import 'dart:async';

import 'package:rimworld_modman/logger.dart';
import 'package:rimworld_modman/mod.dart';
import 'package:rimworld_modman/mod_list.dart';

/// A class that helps find the minimum set of mods that exhibit a bug.
///
/// Provides two main algorithms:
/// - Binary search / bisect: Divides mods into smaller subsets to find problematic ones quickly.
/// - Linear search / batching: Tests mods in small groups to systematically identify issues.
///
/// These approaches help RimWorld mod users identify which mods are causing problems
/// when many mods are installed.
class ModListTroubleshooter {
  final ModList originalModList;
  ModList currentModList;
  int _startIndex = 0;
  int _endIndex = 0;

  ModListTroubleshooter(ModList modList)
    : originalModList = modList,
      currentModList = modList.copyWith(),
      _startIndex = 0,
      _endIndex = modList.activeMods.length;

  ModList binaryForward() {
    final midIndex = (_startIndex + _endIndex) ~/ 2;
    final subset = originalModList.activeMods.keys.toList().sublist(
      midIndex,
      _endIndex,
    );
    currentModList.disableAll();
    currentModList.enableMods(subset);
    _startIndex = midIndex;
    return currentModList;
  }

  ModList binaryBackward() {
    final midIndex = ((_startIndex + _endIndex) / 2).ceil();
    final subset = originalModList.activeMods.keys.toList().sublist(
      _startIndex,
      midIndex,
    );
    currentModList.disableAll();
    currentModList.enableMods(subset);
    _endIndex = midIndex;
    return currentModList;
  }

  ModList linearForward({int stepSize = 20}) {
    final totalMods = originalModList.activeMods.length;
    
    if (_startIndex >= totalMods || _startIndex == _endIndex) {
      int newStart = totalMods - stepSize;
      if (newStart < 0) {
        newStart = 0;
      }
      _startIndex = newStart;
    }

    _startIndex = _startIndex.clamp(0, totalMods);
    _endIndex = (_startIndex + stepSize).clamp(0, totalMods);

    final subset = originalModList.activeMods.keys.toList().sublist(
      _startIndex,
      _endIndex,
    );

    currentModList.disableAll();
    currentModList.enableMods(subset);
    _startIndex = _endIndex;
    
    return currentModList;
  }

  ModList linearBackward({int stepSize = 20}) {
    final totalMods = originalModList.activeMods.length;

    if (_endIndex <= 0 || _startIndex == _endIndex) {
      int newEnd = stepSize;
      if (newEnd > totalMods) {
        newEnd = totalMods;
      }
      _endIndex = newEnd;
    }

    _endIndex = _endIndex.clamp(0, totalMods);
    _startIndex = (_endIndex - stepSize).clamp(0, _endIndex);

    final subset = originalModList.activeMods.keys.toList().sublist(
      _startIndex,
      _endIndex,
    );

    currentModList.disableAll();
    currentModList.enableMods(subset);
    _endIndex = _startIndex;
    
    return currentModList;
  }

  void reset() {
    currentModList = originalModList.copyWith();
  }
}