -1) {
                reasonIdx = headers.findIndex(h => {
                    const s = String(h || '').toUpperCase().trim();
                    return s === 'COMENTARIOS' || s === 'OBSERVACIONES' || s === 'MOTIVO' || s === 'ESTADO';
                });
            }

            // Fallback to previous hardcoded indices if header search fails or for specific known sheet structures
            if (reasonIdx === -1 || (config.country === 'FR' && reasonIdx !== 18) || (config.country === 'UK' && reasonIdx !== 9) || (config.country === 'DE' && reasonIdx !== 13)) {
                if (config.country === 'FR') reasonIdx = 18; // Force Column S for FR (Index 18)
                else if (config.country === 'UK') reasonIdx = 9;  // Force Column J for UK (Index 9)
                else if (config.country === 'DE') reasonIdx = 13; // Force Column N for DE (Index 13)
                else if (reasonIdx === -1) {
                    if (config.country === 'IT') reasonIdx = 12;
                    else if (config.country === 'ES') reasonIdx = 13;
                    else reasonIdx = 13;
                }
            }

            // Also force ASIN column for DE if not correctly detected
            if (config.country === 'DE') finalAsinIdx = 1; // Force Column B for Germany (Index 1)
            if (config.country === 'ES') {
                console.log(`[BuyBox Debug] ES Headers found:`, headers);
            }

            // Skip header row and all rows above it
            for (let i = headerRowIdx + 1; i < jsonData.length; i++) {
                const row = jsonData[i];
                if (!row || row.length <= Math.max(finalAsinIdx, reasonIdx)) continue;

                const rawAsin = String(row[finalAsinIdx] || '').trim().toUpperCase();
                if (!rawAsin || rawAsin.length < 5) continue;

                const rawReason = String(row[reasonIdx] || '').trim();

                // Debug specific ASIN reported by user
                const isTargetAsin = rawAsin === 'B0D3874WSD' || rawAsin.includes('B0D3874WSD');
                if (isTargetAsin) {
                    console.log(`[BuyBox Debug] Found ASIN ${rawAsin} in ${config.country}. Row data at reasonIdx (${reasonIdx}): "${row[reasonIdx]}", Processed Reason: "${rawReason}"`);
                }

                // Only consider as BB lost if there is an Issue Type / Reason specified
                const lowReason = rawReason.toLowerCase();
                if (!rawReason || lowReason === 'fixed' || lowReason === 'ok' || lowReason === 'hecho' || lowReason === 'solucionado' || lowReason === 'corrected') {
                    if (isTargetAsin) {
                        console.log(`[BuyBox Debug] SKIPPING ASIN ${rawAsin} in ${config.country} because reason is empty or matches positive status list ("${rawReason}")`);
                    }
                    continue;
                }

                let entry = buyBoxMap.get(rawAsin);
                if (!entry) {
                    entry = { countries: [], reasons: {} };
                    buyBoxMap.set(rawAsin, entry);
                }

                if (!entry.countries.includes(config.country)) {
                    entry.countries.push(config.country);
                }

                // Collect reason for this country
                entry.reasons[config.country] = rawReason;
            }
        }

        console.log(`[BuyBox] Processed ${buyBoxMap.size} total ASINs with BB lost across all countries`);
        return buyBoxMap;
    } catch (error) {
        console.error("Error processing Buy Box Excel:", error);
        throw error;
    }
};