import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:get_storage/get_storage.dart';
import '../../../core/utils/logger.dart';
import '../models/translation_models.dart';

/// 翻译历史记录管理类
/// 负责管理翻译历史的存储、加载、分页等功能
class TranslationHistoryManager extends GetxController {
  static const String TAG = 'TranslationHistoryManager';

  // 存储相关配置
  static const String _historyKey = 'translation_history';
  static const int _maxStorageItems = 1000; // 存储限制
  static const int _maxDisplayItems = 20; // 显示限制

  final GetStorage _storage = GetStorage();

  // 翻译历史数据
  final translationHistory = <TranslationItem>[].obs;

  // 分页加载相关状态
  final isLoadingMore = false.obs;
  final hasMoreHistory = true.obs;
  final currentPage = 1.obs;
  final pageSize = 20;
  final isLoadingMoreError = false.obs;
  bool _scrollListenerSetup = false;

  // 滚动控制器
  final ScrollController scrollController = ScrollController();

  /// 初始化历史管理器
  void initialize() {
    loadTranslationHistory();
    _setupScrollListener();
  }

  /// 加载翻译历史记录
  /// 初始化时只加载最近的显示条数，提高性能
  void loadTranslationHistory() {
    final historyJson = _storage.read(_historyKey);
    if (historyJson != null) {
      try {
        final List<dynamic> historyList = jsonDecode(historyJson);
        final List<TranslationItem> allHistory =
            historyList.map((item) => TranslationItem.fromJson(item)).toList();

        // 初始化分页状态
        currentPage.value = 1;
        isLoadingMore.value = false;
        isLoadingMoreError.value = false;

        // 主页面只显示最近的记录，保证界面性能
        if (allHistory.length > _maxDisplayItems) {
          translationHistory.value =
              allHistory.sublist(allHistory.length - _maxDisplayItems);
          hasMoreHistory.value = true;
        } else {
          translationHistory.value = allHistory;
          hasMoreHistory.value = false;
        }

        Logger.info('翻译历史加载成功: ${translationHistory.length}条记录');
      } catch (e) {
        _storage.remove(_historyKey);
        Logger.error('加载翻译历史失败: ${e.toString()}');
      }
    } else {
      // 没有历史数据时初始化分页状态
      hasMoreHistory.value = false;
      currentPage.value = 1;
      isLoadingMore.value = false;
      isLoadingMoreError.value = false;
    }
  }

  /// 保存翻译历史记录
  /// 只保存完成态记录，过滤中间态记录
  void saveTranslationHistory() {
    try {
      // 只保存完成态记录
      final List<TranslationItem> finalRecords =
          translationHistory.where((item) => !item.isIntermediate).toList();

      // 应用存储限制
      List<TranslationItem> historyToSave = finalRecords;
      if (finalRecords.length > _maxStorageItems) {
        historyToSave =
            finalRecords.sublist(finalRecords.length - _maxStorageItems);
      }

      // 保存到本地存储
      final List<Map<String, dynamic>> historyJson =
          historyToSave.map((item) => item.toJson()).toList();
      _storage.write(_historyKey, jsonEncode(historyJson));

      Logger.info('翻译历史保存成功: 存储${historyToSave.length}条记录');
    } catch (e) {
      Logger.error('保存翻译历史失败: ${e.toString()}');
    }
  }

  /// 添加新的翻译记录
  /// [item] 要添加的翻译记录
  /// [scrollToBottom] 是否滚动到底部
  void addTranslationItem(TranslationItem item, {bool scrollToBottom = true}) {
    translationHistory.add(item);
    if (scrollToBottom) {
      _scrollToBottom();
    }
  }

  /// 更新翻译记录
  /// [timestamp] 记录的时间戳，用于定位记录
  /// [updater] 更新函数
  bool updateTranslationItem(
      DateTime timestamp, Function(TranslationItem) updater) {
    final index = translationHistory
        .indexWhere((item) => item.timestamp.isAtSameMomentAs(timestamp));
    if (index != -1) {
      updater(translationHistory[index]);
      translationHistory.refresh();
      return true;
    }
    return false;
  }

  /// 加载更多历史记录（分页加载）
  Future<void> loadMoreHistory() async {
    if (isLoadingMore.value || !hasMoreHistory.value) {
      return;
    }

    try {
      isLoadingMore.value = true;
      isLoadingMoreError.value = false;

      final nextPage = currentPage.value + 1;
      Logger.i(TAG, '正在加载第 $nextPage 页翻译历史...');

      // 从存储中获取所有历史记录
      final historyJson = _storage.read(_historyKey);
      if (historyJson != null) {
        final List<dynamic> historyList = jsonDecode(historyJson);
        final List<TranslationItem> allHistory =
            historyList.map((item) => TranslationItem.fromJson(item)).toList();

        // 计算分页参数
        final totalItems = allHistory.length;
        final endIndex = totalItems - ((nextPage - 1) * pageSize);
        final startIndex = totalItems - (nextPage * pageSize);

        if (endIndex > 0) {
          final actualStartIndex = startIndex < 0 ? 0 : startIndex;
          final actualEndIndex = endIndex > totalItems ? totalItems : endIndex;

          final pageItems =
              allHistory.sublist(actualStartIndex, actualEndIndex);

          if (pageItems.isNotEmpty) {
            await Future.delayed(const Duration(milliseconds: 300));

            // reverse模式下：将新记录插入到现有记录列表的开头
            final updatedHistory = [...pageItems, ...translationHistory];
            translationHistory.assignAll(updatedHistory);

            // 更新分页状态
            currentPage.value = nextPage;
            hasMoreHistory.value = startIndex > 0;

            Logger.i(TAG, '成功加载 ${pageItems.length} 条历史记录');
          } else {
            hasMoreHistory.value = false;
          }
        } else {
          hasMoreHistory.value = false;
        }
      } else {
        hasMoreHistory.value = false;
      }
    } catch (e) {
      Logger.e(TAG, '加载更多历史记录失败: $e');
      isLoadingMoreError.value = true;
    } finally {
      isLoadingMore.value = false;
    }
  }

  /// 获取所有完成态历史记录
  List<TranslationItem> getAllHistory() {
    try {
      final List<TranslationItem> result = <TranslationItem>[];
      final Set<String> existingIds = <String>{};

      // 添加存储的历史记录
      final historyJson = _storage.read(_historyKey);
      if (historyJson != null) {
        final List<dynamic> historyList = jsonDecode(historyJson);
        final List<TranslationItem> storedHistory =
            historyList.map((item) => TranslationItem.fromJson(item)).toList();

        for (final item in storedHistory) {
          final id =
              '${item.sessionId}_${item.timestamp.millisecondsSinceEpoch}';
          if (!existingIds.contains(id)) {
            existingIds.add(id);
            result.add(item);
          }
        }
      }

      // 添加当前内存中的完成态记录
      for (final item in translationHistory) {
        if (!item.isIntermediate) {
          final id =
              '${item.sessionId}_${item.timestamp.millisecondsSinceEpoch}';
          if (!existingIds.contains(id)) {
            existingIds.add(id);
            result.add(item);
          }
        }
      }

      // 按时间排序
      result.sort((a, b) => a.timestamp.compareTo(b.timestamp));
      return result;
    } catch (e) {
      Logger.error('获取完整历史记录失败: ${e.toString()}');
      return translationHistory.where((item) => !item.isIntermediate).toList();
    }
  }

  /// 清除所有翻译历史
  void clearTranslationHistory() {
    translationHistory.clear();
    _storage.remove(_historyKey);
    Logger.info('翻译历史已清除');
  }

  /// 删除指定会话的所有翻译记录
  void deleteSessionHistory(String sessionId) {
    try {
      // 从内存中删除
      final originalCount = translationHistory.length;
      translationHistory.removeWhere((item) => item.sessionId == sessionId);
      final removedFromMemory = originalCount - translationHistory.length;

      // 从存储中删除
      final historyJson = _storage.read(_historyKey);
      int removedFromStorage = 0;

      if (historyJson != null) {
        final List<dynamic> historyList = jsonDecode(historyJson);
        final List<TranslationItem> storedHistory =
            historyList.map((item) => TranslationItem.fromJson(item)).toList();

        final originalStoredCount = storedHistory.length;
        storedHistory.removeWhere((item) => item.sessionId == sessionId);
        removedFromStorage = originalStoredCount - storedHistory.length;

        // 重新保存
        final List<Map<String, dynamic>> updatedHistoryJson =
            storedHistory.map((item) => item.toJson()).toList();
        _storage.write(_historyKey, jsonEncode(updatedHistoryJson));
      }

      translationHistory.refresh();

      Logger.info(
          '删除会话历史成功: sessionId=$sessionId, 内存删除${removedFromMemory}条, 存储删除${removedFromStorage}条');
    } catch (e) {
      Logger.error('删除会话历史失败: ${e.toString()}');
      rethrow;
    }
  }

  /// 删除指定的单条翻译记录
  void deleteTranslationItem(String sessionId, DateTime timestamp) {
    try {
      // 从内存中删除
      final originalCount = translationHistory.length;
      translationHistory.removeWhere((item) =>
          item.sessionId == sessionId &&
          item.timestamp.millisecondsSinceEpoch ==
              timestamp.millisecondsSinceEpoch);
      final removedFromMemory = originalCount - translationHistory.length;

      // 从存储中删除
      final historyJson = _storage.read(_historyKey);
      int removedFromStorage = 0;

      if (historyJson != null) {
        final List<dynamic> historyList = jsonDecode(historyJson);
        final List<TranslationItem> storedHistory =
            historyList.map((item) => TranslationItem.fromJson(item)).toList();

        final originalStoredCount = storedHistory.length;
        storedHistory.removeWhere((item) =>
            item.sessionId == sessionId &&
            item.timestamp.millisecondsSinceEpoch ==
                timestamp.millisecondsSinceEpoch);
        removedFromStorage = originalStoredCount - storedHistory.length;

        // 重新保存
        final List<Map<String, dynamic>> updatedHistoryJson =
            storedHistory.map((item) => item.toJson()).toList();
        _storage.write(_historyKey, jsonEncode(updatedHistoryJson));
      }

      translationHistory.refresh();

      Logger.info(
          '删除单条翻译记录成功: sessionId=$sessionId, 内存删除${removedFromMemory}条, 存储删除${removedFromStorage}条');
    } catch (e) {
      Logger.error('删除单条翻译记录失败: ${e.toString()}');
      rethrow;
    }
  }

  /// 滚动到底部
  void scrollToBottom({bool animate = true}) {
    _scrollToBottom(animate: animate);
  }

  /// 设置滚动监听器
  void _setupScrollListener() {
    if (_scrollListenerSetup) return;

    scrollController.addListener(() {
      // reverse模式下：检查是否滚动到底部
      if (scrollController.position.pixels >=
          scrollController.position.maxScrollExtent - 100) {
        if (hasMoreHistory.value && !isLoadingMore.value) {
          Logger.d(TAG, '触发加载更多翻译历史记录');
          loadMoreHistory();
        }
      }
    });

    _scrollListenerSetup = true;
  }

  /// 内部滚动到底部方法
  void _scrollToBottom({bool animate = true}) {
    if (scrollController.hasClients && translationHistory.isNotEmpty) {
      try {
        const targetPosition = 0.0; // reverse模式下最新消息在顶部

        if (animate) {
          scrollController.animateTo(
            targetPosition,
            duration: const Duration(milliseconds: 300),
            curve: Curves.easeOut,
          );
        } else {
          scrollController.jumpTo(targetPosition);
        }
      } catch (e) {
        Logger.error('滚动到顶部失败: ${e.toString()}');
      }
    }
  }

  /// 释放资源
  void dispose() {
    scrollController.dispose();
    Logger.info('翻译历史管理器已释放');
  }
}