import React, { useState, useMemo, useEffect, useCallback, Suspense, lazy } from 'react';
import FileUpload from './components/FileUpload';
import Dashboard from './components/Dashboard';
import FilterBar from './components/FilterBar';
import AIChat from './components/AIChat';
import CrazeLogo from './components/CrazeLogo';
import { processCSV, processExcel, filterData, aggregateData, processAdsCSV, processAdsExcel, mergeSalesAndAdsData, processTrafficExcel, processStockExcel, filterAdsData, calculateForecastViewData, processVendorStockExcel, processUKInventoryExcel, calculateVelocityMap, getUniqueValues, processForecastExcel, processBuyBoxExcel, processVendorCSV } from './services/dataProcessor';
import { SalesRecord, FilterState, AggregatedData, AdsRecord, TrafficRecord, ForecastRecord, ProductForecastData, ActiveExperiment } from './types';
import { queryGemini } from './services/geminiService';
import { ChartIcon, TableIcon, UploadIcon, DownloadIcon, CloseIcon, TrendingIcon, MegaphoneIcon } from './components/Icons';
import { loadSalesData, saveSalesData, clearSalesData, loadAdsData, saveAdsData, clearAdsData } from './services/storage';
import { getActiveExperimentsForASINs } from './services/experiments';

// Lazy load heavy components for better initial performance
const DataGrid = lazy(() => import('./components/DataGrid'));
const WeeklyGrid = lazy(() => import('./components/WeeklyGrid'));
const TopMovers = lazy(() => import('./components/TopMovers'));
const AdsPerformance = lazy(() => import('./components/AdsPerformance'));
const ForecastView = lazy(() => import('./components/ForecastView'));
const VendorDataView = lazy(() => import('./components/VendorDataView'));
const ExperimentsView = lazy(() => import('./components/ExperimentsView'));
const ExperimentDetail = lazy(() => import('./components/ExperimentDetail'));
const ExperimentForm = lazy(() => import('./components/ExperimentForm'));

// Loading fallback component
const LoadingSpinner = () => (
  <div className="flex items-center justify-center h-96">
    <div className="animate-spin rounded-full h-12 w-12 border-t-2 border-b-2 border-indigo-500"></div>
  </div>
);

// New Refresh Icon
const RefreshIcon = ({ className }: { className?: string }) => (
  <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" strokeWidth={1.5} stroke="currentColor" className={className || "w-5 h-5"}>
    <path strokeLinecap="round" strokeLinejoin="round" d="M16.023 9.348h4.992v-.001M2.985 19.644v-4.992m0 0h4.992m-4.993 0 3.181 3.183a8.25 8.25 0 0 0 13.803-3.7M4.031 9.865a8.25 8.25 0 0 1 13.803-3.7l3.181 3.182m0-4.991v4.99" />
  </svg>
);

// Hardcoded Permanent URL for Auto-Loading
// Using the original share link to leverage Dropbox's redirect for robust fetching.
const PERMANENT_DROPBOX_URL = "https://www.dropbox.com/scl/fi/b9zxn4z5i7sxwfakk5g5y/Amazon-Sell-Out-2023-2025.csv?rlkey=uoto6v0mm99py8nszy8ldtez8&st=pzn1zkrg&dl=0";
const PERMANENT_ADS_URL = "https://www.dropbox.com/scl/fi/wng8tep7awhvzd65amwad/Ads-Weekly.xlsx?rlkey=kcmoq8dxgibsb2eb8zz47xvyo&st=z02m4w3g&dl=0";

const App: React.FC = () => {
  const [rawData, setRawData] = useState<SalesRecord[]>([]);
  const [adsData, setAdsData] = useState<AdsRecord[]>([]);
  const [trafficData, setTrafficData] = useState<TrafficRecord[]>([]);
  const [loading, setLoading] = useState(true);
  const [syncing, setSyncing] = useState(false);
  const [view, setView] = useState<'dashboard' | 'table' | 'weekly' | 'movers' | 'ads' | 'forecast' | 'vendor' | 'experiments'>('dashboard');
  const [forecastData, setForecastData] = useState<ProductForecastData[]>([]);
  const [isChatOpen, setIsChatOpen] = useState(false);
  const [activeUrl, setActiveUrl] = useState<string | null>(() => localStorage.getItem('craze_csv_url') || PERMANENT_DROPBOX_URL);
  const [lastUpdated, setLastUpdated] = useState<string | null>(null);
  const [stockMap, setStockMap] = useState<Map<string, number>>(new Map());
  const [vendorStockMap, setVendorStockMap] = useState<Map<string, { eu: number; uk: number }>>(new Map());
  const [cachedForecastRecords, setCachedForecastRecords] = useState<ForecastRecord[]>([]);
  const [lastForecastFile, setLastForecastFile] = useState<string | null>(null);
  const [buyBoxLostMap, setBuyBoxLostMap] = useState<Map<string, { countries: string[]; reasons: Record<string, string> }>>(new Map());
  
  // Experiments state
  const [experimentMap, setExperimentMap] = useState<Map<string, ActiveExperiment[]>>(new Map());
  const [selectedExperimentId, setSelectedExperimentId] = useState<string | null>(null);
  const [showCreateExperiment, setShowCreateExperiment] = useState(false);
  const [preselectedAsins, setPreselectedAsins] = useState<string[]>([]);
  const [preselectedMarketplace, setPreselectedMarketplace] = useState<string>('');
  const [preselectedLine, setPreselectedLine] = useState<string>('');
  
  // Available product lines (for experiment form)
  const availableProductLines = useMemo(() => {
    const lines = new Set(rawData.map(r => r.line).filter(Boolean));
    return Array.from(lines).sort();
  }, [rawData]);

  // Modal State
  const [isDataModalOpen, setIsDataModalOpen] = useState(false);

  const [filters, setFilters] = useState<FilterState>({
    customer: [],
    year: [],
    month: [],
    line: [],
    asin: [],
    sku: [],
    title: [],
    week: [],
    stock: [],
    vendorStock: [],
    woc: [],
    bulkSearch: '',
  });

  const top50Mode = useMemo(() => {
    const hasUK = filters.customer.includes('Amazon UK');
    const hasEU = filters.customer.some(c => ['Amazon DE', 'Amazon IT', 'Amazon FR', 'Amazon ES'].includes(c));
    if (hasUK) return 'uk';
    return 'eu';
  }, [filters.customer]);

  // Calculate 4-week Sales Velocity Map (Context-Aware)
  // MOVED HERE TO AVOID REFERENCE ERROR in handleForecastFetch
  const velocityMap = useMemo(() => {
    // Determine which dataset to use for velocity calculation based on region filter
    // If 'uk', use UK data. If 'eu', use EU data.
    // IMPOTANT: We do NOT filter by Week/Month here, so we get the full history for velocity calculation
    const regionData = rawData.filter(r => {
      if (top50Mode === 'uk') return r.customer.toLowerCase().includes('uk');
      // for EU, exclude UK
      return !r.customer.toLowerCase().includes('uk');
    });
    return calculateVelocityMap(regionData);
  }, [rawData, top50Mode]);

  // Handle Data Fetch (Simplified)
  const handleDataFetch = useCallback(async () => {
    setSyncing(true);
    try {
      console.log('[App] Fetching data from /api/fetch-data...');
      const response = await fetch('/api/fetch-data');

      if (!response.ok) {
        throw new Error(`Failed to fetch CSV: ${response.status} ${response.statusText}`);
      }

      const csvText = await response.text();
      const data = await processCSV(csvText);

      await saveSalesData(data);

      initializeData(data);
      setActiveUrl(PERMANENT_DROPBOX_URL);
      const now = new Date().toISOString();
      setLastUpdated(now);
      localStorage.setItem('craze_last_updated', now);
      localStorage.setItem('craze_csv_url', PERMANENT_DROPBOX_URL);
      setIsDataModalOpen(false);

      console.log('[App] Successfully loaded', data.length, 'rows');

      // Refresh forecast too
      handleForecastFetch(data, data, filters);
    } catch (error) {
      console.error("Failed to fetch/parse CSV", error);
      alert("Error loading data. Please refresh the page.");
      throw error;
    } finally {
      setSyncing(false);
      setLoading(false);
    }
  }, []);

  const handleAdsFetch = useCallback(async () => {
    setSyncing(true);
    try {
      console.log('[App] Fetching ads from /api/fetch-ads...');
      const response = await fetch('/api/fetch-ads');

      if (!response.ok) {
        throw new Error(`Failed to fetch Ads: ${response.status} ${response.statusText}`);
      }

      const buffer = await response.arrayBuffer();
      const data = await processAdsExcel(buffer);

      await saveAdsData(data);
      setAdsData(data);
      console.log('[App] Successfully loaded', data.length, 'ads records');
    } catch (error) {
      console.error("Failed to fetch/parse Ads", error);
    } finally {
      setSyncing(false);
    }
  }, []);

  const handleTrafficFetch = useCallback(async () => {
    try {
      console.log('[App] Fetching traffic from /api/fetch-traffic...');
      const response = await fetch('/api/fetch-traffic');
      if (!response.ok) throw new Error(`Failed to fetch traffic: ${response.status}`);

      const buffer = await response.arrayBuffer();
      const data = await processTrafficExcel(buffer);
      setTrafficData(data);
      console.log('[App] Successfully loaded', data.length, 'traffic records');
    } catch (error) {
      console.error("Failed to fetch/parse Traffic", error);
    }
  }, []);

  const handleStockFetch = useCallback(async () => {
    try {
      console.log('[App] Fetching stock from /api/fetch-stock...');
      const response = await fetch('/api/fetch-stock');
      if (!response.ok) throw new Error(`Failed to fetch stock: ${response.status}`);

      const buffer = await response.arrayBuffer();
      const data = await processStockExcel(buffer);
      setStockMap(data);
      console.log('[App] Successfully loaded stock for', data.size, 'normalized SKUs');
    } catch (error) {
      console.error("Failed to fetch/parse Stock", error);
    }
  }, []);

  const handleVendorStockFetch = useCallback(async () => {
    try {
      console.log('[App] Fetching vendor stock (PANEU + UK) from Dropbox...');

      // Fetch both PANEU and UK inventory in parallel
      const [paneuResponse, ukResponse] = await Promise.all([
        fetch('/api/fetch-paneu-stock'),
        fetch('/api/fetch-uk-inventory')
      ]);

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

      // Process PANEU stock (EU countries)
      if (paneuResponse.ok) {
        const paneuBuffer = await paneuResponse.arrayBuffer();
        combinedMap = await processVendorStockExcel(paneuBuffer);
        console.log('[App] PANEU stock loaded:', combinedMap.size, 'ASINs');
      } else {
        console.warn('[App] PANEU fetch failed:', paneuResponse.status);
      }

      // Process UK inventory and merge with existing map
      if (ukResponse.ok) {
        const ukBuffer = await ukResponse.arrayBuffer();
        combinedMap = await processUKInventoryExcel(ukBuffer, combinedMap);
        console.log('[App] UK inventory merged. Total ASINs:', combinedMap.size);
      } else {
        console.warn('[App] UK inventory fetch failed:', ukResponse.status);
      }

      setVendorStockMap(combinedMap);
      console.log('[App] Successfully loaded combined vendor stock for', combinedMap.size, 'ASINs');
    } catch (error) {
      console.error("Failed to fetch/parse Vendor Stock", error);
    }
  }, []);

  const handleBuyBoxFetch = useCallback(async () => {
    try {
      console.log('[App] Fetching Buy Box data from /api/fetch-buybox...');
      const response = await fetch('/api/fetch-buybox');
      if (!response.ok) throw new Error(`Failed to fetch Buy Box data: ${response.status}`);

      const buffer = await response.arrayBuffer();
      const data = await processBuyBoxExcel(buffer);
      setBuyBoxLostMap(data);
      (window as any).debugBuyBox = data;
      console.log('[App] Successfully loaded Buy Box lost data for', data.size, 'ASINs. Access via window.debugBuyBox');
    } catch (error) {
      console.error("Failed to fetch/parse Buy Box data", error);
    }
  }, []);

  const handleExperimentsFetch = useCallback(async () => {
    try {
      const allAsins: string[] = Array.from(new Set(rawData.map(r => String(r.asin).toUpperCase())));
      const expMap = await getActiveExperimentsForASINs(allAsins);
      setExperimentMap(expMap);
      console.log('[App] Loaded experiments for', expMap.size, 'ASINs');
    } catch (error) {
      console.error("Failed to fetch experiments", error);
    }
  }, [rawData]);


  const handleForecastFetch = useCallback(async (sales: SalesRecord[], globalSales: SalesRecord[], activeFilters: FilterState) => {
    try {
      const isUK = activeFilters.customer.includes('Amazon UK');
      const filename = isUK ? '/fc UK 26.xlsx' : '/fc 26.xlsx';

      let fcRecords = cachedForecastRecords;

      if (lastForecastFile !== filename || cachedForecastRecords.length === 0) {
        console.log(`[App] Fetching fresh forecast from ${filename}...`);
        const response = await fetch(filename);
        if (!response.ok) throw new Error(`Forecast file ${filename} not found`);

        const buffer = await response.arrayBuffer();
        fcRecords = await processForecastExcel(buffer);
        setCachedForecastRecords(fcRecords);
        setLastForecastFile(filename);
      } else {
        console.log(`[App] Using cached forecast for ${filename}`);
      }

      // Build precise metadata map from GLOBAL sales records to ensure info is found even if filtered for market
      const meta = new Map<string, { sku: string; title: string; line: string }>();
      const metaDataSource = globalSales.length > 0 ? globalSales : sales;

      metaDataSource.forEach(r => {
        const asin = r.asin.trim().toUpperCase();
        const existing = meta.get(asin);
        if (!existing || (r.title && r.title.length > (existing.title?.length || 0))) {
          meta.set(asin, { sku: r.sku, title: r.title, line: r.line });
        }
      });

      const viewData = calculateForecastViewData(sales, fcRecords, meta, activeFilters, velocityMap, globalSales.length > 0 ? globalSales : undefined);
      setForecastData(viewData);
      console.log('[App] Forecast calculation complete:', viewData.length, 'records');
    } catch (error) {
      console.warn("Forecast fetch failed:", error);
    }
  }, [velocityMap, cachedForecastRecords, lastForecastFile]);

  // Update forecast when filters change
  useEffect(() => {
    if (rawData.length > 0) {
      // Filter rawData to respect customer selections but keep all years (2025 for seasonality, 2026 for actuals)
      const forecastRelevantData = filterData(rawData, {
        ...filters,
        year: [], // Ensure we don't filter out 2025/2026 if a single year is selected in UI
        month: [] // EXCLUDE month filtering to preserve seasonality calculation in calculateForecastViewData
      });
      handleForecastFetch(forecastRelevantData, rawData, filters);
    }
  }, [filters, rawData, handleForecastFetch]);

  const initializeData = (data: SalesRecord[]) => {
    setRawData(data);
    setFilters({
      customer: [],
      year: [],
      month: [],
      line: [],
      asin: [],
      sku: [],
      title: [],
      week: [],
      stock: [],
      vendorStock: [],
      woc: [],
    });
  };

  const handleSkuDrillDown = useCallback((sku: string) => {
    if (!sku) return;
    setFilters(prev => ({
      ...prev,
      sku: [sku]
    }));
    setView('ads');
  }, []);

  // Create experiment for a specific line
  const handleCreateExperimentForLine = useCallback((line: string) => {
    if (!line) return;
    setPreselectedLine(line);
    setPreselectedMarketplace(filters.customer[0] || '');
    setShowCreateExperiment(true);
  }, [filters.customer]);

  // 1. Initial Load from Cache (IndexedDB) or Auto-Fetch Permanent URL
  useEffect(() => {
    const initApp = async () => {
      setLoading(true);

      const currentStoredUrl = localStorage.getItem('craze_csv_url');
      let shouldUseCache = true;

      // Force refresh if URL has changed
      if (currentStoredUrl !== PERMANENT_DROPBOX_URL) {
        console.log("URL changed, forcing refresh...");
        localStorage.setItem('craze_csv_url', PERMANENT_DROPBOX_URL);
        setActiveUrl(PERMANENT_DROPBOX_URL);
        shouldUseCache = false;
      }

      // Try to load from cache first IF the URL hasn't changed
      let cachedData = null;
      let cachedDate = null;
      if (shouldUseCache) {
        const result = await loadSalesData();
        cachedData = result.data;
        cachedDate = result.lastUpdated;
      }

      if (cachedData && cachedData.length > 0) {
        console.log("Loaded data from cache:", cachedData.length, "rows");
        initializeData(cachedData);
        setLastUpdated(cachedDate);
        setLoading(false);
        // Trigger background sync to ensure data is fresh
        handleDataFetch().catch(e => console.warn("Background sales sync failed", e));
      } else {
        console.log("Fetching fresh data from Permanent URL...");
        handleDataFetch().catch(e => {
          console.error("Initial fetch failed.");
        });
      }

      // 1b. Load Ads from cache or auto-fetch
      const { data: cachedAds, lastUpdated: adsLastUpdated } = await loadAdsData();
      if (cachedAds && cachedAds.length > 0) {
        console.log("Loaded ads from cache:", cachedAds.length, "records");
        setAdsData(cachedAds);
        // Trigger background sync
        handleAdsFetch();
      } else {
        console.log("Fetching fresh Ads from URL...");
        handleAdsFetch();
      }

      // 1c-1f. Fetch other data in parallel (non-blocking)
      Promise.all([
        handleTrafficFetch(),
        handleStockFetch(),
        handleVendorStockFetch(),
        handleBuyBoxFetch(),
        handleExperimentsFetch()
      ]).catch(e => console.warn("Background fetch failed", e));

      // 1f. Fetch Forecast data
      handleForecastFetch(cachedData || [], cachedData || [], filters);
    };
    initApp();
  }, [handleDataFetch]);

  // Handle uploaded Sales file (Manual)
  const handleSalesUpload = async (file: File) => {
    setSyncing(true);
    try {
      const data = await processCSV(file);
      await saveSalesData(data);
      initializeData(data);
      setLastUpdated(new Date().toISOString());
      setIsDataModalOpen(false);
      // Also trigger ads fetch if not loaded to maintain sync
      if (adsData.length === 0) handleAdsFetch();
    } catch (error) {
      console.error("Failed to parse CSV", error);
      alert("Error parsing CSV. Please check the format.");
    } finally {
      setSyncing(false);
    }
  };

  // Handle uploaded Ads file (Manual) - Supports both CSV and Excel
  const handleAdsUpload = async (file: File) => {
    setSyncing(true);
    try {
      const isExcel = file.name.endsWith('.xlsx') || file.name.endsWith('.xls');
      const data = isExcel ? await processAdsExcel(file) : await processAdsCSV(file);
      setAdsData(data);
      await saveAdsData(data);
      console.log("Ads loaded:", data.length, "records from", file.name);
      setIsDataModalOpen(false);
    } catch (error: any) {
      console.error("Failed to parse Ads file", error);
      alert(`Error parsing Ads file: ${error.message || 'Unknown error'}. Please check the format.`);
    } finally {
      setSyncing(false);
    }
  };

  // Handle uploaded Traffic file (Manual)
  const handleTrafficUpload = async (file: File) => {
    setSyncing(true);
    try {
      const data = await processTrafficExcel(file);
      setTrafficData(data);
      console.log("Traffic loaded:", data.length, "records from", file.name);
      setIsDataModalOpen(false);
    } catch (error: any) {
      console.error("Failed to parse Traffic file", error);
      alert(`Error parsing Traffic file: ${error.message || 'Unknown error'}. Please check the format.`);
    } finally {
      setSyncing(false);
    }
  };

  // Handle uploaded Vendor CSV (sends to Supabase via API with batching)
  const handleVendorUpload = async (file: File) => {
    setSyncing(true);
    try {
      console.log("[App] Parsing Vendor CSV on client...");
      const rows = await processVendorCSV(file);

      if (rows.length === 0) {
        alert("No valid rows found in CSV.");
        return;
      }

      console.log(`[App] Uploading ${rows.length} rows in batches...`);

      const BATCH_SIZE = 500;
      let totalUpserted = 0;

      for (let i = 0; i < rows.length; i += BATCH_SIZE) {
        const batch = rows.slice(i, i + BATCH_SIZE);
        const response = await fetch('/api/upload-vendor-data', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify(batch),
        });

        const result = await response.json();
        if (!response.ok) throw new Error(result.error || `Batch ${i / BATCH_SIZE + 1} failed`);

        totalUpserted += result.rowsUpserted;
        console.log(`[App] Batch ${Math.floor(i / BATCH_SIZE) + 1} complete. Total: ${totalUpserted}`);
      }

      alert(`Vendor data uploaded: ${totalUpserted} rows processed successfully.`);
      setIsDataModalOpen(false);
    } catch (error: any) {
      console.error("Failed to upload vendor data", error);
      alert(`Error uploading vendor data: ${error.message}`);
    } finally {
      setSyncing(false);
    }
  };

  // 2. Schedule Auto-Refresh (Background)
  useEffect(() => {
    const checkAndRefresh = () => {
      const now = new Date();
      const today = now.toISOString().split('T')[0]; // YYYY-MM-DD
      const lastRefreshDate = localStorage.getItem('craze_last_refresh_date');

      // Refresh if it's after 7 AM and we haven't refreshed today
      if (now.getHours() >= 7 && lastRefreshDate !== today) {
        console.log("Triggering daily data refresh...");
        handleDataFetch().then(() => {
          localStorage.setItem('craze_last_refresh_date', today);
          console.log("Daily refresh successful.");
          // Also refresh ads
          handleAdsFetch();
        }).catch(err => {
          console.error("Daily refresh failed, will retry later.", err);
        });
      }
    };

    // Check immediately on load in case the user opens the app after 7 AM
    checkAndRefresh();

    // And then check periodically (e.g., every 15 minutes) in case app is left open across midnight
    const interval = setInterval(checkAndRefresh, 15 * 60 * 1000);

    return () => clearInterval(interval);
  }, [handleDataFetch]);


  // Derive Data
  const globalAsinMetadata = useMemo(() => {
    const metaMap = new Map<string, { sku: string; title: string; line: string }>();
    rawData.forEach(r => {
      const asin = r.asin.trim().toUpperCase();
      const existing = metaMap.get(asin);
      // Keep most complete title
      if (!existing || (r.title && r.title.length > (existing.title?.length || 0))) {
        metaMap.set(asin, { sku: r.sku, title: r.title, line: r.line });
      }
    });
    return metaMap;
  }, [rawData]);

  const filteredData = useMemo(() => filterData(rawData, filters, stockMap, vendorStockMap, top50Mode), [rawData, filters, stockMap, vendorStockMap, top50Mode]);
  const filteredAdsData = useMemo(() => filterAdsData(adsData, filters, globalAsinMetadata, stockMap, vendorStockMap, top50Mode), [adsData, filters, globalAsinMetadata, stockMap, vendorStockMap, top50Mode]);
  const aggregatedData = useMemo(() => aggregateData(filteredData), [filteredData]);

  // Calculate country-aware Top 50 Best Sellers for 2025
  const top50Ranking2025 = useMemo(() => {
    // Filter only 2025 data
    const data2025 = rawData.filter(r => r.year === 2025);

    const calculateTop50 = (entries: SalesRecord[]) => {
      const asinTotals = new Map<string, number>();
      entries.forEach(r => {
        const asin = r.asin.trim().toUpperCase();
        asinTotals.set(asin, (asinTotals.get(asin) || 0) + r.sellOut);
      });

      const sorted = Array.from(asinTotals.entries())
        .sort((a, b) => b[1] - a[1])
        .slice(0, 50);

      const rankMap = new Map<string, number>();
      sorted.forEach(([asin], index) => {
        rankMap.set(asin, index + 1);
      });
      return rankMap;
    };

    const euData = data2025.filter(r => !r.customer.toLowerCase().includes('uk'));
    const ukData = data2025.filter(r => r.customer.toLowerCase().includes('uk'));

    return {
      eu: calculateTop50(euData),
      uk: calculateTop50(ukData)
    };
  }, [rawData]);

  // Determine which dataset to use for velocity calculation based on top50Mode

  // Combine Sales & Ads Data dynamically based on current filters
  const combinedAdsData = useMemo(() => {
    return mergeSalesAndAdsData(filteredData, filteredAdsData, globalAsinMetadata, trafficData, velocityMap);
  }, [filteredData, filteredAdsData, globalAsinMetadata, trafficData, velocityMap]);

  // Derived Data for Grid (YTD Filtered - Isolated)
  // 1. Identify "Current Year" max week
  const gridContext = useMemo(() => {
    if (rawData.length === 0) return { minWeek: 1, maxWeek: 53, currentYear: new Date().getFullYear() };

    const currentYear = Math.max(...rawData.map(r => r.year));
    const currentYearData = rawData.filter(r => r.year === currentYear);
    const maxWeek = Math.max(...currentYearData.map(r => r.week).filter(Boolean));

    return { minWeek: 1, maxWeek: maxWeek || 53, currentYear };
  }, [rawData]);

  const ytdGridData = useMemo(() => {
    // Smart YTD Logic:
    // Only apply the "Max Week" cutoff if the user has NOT explicitly selected a specific time period.
    // If Month or Week filters are active, we show exactly what was asked (e.g., Full Year 2024).
    // If no time filters are active, we default to YTD (Like-for-Like) comparison.
    const isTimeFilterActive = filters.month.length > 0 || filters.week.length > 0;

    if (!combinedAdsData) return [];

    if (isTimeFilterActive) {
      return combinedAdsData;
    }

    return combinedAdsData.filter(item => {
      if (!item.week) return true;
      return item.week <= gridContext.maxWeek;
    });
  }, [combinedAdsData, gridContext.maxWeek, filters.month, filters.week]);

  // Derived Data for Dashboard (YTD Filtered - Isolated)
  // Dashboard needs aggregated data respecting the max week limit of current year.
  // Dashboard needs aggregated data respecting the max week limit of current year...
  // UNLESS the user explicitly filters for a period.
  const ytdFilteredData = useMemo(() => {
    const isTimeFilterActive = filters.month.length > 0 || filters.week.length > 0;
    if (isTimeFilterActive) return filteredData;

    return filteredData.filter(r => r.week <= gridContext.maxWeek);
  }, [filteredData, gridContext.maxWeek, filters.month, filters.week]);

  const ytdFilteredAdsData = useMemo(() => {
    const isTimeFilterActive = filters.month.length > 0 || filters.week.length > 0;
    if (isTimeFilterActive) return filteredAdsData;

    return filteredAdsData.filter(r => r.week <= gridContext.maxWeek);
  }, [filteredAdsData, gridContext.maxWeek, filters.month, filters.week]);

  const ytdAggregatedData = useMemo(() => {
    return aggregateData(ytdFilteredData);
  }, [ytdFilteredData]);

  // Derived Data for Views
  const years = useMemo(() => getUniqueValues(rawData, 'year').sort().reverse(), [rawData]);

  // Derive Context Data (Product Line Context when drilling down)
  const contextAggregatedData = useMemo(() => {
    // Check if we are filtering by specific items (SKU, ASIN, Title)
    const hasItemFilters = filters.sku.length > 0 || filters.asin.length > 0 || filters.title.length > 0;

    if (!hasItemFilters || filteredData.length === 0) {
      return null;
    }

    // 1. Identify the Product Lines associated with the currently filtered items
    const activeLines = Array.from(new Set(filteredData.map(r => r.line)));

    // 2. Create a "broad" filter: Keep Year/Customer/Month, but CLEAR Item filters, and restrict to these Lines
    const contextFilters: FilterState = {
      ...filters,
      line: activeLines, // Force these lines
      sku: [],          // Clear specific item filters
      asin: [],
      title: [],
      stock: []
    };

    // 3. Process this broader dataset
    const broadData = filterData(rawData, contextFilters);
    return aggregateData(broadData);

  }, [rawData, filters, filteredData]);


  // Derive Options for Filter Dropdowns
  const filterOptions = useMemo(() => {
    return {
      customer: getUniqueValues(rawData, 'customer'),
      year: getUniqueValues(rawData, 'year'),
      month: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'],
      line: getUniqueValues(rawData, 'line'),
      asin: getUniqueValues(rawData, 'asin'),
      sku: getUniqueValues(rawData, 'sku'),
      title: getUniqueValues(rawData, 'title'),
      week: Array.from(new Set(rawData.map(r => r.week).filter(w => w !== undefined))).sort((a, b) => (a as number) - (b as number)).map(w => `W${w}`),
      stock: [
        'Out of Stock (0)',
        'In Stock (>0)',
        'Low Stock (<10)',
        ...Array.from(new Set(Array.from(stockMap.values()).map(String))).sort((a, b) => parseFloat(a) - parseFloat(b))
      ]
    };
  }, [rawData, stockMap]);

  const handleFilterChange = (key: keyof FilterState, value: string[]) => {
    setFilters(prev => ({ ...prev, [key]: value }));
  };

  const handleAskGemini = async (text: string) => {
    return await queryGemini(text, aggregatedData, filteredData.length);
  };

  const disconnectUrl = async () => {
    // Allow disconnecting to clear data, but the app will likely re-connect on next reload due to "Permanent" requirement
    localStorage.removeItem('craze_csv_url');
    await clearSalesData();
    await clearAdsData();
    setActiveUrl(null);
    setRawData([]);
    setAdsData([]);
  };

  return (
    <div className="min-h-screen flex flex-col bg-background text-slate-200">

      {/* Header */}
      <header className="bg-slate-950/90 backdrop-blur border-b border-border py-2 px-3 md:py-4 md:px-6 relative z-40 shadow-2xl">
        <div className="max-w-7xl mx-auto flex justify-between items-center">
          <div className="flex items-center gap-3 md:gap-8">
            {/* Logo Container - Smaller on mobile */}
            <div className="h-10 w-32 md:h-16 md:w-64 relative flex-shrink-0">
              <CrazeLogo />
            </div>

            {/* Title & Status */}
            <div className="hidden lg:block border-l border-slate-700 pl-6">
              <h1 className="text-xl font-bold tracking-tight text-white text-shadow-sm">Analytics Dashboard</h1>
              <div className="flex items-center gap-3 mt-1.5">
                <div className="flex items-center gap-1.5 px-2 py-0.5 bg-emerald-500/10 border border-emerald-500/20 rounded-full">
                  <span className={`w-1.5 h-1.5 rounded-full bg-emerald-400 ${syncing ? 'animate-ping' : ''}`}></span>
                  <span className="text-[9px] text-emerald-400 font-black uppercase tracking-wider">Live Sync</span>
                </div>
                {lastUpdated && (
                  <span className="text-[9px] text-slate-500 font-bold uppercase tracking-wider">
                    Last: {new Date(lastUpdated).toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' })}
                  </span>
                )}
              </div>
            </div>
          </div>

          <div className="flex items-center gap-3 md:gap-6">
            {/* Data Source Settings */}
            <button
              onClick={() => setIsDataModalOpen(true)}
              className="flex items-center gap-2 px-3 py-1.5 md:px-4 md:py-2 rounded-xl text-sm font-black uppercase tracking-widest transition-all bg-slate-900 text-slate-300 border border-border hover:border-emerald-500/50 hover:text-white shadow-lg active:scale-95"
              title="Upload Data"
            >
              <UploadIcon />
              <span className="hidden sm:inline">Upload</span>
            </button>
            {/* Force Sync Action */}
            <button
              onClick={() => { handleDataFetch(); handleAdsFetch(); handleTrafficFetch(); handleVendorStockFetch(); handleBuyBoxFetch(); }}
              disabled={syncing}
              className={`flex items-center gap-2 px-3 py-1.5 md:px-4 md:py-2 rounded-xl text-sm font-black uppercase tracking-widest transition-all
                ${syncing
                  ? 'bg-indigo-500/20 text-indigo-400 border border-indigo-500/30'
                  : 'bg-slate-900 text-slate-300 border border-border hover:border-indigo-500/50 hover:text-white shadow-lg active:scale-95'}`}
            >
              <RefreshIcon className={`w-4 h-4 ${syncing ? 'animate-spin' : ''}`} />
              <span className="hidden sm:inline">{syncing ? 'Syncing...' : 'Sync Now'}</span>
            </button>
            {/* View Switcher - Hidden on mobile (shown in bottom nav instead) */}
            <div className="hidden md:flex bg-slate-900 rounded-lg p-1 border border-border">
              <button
                onClick={() => setView('dashboard')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'dashboard' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <ChartIcon /> <span className="hidden lg:inline">Dashboard</span>
              </button>
              <button
                onClick={() => setView('table')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'table' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <TableIcon /> <span className="hidden lg:inline">Grid</span>
              </button>
              <button
                onClick={() => setView('weekly')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'weekly' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <TrendingIcon /> <span className="hidden lg:inline">Weekly Sales</span>
              </button>
              <button
                onClick={() => setView('movers')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'movers' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <TrendingIcon /> <span className="hidden lg:inline">Movers</span>
              </button>
              <button
                onClick={() => setView('ads')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'ads' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <MegaphoneIcon /> <span className="hidden lg:inline">Ads</span>
              </button>
              <button
                onClick={() => setView('forecast')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'forecast' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <ChartIcon /> <span className="hidden lg:inline">Fc 26</span>
              </button>
              <button
                onClick={() => setView('vendor')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'vendor' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <ChartIcon /> <span className="hidden lg:inline">Vendor</span>
              </button>
              <button
                onClick={() => setView('experiments')}
                className={`flex items-center gap-2 px-3 py-2 rounded-md text-sm font-medium transition-all
                  ${view === 'experiments' ? 'bg-slate-800 text-white shadow-sm ring-1 ring-white/10' : 'text-slate-400 hover:text-white hover:bg-slate-800/50'}`}
              >
                <span className="text-lg">🧪</span> <span className="hidden lg:inline">Experiments</span>
              </button>
            </div>
          </div>
        </div>
      </header>

      {/* Main Content */}
      <main className="flex-1 relative">
        {loading ? (
          // Initial loading spinner
          <div className="flex flex-col items-center justify-center h-[80vh] gap-4">
            <div className="w-16 h-16 border-4 border-indigo-500 border-t-transparent rounded-full animate-spin"></div>
            <h2 className="text-xl font-bold text-slate-300">Loading Dashboard...</h2>
            <p className="text-sm text-slate-500">Syncing with Dropbox...</p>
          </div>
        ) : (
          <>
            <FilterBar filters={filters} onFilterChange={handleFilterChange} options={filterOptions} />
            <div className="mt-6">
              <div className={view === 'dashboard' ? '' : 'hidden'}>
                <Dashboard data={ytdAggregatedData} filterState={filters} adsData={ytdFilteredAdsData} stockMap={stockMap} />
              </div>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'table' ? '' : 'hidden'}>
                  <DataGrid
                    data={ytdGridData}
                    filters={filters}
                    hasCustomerFilter={filters.customer.length > 0}
                    adsData={filteredAdsData}
                    stockMap={stockMap}
                    vendorStockMap={vendorStockMap}
                    top50Ranking={top50Ranking2025}
                    top50Mode={filters.customer.includes('Amazon UK') ? 'uk' : 'eu'}
                    velocityMap={velocityMap}
                    buyBoxLostMap={buyBoxLostMap}
                    defaultSort={{ key: `total_sellOut_${gridContext.currentYear}`, direction: 'desc' }}
                  />
                </div>
              </Suspense>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'weekly' ? '' : 'hidden'}>
                  <WeeklyGrid
                    data={combinedAdsData}
                    onDrillDown={handleSkuDrillDown}
                    stockMap={stockMap}
                    vendorStockMap={vendorStockMap}
                    stockFilter={filters.stock}
                    onStockFilterChange={(s) => setFilters(prev => ({ ...prev, stock: s }))}
                    vendorStockFilter={filters.vendorStock}
                    onVendorStockFilterChange={(s) => setFilters(prev => ({ ...prev, vendorStock: s }))}
                    wocFilter={filters.woc}
                    onWocFilterChange={(s) => setFilters(prev => ({ ...prev, woc: s }))}
                    customerFilters={filters.customer}
                    top50Mode={filters.customer.includes('Amazon UK') ? 'uk' : 'eu'}
                    top50Ranking={top50Ranking2025}
                    velocityMap={velocityMap}
                    buyBoxLostMap={buyBoxLostMap}
                    experimentMap={experimentMap}
                    onOpenExperiment={(id) => setSelectedExperimentId(id)}
                  />
                </div>
              </Suspense>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'movers' ? '' : 'hidden'}>
                  <TopMovers data={filteredData} stockMap={stockMap} />
                </div>
              </Suspense>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'ads' ? '' : 'hidden'}>
                  <AdsPerformance
                    data={combinedAdsData}
                    filters={filters}
                    top50Ranking={top50Ranking2025}
                    stockMap={stockMap}
                    vendorStockMap={vendorStockMap}
                    stockFilter={filters.stock}
                    onStockFilterChange={(s) => setFilters(prev => ({ ...prev, stock: s }))}
                    vendorStockFilter={filters.vendorStock}
                    onVendorStockFilterChange={(s) => setFilters(prev => ({ ...prev, vendorStock: s }))}
                    wocFilter={filters.woc}
                    onWocFilterChange={(s) => setFilters(prev => ({ ...prev, woc: s }))}
                    top50Mode={filters.customer.includes('Amazon UK') ? 'uk' : 'eu'}
                    buyBoxLostMap={buyBoxLostMap}
                  />
                </div>
              </Suspense>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'forecast' ? '' : 'hidden'}>
                  <ForecastView
                    data={forecastData}
                    filters={filters}
                    top50Ranking={top50Ranking2025}
                    stockMap={stockMap}
                    vendorStockMap={vendorStockMap}
                    stockFilter={filters.stock}
                    onStockFilterChange={(s) => setFilters(prev => ({ ...prev, stock: s }))}
                    vendorStockFilter={filters.vendorStock}
                    onVendorStockFilterChange={(s) => setFilters(prev => ({ ...prev, vendorStock: s }))}
                    wocFilter={filters.woc}
                    onWocFilterChange={(s) => setFilters(prev => ({ ...prev, woc: s }))}
                    top50Mode={filters.customer.includes('Amazon UK') ? 'uk' : 'eu'}
                    buyBoxLostMap={buyBoxLostMap}
                  />
                </div>
              </Suspense>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'vendor' ? '' : 'hidden'}>
                  <VendorDataView />
                </div>
              </Suspense>

              <Suspense fallback={<LoadingSpinner />}>
                <div className={view === 'experiments' ? '' : 'hidden'}>
                  <ExperimentsView
                    onOpenDetail={(id) => setSelectedExperimentId(id)}
                    onOpenCreate={() => {
                      setPreselectedAsins([]);
                      setPreselectedMarketplace(filters.customer[0] || '');
                      setShowCreateExperiment(true);
                    }}
                  />
                </div>
              </Suspense>
            </div>
          </>
        )}
      </main>

      {/* Chat Assistant */}
      <AIChat onSendMessage={handleAskGemini} isOpen={isChatOpen} setIsOpen={setIsChatOpen} />

      {/* Mobile Bottom Navigation */}
      <nav className="fixed bottom-0 left-0 right-0 z-50 bg-slate-950/95 backdrop-blur border-t border-border md:hidden pb-safe">
        <div className="grid grid-cols-8 gap-0">
          {([
            { key: 'dashboard' as const, icon: <ChartIcon />, label: 'Home' },
            { key: 'table' as const, icon: <TableIcon />, label: 'Grid' },
            { key: 'weekly' as const, icon: <TrendingIcon />, label: 'Weekly' },
            { key: 'movers' as const, icon: <TrendingIcon />, label: 'Movers' },
            { key: 'ads' as const, icon: <MegaphoneIcon />, label: 'Ads' },
            { key: 'forecast' as const, icon: <ChartIcon />, label: 'Fc 26' },
            { key: 'vendor' as const, icon: <ChartIcon />, label: 'Vendor' },
            { key: 'experiments' as const, icon: <span className="text-lg">🧪</span>, label: 'Exp' },
          ]).map(({ key, icon, label }) => (
            <button
              key={key}
              onClick={() => setView(key)}
              className={`flex flex-col items-center justify-center py-2 gap-0.5 transition-colors
                ${view === key ? 'text-primary' : 'text-slate-500 active:text-slate-300'}`}
            >
              {icon}
              <span className="text-[9px] font-bold uppercase tracking-wider">{label}</span>
            </button>
          ))}
        </div>
      </nav>

      {/* DATA MODAL */}
      {
        isDataModalOpen && (
          <div className="fixed inset-0 z-[100] flex items-center justify-center bg-black/70 backdrop-blur-sm animate-fade-in p-4">
            <div className="bg-slate-950 border border-border rounded-2xl shadow-2xl w-full max-w-lg relative overflow-hidden">
              <div className="bg-slate-900 px-6 py-4 border-b border-border flex justify-between items-center">
                <h2 className="text-lg font-bold text-white">Data Source Settings</h2>
                <button onClick={() => setIsDataModalOpen(false)} className="text-slate-400 hover:text-white transition-colors">
                  <CloseIcon />
                </button>
              </div>

              <div className="p-6">
                <FileUpload
                  onSalesUpload={handleSalesUpload}
                  onAdsUpload={handleAdsUpload}
                  onTrafficUpload={handleTrafficUpload}
                  onVendorUpload={handleVendorUpload}
                  onUrlSubmit={handleDataFetch}
                  isLoading={syncing}
                  activeUrl={activeUrl}
                  onDisconnect={disconnectUrl}
                  lastUpdated={lastUpdated}
                />
              </div>
            </div>
          </div>
        )
      }

      {/* Experiment Detail Modal */}
      {selectedExperimentId && (
        <ExperimentDetail
          experimentId={selectedExperimentId}
          onClose={() => setSelectedExperimentId(null)}
          salesData={rawData}
        />
      )}

      {/* Create Experiment Modal */}
      {showCreateExperiment && (
        <ExperimentForm
          onClose={() => {
            setShowCreateExperiment(false);
            setPreselectedAsins([]);
            setPreselectedMarketplace('');
            setPreselectedLine('');
          }}
          onSuccess={() => {
            handleExperimentsFetch();
          }}
          initialAsins={preselectedAsins}
          initialMarketplace={preselectedMarketplace}
          initialLine={preselectedLine}
          availableLines={availableProductLines}
        />
      )}

    </div >
  );
};

export default App;