import React, { useMemo, useState, useEffect, useCallback, useRef } from 'react';
import * as XLSX from 'xlsx';
import { CombinedKPIs } from '../types';
import { pivotWeeklySalesData, WeeklyPivotRow, PAN_EU_COUNTRIES } from '../services/dataProcessor';
import { StockBadge } from './StockBadge';
import { InColumnStockFilter } from './InColumnStockFilter';
import { Top50Badge } from './Top50Badge';
import { VendorStockBadge } from './VendorStockBadge';
import { BuyBoxWarningBadge } from './BuyBoxWarningBadge';
import { WarehouseIcon, AmazonSmileIcon, CoverageIcon } from './Icons';

interface WeeklyGridProps {
    data: CombinedKPIs[];
    top50Ranking?: {
        eu: Map<string, number>;
        uk: Map<string, number>;
    };
    onDrillDown?: (sku: string) => void;
    stockMap?: Map<string, number>;
    stockFilter: string[];
    onStockFilterChange: (newFilters: string[]) => void;
    customerFilters: string[];
    vendorStockMap?: Map<string, { eu: number; uk: number }>;
    vendorStockFilter: string[];
    onVendorStockFilterChange: (newFilters: string[]) => void;
    wocFilter: string[];
    onWocFilterChange: (newFilters: string[]) => void;
    velocityMap?: Map<string, number>;
    buyBoxLostMap?: Map<string, { countries: string[]; reasons: Record<string, string> }>;
    top50Mode?: 'eu' | 'uk';
}

type SortConfig = {
    key: string; // weekKey or 'rank'
    direction: 'asc' | 'desc';
    metric: 'units' | 'spend' | 'rank' | 'gv';
} | null;

const ROWS_PER_PAGE = 50;
const MAX_VISIBLE_WEEKS = 20; // Limit visible weeks for performance

// Debounce hook for search
const useDebounce = (value: string, delay: number) => {
    const [debouncedValue, setDebouncedValue] = useState(value);
    useEffect(() => {
        const handler = setTimeout(() => setDebouncedValue(value), delay);
        return () => clearTimeout(handler);
    }, [value, delay]);
    return debouncedValue;
};

const WeeklyRow: React.FC<{
    row: WeeklyPivotRow;
    weeks: string[];
    onDrillDown?: (sku: string) => void;
    stockMap?: Map<string, number>;
    top50Ranking?: { eu: Map<string, number>; uk: Map<string, number> };
    top50Mode: 'eu' | 'uk';
    sortConfig: SortConfig;
    renderGrowth: (current: number, previous: number) => React.ReactNode;
    customerFilters: string[];
    vendorStockMap?: Map<string, { eu: number; uk: number }>;
    velocityMap?: Map<string, number>;
    buyBoxLostMap?: Map<string, { countries: string[]; reasons: Record<string, string> }>;
}> = React.memo(({ row, weeks, onDrillDown, stockMap, top50Ranking, top50Mode, sortConfig, renderGrowth, customerFilters, vendorStockMap, velocityMap, buyBoxLostMap }) => {
    const ranks: { rank: number; label: string; theme: 'amber' | 'blue' | 'indigo' }[] = [];
    const asin = row.asin.trim().toUpperCase();

    if (top50Ranking) {
        if (top50Mode === 'eu') {
            const rank = top50Ranking.eu.get(asin);
            if (rank) ranks.push({ rank, label: 'EU', theme: 'indigo' });
        } else {
            const rank = top50Ranking.uk.get(asin);
            if (rank) ranks.push({ rank, label: 'UK', theme: 'blue' });
        }
    }

    return (
        <tr className="hover:bg-white/[0.02] transition-colors group">
            <td className="p-3 py-2 sticky left-0 z-10 bg-slate-900 group-hover:bg-slate-800 border-r border-white/10">
                <div className="flex flex-col">
                    <div className="flex items-center gap-2 mb-0.5">
                        {ranks.map((r, i) => (
                            <Top50Badge key={i} rank={r.rank} label={r.label} theme={r.theme} />
                        ))}
                        <span
                            onClick={() => onDrillDown?.(row.sku)}
                            className={`text-xs font-black uppercase tracking-tighter truncate max-w-[120px] transition-all
                                ${onDrillDown ? 'text-indigo-400 cursor-pointer hover:text-indigo-300 hover:underline' : 'text-indigo-400/70'}`}
                            title={onDrillDown ? `Click to see Ads detail for ${row.sku}` : ''}
                        >
                            {row.sku || '-'}
                        </span>
                        <span className="text-[10px] font-bold text-slate-500 bg-slate-800 px-1.5 py-0.5 rounded border border-white/5">{row.asin}</span>
                    </div>
                    <div className="flex items-start gap-2 mb-1">
                        <span className="text-[11px] text-white/70 truncate w-[190px] leading-tight" title={row.title}>{row.title}</span>
                        {stockMap && (
                            <StockBadge stock={stockMap.get(row.sku?.replace(/(DE|EN)$/i, ''))} />
                        )}
                        <VendorStockBadge
                            asin={asin}
                            vendorStockMap={vendorStockMap}
                            mode={top50Mode}
                            avgWeeklySales={velocityMap?.get(asin)}
                        />
                        <BuyBoxWarningBadge asin={asin} buyBoxLostMap={buyBoxLostMap} />
                    </div>
                    <span className="text-[9px] text-fuchsia-400/80 font-bold uppercase tracking-widest">{row.line}</span>
                </div>
            </td>
            {weeks.map((week, idx) => {
                const val = row.unitsByWeek[week] || 0;
                const prevVal = row.unitsByWeek[weeks[idx + 1]] || 0;
                const spend = row.spendByWeek[week] || 0;
                const prevSpend = row.spendByWeek[weeks[idx + 1]] || 0;
                return (
                    <td key={week} className={`p-3 py-2 text-center border-r border-white/5 align-middle ${sortConfig?.key === week ? 'bg-white/[0.01]' : ''}`}>
                        <div className="flex flex-col items-center justify-center gap-0.5">
                            <div className="flex items-center gap-1">
                                <span className={`text-sm font-bold ${val > 0 ? (sortConfig?.key === week && sortConfig.metric === 'units' ? 'text-indigo-400' : 'text-white') : 'text-slate-700'}`}>
                                    {val > 0 ? val.toLocaleString('de-DE') : '-'}
                                </span>
                                {val > 0 && renderGrowth(val, prevVal)}
                            </div>
                            <div className="flex flex-col items-center">
                                {spend > 0 && (
                                    <div className="flex items-center gap-1">
                                        <span className={`text-[11px] font-medium ${sortConfig?.key === week && sortConfig.metric === 'spend' ? 'text-amber-300' : 'text-indigo-400/80'}`}>
                                            €{spend.toLocaleString('de-DE', { minimumFractionDigits: 0, maximumFractionDigits: 0 })}
                                        </span>
                                        {renderGrowth(spend, prevSpend)}
                                    </div>
                                )}
                                {row.gvByWeek?.[week] > 0 && (
                                    <div className="flex items-center gap-1">
                                        <span className={`text-[9px] font-black tracking-tighter ${sortConfig?.key === week && sortConfig.metric === 'gv' ? 'text-teal-300' : 'text-teal-500/70'}`}>
                                            GV: {row.gvByWeek[week].toLocaleString('de-DE')}
                                        </span>
                                        {renderGrowth(row.gvByWeek[week], row.gvByWeek?.[weeks[idx + 1]] || 0)}
                                    </div>
                                )}
                            </div>
                        </div>
                    </td>
                );
            })}
        </tr>
    );
});

const WeeklyGrid: React.FC<WeeklyGridProps & { top50Mode: 'eu' | 'uk' }> = ({
    data,
    top50Ranking,
    onDrillDown,
    stockMap,
    vendorStockMap,
    stockFilter,
    onStockFilterChange,
    vendorStockFilter,
    onVendorStockFilterChange,
    wocFilter,
    onWocFilterChange,
    customerFilters,
    top50Mode,
    velocityMap,
    buyBoxLostMap
}) => {
    // Pivot data - memoized
    const { rows, weeks: allWeeks } = useMemo(() => pivotWeeklySalesData(data), [data]);

    // Limit visible weeks for performance
    const weeks = useMemo(() => allWeeks.slice(0, MAX_VISIBLE_WEEKS), [allWeeks]);

    const [searchTerm, setSearchTerm] = useState('');
    const debouncedSearch = useDebounce(searchTerm, 300);
    const [currentPage, setCurrentPage] = useState(1);
    const [growthFilterMode, setGrowthFilterMode] = useState<'all' | 'up' | 'down' | 'stable'>('all');
    const [growthThreshold, setGrowthThreshold] = useState(10);
    const [showOnlyTop50, setShowOnlyTop50] = useState(false);
    const [displayCount, setDisplayCount] = useState(50);
    const scrollContainerRef = useRef<HTMLDivElement>(null);

    // Default sort: most recent week, descending, units
    const [sortConfig, setSortConfig] = useState<SortConfig>(() => {
        if (weeks.length > 0) {
            return { key: weeks[0], direction: 'desc', metric: 'units' };
        }
        return null;
    });

    // Reset pagination when search changes
    useEffect(() => {
        setCurrentPage(1);
        setDisplayCount(50);
    }, [debouncedSearch, showOnlyTop50, top50Mode]);

    const handleSort = useCallback((weekKey: string, metric: 'units' | 'spend' | 'rank' | 'gv') => {
        setSortConfig(prev => {
            if (prev?.key === weekKey && prev.metric === metric) {
                return { key: weekKey, direction: prev.direction === 'asc' ? 'desc' : 'asc', metric };
            }
            return { key: weekKey, direction: metric === 'rank' ? 'asc' : 'desc', metric };
        });
    }, []);

    // Calculate totals in a SINGLE PASS
    const weekTotals = useMemo(() => {
        const totals: { [weekKey: string]: { units: number, spend: number, gv: number } } = {};
        const visibleWeeks = weeks;

        // Initialize visible weeks
        for (let i = 0; i < visibleWeeks.length; i++) {
            totals[visibleWeeks[i]] = { units: 0, spend: 0, gv: 0 };
        }

        // Single pass through rows
        for (let i = 0; i < rows.length; i++) {
            const row = rows[i];
            for (let j = 0; j < visibleWeeks.length; j++) {
                const w = visibleWeeks[j];
                totals[w].units += (row.unitsByWeek[w] || 0);
                totals[w].spend += (row.spendByWeek[w] || 0);
                totals[w].gv += (row.gvByWeek?.[w] || 0);
            }
        }
        return totals;
    }, [rows, weeks]);

    // 1. Filter by search term, Top 50, and growth (using debounced value)
    const filteredRows = useMemo(() => {
        let result = rows;

        // Top 50 Filter
        if (showOnlyTop50 && top50Ranking) {
            result = result.filter(r => {
                const asin = r.asin.trim().toUpperCase();
                const isUK = r.customer.toLowerCase().includes('uk');

                if (top50Mode === 'eu') {
                    return !isUK && top50Ranking.eu.has(asin);
                } else {
                    return isUK && top50Ranking.uk.has(asin);
                }
            });
        }

        // Search Filter
        if (debouncedSearch) {
            const lowSearch = debouncedSearch.toLowerCase();
            result = result.filter(r =>
                r.sku.toLowerCase().includes(lowSearch) ||
                r.asin.toLowerCase().includes(lowSearch) ||
                r.title.toLowerCase().includes(lowSearch) ||
                r.line.toLowerCase().includes(lowSearch)
            );
        }

        // Growth Filter (if active)
        if (growthFilterMode !== 'all' && sortConfig) {
            const currentWeek = sortConfig.key;
            const currentWeekIdx = weeks.indexOf(currentWeek);
            const prevWeek = weeks[currentWeekIdx + 1];

            if (prevWeek) {
                result = result.filter(r => {
                    const currentUnits = r.unitsByWeek[currentWeek] || 0;
                    const prevUnits = r.unitsByWeek[prevWeek] || 0;

                    if (prevUnits === 0) {
                        if (currentUnits === 0) return growthFilterMode === 'stable';
                        return growthFilterMode === 'up';
                    }

                    const growth = ((currentUnits - prevUnits) / prevUnits) * 100;

                    if (growthFilterMode === 'up') return growth >= growthThreshold;
                    if (growthFilterMode === 'down') return growth <= -Math.abs(growthThreshold);
                    if (growthFilterMode === 'stable') return Math.abs(growth) < growthThreshold;
                    return true;
                });
            }
        }

        // WOC Filter
        if (wocFilter && wocFilter.length > 0 && velocityMap && vendorStockMap) {
            result = result.filter(r => {
                const asin = r.asin.trim().toUpperCase();
                const stockData = vendorStockMap.get(asin);
                if (!stockData) return false;

                const stock = top50Mode === 'uk' ? stockData.uk : stockData.eu;
                const velocity = velocityMap.get(asin) || 0;

                let woc: number = 0;
                if (velocity > 0) {
                    woc = stock / velocity;
                } else if (stock > 0) {
                    woc = 999;
                }

                return wocFilter.some(f => {
                    if (f === '< 4 Weeks') return woc < 4;
                    if (f === '> 4 Weeks') return woc >= 4;
                    if (f === 'Out of Stock') return woc === 0;
                    if (f === 'Infinite Cover') return woc === 999;
                    return true;
                });
            });
        }

        return result;
    }, [rows, debouncedSearch, showOnlyTop50, top50Ranking, growthFilterMode, growthThreshold, sortConfig, weeks, top50Mode, wocFilter, velocityMap, vendorStockMap]);

    // 2. Sort results
    const sortedRows = useMemo(() => {
        if (!sortConfig || filteredRows.length === 0) return filteredRows;

        const result = [...filteredRows];
        const { key: weekKey, direction, metric } = sortConfig;

        if (metric === 'rank') {
            if (!top50Ranking) return result;
            const rankMap = top50Mode === 'eu' ? top50Ranking.eu : top50Ranking.uk;

            result.sort((a, b) => {
                const asinA = a.asin.trim().toUpperCase();
                const asinB = b.asin.trim().toUpperCase();
                const rankA = rankMap.get(asinA) || 999;
                const rankB = rankMap.get(asinB) || 999;
                return direction === 'asc' ? rankA - rankB : rankB - rankA;
            });
        } else {
            const metricKey = metric === 'units' ? 'unitsByWeek' :
                metric === 'spend' ? 'spendByWeek' : 'gvByWeek';

            result.sort((a, b) => {
                const valA = a[metricKey][weekKey] || 0;
                const valB = b[metricKey][weekKey] || 0;
                if (valA === valB) return 0;
                return direction === 'asc' ? valA - valB : valB - valA;
            });
        }

        return result;
    }, [filteredRows, sortConfig, top50Ranking, top50Mode]);

    // 3. Paginate
    const paginatedRows = useMemo(() => {
        const start = (currentPage - 1) * ROWS_PER_PAGE;
        return sortedRows.slice(start, start + ROWS_PER_PAGE);
    }, [sortedRows, currentPage]);

    const totalPages = Math.ceil(sortedRows.length / ROWS_PER_PAGE);

    const renderGrowth = useCallback((current: number, previous: number) => {
        if (!previous || previous === 0) return null;
        const pct = ((current - previous) / previous) * 100;
        const isPositive = pct >= 0;

        return (
            <span className={`text-[10px] font-bold ${isPositive ? 'text-emerald-400' : 'text-red-400'}`}>
                {isPositive ? '▲' : '▼'}{Math.abs(pct).toFixed(0)}%
            </span>
        );
    }, []);

    // Export to Excel
    const handleExportExcel = useCallback(() => {
        const exportData = sortedRows.map(row => {
            const rowData: { [key: string]: string | number } = {
                SKU: row.sku,
                ASIN: row.asin,
                Title: row.title,
                Line: row.line,
            };
            allWeeks.forEach(week => {
                rowData[`${week} Units`] = row.unitsByWeek[week] || 0;
                rowData[`${week} Spend`] = row.spendByWeek[week] || 0;
                rowData[`${week} GV`] = row.gvByWeek[week] || 0;
            });
            return rowData;
        });

        const totalsRow: any = {
            SKU: 'TOTALS',
            ASIN: '',
            Title: 'ALL FILTERED PRODUCTS',
            Line: '',
        };
        allWeeks.forEach(week => {
            totalsRow[`${week} Units`] = weekTotals[week]?.units || 0;
            totalsRow[`${week} Spend`] = weekTotals[week]?.spend || 0;
            totalsRow[`${week} GV`] = weekTotals[week]?.gv || 0;
        });
        exportData.push(totalsRow);

        const ws = XLSX.utils.json_to_sheet(exportData);
        const wb = XLSX.utils.book_new();
        XLSX.utils.book_append_sheet(wb, ws, 'Weekly Sales');
        XLSX.writeFile(wb, `Weekly_Sales_Export_${new Date().toISOString().slice(0, 10)}.xlsx`);
    }, [sortedRows, allWeeks, weekTotals]);

    return (
        <div className="flex flex-col gap-4 animate-fade-in">
            {/* Toolbar: Search & Pagination */}
            <div className="flex flex-col lg:flex-row justify-between items-center gap-4 bg-slate-900 border border-white/10 p-4 rounded-xl shadow-lg">
                <div className="flex flex-wrap items-center gap-4 w-full lg:w-auto">
                    {/* Search Input */}
                    <div className="relative w-full md:w-80">
                        <input
                            type="text"
                            placeholder="Search SKU, Title, or ASIN..."
                            value={searchTerm}
                            onChange={(e) => setSearchTerm(e.target.value)}
                            className="w-full bg-slate-950 border border-white/10 rounded-lg px-4 py-2 text-sm text-white focus:outline-none focus:ring-2 focus:ring-indigo-500 transition-all pl-10"
                        />
                        <svg className="absolute left-3 top-2.5 w-4 h-4 text-slate-500" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M21 21l-6-6m2-5a7 7 0 11-14 0 7 7 0 0114 0z" />
                        </svg>
                    </div>

                    {/* Growth Filter */}
                    <div className="flex items-center gap-2 bg-slate-950/50 p-1.5 px-3 rounded-lg border border-white/5">
                        <span className="text-[11px] font-black text-slate-500 uppercase tracking-widest">Growth Filter</span>
                        <select
                            value={growthFilterMode}
                            onChange={(e) => setGrowthFilterMode(e.target.value as any)}
                            className="bg-slate-900 border border-white/10 rounded px-2 py-1 text-xs text-white focus:outline-none focus:ring-1 focus:ring-indigo-500"
                        >
                            <option value="all">All Products</option>
                            <option value="up">Gaining</option>
                            <option value="down">Dropping</option>
                            <option value="stable">Stable</option>
                        </select>
                        {growthFilterMode !== 'all' && (
                            <div className="flex items-center gap-1.5 ml-1 border-l border-white/10 pl-3">
                                <span className="text-[10px] text-slate-500 font-bold">Thresh:</span>
                                <input
                                    type="number"
                                    value={growthThreshold}
                                    onChange={(e) => setGrowthThreshold(Number(e.target.value))}
                                    className="w-12 bg-slate-900 border border-white/10 rounded px-1.5 py-1 text-xs text-white text-center focus:outline-none focus:ring-1 focus:ring-indigo-500"
                                />
                                <span className="text-[10px] text-slate-500">%</span>
                            </div>
                        )}
                    </div>

                    {/* Top 50 Filter Toggle */}
                    {top50Ranking && (
                        (top50Ranking.eu.size || 0) > 0 ||
                        (top50Ranking.uk.size || 0) > 0
                    ) && (
                            <div className="flex bg-slate-950/50 p-1 rounded-xl border border-white/10 shadow-sm">
                                <button
                                    onClick={() => {
                                        const newMode = !showOnlyTop50;
                                        setShowOnlyTop50(newMode);
                                        if (newMode) handleSort('rank', 'rank');
                                    }}
                                    className={`flex items-center gap-2 px-3 py-1.5 rounded-lg text-xs font-bold transition-all ${showOnlyTop50
                                        ? 'bg-gradient-to-r from-amber-500 to-orange-500 text-white shadow-lg shadow-amber-500/20'
                                        : 'text-slate-400 hover:text-amber-400'
                                        }`}
                                >
                                    <span className="text-sm">🏆</span>
                                    Top 50 ({top50Mode.toUpperCase()})
                                </button>
                            </div>
                        )}

                    {/* Export Button */}
                    <button
                        onClick={handleExportExcel}
                        className="flex items-center gap-2 bg-emerald-600 hover:bg-emerald-500 text-white px-3 py-1.5 rounded-lg text-xs font-bold transition-colors border border-emerald-500/50"
                    >
                        <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                            <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 10v6m0 0l-3-3m3 3l3-3m2 8H7a2 2 0 01-2-2V5a2 2 0 012-2h5.586a1 1 0 01.707.293l5.414 5.414a1 1 0 01.293.707V19a2 2 0 01-2 2z" />
                        </svg>
                        Export Excel
                    </button>
                </div>

                <div className="flex items-center gap-3">
                    <span className="text-sm text-slate-500 whitespace-nowrap">
                        Showing {Math.min(filteredRows.length, (currentPage - 1) * ROWS_PER_PAGE + 1)}-{Math.min(filteredRows.length, currentPage * ROWS_PER_PAGE)} of {filteredRows.length}
                    </span>
                    <div className="flex items-center gap-1">
                        <button
                            onClick={() => setCurrentPage(p => Math.max(1, p - 1))}
                            disabled={currentPage === 1}
                            className="p-2 bg-slate-800 hover:bg-slate-700 disabled:opacity-30 disabled:hover:bg-slate-800 rounded-lg transition-colors border border-white/5"
                        >
                            <svg className="w-4 h-4 text-white" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 19l-7-7 7-7" /></svg>
                        </button>
                        <span className="bg-slate-950 border border-white/10 px-3 py-1.5 rounded-lg text-xs font-bold text-white min-w-[60px] text-center">
                            {currentPage} / {Math.max(1, totalPages)}
                        </span>
                        <button
                            onClick={() => setCurrentPage(p => Math.min(totalPages, p + 1))}
                            disabled={currentPage >= totalPages}
                            className="p-2 bg-slate-800 hover:bg-slate-700 disabled:opacity-30 disabled:hover:bg-slate-800 rounded-lg transition-colors border border-white/5"
                        >
                            <svg className="w-4 h-4 text-white" fill="none" stroke="currentColor" viewBox="0 0 24 24"><path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 5l7 7-7 7" /></svg>
                        </button>
                    </div>
                </div>
            </div>

            <div className="bg-slate-900 border border-white/10 rounded-xl overflow-hidden shadow-2xl flex-1 min-h-0">
                <div className="overflow-x-auto overflow-y-auto h-full max-h-[calc(100vh-220px)] custom-scrollbar">
                    <table className="w-full text-left border-collapse min-w-[max-content]">
                        <thead className="sticky top-0 z-20 bg-slate-900">
                            <tr className="bg-slate-900 border-b border-white/10 relative z-30">
                                <th
                                    onClick={() => handleSort('rank', 'rank')}
                                    className="p-3 text-[11px] font-black text-slate-400 uppercase tracking-widest sticky left-0 z-40 bg-slate-900 border-r border-white/10 min-w-[240px] cursor-pointer hover:bg-white/5 transition-colors group"
                                >
                                    <div className="flex items-center gap-2">
                                        <span>Product Details</span>
                                        <div className="flex items-center gap-1">
                                            <InColumnStockFilter
                                                currentFilters={stockFilter}
                                                onFilterChange={onStockFilterChange}
                                                title="Warehouse Stock"
                                                icon={<WarehouseIcon className="w-3.5 h-3.5 text-fuchsia-400" />}
                                            />
                                            <InColumnStockFilter
                                                currentFilters={vendorStockFilter}
                                                onFilterChange={onVendorStockFilterChange}
                                                title="Vendor Stock"
                                                icon={<AmazonSmileIcon className="w-5 h-5 text-amber-500" />}
                                                options={[
                                                    'Out of Stock (0)',
                                                    'In Stock (>0)',
                                                    'In Stock (>20)',
                                                    'Low Stock (<10)',
                                                ]}
                                            />
                                            <InColumnStockFilter
                                                currentFilters={wocFilter}
                                                onFilterChange={onWocFilterChange}
                                                title="Week Coverage"
                                                icon={<CoverageIcon className="w-3.5 h-3.5 text-emerald-400" />}
                                                options={[
                                                    '< 4 Weeks',
                                                    '> 4 Weeks',
                                                    'Out of Stock',
                                                    'Infinite Cover'
                                                ]}
                                            />
                                        </div>
                                        {sortConfig?.metric === 'rank' && (
                                            <span className="text-amber-500 font-black text-sm animate-bounce-subtle">
                                                {sortConfig.direction === 'asc' ? '↑' : '↓'}
                                            </span>
                                        )}
                                    </div>
                                </th>
                                {weeks.map(week => (
                                    <th
                                        key={week}
                                        className={`p-0 text-[10px] font-black uppercase tracking-widest text-center border-r border-white/10 min-w-[130px] transition-colors select-none ${sortConfig?.key === week ? 'bg-white/[0.02]' : ''}`}
                                    >
                                        <div className="flex flex-col h-full">
                                            <div className="p-2 border-b border-white/5 bg-slate-800/30 text-xs text-white">
                                                {week.split('-')[1]}/{week.split('-')[0].slice(-2)}
                                            </div>

                                            <div
                                                onClick={() => handleSort(week, 'units')}
                                                className={`flex-1 p-1.5 cursor-pointer hover:bg-indigo-500/10 transition-colors flex items-center justify-center gap-1 border-b border-white/5 ${sortConfig?.key === week && sortConfig.metric === 'units' ? 'bg-indigo-500/5 text-indigo-400' : 'text-slate-500 hover:text-slate-300'}`}
                                            >
                                                <span className="text-[9px]">Units</span>
                                                {sortConfig?.key === week && sortConfig.metric === 'units' && (
                                                    <span className="text-xs font-bold leading-none">{sortConfig.direction === 'asc' ? '↑' : '↓'}</span>
                                                )}
                                            </div>

                                            <div
                                                onClick={() => handleSort(week, 'spend')}
                                                className={`flex-1 p-1.5 cursor-pointer hover:bg-amber-500/10 transition-colors flex items-center justify-center gap-1 border-b border-white/5 ${sortConfig?.key === week && sortConfig.metric === 'spend' ? 'bg-amber-500/5 text-amber-400' : 'text-slate-500 hover:text-slate-300'}`}
                                            >
                                                <span className="text-[9px]">Spend</span>
                                                {sortConfig?.key === week && sortConfig.metric === 'spend' && (
                                                    <span className="text-xs font-bold leading-none">{sortConfig.direction === 'asc' ? '↑' : '↓'}</span>
                                                )}
                                            </div>

                                            <div
                                                onClick={() => handleSort(week, 'gv')}
                                                className={`flex-1 p-1.5 cursor-pointer hover:bg-teal-500/10 transition-colors flex items-center justify-center gap-1 ${sortConfig?.key === week && sortConfig.metric === 'gv' ? 'bg-teal-500/5 text-teal-400' : 'text-slate-500 hover:text-slate-300'}`}
                                            >
                                                <span className="text-[9px]">GV</span>
                                                {sortConfig?.key === week && sortConfig.metric === 'gv' && (
                                                    <span className="text-xs font-bold leading-none">{sortConfig.direction === 'asc' ? '↑' : '↓'}</span>
                                                )}
                                            </div>
                                        </div>
                                    </th>
                                ))}
                            </tr>
                            <tr className="bg-indigo-950 border-b border-white/10 relative z-20">
                                <th className="p-3 text-sm font-black text-white sticky left-0 z-40 bg-indigo-950 border-r border-white/10">TOTALS</th>
                                {weeks.map((week, idx) => (
                                    <th key={week} className="p-3 text-sm font-black text-white text-center border-r border-white/10">
                                        <div className="flex flex-col items-center">
                                            <div className="flex items-center gap-1">
                                                <span>{weekTotals[week]?.units.toLocaleString('de-DE') || 0}</span>
                                                {renderGrowth(weekTotals[week]?.units || 0, weekTotals[weeks[idx + 1]]?.units || 0)}
                                            </div>
                                            <div className="flex items-center justify-center gap-1 text-[10px] text-indigo-400 font-bold">
                                                <span>€{(weekTotals[week]?.spend || 0).toLocaleString('de-DE', { minimumFractionDigits: 0, maximumFractionDigits: 0 })}</span>
                                                {renderGrowth(weekTotals[week]?.spend || 0, weekTotals[weeks[idx + 1]]?.spend || 0)}
                                            </div>
                                            <div className="flex items-center justify-center gap-1 text-[9px] text-teal-400 font-black tracking-tight mt-0.5">
                                                <span>GV: {(weekTotals[week]?.gv || 0).toLocaleString('de-DE')}</span>
                                                {renderGrowth(weekTotals[week]?.gv || 0, weekTotals[weeks[idx + 1]]?.gv || 0)}
                                            </div>
                                        </div>
                                    </th>
                                ))}
                            </tr>
                        </thead>
                        <tbody className="divide-y divide-white/5">
                            {sortedRows.length > 0 ? (
                                (() => {
                                    const displayRows = sortedRows.slice(0, displayCount);
                                    return (
                                        <>
                                            {displayRows.map(row => (
                                                <WeeklyRow
                                                    key={row.id}
                                                    row={row}
                                                    weeks={weeks}
                                                    onDrillDown={onDrillDown}
                                                    stockMap={stockMap}
                                                    vendorStockMap={vendorStockMap}
                                                    top50Ranking={top50Ranking}
                                                    top50Mode={top50Mode}
                                                    sortConfig={sortConfig}
                                                    renderGrowth={renderGrowth}
                                                    customerFilters={customerFilters}
                                                    velocityMap={velocityMap}
                                                    buyBoxLostMap={buyBoxLostMap}
                                                />
                                            ))}
                                            {displayCount < sortedRows.length && (
                                                <tr>
                                                    <td colSpan={weeks.length + 1} className="p-6 text-center bg-slate-900/50 backdrop-blur-sm border-t border-white/5">
                                                        <button
                                                            onClick={() => setDisplayCount(prev => prev + 100)}
                                                            className="px-6 py-2.5 bg-indigo-600 hover:bg-indigo-500 text-white rounded-xl text-xs font-black uppercase tracking-widest shadow-xl transition-all active:scale-95 border border-indigo-400/30"
                                                        >
                                                            Load More SKUs ({sortedRows.length - displayCount} remaining)
                                                        </button>
                                                    </td>
                                                </tr>
                                            )}
                                        </>
                                    );
                                })()
                            ) : (
                                <tr>
                                    <td colSpan={weeks.length + 1} className="p-10 text-center text-slate-500 italic text-base">
                                        No SKUs found matching "{debouncedSearch}"
                                    </td>
                                </tr>
                            )}
                        </tbody>
                    </table>
                </div>
            </div>
        </div>
    );
};

export default WeeklyGrid;