// lib/features/tournament/presentation/provider/shuffle_provider.dart

import 'dart:math';
import 'package:collection/collection.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../data/models/player_model.dart';
import 'active_players_provider.dart';
import 'shuffle_settings_provider.dart';

class ShuffleResult {
  final List<List<PlayerModel>> fields; // 3 Felder à max 12
  final List<PlayerModel> bench;
  final String message;

  ShuffleResult(this.fields, this.bench, {this.message = ''});
}

// Dies ist jetzt ein STATEFUL Provider → wird nur bei explizitem Aufruf neu berechnet
final shuffleResultProvider =
StateProvider<ShuffleResult>((ref) => ShuffleResult([], [], message: 'Noch nicht gemischt'));

final shuffleControllerProvider = Provider((ref) => ShuffleController(ref));

class ShuffleController {
  final Ref _ref;
  ShuffleController(this._ref);

  /// Hauptfunktion – wird nur vom Button aufgerufen
  void shuffle() {
    final activePlayers = _ref.read(activePlayersProvider);
    final settings = _ref.read(shuffleSettingsProvider);

    if (activePlayers.isEmpty) {
      _ref.read(shuffleResultProvider.notifier).state =
          ShuffleResult([], [], message: 'Keine aktiven Spieler');
      return;
    }

    final result = ShuffleAlgorithm().run(activePlayers, settings);

    // Jetzt erst speichern (einmalig!)
    _commitAllChanges(result);

    // UI aktualisieren
    _ref.read(shuffleResultProvider.notifier).state = result;
  }

  void _commitAllChanges(ShuffleResult result) {
    // Aussetzer markieren
    for (final p in result.bench) {
      p.hasSatOut = true;
      p.save();
    }

    // Alle anderen zurücksetzen (falls nötig)
    final allActive = _ref.read(activePlayersProvider);
    for (final p in allActive) {
      if (!result.bench.contains(p)) {
        p.hasSatOut = false;
        p.save();
      }
    }
  }
}

class ShuffleAlgorithm {
  final Random _random = Random();

  ShuffleResult run(List<PlayerModel> players, ShuffleSettings settings) {
    // 1. Aussetzer bestimmen
    final bench = _determineBench(players);
    final playing = players.where((p) => !bench.contains(p)).toList();

    // 2. Mischen
    List<PlayerModel> ordered;
    switch (settings.mode) {
      case ShuffleMode.random:
        ordered = playing..shuffle(_random);
        break;
      default:
        ordered = _balancedShuffle(playing, settings);
        break;
    }

    // 3. Auf 3 Felder verteilen
    final fields = <List<PlayerModel>>[];
    for (int i = 0; i < 3; i++) {
      final start = i * 12;
      final end = (start + 12).clamp(0, ordered.length);
      fields.add(start < ordered.length ? ordered.sublist(start, end) : []);
    }

    return ShuffleResult(
      fields,
      bench,
      message: 'Gemischte Teams (${ordered.length} Spieler)',
    );
  }

  List<PlayerModel> _determineBench(List<PlayerModel> players) {
    if (players.length <= 36) return [];

    final excess = players.length - 36;
    final never = players.where((p) => !p.hasSatOut).toList();
    final already = players.where((p) => p.hasSatOut).toList();

    final bench = <PlayerModel>[];
    bench.addAll(never.take(excess));
    if (bench.length < excess) {
      bench.addAll(already.take(excess - bench.length));
    }
    return bench;
  }

  List<PlayerModel> _balancedShuffle(List<PlayerModel> players, ShuffleSettings settings) {
    players.sort((a, b) {
      if (settings.prioritizeGenderBalance) {
        final g = a.gender.index.compareTo(b.gender.index);
        if (g != 0) return g;
      }
      if (settings.prioritizeLevelBalance) {
        final l = b.skillLevel.index.compareTo(a.skillLevel.index);
        if (l != 0) return l;
      }
      if (settings.usePositions) {
        final az = a.positions.contains(Position.zuspieler) ? 1 : 0;
        final bz = b.positions.contains(Position.zuspieler) ? 1 : 0;
        if (az != bz) return bz.compareTo(az);
      }
      return 0;
    });

    final teams = List.generate(6, (_) => <PlayerModel>[]);
    for (int i = 0; i < players.length; i++) {
      teams[i % 6].add(players[i]);
    }
    for (final t in teams) t.shuffle(_random);

    final result = <PlayerModel>[];
    for (int i = 0; i < 3; i++) {
      result.addAll(teams[i]);
      result.addAll(teams[i + 3]);
    }
    return result;
  }
}