import 'dart:convert';

import 'package:drift/drift.dart' hide isNull, isNotNull;
import 'package:drift/native.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:kooltap/database/app_database.dart';
import 'package:kooltap/models/bar_tab.dart';
import 'package:kooltap/models/payment_method.dart';
import 'package:kooltap/models/product.dart';
import 'package:kooltap/models/tab_event.dart';
import 'package:kooltap/services/bar_tab_service.dart';
import 'package:kooltap/services/product_service.dart';

const _cola = Product(
  id: 'prod-1',
  name: 'Cola',
  category: 'Drinks',
  stockQuantity: 100,
  lowStockThreshold: 10,
  priceInCents: 250,
);

void main() {
  late AppDatabase database;
  late DriftBarTabService service;

  setUp(() async {
    database = AppDatabase(NativeDatabase.memory());
    service = DriftBarTabService(database: database);

    await database
        .into(database.products)
        .insert(
          ProductsCompanion.insert(
            id: _cola.id,
            name: _cola.name,
            category: _cola.category,
            stockQuantity: _cola.stockQuantity,
            lowStockThreshold: _cola.lowStockThreshold,
            priceInCents: _cola.priceInCents,
          ),
        );
  });

  tearDown(() async {
    await database.close();
  });

  Future<List<Map<String, dynamic>>> outbox() async {
    final rows =
        await (database.select(database.tabEvents)..orderBy([
              (row) => OrderingTerm.asc(const CustomExpression('rowid')),
            ]))
            .get();
    return [
      for (final row in rows) jsonDecode(row.payload) as Map<String, dynamic>,
    ];
  }

  Future<String> lineIdOf(String tabId) async {
    return (await service.getTabById(tabId))!.items.single.id;
  }

  /// Opens a tab and drops its `tab_opened` event.
  Future<BarTab> openTab(String name) async {
    final tab = await service.createTab(customerName: name);
    await database.delete(database.tabEvents).go();
    return tab;
  }

  Future<BarTabRow> tabWithTwoColas() async {
    final tab = await openTab('Jan');
    await service.addProductToTab(tabId: tab.id, product: _cola);
    await service.addProductToTab(tabId: tab.id, product: _cola);
    await database.delete(database.tabEvents).go();
    return (database.select(
      database.barTabs,
    )..where((row) => row.id.equals(tab.id))).getSingle();
  }

  group('line events', () {
    test('adding a product writes line_added with the common fields', () async {
      final tab = await openTab('Jan');
      await service.addProductToTab(tabId: tab.id, product: _cola);

      final event = (await outbox()).single;
      expect(event['type'], 'line_added');
      expect(event['tabId'], tab.id);
      expect(event['customerName'], 'Jan');
      expect(event['productId'], 'prod-1');
      expect(event['lineId'], await lineIdOf(tab.id));
      expect(event['productName'], 'Cola');
      expect(event['unitPriceInCents'], 250);
      expect(event['quantity'], 1);
      expect(event['id'], matches(RegExp(r'^[0-9a-f-]{36}$')));
      expect(event['occurredAt'], endsWith('Z'));

      final row = await database.select(database.tabEvents).getSingle();
      expect(row.id, event['id']);
    });

    test(
      'a drink at a new price goes on a new line, with that price',
      () async {
        final tab = await openTab('Jan');
        await service.addProductToTab(tabId: tab.id, product: _cola);
        await service.addProductToTab(
          tabId: tab.id,
          product: _cola.copyWith(priceInCents: 300),
        );

        final events = await outbox();
        expect(events.map((event) => event['unitPriceInCents']), [250, 300]);
        expect(events.map((event) => event['productId']), ['prod-1', 'prod-1']);
        // A different line, so the server doesn't put it on the old one either
        expect(events[0]['lineId'], isNot(events[1]['lineId']));
      },
    );

    test(
      '+ on a line at an old price sends the new price, on a new line',
      () async {
        final tab = await openTab('Jan');
        await service.addProductToTab(tabId: tab.id, product: _cola);
        final oldLine = await lineIdOf(tab.id);
        await (database.update(database.products)
              ..where((row) => row.id.equals('prod-1')))
            .write(const ProductsCompanion(priceInCents: Value(300)));

        await service.adjustTabItemQuantity(tabItemId: oldLine, delta: 1);

        final added = (await outbox()).last;
        expect(added['type'], 'line_added');
        expect(added['unitPriceInCents'], 300);
        expect(added['quantity'], 1);
        expect(added['lineId'], isNot(oldLine));
      },
    );

    test('a line without a product sends no productId', () async {
      final tab = await openTab('Jan');
      // As taken over from the tablet's own tabs: the line has no product
      await database
          .into(database.tabItems)
          .insert(
            TabItemsCompanion.insert(
              id: 'seed:${tab.id}:0',
              tabId: tab.id,
              productId: '',
              productName: 'Cola',
              quantity: 1,
              unitPriceInCents: 250,
              createdAt: DateTime.now(),
            ),
          );

      await service.adjustTabItemQuantity(
        tabItemId: 'seed:${tab.id}:0',
        delta: -1,
      );

      final event = (await outbox()).last;
      expect(event['type'], 'line_removed');
      expect(event.containsKey('productId'), isFalse);
      expect(event['productName'], 'Cola');
    });

    test('a drink at the same price goes on the same line', () async {
      final tab = await openTab('Jan');
      await service.addProductToTab(tabId: tab.id, product: _cola);
      await service.addProductToTab(tabId: tab.id, product: _cola);

      final events = await outbox();
      expect(events[0]['lineId'], events[1]['lineId']);
    });

    test('changing a quantity writes the difference', () async {
      final tab = await openTab('Jan');
      await service.addProductToTab(tabId: tab.id, product: _cola);
      await service.addProductToTab(tabId: tab.id, product: _cola);
      final lineId = await lineIdOf(tab.id);

      await service.adjustTabItemQuantity(tabItemId: lineId, delta: 3);
      await service.adjustTabItemQuantity(tabItemId: lineId, delta: -4);

      final events = (await outbox()).skip(2).toList();
      expect(events[0]['type'], 'line_added');
      expect(events[0]['quantity'], 3);
      expect(events[1]['type'], 'line_removed');
      expect(events[1]['quantity'], 4);
      expect(events[1]['unitPriceInCents'], 250);
    });

    test('removing a line writes line_removed for what was left', () async {
      final tab = await tabWithTwoColas();
      final lineId = await lineIdOf(tab.id);

      // More than is on the tab: only the 2 that were there are removed
      await service.adjustTabItemQuantity(tabItemId: lineId, delta: -5);

      final event = (await outbox()).single;
      expect(event['type'], 'line_removed');
      expect(event['quantity'], 2);
    });

    test('a change that does nothing writes no event', () async {
      final tab = await openTab('Jan');
      await service.addProductToTab(tabId: tab.id, product: _cola);
      final lineId = await lineIdOf(tab.id);
      await service.adjustTabItemQuantity(tabItemId: lineId, delta: -1);
      await database.delete(database.tabEvents).go();

      await service.adjustTabItemQuantity(tabItemId: lineId, delta: -1);
      await service.adjustTabItemQuantity(tabItemId: lineId, delta: 0);

      expect(await outbox(), isEmpty);
    });

    test(
      'deleting a tab writes line_removed for each line, then tab_deleted',
      () async {
        final tab = await tabWithTwoColas();

        await service.deleteTab(tab.id);

        final events = await outbox();
        expect(events.map((event) => event['type']), [
          'line_removed',
          'tab_deleted',
        ]);
        expect(events.first['quantity'], 2);
        expect(events.first['customerName'], 'Jan');
        expect(events.last['tabId'], tab.id);
      },
    );

    test('later events use the new name after a rename', () async {
      final tab = await openTab('Jan');
      await service.renameTab(tabId: tab.id, customerName: 'Janneke');
      await service.addProductToTab(tabId: tab.id, product: _cola);

      final events = await outbox();
      expect(events.map((event) => event['type']), [
        'tab_renamed',
        'line_added',
      ]);
      expect(events.map((event) => event['customerName']), [
        'Janneke',
        'Janneke',
      ]);
    });

    test('a failed change writes no event', () async {
      await expectLater(
        service.addProductToTab(tabId: 'missing', product: _cola),
        throwsA(isA<TabNotFoundException>()),
      );

      expect(await outbox(), isEmpty);
    });
  });

  group('tab events', () {
    test('opening a tab writes tab_opened in the same transaction', () async {
      final tab = await service.createTab(customerName: 'Jan');

      final event = (await outbox()).single;
      expect(event['type'], 'tab_opened');
      expect(event['tabId'], tab.id);
      expect(event['customerName'], 'Jan');
      // The database keeps whole seconds
      final openedAt = DateTime.parse(event['openedAt'] as String);
      expect(openedAt.difference(tab.openedAt).inSeconds, 0);
    });

    test('a rename of an unknown tab writes nothing', () async {
      await expectLater(
        service.renameTab(tabId: 'missing', customerName: 'X'),
        throwsA(isA<TabNotFoundException>()),
      );

      expect(await outbox(), isEmpty);
    });
  });

  group('settled events', () {
    test('settling writes one settled event and no removals', () async {
      final tab = await tabWithTwoColas();

      await service.closeTab(tab.id, paymentMethod: PaymentMethod.payconiq);

      final event = (await outbox()).single;
      expect(event['type'], 'settled');
      expect(event['customerName'], 'Jan');
      expect(event['amountInCents'], 500);
      expect(event['paymentMethod'], 'payconiq');
      expect(event.containsKey('commandId'), false);
      expect(event['items'], [
        {
          'productId': 'prod-1',
          'productName': 'Cola',
          'quantity': 2,
          'unitPriceInCents': 250,
        },
      ]);
      // History and the server's settlement feed share the event's id
      final closed = await service.getClosedTabs();
      expect(closed.single.id, event['id']);
    });

    test('lines that were taken back are not settled', () async {
      final tab = await tabWithTwoColas();
      final lineId = await lineIdOf(tab.id);
      await service.adjustTabItemQuantity(tabItemId: lineId, delta: -1);

      await service.closeTab(tab.id);

      final settled = (await outbox()).last;
      expect(settled['amountInCents'], 250);
      expect(settled['paymentMethod'], 'cash');
      expect((settled['items'] as List).single['quantity'], 1);
    });

    test('settling an empty tab writes nothing', () async {
      final tab = await openTab('Jan');

      await service.closeTab(tab.id);

      expect(await outbox(), isEmpty);
    });

    test('a version conflict writes nothing', () async {
      final tab = await tabWithTwoColas();

      await expectLater(
        service.closeTab(tab.id, expectedVersion: tab.version - 1),
        throwsA(isA<TabVersionConflictException>()),
      );

      expect(await outbox(), isEmpty);
    });

    test('carries the command id when given', () async {
      final tab = await tabWithTwoColas();

      await service.closeTab(
        tab.id,
        paymentMethod: PaymentMethod.paymentPending,
        commandId: 'cmd-1',
      );

      final event = (await outbox()).single;
      expect(event['commandId'], 'cmd-1');
      expect(event['paymentMethod'], 'payment_pending');
    });
  });

  group('stock', () {
    Future<int> colaStock() async {
      final row = await (database.select(
        database.products,
      )..where((row) => row.id.equals(_cola.id))).getSingle();
      return row.stockQuantity;
    }

    test('moves with every line event', () async {
      final tab = await openTab('Jan');
      for (var i = 0; i < 3; i++) {
        await service.addProductToTab(tabId: tab.id, product: _cola);
      }
      expect(await colaStock(), 97);

      await service.adjustTabItemQuantity(
        tabItemId: await lineIdOf(tab.id),
        delta: -2,
      );
      expect(await colaStock(), 99);

      await service.deleteTab(tab.id);
      expect(await colaStock(), 100);
    });

    test('settling leaves the stock alone', () async {
      final tab = await tabWithTwoColas();

      await service.closeTab(tab.id);

      expect(await colaStock(), 98);
    });

    test('a product without tracked stock never changes', () async {
      await (database.update(database.products)
            ..where((row) => row.id.equals(_cola.id)))
          .write(const ProductsCompanion(infiniteStock: Value(true)));
      final tab = await openTab('Jan');

      await service.addProductToTab(tabId: tab.id, product: _cola);
      await service.addProductToTab(tabId: tab.id, product: _cola);
      await service.deleteTab(tab.id);

      expect(await colaStock(), 100);
      expect(await outbox(), hasLength(4));
    });

    test('a line whose product is gone changes no stock', () async {
      final tab = await tabWithTwoColas();
      await (database.delete(
        database.products,
      )..where((row) => row.id.equals(_cola.id))).go();

      await service.deleteTab(tab.id);

      expect((await outbox()).first['type'], 'line_removed');
      expect(await service.getTabById(tab.id), isNull);
    });

    test('the stock only changes when its event is stored', () async {
      service = DriftBarTabService(
        database: database,
        eventFactory: _FixedIdEventFactory(),
      );
      final tab = await openTab('Jan');
      await service.addProductToTab(tabId: tab.id, product: _cola);

      // The second event reuses the id, so storing it fails
      await expectLater(
        service.addProductToTab(tabId: tab.id, product: _cola),
        throwsA(anything),
      );

      expect(await colaStock(), 99);
      expect(await outbox(), hasLength(1));
    });
  });

  group('product events', () {
    late DriftProductService products;

    setUp(() {
      products = DriftProductService(
        database: database,
        eventFactory: TabEventFactory(
          now: () => DateTime.utc(2026, 10, 24, 15, 3, 40),
        ),
      );
    });

    Future<List<Map<String, dynamic>>> productEvents() async => [
      for (final event in await outbox())
        if ((event['type'] as String).startsWith('product_')) event,
    ];

    Future<List<PendingImageUploadRow>> uploads() =>
        database.select(database.pendingImageUploads).get();

    test('a new product goes out with its fields, then its stock', () async {
      await products.createProduct(
        name: 'Ice Coffee',
        category: 'Koffie',
        stockQuantity: 12,
        lowStockThreshold: 3,
        priceInCents: 350,
        imagePath: null,
      );

      final id = (await products.getProducts())
          .firstWhere((p) => p.name == 'Ice Coffee')
          .id;
      final events = await outbox();
      expect(events.map((e) => e['type']), ['product_created', 'stock_set']);
      expect(events.first, {
        'id': events.first['id'],
        'type': 'product_created',
        'productId': id,
        'product': {
          'name': 'Ice Coffee',
          'category': 'Koffie',
          'priceInCents': 350,
          'lowStockThreshold': 3,
        },
        'occurredAt': '2026-10-24T15:03:40.000Z',
      });
      expect(events.first.containsKey('tabId'), isFalse);
    });

    test(
      'an untracked new product has no count, and no category is null',
      () async {
        await products.createProduct(
          name: 'Tap water',
          category: '  ',
          stockQuantity: 0,
          lowStockThreshold: 0,
          infiniteStock: true,
          priceInCents: 0,
          imagePath: null,
        );

        final events = await outbox();
        expect(events.map((e) => e['type']), ['product_created']);
        expect(events.single['product'], containsPair('category', null));
      },
    );

    test('a change sends only the fields that changed', () async {
      final cola = (await products.getProductById('prod-1'))!;

      await products.updateProduct(
        cola.copyWith(name: 'Coca-Cola', priceInCents: 270),
      );

      expect(
        (await productEvents()).single,
        containsPair('product', {'name': 'Coca-Cola', 'priceInCents': 270}),
      );
    });

    test('saving without changes sends nothing', () async {
      final cola = (await products.getProductById('prod-1'))!;

      await products.updateProduct(cola);

      expect(await outbox(), isEmpty);
    });

    test('deleting archives it for every tablet', () async {
      await products.deleteProduct('prod-1');

      expect(
        (await productEvents()).single,
        containsPair('type', 'product_archived'),
      );
      expect(await products.getProducts(), isEmpty);
    });

    test(
      'a picked picture waits for upload, a newer one replaces it',
      () async {
        final cola = (await products.getProductById('prod-1'))!;

        await products.updateProduct(
          cola.copyWith(imagePath: '/pictures/a.jpg'),
        );
        await products.updateProduct(
          cola.copyWith(imagePath: '/pictures/b.jpg'),
        );
        // Saving again with the same picture uploads nothing new
        await products.updateProduct(
          cola.copyWith(imagePath: '/pictures/b.jpg', name: 'Coke'),
        );

        final waiting = await uploads();
        expect(waiting.single.productId, 'prod-1');
        expect(waiting.single.localPath, '/pictures/b.jpg');
        // The picture itself is linked once uploaded, not now
        expect(
          (await productEvents()).where(
            (e) => (e['product'] as Map?)?.containsKey('imageId') ?? false,
          ),
          isEmpty,
        );
      },
    );

    test('a new product with a picture queues it for upload', () async {
      await products.createProduct(
        name: 'Ice Coffee',
        category: 'Koffie',
        stockQuantity: 12,
        lowStockThreshold: 3,
        priceInCents: 350,
        imagePath: '/pictures/ice.jpg',
      );

      expect((await uploads()).single.localPath, '/pictures/ice.jpg');
    });

    test('are skipped when replaying the outbox onto server tabs', () async {
      final tab = await openTab('Jan');
      await products.deleteProduct('prod-1');

      await service.applyServerState([]);

      expect(await service.getTabById(tab.id), isNull);
      expect(await productEvents(), hasLength(1));
    });
  });

  group('stock_set events', () {
    late DriftProductService products;

    setUp(() {
      products = DriftProductService(
        database: database,
        eventFactory: TabEventFactory(
          now: () => DateTime.utc(2026, 10, 24, 15, 3, 40),
        ),
      );
    });

    test('have a product and quantity but no tab', () {
      final event = TabEventFactory(
        now: () => DateTime.utc(2026, 10, 24, 15, 3, 40),
      ).stockSet(productId: 'prod-1', quantity: 30);

      expect(event.payload, {
        'id': event.id,
        'type': 'stock_set',
        'productId': 'prod-1',
        'quantity': 30,
        'occurredAt': '2026-10-24T15:03:40.000Z',
      });
    });

    test('a new product queues its starting stock', () async {
      await products.createProduct(
        name: 'Water',
        category: 'Drinks',
        stockQuantity: 24,
        lowStockThreshold: 5,
        priceInCents: 200,
        imagePath: null,
      );
      await products.createProduct(
        name: 'Tap water',
        category: 'Drinks',
        stockQuantity: 0,
        lowStockThreshold: 0,
        infiniteStock: true,
        priceInCents: 0,
        imagePath: null,
      );

      final water = (await products.getProducts()).firstWhere(
        (product) => product.name == 'Water',
      );
      final counts = [
        for (final event in await outbox())
          if (event['type'] == 'stock_set') event,
      ];
      expect(counts, hasLength(1));
      expect(counts.single, containsPair('productId', water.id));
      expect(counts.single, containsPair('quantity', 24));
    });

    test('a stock or tracking change queues a count', () async {
      final cola = (await products.getProductById('prod-1'))!;

      final renamed = cola.copyWith(name: 'Coca-Cola');
      await products.updateProduct(renamed);
      expect(
        (await outbox()).where((event) => event['type'] == 'stock_set'),
        isEmpty,
      );

      await products.updateProduct(renamed.copyWith(stockQuantity: 40));
      await products.updateProduct(
        renamed.copyWith(stockQuantity: 40, infiniteStock: true),
      );
      await products.updateProduct(renamed.copyWith(stockQuantity: 40));

      expect(
        [
          for (final event in await outbox())
            if (event['type'] == 'stock_set') event['quantity'],
        ],
        [40, null, 40],
      );
    });

    test('are skipped when replaying the outbox onto server tabs', () async {
      final tab = await openTab('Jan');
      await products.updateProduct(
        (await products.getProductById('prod-1'))!.copyWith(stockQuantity: 5),
      );

      await service.applyServerState([]);

      expect(await service.getTabById(tab.id), isNull);
      expect(await outbox(), hasLength(1));
    });
  });

  test('occurredAt is the UTC time it happened', () {
    final factory = TabEventFactory(
      now: () => DateTime.utc(2026, 10, 24, 21, 41, 3, 120),
    );

    final event = factory.lineAdded(
      tabId: 'a1b2',
      customerName: 'Jan',
      lineId: 'line-1',
      productId: 'prod-1',
      productName: 'Cola',
      unitPriceInCents: 250,
      quantity: 2,
    );

    expect(event.payload['occurredAt'], '2026-10-24T21:41:03.120Z');
    expect(
      () => factory.lineRemoved(
        tabId: 'a1b2',
        customerName: 'Jan',
        lineId: 'line-1',
        productId: 'prod-1',
        productName: 'Cola',
        unitPriceInCents: 250,
        quantity: 0,
      ),
      throwsArgumentError,
    );
  });
}

/// Gives every event the same id, so the second one can't be stored.
class _FixedIdEventFactory extends TabEventFactory {
  @override
  TabEvent lineAdded({
    required String tabId,
    required String customerName,
    required String lineId,
    required String productId,
    required String productName,
    required int unitPriceInCents,
    required int quantity,
  }) {
    final event = super.lineAdded(
      tabId: tabId,
      customerName: customerName,
      lineId: lineId,
      productId: productId,
      productName: productName,
      unitPriceInCents: unitPriceInCents,
      quantity: quantity,
    );
    return TabEvent(id: 'fixed', payload: {...event.payload, 'id': 'fixed'});
  }
}