feat: implement Forecast 2026 (Fc 26) tab with seasonality logic and actual sales comparison

services/dataProcessor.ts

@@ -1,4 +1,4 @@
-import { SalesRecord, AdsRecord, TrafficRecord, CombinedKPIs, FilterState, AggregatedData, LineGrowthMetric, ItemGrowthMetric, SeasonalityPoint, YearlySplitData, PivotRow, YearlyData, TimeSeriesData, ComparisonTimeSeriesPoint } from '../types';
+import { SalesRecord, AdsRecord, TrafficRecord, CombinedKPIs, FilterState, AggregatedData, LineGrowthMetric, ItemGrowthMetric, SeasonalityPoint, YearlySplitData, PivotRow, YearlyData, TimeSeriesData, ComparisonTimeSeriesPoint, ForecastRecord, MonthlyForecastPoint, ProductForecastData } from '../types';
 import * as XLSX from 'xlsx';
 import Papa from 'papaparse';
 
@@ -1496,3 +1496,96 @@ export const pivotWeeklySalesData = (data: CombinedKPIs[]): {
         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'))
+        })).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 }>
+): ProductForecastData[] => {
+    const data2025 = rawData.filter(r => r.year === 2025);
+    const data2026 = rawData.filter(r => r.year === 2026);
+
+    // Calculate Global Seasonality weights for 2025
+    const getWeights = (records: SalesRecord[]) => {
+        const weights = new Array(12).fill(0);
+        let total = 0;
+        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 (total === 0) return new Array(12).fill(1 / 12);
+        return weights.map(w => w / total);
+    };
+
+    const globalWeights = getWeights(data2025);
+
+    // Map 2025 data by ASIN for quick access
+    const dataByAsin2025 = new Map<string, SalesRecord[]>();
+    data2025.forEach(r => {
+        const key = r.asin.trim().toUpperCase();
+        if (!dataByAsin2025.has(key)) dataByAsin2025.set(key, []);
+        dataByAsin2025.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);
+    });
+
+    return forecastData.map(fc => {
+        const identifier = fc.asin.toUpperCase();
+        const meta = asinMetadata.get(identifier);
+
+        // 1. Determine weights (Product specific or global backup)
+        const productRecords2025 = dataByAsin2025.get(identifier) || [];
+        const weights = productRecords2025.length > 0 ? getWeights(productRecords2025) : globalWeights;
+
+        // 2. Build monthly points
+        const monthlyData: MonthlyForecastPoint[] = MONTH_ORDER.map((m, idx) => {
+            const forecastUnits = Math.round(fc.annualForecast * weights[idx]);
+            const actualUnits = actuals2026.get(identifier)?.get(m) || 0;
+            return {
+                month: m,
+                forecastUnits,
+                actualUnits
+            };
+        });
+
+        return {
+            asin: identifier,
+            sku: meta?.sku || identifier, // Fallback to ASIN if SKU not found
+            title: meta?.title || identifier,
+            annualForecast: fc.annualForecast,
+            monthlyData
+        };
+    });
+};