/// Local SQLite store of products and shopping trips.
library;

import 'dart:io';

import 'package:path/path.dart' as p;
import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';

import '../models/line_item.dart';
import '../models/product.dart';
import '../models/purchase.dart';
import '../models/shop.dart';
import '../models/supermarket.dart';
import '../utils/money.dart';
import '../utils/supermarkets.dart';

class ProductRepository {
  ProductRepository({this.databasePath});

  final String? databasePath;
  Database? _db;

  Future<Database> get _database async {
    _db ??= await _open();
    return _db!;
  }

  Future<Database> _open() async {
    final path = databasePath ??
        p.join((await getApplicationDocumentsDirectory()).path, 'receipity.db');
    return openDatabase(
      path,
      version: 4,
      onCreate: (db, version) async {
        await _createProducts(db);
        await _createShopTables(db);
        await _createSettingsTables(db);
        await _seedSupermarkets(db);
      },
      onUpgrade: (db, oldVersion, newVersion) async {
        if (oldVersion < 2) {
          await db.execute(
            'ALTER TABLE products ADD COLUMN favourite INTEGER NOT NULL DEFAULT 0',
          );
          await db.execute('ALTER TABLE products ADD COLUMN image_path TEXT');
          await db.execute('ALTER TABLE products ADD COLUMN supermarket TEXT');
          await _createShopTables(db);
        }
        if (oldVersion < 3) {
          await db.execute('ALTER TABLE products ADD COLUMN notes TEXT');
          await _createSettingsTables(db);
          await _seedSupermarkets(db);
        }
        if (oldVersion < 4) {
          await db.execute('ALTER TABLE products ADD COLUMN category TEXT');
        }
      },
    );
  }

  Future<void> _createProducts(Database db) async {
    await db.execute('''
      CREATE TABLE products (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT NOT NULL,
        normalized_name TEXT NOT NULL UNIQUE,
        last_price REAL NOT NULL,
        times_seen INTEGER NOT NULL DEFAULT 1,
        favourite INTEGER NOT NULL DEFAULT 0,
        image_path TEXT,
        supermarket TEXT,
        notes TEXT,
        category TEXT,
        created_at TEXT NOT NULL,
        updated_at TEXT NOT NULL
      )
    ''');
  }

  Future<void> _createSettingsTables(DatabaseExecutor db) async {
    await db.execute('''
      CREATE TABLE IF NOT EXISTS app_settings (
        key TEXT PRIMARY KEY,
        value TEXT NOT NULL
      )
    ''');
    await db.execute('''
      CREATE TABLE IF NOT EXISTS supermarkets (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        name TEXT NOT NULL UNIQUE,
        color INTEGER NOT NULL,
        sort_order INTEGER NOT NULL
      )
    ''');
  }

  Future<void> _seedSupermarkets(DatabaseExecutor db) async {
    final existing = await db.query('supermarkets', limit: 1);
    if (existing.isNotEmpty) return;
    for (final store in kDefaultSupermarkets) {
      await db.insert('supermarkets', {
        'name': store.name,
        'color': store.colorValue,
        'sort_order': store.sortOrder,
      });
    }
  }

  Future<void> _createShopTables(DatabaseExecutor db) async {
    await db.execute('''
      CREATE TABLE shops (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        supermarket TEXT NOT NULL,
        shopped_at TEXT NOT NULL,
        receipt_image_path TEXT,
        total REAL NOT NULL,
        created_at TEXT NOT NULL
      )
    ''');
    await db.execute('''
      CREATE TABLE shop_items (
        id INTEGER PRIMARY KEY AUTOINCREMENT,
        shop_id INTEGER NOT NULL,
        product_id INTEGER NOT NULL,
        name TEXT NOT NULL,
        price REAL NOT NULL,
        quantity INTEGER,
        unit_price REAL,
        FOREIGN KEY (shop_id) REFERENCES shops(id) ON DELETE CASCADE,
        FOREIGN KEY (product_id) REFERENCES products(id)
      )
    ''');
  }

  static String normalizeName(String name) =>
      name.trim().toUpperCase().replaceAll(RegExp(r'\s+'), ' ');

  Future<String> _persistImage(String sourcePath, String relativePath) async {
    final dir = await getApplicationDocumentsDirectory();
    final dest = File(p.join(dir.path, relativePath));
    await dest.parent.create(recursive: true);
    if (p.normalize(sourcePath) == p.normalize(dest.path)) {
      return dest.path;
    }
    await File(sourcePath).copy(dest.path);
    return dest.path;
  }

  /// Saves a shopping trip and upserts each line into the product catalog.
  Future<int> saveShop({
    required String supermarket,
    required DateTime shoppedAt,
    required List<LineItem> items,
    String? receiptImagePath,
  }) async {
    final db = await _database;
    final now = DateTime.now().toIso8601String();
    final total = roundMoney(
      items.fold<double>(0, (sum, item) => sum + item.price),
    );

    final shopId = await db.transaction((txn) async {
      final id = await txn.insert('shops', {
        'supermarket': supermarket,
        'shopped_at': shoppedAt.toIso8601String(),
        'total': total,
        'created_at': now,
      });

      for (final item in items) {
        final productId = await _upsertProduct(
          txn,
          item: item,
          supermarket: supermarket,
          now: now,
        );
        await txn.insert('shop_items', {
          'shop_id': id,
          'product_id': productId,
          'name': item.name.trim(),
          'price': item.price,
          'quantity': item.quantity,
          'unit_price': item.unitPrice,
        });
      }
      return id;
    });

    if (receiptImagePath != null && receiptImagePath.isNotEmpty) {
      try {
        final stored = await _persistImage(
          receiptImagePath,
          'receipts/shop_$shopId.jpg',
        );
        await db.update(
          'shops',
          {'receipt_image_path': stored},
          where: 'id = ?',
          whereArgs: [shopId],
        );
      } catch (_) {
        // Trip is still saved if the photo cannot be copied.
      }
    }

    return shopId;
  }

  Future<int> _upsertProduct(
    Transaction txn, {
    required LineItem item,
    required String supermarket,
    required String now,
  }) async {
    final key = normalizeName(item.name);
    final existing = await txn.query(
      'products',
      where: 'normalized_name = ?',
      whereArgs: [key],
      limit: 1,
    );

    if (existing.isEmpty) {
      return txn.insert('products', {
        'name': item.name.trim(),
        'normalized_name': key,
        'last_price': item.unitPrice ?? item.price,
        'times_seen': 1,
        'favourite': 0,
        'supermarket': supermarket,
        'created_at': now,
        'updated_at': now,
      });
    }

    final row = existing.first;
    final values = <String, Object?>{
      'last_price': item.unitPrice ?? item.price,
      'times_seen': (row['times_seen']! as int) + 1,
      'updated_at': now,
    };
    if ((row['supermarket'] as String?) == null ||
        (row['supermarket'] as String).isEmpty) {
      values['supermarket'] = supermarket;
    }
    await txn.update(
      'products',
      values,
      where: 'id = ?',
      whereArgs: [row['id']],
    );
    return row['id']! as int;
  }

  /// Kept for tests and older callers; saves items without a shop trip.
  Future<void> upsertItems(List<LineItem> items) async {
    await saveShop(
      supermarket: 'Other',
      shoppedAt: DateTime.now(),
      items: items,
    );
  }

  Future<List<Product>> getAll({
    ProductSort sort = ProductSort.name,
    bool favouritesOnly = false,
  }) async {
    final db = await _database;
    final orderBy = switch (sort) {
      ProductSort.name => 'name COLLATE NOCASE ASC',
      ProductSort.preferred => 'times_seen DESC, name COLLATE NOCASE ASC',
    };
    final rows = await db.rawQuery('''
      SELECT
        products.*,
        (
          SELECT COALESCE(shop_items.unit_price, shop_items.price)
          FROM shop_items
          JOIN shops ON shops.id = shop_items.shop_id
          WHERE shop_items.product_id = products.id
          ORDER BY shops.shopped_at DESC, shop_items.id DESC
          LIMIT 1
        ) AS display_price
      FROM products
      ${favouritesOnly ? 'WHERE favourite = 1' : ''}
      ORDER BY $orderBy
    ''');
    return rows.map(Product.fromMap).toList();
  }

  Future<Product?> getProduct(int id) async {
    final db = await _database;
    final rows = await db.rawQuery(
      '''
      SELECT
        products.*,
        (
          SELECT COALESCE(shop_items.unit_price, shop_items.price)
          FROM shop_items
          JOIN shops ON shops.id = shop_items.shop_id
          WHERE shop_items.product_id = products.id
          ORDER BY shops.shopped_at DESC, shop_items.id DESC
          LIMIT 1
        ) AS display_price
      FROM products
      WHERE products.id = ?
      LIMIT 1
      ''',
      [id],
    );
    if (rows.isEmpty) return null;
    return Product.fromMap(rows.first);
  }

  Future<List<String>> getUsedCategories() async {
    final db = await _database;
    final rows = await db.rawQuery(
      '''
      SELECT DISTINCT category FROM products
      WHERE category IS NOT NULL AND TRIM(category) != ''
      ORDER BY category COLLATE NOCASE ASC
      ''',
    );
    return [
      for (final row in rows)
        if (row['category'] is String) row['category']! as String,
    ];
  }

  Future<void> updateProduct({
    required int id,
    String? name,
    bool? favourite,
    String? supermarket,
    String? imagePath,
    String? notes,
    String? category,
    bool clearImage = false,
    bool clearSupermarket = false,
    bool clearNotes = false,
    bool clearCategory = false,
  }) async {
    final db = await _database;
    final values = <String, Object?>{
      'updated_at': DateTime.now().toIso8601String(),
    };
    if (name != null) {
      values['name'] = name.trim();
      values['normalized_name'] = normalizeName(name);
    }
    if (favourite != null) values['favourite'] = favourite ? 1 : 0;
    if (clearSupermarket) {
      values['supermarket'] = null;
    } else if (supermarket != null) {
      values['supermarket'] = supermarket;
    }
    if (clearImage) {
      values['image_path'] = null;
    } else if (imagePath != null) {
      values['image_path'] = imagePath;
    }
    if (clearNotes) {
      values['notes'] = null;
    } else if (notes != null) {
      values['notes'] = notes;
    }
    if (clearCategory) {
      values['category'] = null;
    } else if (category != null) {
      values['category'] = category.trim();
    }
    await db.update('products', values, where: 'id = ?', whereArgs: [id]);
  }

  Future<void> setFavourite(int id, bool favourite) =>
      updateProduct(id: id, favourite: favourite);

  Future<String?> setProductImage(int id, String sourcePath) async {
    final stored = await _persistImage(sourcePath, 'products/product_$id.jpg');
    await updateProduct(id: id, imagePath: stored);
    return stored;
  }

  Future<List<Purchase>> getPurchases(int productId) async {
    final db = await _database;
    final rows = await db.rawQuery(
      '''
      SELECT
        shop_items.shop_id,
        shop_items.price,
        shop_items.quantity,
        shop_items.unit_price,
        shops.shopped_at,
        shops.supermarket,
        shops.receipt_image_path
      FROM shop_items
      JOIN shops ON shops.id = shop_items.shop_id
      WHERE shop_items.product_id = ?
      ORDER BY shops.shopped_at DESC, shop_items.id DESC
      ''',
      [productId],
    );
    return rows.map(Purchase.fromMap).toList();
  }

  Future<List<Shop>> getShops() async {
    final db = await _database;
    final rows = await db.rawQuery('''
      SELECT
        shops.id,
        shops.supermarket,
        shops.shopped_at,
        shops.receipt_image_path,
        shops.total,
        COUNT(shop_items.id) AS item_count
      FROM shops
      LEFT JOIN shop_items ON shop_items.shop_id = shops.id
      GROUP BY shops.id
      ORDER BY shops.shopped_at DESC, shops.id DESC
    ''');
    return rows.map(Shop.fromMap).toList();
  }

  Future<Shop?> getShop(int id) async {
    final db = await _database;
    final rows = await db.rawQuery(
      '''
      SELECT
        shops.id,
        shops.supermarket,
        shops.shopped_at,
        shops.receipt_image_path,
        shops.total,
        COUNT(shop_items.id) AS item_count
      FROM shops
      LEFT JOIN shop_items ON shop_items.shop_id = shops.id
      WHERE shops.id = ?
      GROUP BY shops.id
      ''',
      [id],
    );
    if (rows.isEmpty) return null;
    return Shop.fromMap(rows.first);
  }

  Future<List<ShopItem>> getShopItems(int shopId) async {
    final db = await _database;
    final rows = await db.query(
      'shop_items',
      where: 'shop_id = ?',
      whereArgs: [shopId],
      orderBy: 'id ASC',
    );
    return rows.map(ShopItem.fromMap).toList();
  }

  Future<bool> getDarkMode() async {
    final db = await _database;
    final rows = await db.query(
      'app_settings',
      where: 'key = ?',
      whereArgs: ['dark_mode'],
      limit: 1,
    );
    if (rows.isEmpty) return false;
    return rows.first['value'] == '1';
  }

  Future<void> setDarkMode(bool enabled) async {
    final db = await _database;
    await db.insert(
      'app_settings',
      {'key': 'dark_mode', 'value': enabled ? '1' : '0'},
      conflictAlgorithm: ConflictAlgorithm.replace,
    );
  }

  Future<List<Supermarket>> getSupermarkets() async {
    final db = await _database;
    final rows = await db.query('supermarkets', orderBy: 'sort_order ASC, id ASC');
    if (rows.isEmpty) {
      await _seedSupermarkets(db);
      return getSupermarkets();
    }
    return rows.map(Supermarket.fromMap).toList();
  }

  Future<Supermarket> addSupermarket({
    required String name,
    required int colorValue,
  }) async {
    final db = await _database;
    final maxOrder = Sqflite.firstIntValue(
      await db.rawQuery('SELECT MAX(sort_order) FROM supermarkets'),
    );
    final id = await db.insert('supermarkets', {
      'name': name.trim(),
      'color': colorValue,
      'sort_order': (maxOrder ?? -1) + 1,
    });
    return Supermarket(
      id: id,
      name: name.trim(),
      colorValue: colorValue,
      sortOrder: (maxOrder ?? -1) + 1,
    );
  }

  Future<void> updateSupermarket(Supermarket store) async {
    final id = store.id;
    if (id == null) return;
    final db = await _database;
    final existing = await db.query(
      'supermarkets',
      where: 'id = ?',
      whereArgs: [id],
      limit: 1,
    );
    if (existing.isEmpty) return;
    final oldName = existing.first['name']! as String;
    await db.update(
      'supermarkets',
      {
        'name': store.name.trim(),
        'color': store.colorValue,
        'sort_order': store.sortOrder,
      },
      where: 'id = ?',
      whereArgs: [id],
    );
    if (oldName != store.name.trim()) {
      await db.update(
        'products',
        {'supermarket': store.name.trim()},
        where: 'supermarket = ?',
        whereArgs: [oldName],
      );
      await db.update(
        'shops',
        {'supermarket': store.name.trim()},
        where: 'supermarket = ?',
        whereArgs: [oldName],
      );
    }
  }

  Future<void> deleteSupermarket(int id) async {
    final db = await _database;
    await db.delete('supermarkets', where: 'id = ?', whereArgs: [id]);
  }

  Future<List<Map<String, Object?>>> dumpTable(String table) async {
    final db = await _database;
    return db.query(table, orderBy: 'id ASC');
  }

  Future<String> writeImageBytes(String relativePath, List<int> bytes) async {
    final dir = await getApplicationDocumentsDirectory();
    final dest = File(p.join(dir.path, relativePath));
    await dest.parent.create(recursive: true);
    await dest.writeAsBytes(bytes, flush: true);
    return dest.path;
  }

  Future<void> clearImageFolders() async {
    final dir = await getApplicationDocumentsDirectory();
    for (final name in ['receipts', 'products']) {
      final folder = Directory(p.join(dir.path, name));
      if (await folder.exists()) {
        await folder.delete(recursive: true);
      }
    }
  }

  Future<void> replaceAllData({
    required List<Map<String, Object?>> supermarkets,
    required List<Map<String, Object?>> products,
    required List<Map<String, Object?>> shops,
    required List<Map<String, Object?>> shopItems,
    required bool darkMode,
  }) async {
    final db = await _database;
    await db.transaction((txn) async {
      await txn.delete('shop_items');
      await txn.delete('shops');
      await txn.delete('products');
      await txn.delete('supermarkets');
      await txn.delete('app_settings');

      for (final row in supermarkets) {
        await txn.insert('supermarkets', _sqlRow(row, _supermarketColumns));
      }
      for (final row in products) {
        await txn.insert('products', _sqlRow(row, _productColumns));
      }
      for (final row in shops) {
        await txn.insert('shops', _sqlRow(row, _shopColumns));
      }
      for (final row in shopItems) {
        await txn.insert('shop_items', _sqlRow(row, _shopItemColumns));
      }
      await txn.insert('app_settings', {
        'key': 'dark_mode',
        'value': darkMode ? '1' : '0',
      });

      await _resetSequence(txn, 'supermarkets');
      await _resetSequence(txn, 'products');
      await _resetSequence(txn, 'shops');
      await _resetSequence(txn, 'shop_items');
    });
  }

  static const _supermarketColumns = {
    'id',
    'name',
    'color',
    'sort_order',
  };
  static const _productColumns = {
    'id',
    'name',
    'normalized_name',
    'last_price',
    'times_seen',
    'favourite',
    'image_path',
    'supermarket',
    'notes',
    'category',
    'created_at',
    'updated_at',
  };
  static const _shopColumns = {
    'id',
    'supermarket',
    'shopped_at',
    'receipt_image_path',
    'total',
    'created_at',
  };
  static const _shopItemColumns = {
    'id',
    'shop_id',
    'product_id',
    'name',
    'price',
    'quantity',
    'unit_price',
  };

  Map<String, Object?> _sqlRow(
    Map<String, Object?> source,
    Set<String> columns,
  ) {
    final row = <String, Object?>{};
    for (final column in columns) {
      if (!source.containsKey(column)) continue;
      row[column] = _sqlValue(source[column]);
    }
    return row;
  }

  Object? _sqlValue(Object? value) {
    if (value == null) return null;
    if (value is bool) return value ? 1 : 0;
    if (value is int) return value;
    if (value is double) {
      if (value == value.roundToDouble()) return value.toInt();
      return value;
    }
    if (value is num) return value.toDouble();
    return value.toString();
  }

  Future<void> _resetSequence(DatabaseExecutor db, String table) async {
    try {
      final max = Sqflite.firstIntValue(
        await db.rawQuery('SELECT MAX(id) FROM $table'),
      );
      await db.delete('sqlite_sequence', where: 'name = ?', whereArgs: [table]);
      if (max != null) {
        await db.insert('sqlite_sequence', {'name': table, 'seq': max});
      }
    } catch (_) {
      // sqlite_sequence is missing on some empty databases.
    }
  }
}