import 'package:flutter/widgets.dart';
import 'package:seshat/data/repositories/bal_repository.dart';
import 'package:seshat/data/repositories/owner_repository.dart';
import 'package:seshat/domain/models/bal.dart';
import 'package:seshat/domain/models/bal_stats.dart';
import 'package:seshat/domain/models/book.dart';
import 'package:seshat/domain/models/book_instance.dart';
import 'package:seshat/domain/models/enums.dart';
import 'package:seshat/domain/models/return_owner.dart';
import 'package:seshat/domain/models/search_result.dart';
import 'package:seshat/utils/command.dart';
import 'package:seshat/utils/result.dart';

class BalViewModel extends ChangeNotifier {
  BalViewModel({
    required BalRepository balRepository,
    required this.selectedBalId,
    required OwnerRepository ownerRepository,
  }) : _balRepository = balRepository,
       _ownerRepository = ownerRepository {
    load = Command0(_load)..execute();
  }

  final BalRepository _balRepository;
  final OwnerRepository _ownerRepository;

  /*
 * =====================
 * =====< General >=====
 * =====================
*/

  /// Selected [Bal]
  Bal? _selectedBal;

  /// Selected [Bal]
  Bal? get selectedBal => _selectedBal;

  /// Selected [Bal.id] from path parameters
  int selectedBalId;

  /// Is one of the [Bal] [BalState.ongoing]
  bool isABalOngoing = false;

  /// Stops a [Bal]
  Future<Result<void>> stopBal(int balId) async {
    isLoaded = false;
    notifyListeners();
    final result = await _balRepository.stopBal(balId);
    switch (result) {
      case Ok():
        _selectedBal = result.value;
        break;
      default:
    }
    final result2 = await _loadEnded();
    switch (result2) {
      case Ok():
        isLoaded = true;
        break;
      case Error():
        break;
    }
    notifyListeners();
    return result;
  }

  /// Starts a [Bal]
  Future<Result<void>> startBal(int balId) async {
    if (isABalOngoing) {
      return Result.error(Exception("Cannot have multiple BALs ongoing !"));
    }
    final result = await _balRepository.startBal(balId);
    switch (result) {
      case Ok():
        _selectedBal = result.value;
        notifyListeners();
        break;
      default:
    }
    return result;
  }

  /// Edits a [Bal]'s [name], [startTime] or [endTime]
  Future<Result<void>> editBal(
    int id,
    String name,
    DateTime startTime,
    DateTime endTime,
  ) async {
    final result = await _balRepository.editBal(id, name, startTime, endTime);
    switch (result) {
      case Ok():
        _selectedBal = result.value;
        notifyListeners();
        break;
      case Error():
        break;
    }
    return result;
  }

  /*
 * ============================
 * =====< State Specific >=====
 * ============================
*/

  // Specific to ended state

  /// Owners a book or money is owed to
  List<ReturnOwner>? owedToOwners;

  /// Statistics about the [_selectedBal]
  BalStats? stats;

  /// Froms [books], updates [owners] to include all the necessary information
  /// See [the api doc](https://bal.ueauvergne.fr/docs/#/bal-api/get_bal_accounting) for more details
  Future<void> _updateOwedToOwnersWithBooks(
    List<ReturnOwner> owners,
    Map<String, Book> books,
  ) async {
    owedToOwners = owners;
    for (ReturnOwner owedToOwner in owedToOwners!) {
      var res = await _ownerRepository.getOwnerById(owedToOwner.ownerId);
      switch (res) {
        case Ok():
          owedToOwner.owner = res.value;
          break;
        default:
      }
      owedToOwner.owed = [];
      for (BookInstance instance in owedToOwner.owedInstances) {
        final bookId = instance.bookId;
        owedToOwner.owed.add(SearchResult(instance, books[bookId.toString()]!));
      }
    }
  }

  /// Returns either Books, Money or All ([ReturnType]) to an [Owner]
  Future<Result<void>> returnById(ReturnType type, int ownerId) async {
    final result = await _balRepository.returnToId(
      selectedBalId,
      ownerId,
      type,
    );
    final result2 = await _balRepository.getAccounting(selectedBalId);
    switch (result2) {
      case Ok():
        _updateOwedToOwnersWithBooks(result2.value.owners, result2.value.books);
        break;
      case Error():
        break;
    }
    notifyListeners();
    return result;
  }

  /*
 * =================================
 * =====< COMMAND AND LOADING >=====
 * =================================
*/

  /// Loads all the necessary information
  late final Command0 load;
  bool isLoaded = false;

  /// Manages loaders
  Future<Result<void>> _load() async {
    isABalOngoing = _balRepository.isABalOngoing();
    final result1 = await _loadBal();
    switch (result1) {
      case Ok():
        isLoaded =
            (_selectedBal == null || _selectedBal?.state != BalState.ended)
            ? true
            : false;
        break;
      default:
        break;
    }
    if (_selectedBal?.state == BalState.ended) {
      final result2 = await _loadEnded();
      switch (result2) {
        case Ok():
          isLoaded = true;
          break;
        case Error():
          break;
      }
    }
    notifyListeners();
    return result1;
  }

  /// Loads all common [Bal] information
  Future<Result<void>> _loadBal() async {
    final result = await _balRepository.balById(selectedBalId);
    switch (result) {
      case Ok():
        _selectedBal = result.value;
        break;
      case Error():
        break;
    }

    return result;
  }

  /// Loads [Bal] information when it is [BalState.ended]
  Future<Result<void>> _loadEnded() async {
    final result = await _balRepository.getAccountingNoCache(selectedBalId);
    switch (result) {
      case Ok():
        _updateOwedToOwnersWithBooks(result.value.owners, result.value.books);
        break;
      default:
    }
    final result2 = await _balRepository.getBalStats(selectedBalId);
    switch (result2) {
      case Ok():
        stats = result2.value;
        break;
      default:
    }
    return result;
  }
}