// Data source: NocoDB only
// Offline mode: caches data to localStorage for resilience

import type {
  MuseumRecord,
  Metrics,
  Filters,
  DateRangeFilters,
  CacheStatus,
  CacheResult,
  FetchResult,
  GroupedData,
  DistrictMuseumMap,
  UmrahData,
  NocoDBDistrict,
  NocoDBMuseum,
  NocoDBDailyStat
} from '../types';

const NOCODB_URL = process.env.REACT_APP_NOCODB_URL || '';
const NOCODB_TOKEN = process.env.REACT_APP_NOCODB_TOKEN || '';

// Table IDs
const NOCODB_TABLES = {
  districts: 'm8cup7lesbet0sa',
  museums: 'm1c7od7mdirffvu',
  dailyStats: 'mc7qhbdh3mjjwl8'
};

// Cache keys
const CACHE_KEY = 'hihala_data_cache';
const CACHE_TIMESTAMP_KEY = 'hihala_data_cache_timestamp';
const CACHE_MAX_AGE_MS = 7 * 24 * 60 * 60 * 1000; // 7 days 

export const umrahData: UmrahData = {
  2024: { 1: 11574494, 2: 10521465, 3: 3364627, 4: 7435625 },
  2025: { 1: 15222497, 2: 5443393, 3: null, 4: null }
};

// ============================================
// Offline Cache Functions
// ============================================

function saveToCache(data: MuseumRecord[]): void {
  try {
    localStorage.setItem(CACHE_KEY, JSON.stringify(data));
    localStorage.setItem(CACHE_TIMESTAMP_KEY, Date.now().toString());
    console.log(`Cached ${data.length} rows to localStorage`);
  } catch (err) {
    console.warn('Failed to save to cache:', (err as Error).message);
  }
}

function loadFromCache(): CacheResult | null {
  try {
    const cached = localStorage.getItem(CACHE_KEY);
    const timestamp = localStorage.getItem(CACHE_TIMESTAMP_KEY);
    
    if (!cached) return null;
    
    const data: MuseumRecord[] = JSON.parse(cached);
    const age = timestamp ? Date.now() - parseInt(timestamp) : Infinity;
    const isStale = age > CACHE_MAX_AGE_MS;
    
    console.log(`Loaded ${data.length} rows from cache (age: ${Math.round(age / 1000 / 60)} min, stale: ${isStale})`);
    
    return { data, isStale, timestamp: parseInt(timestamp || '0') };
  } catch (err) {
    console.warn('Failed to load from cache:', (err as Error).message);
    return null;
  }
}

export function getCacheStatus(): CacheStatus {
  const timestamp = localStorage.getItem(CACHE_TIMESTAMP_KEY);
  const cached = localStorage.getItem(CACHE_KEY);
  
  if (!cached || !timestamp) {
    return { available: false, timestamp: null, age: null, rows: 0 };
  }
  
  const ts = parseInt(timestamp);
  const data: MuseumRecord[] = JSON.parse(cached);
  
  return {
    available: true,
    timestamp: new Date(ts).toISOString(),
    age: Date.now() - ts,
    rows: data.length,
    isStale: (Date.now() - ts) > CACHE_MAX_AGE_MS
  };
}

export function clearCache(): void {
  localStorage.removeItem(CACHE_KEY);
  localStorage.removeItem(CACHE_TIMESTAMP_KEY);
  console.log('Cache cleared');
}

// ============================================
// NocoDB Data Fetching
// ============================================

async function fetchNocoDBTable<T>(tableId: string, limit: number = 1000): Promise<T[]> {
  let allRecords: T[] = [];
  let offset = 0;
  
  while (true) {
    const response = await fetch(
      `${NOCODB_URL}/api/v2/tables/${tableId}/records?limit=${limit}&offset=${offset}`,
      { headers: { 'xc-token': NOCODB_TOKEN } }
    );
    
    if (!response.ok) throw new Error(`HTTP ${response.status}`);
    
    const json = await response.json();
    const records: T[] = json.list || [];
    allRecords = allRecords.concat(records);
    
    if (records.length < limit) break;
    offset += limit;
  }
  
  return allRecords;
}

interface MuseumMapEntry {
  code: string;
  name: string;
  district: string;
}

async function fetchFromNocoDB(): Promise<MuseumRecord[]> {
  console.log('Fetching from NocoDB...');
  
  // Fetch all three tables in parallel
  const [districts, museums, dailyStats] = await Promise.all([
    fetchNocoDBTable<NocoDBDistrict>(NOCODB_TABLES.districts),
    fetchNocoDBTable<NocoDBMuseum>(NOCODB_TABLES.museums),
    fetchNocoDBTable<NocoDBDailyStat>(NOCODB_TABLES.dailyStats)
  ]);
  
  // Build lookup maps
  const districtMap: Record<number, string> = {};
  districts.forEach(d => { districtMap[d.Id] = d.Name; });
  
  const museumMap: Record<number, MuseumMapEntry> = {};
  museums.forEach(m => {
    museumMap[m.Id] = {
      code: m.Code,
      name: m.Name,
      district: districtMap[m['nc_epk____Districts_id']] || 'Unknown'
    };
  });
  
  // Join data into flat structure
  const data: MuseumRecord[] = dailyStats.map(row => {
    const museum = museumMap[row['nc_epk____Museums_id']] || { code: '', name: '', district: '' };
    const date = row.Date;
    const year = date ? date.substring(0, 4) : '';
    const month = date ? parseInt(date.substring(5, 7)) : 0;
    const quarter = month <= 3 ? '1' : month <= 6 ? '2' : month <= 9 ? '3' : '4';
    
    // GrossRevenue = including VAT, NetRevenue = excluding VAT
    const grossRevenue = row.GrossRevenue || 0;
    const netRevenue = row.NetRevenue || (grossRevenue / 1.15);
    
    return {
      date: date,
      museum_code: museum.code,
      museum_name: museum.name,
      district: museum.district,
      visits: row.Visits,
      tickets: row.Tickets,
      revenue_gross: grossRevenue,
      revenue_net: netRevenue,
      revenue_incl_tax: grossRevenue, // Legacy compatibility
      year: year,
      quarter: quarter
    };
  }).filter(r => r.date && r.museum_name);
  
  console.log(`Loaded ${data.length} rows from NocoDB`);
  return data;
}

// ============================================
// Main Data Fetcher (with offline fallback)
// ============================================

export async function fetchData(): Promise<FetchResult> {
  // Check if NocoDB is configured
  if (!NOCODB_URL || !NOCODB_TOKEN) {
    // Try cache
    const cached = loadFromCache();
    if (cached) {
      console.warn('NocoDB not configured, using cached data');
      return { data: cached.data, fromCache: true, cacheTimestamp: cached.timestamp };
    }
    throw new Error('NocoDB not configured and no cached data available. Set REACT_APP_NOCODB_URL and REACT_APP_NOCODB_TOKEN in .env.local');
  }
  
  try {
    // Try to fetch fresh data
    const data = await fetchFromNocoDB();
    
    // Save to cache on success
    saveToCache(data);
    
    return { data, fromCache: false };
  } catch (err) {
    console.error('NocoDB fetch failed:', (err as Error).message);
    
    // Try to load from cache
    const cached = loadFromCache();
    if (cached) {
      console.warn(`Using cached data from ${new Date(cached.timestamp).toLocaleString()} (offline mode)`);
      return { data: cached.data, fromCache: true, cacheTimestamp: cached.timestamp };
    }
    
    throw new Error(`Database unavailable and no cached data: ${(err as Error).message}`);
  }
}

// Force refresh (bypass cache read, but still write to cache)
export async function refreshData(): Promise<FetchResult> {
  if (!NOCODB_URL || !NOCODB_TOKEN) {
    throw new Error('NocoDB not configured');
  }
  
  const data = await fetchFromNocoDB();
  saveToCache(data);
  return { data, fromCache: false };
}

// ============================================
// Data Filtering & Metrics
// ============================================

export function filterData(data: MuseumRecord[], filters: Filters): MuseumRecord[] {
  return data.filter(row => {
    if (filters.year && filters.year !== 'all' && row.year !== filters.year) return false;
    if (filters.district && filters.district !== 'all' && row.district !== filters.district) return false;
    if (filters.museum && filters.museum !== 'all' && row.museum_name !== filters.museum) return false;
    if (filters.quarter && filters.quarter !== 'all' && row.quarter !== filters.quarter) return false;
    return true;
  });
}

export function filterDataByDateRange(
  data: MuseumRecord[], 
  startDate: string, 
  endDate: string, 
  filters: Partial<DateRangeFilters> = {}
): MuseumRecord[] {
  return data.filter(row => {
    if (!row.date) return false;
    if (row.date < startDate || row.date > endDate) return false;
    if (filters.district && filters.district !== 'all' && row.district !== filters.district) return false;
    if (filters.museum && filters.museum !== 'all' && row.museum_name !== filters.museum) return false;
    return true;
  });
}

export function calculateMetrics(data: MuseumRecord[], includeVAT: boolean = true): Metrics {
  const revenueField = includeVAT ? 'revenue_gross' : 'revenue_net';
  const revenue = data.reduce((sum, row) => sum + (row[revenueField] || row.revenue_incl_tax || 0), 0);
  const visitors = data.reduce((sum, row) => sum + (row.visits || 0), 0);
  const tickets = data.reduce((sum, row) => sum + (row.tickets || 0), 0);
  const avgRevPerVisitor = visitors > 0 ? revenue / visitors : 0;
  return { revenue, visitors, tickets, avgRevPerVisitor };
}

// ============================================
// Formatting Functions
// ============================================

export function formatCurrency(num: number): string {
  if (isNaN(num)) return 'SAR 0';
  return new Intl.NumberFormat('en-US', {
    style: 'currency',
    currency: 'SAR',
    maximumFractionDigits: 0
  }).format(num);
}

export function formatNumber(num: number): string {
  if (isNaN(num)) return '0';
  return new Intl.NumberFormat('en-US').format(Math.round(num));
}

export function formatCompact(num: number): string {
  if (isNaN(num)) return '0';
  const absNum = Math.abs(num);
  if (absNum >= 1000000) return (num / 1000000).toFixed(1) + 'M';
  if (absNum >= 1000) return (num / 1000).toFixed(0) + 'K';
  return formatNumber(num);
}

export function formatCompactCurrency(num: number): string {
  if (isNaN(num)) return 'SAR 0';
  const absNum = Math.abs(num);
  if (absNum >= 1000000) return 'SAR ' + (num / 1000000).toFixed(1) + 'M';
  if (absNum >= 1000) return 'SAR ' + (num / 1000).toFixed(0) + 'K';
  return formatCurrency(num);
}

// ============================================
// Grouping Functions
// ============================================

export function getWeekStart(dateStr: string): string | null {
  if (!dateStr || !dateStr.match(/^\d{4}-\d{2}-\d{2}$/)) return null;
  
  const [year, month, day] = dateStr.split('-').map(Number);
  const date = new Date(year, month - 1, day);
  const dayOfWeek = date.getDay();
  const diff = dayOfWeek === 0 ? -6 : 1 - dayOfWeek;
  
  const monday = new Date(year, month - 1, day + diff);
  const y = monday.getFullYear();
  const m = String(monday.getMonth() + 1).padStart(2, '0');
  const d = String(monday.getDate()).padStart(2, '0');
  
  return `${y}-${m}-${d}`;
}

export function groupByWeek(data: MuseumRecord[], includeVAT: boolean = true): Record<string, GroupedData> {
  const revenueField = includeVAT ? 'revenue_gross' : 'revenue_net';
  const grouped: Record<string, GroupedData> = {};
  data.forEach(row => {
    if (!row.date) return;
    const weekStart = getWeekStart(row.date);
    if (!weekStart) return;
    if (!grouped[weekStart]) grouped[weekStart] = { revenue: 0, visitors: 0, tickets: 0 };
    grouped[weekStart].revenue += row[revenueField] || row.revenue_incl_tax || 0;
    grouped[weekStart].visitors += row.visits || 0;
    grouped[weekStart].tickets += row.tickets || 0;
  });
  return grouped;
}

export function groupByMuseum(data: MuseumRecord[], includeVAT: boolean = true): Record<string, GroupedData> {
  const revenueField = includeVAT ? 'revenue_gross' : 'revenue_net';
  const grouped: Record<string, GroupedData> = {};
  data.forEach(row => {
    if (!row.museum_name) return;
    if (!grouped[row.museum_name]) grouped[row.museum_name] = { revenue: 0, visitors: 0, tickets: 0 };
    grouped[row.museum_name].revenue += row[revenueField] || row.revenue_incl_tax || 0;
    grouped[row.museum_name].visitors += row.visits || 0;
    grouped[row.museum_name].tickets += row.tickets || 0;
  });
  return grouped;
}

export function groupByDistrict(data: MuseumRecord[], includeVAT: boolean = true): Record<string, GroupedData> {
  const revenueField = includeVAT ? 'revenue_gross' : 'revenue_net';
  const grouped: Record<string, GroupedData> = {};
  data.forEach(row => {
    if (!row.district) return;
    if (!grouped[row.district]) grouped[row.district] = { revenue: 0, visitors: 0, tickets: 0 };
    grouped[row.district].revenue += row[revenueField] || row.revenue_incl_tax || 0;
    grouped[row.district].visitors += row.visits || 0;
    grouped[row.district].tickets += row.tickets || 0;
  });
  return grouped;
}

// ============================================
// Data Extraction Helpers
// ============================================

export function getUniqueYears(data: MuseumRecord[]): string[] {
  const years = [...new Set(data.map(r => r.year).filter(Boolean))];
  return years.sort((a, b) => parseInt(a) - parseInt(b));
}

export function getUniqueDistricts(data: MuseumRecord[]): string[] {
  return [...new Set(data.map(r => r.district).filter(Boolean))].sort();
}

export function getDistrictMuseumMap(data: MuseumRecord[]): DistrictMuseumMap {
  const map: Record<string, Set<string>> = {};
  data.forEach(row => {
    if (!row.district || !row.museum_name) return;
    if (!map[row.district]) map[row.district] = new Set();
    map[row.district].add(row.museum_name);
  });
  const result: DistrictMuseumMap = {};
  Object.keys(map).forEach(d => {
    result[d] = [...map[d]].sort();
  });
  return result;
}

export function getMuseumsForDistrict(districtMuseumMap: DistrictMuseumMap, district: string): string[] {
  if (district === 'all') {
    return Object.values(districtMuseumMap).flat().sort();
  }
  return districtMuseumMap[district] || [];
}

export function getLatestYear(data: MuseumRecord[]): string {
  const years = getUniqueYears(data);
  return years.length > 0 ? years[years.length - 1] : '2025';
}