import { listChallenges } from '@/services/challengesApi';
import { store } from '@/store';
import { getWaterIntakeFromHealthKit } from '@/utils/health';
import AsyncStorage from '@/utils/kvStore';
import { log } from '@/utils/logger';
import { ChallengeNotificationHelpers, WaterNotificationHelpers } from '@/utils/notificationHelpers';
import { getWaterGoalFromStorage } from '@/utils/userPreferences';
import { resyncFastingNotifications } from '@/services/fastingNotifications';
import { selectActiveFastingSchedule, selectActiveFastingPlan } from '@/store/fastingSlice';
import dayjs from 'dayjs';
import * as BackgroundTask from 'expo-background-task';
import * as TaskManager from 'expo-task-manager';
import { TaskManagerTaskBody } from 'expo-task-manager';

export const BACKGROUND_TASK_IDENTIFIER = 'com.anonymous.digitalpilates.task';



// 检查通知权限
async function checkNotificationPermissions(): Promise<boolean> {
  try {
    const Notifications = await import('expo-notifications');
    const { status } = await Notifications.getPermissionsAsync();
    return status === 'granted';
  } catch (error) {
    console.error('检查通知权限失败:', error);
    return false;
  }
}

// 执行喝水提醒后台任务
async function executeWaterReminderTask(): Promise<void> {
  try {
    console.log('执行喝水提醒后台任务...');

    // 获取当前状态，添加错误处理
    let state;
    try {
      state = store.getState();
    } catch (error) {
      console.log('无法获取 Redux state，使用本地存储:', error);
      // 使用本地存储作为后备方案
      const dailyGoal = await getWaterGoalFromStorage();
      if (!dailyGoal || dailyGoal <= 0) {
        console.log('没有设置喝水目标，跳过喝水提醒');
        return;
      }
      // 简化的提醒逻辑
      await sendSimpleWaterReminder();
      return;
    }

    const waterStats = state.water?.todayStats;
    const userProfile = state.user?.profile;

    // 优先使用 Redux 中的目标，若无则读取本地存储
    let dailyGoal = waterStats?.dailyGoal ?? 0;
    if (!dailyGoal || dailyGoal <= 0) {
      dailyGoal = await getWaterGoalFromStorage();
    }

    if (!dailyGoal || dailyGoal <= 0) {
      console.log('没有设置喝水目标，跳过喝水提醒');
      return;
    }

    // 检查时间限制（避免深夜打扰）
    const currentHour = new Date().getHours();

    // 获取用户名
    const userName = userProfile?.name || '朋友';

    const todayRange = {
      startDate: dayjs().startOf('day').toDate().toISOString(),
      endDate: dayjs().endOf('day').toDate().toISOString()
    };

    let totalAmount = waterStats?.totalAmount ?? 0;
    let completionRate = waterStats?.completionRate ?? (dailyGoal > 0 ? (totalAmount / dailyGoal) * 100 : 0);

    try {
      const healthKitRecords = await getWaterIntakeFromHealthKit(todayRange);
      if (Array.isArray(healthKitRecords) && healthKitRecords.length > 0) {
        totalAmount = healthKitRecords.reduce((sum: number, record: unknown) => {
          if (record && typeof record === 'object' && 'value' in record) {
            const { value } = record as { value?: number | string };
            const numericValue = Number(value ?? 0);
            return Number.isFinite(numericValue) ? sum + numericValue : sum;
          }
          return sum;
        }, 0);
        completionRate = Math.min((totalAmount / dailyGoal) * 100, 100);
      } else {
        console.log('HealthKit 未返回今日饮水记录，使用应用内缓存数据');
      }
    } catch (healthKitError) {
      console.error('从HealthKit获取饮水记录失败，使用应用内缓存数据:', healthKitError);
    }

    // 构造今日统计数据
    const todayWaterStats = {
      totalAmount,
      dailyGoal,
      completionRate: Number.isFinite(completionRate) ? completionRate : 0
    };

    // 调用喝水通知检查函数
    const notificationSent = await WaterNotificationHelpers.checkWaterGoalAndNotify(
      userName,
      todayWaterStats,
      currentHour
    );

    if (notificationSent) {
      console.log('后台喝水提醒通知已发送');
      // 记录后台任务执行时间
      await AsyncStorage.setItem('@last_background_water_check', Date.now().toString());
    } else {
      console.log('无需发送后台喝水提醒通知');
    }

  } catch (error) {
    console.error('执行喝水提醒后台任务失败:', error);
  }
}

async function executeChallengeReminderTask(): Promise<void> {
  try {
    console.log('执行挑战鼓励提醒后台任务...');

    let userName = '朋友';
    try {
      const state = store.getState();
      const normalizedUserName = state.user?.profile?.name?.trim();
      userName = normalizedUserName && normalizedUserName.length > 0 ? normalizedUserName : '朋友';
    } catch (error) {
      console.log('无法获取用户名，使用默认值:', error);
    }

    const challenges = await listChallenges();
    const joinedChallenges = challenges.filter((challenge) => challenge.isJoined && challenge.progress);

    if (!joinedChallenges.length) {
      console.log('没有加入的挑战或挑战没有进度，跳过挑战提醒');
      return;
    }

    const todayKey = new Date().toISOString().slice(0, 10);

    // 筛选出需要发送通知的挑战（未签到且今天未发送过通知）
    const eligibleChallenges = [];
    for (const challenge of joinedChallenges) {
      const progress = challenge.progress;
      if (!progress || progress.checkedInToday) {
        continue;
      }

      const storageKey = `@challenge_encouragement_sent:${challenge.id}`;
      const lastSent = await AsyncStorage.getItem(storageKey);
      if (lastSent === todayKey) {
        continue;
      }

      eligibleChallenges.push(challenge);
    }

    // 如果有符合条件的挑战，随机选择一个发送通知
    if (eligibleChallenges.length > 0) {
      const randomIndex = Math.floor(Math.random() * eligibleChallenges.length);
      const selectedChallenge = eligibleChallenges[randomIndex];

      try {
        await ChallengeNotificationHelpers.sendEncouragementNotification({
          userName,
          challengeTitle: selectedChallenge.title,
          challengeId: selectedChallenge.id,
        });

        const storageKey = `@challenge_encouragement_sent:${selectedChallenge.id}`;
        await AsyncStorage.setItem(storageKey, todayKey);

        console.log(`已随机选择并发送挑战鼓励通知: ${selectedChallenge.title}`);
      } catch (notificationError) {
        console.error('发送挑战鼓励通知失败:', notificationError);
      }
    } else {
      console.log('没有符合条件的挑战需要发送鼓励通知');
    }

    console.log('挑战鼓励提醒后台任务完成');
  } catch (error) {
    console.error('执行挑战鼓励提醒后台任务失败:', error);
  }
}

// 执行断食通知后台任务
async function executeFastingNotificationTask(): Promise<void> {
  try {
    console.log('执行断食通知后台任务...');

    let state;
    try {
      state = store.getState();
    } catch (error) {
      console.log('无法获取 Redux state，跳过断食通知任务:', error);
      return;
    }

    const activeSchedule = selectActiveFastingSchedule(state);
    const activePlan = selectActiveFastingPlan(state);

    if (!activeSchedule || !activePlan) {
      console.log('没有激活的断食计划，跳过断食通知任务');
      return;
    }

    // 检查断食计划是否已结束
    const end = dayjs(activeSchedule.endISO);
    if (end.isBefore(dayjs())) {
      console.log('断食计划已结束，跳过断食通知任务');
      return;
    }

    console.log('正在同步断食通知...', {
      planId: activePlan.id,
      start: activeSchedule.startISO,
      end: activeSchedule.endISO,
    });

    // 重新同步断食通知
    await resyncFastingNotifications({
      schedule: activeSchedule,
      plan: activePlan,
      enabled: true,
    });

    console.log('断食通知后台同步完成');

  } catch (error) {
    console.error('执行断食通知后台任务失败:', error);
  }
}

// 发送测试通知以验证后台任务执行
async function sendTestNotification(): Promise<void> {
  try {
    console.log('发送后台任务测试通知...');

    const Notifications = await import('expo-notifications');

    // 发送简单的测试通知
    await Notifications.scheduleNotificationAsync({
      content: {
        title: '后台任务测试',
        body: `后台任务正在执行中... 时间: ${new Date().toLocaleTimeString()}`,
        data: {
          type: 'background_task_test',
          timestamp: Date.now()
        }
      },
      trigger: null, // 立即发送
    });

    console.log('后台任务测试通知发送成功');

    // 记录测试通知发送时间
    await AsyncStorage.setItem('@last_background_test_notification', Date.now().toString());

  } catch (error) {
    console.error('发送测试通知失败:', error);
  }
}

/**
 * 发送简单的喝水提醒（后备方案）
 */
async function sendSimpleWaterReminder(): Promise<void> {
  try {
    const userName = '朋友'; // 默认用户名
    const Notifications = await import('expo-notifications');

    const notificationId = await Notifications.scheduleNotificationAsync({
      content: {
        title: '💧 该喝水啦！',
        body: `${userName}，记得补充水分，保持身体健康～`,
        data: {
          type: 'water_reminder',
          url: '/statistics'
        },
        sound: 'default',
      },
      trigger: null, // 立即发送
    });

    console.log('简单喝水提醒已发送，ID:', notificationId);
  } catch (error) {
    console.error('发送简单喝水提醒失败:', error);
  }
}

// 后台任务执行函数
async function executeBackgroundTasks(): Promise<void> {
  console.log('开始执行后台任务...');

  try {
    // 检查应用权限和用户设置
    const hasPermission = await checkNotificationPermissions();
    if (!hasPermission) {
      console.log('没有通知权限，跳过后台任务');
      return;
    }

    // 确保 Redux store 已初始化
    try {
      const state = store.getState();
      if (!state) {
        console.log('Redux store 未初始化，跳过后台任务');
        return;
      }
    } catch (error) {
      console.log('无法访问 Redux store，跳过后台任务:', error);
      return;
    }

    // await sendTestNotification() // 可选：启用测试通知

    // 检查是否启用测试通知
    const testNotificationsEnabled = await AsyncStorage.getItem('@background_test_notifications_enabled') === 'true';
    if (testNotificationsEnabled) {
      await sendTestNotification();
    }

    // 执行喝水提醒检查任务
    await executeWaterReminderTask();

    // 执行挑战鼓励提醒任务
    await executeChallengeReminderTask();

    // 执行断食通知任务
    await executeFastingNotificationTask();

    console.log('后台任务执行完成');
  } catch (error) {
    console.error('执行后台任务失败:', error);
  }
}

/**
 * 后台任务管理器
 * 负责配置和管理应用的后台任务执行
 */
export class BackgroundTaskManager {
  private static instance: BackgroundTaskManager;
  private isInitialized = false;

  static getInstance(): BackgroundTaskManager {
    if (!BackgroundTaskManager.instance) {
      BackgroundTaskManager.instance = new BackgroundTaskManager();
    }
    return BackgroundTaskManager.instance;
  }

  /**
   * 初始化后台任务管理器
   */
  async initialize(): Promise<void> {
    if (this.isInitialized) {
      console.log('后台任务管理器已初始化');
      return;
    }

    try {
      // 定义后台任务
      TaskManager.defineTask(BACKGROUND_TASK_IDENTIFIER, async (_body: TaskManagerTaskBody) => {
        try {
          log.info(`[BackgroundTask] 后台任务执行, 任务 ID: ${BACKGROUND_TASK_IDENTIFIER}`);
          await executeBackgroundTasks();
        } catch (error) {
          console.error('[BackgroundTask] 任务执行失败:', error);
          return BackgroundTask.BackgroundTaskResult.Failed;
        }
        return BackgroundTask.BackgroundTaskResult.Success;

      });

      if (await TaskManager.isTaskRegisteredAsync(BACKGROUND_TASK_IDENTIFIER)) {
        log.info('[BackgroundTask] 任务已注册');
      } else {
        log.info('[BackgroundTask] 任务未注册，开始注册...');
        await BackgroundTask.registerTaskAsync(BACKGROUND_TASK_IDENTIFIER);
        log.info('[BackgroundTask] 任务注册完成');
      }

      // 验证任务状态
      const status = await BackgroundTask.getStatusAsync();
      log.info(`[BackgroundTask] 任务状态: ${status}`);

      this.isInitialized = true;
      log.info('后台任务管理器初始化完成');

    } catch (error) {
      console.error('初始化后台任务管理器失败:', error);
      throw error;
    }
  }




  /**
   * 停止后台任务
   */
  async stop(): Promise<void> {
    try {
      await BackgroundTask.unregisterTaskAsync(BACKGROUND_TASK_IDENTIFIER);
      console.log('后台任务已停止');
    } catch (error) {
      console.error('停止后台任务失败:', error);
    }
  }

  /**
   * 获取后台任务状态
   */
  async getStatus(): Promise<BackgroundTask.BackgroundTaskStatus> {
    try {
      const status = await BackgroundTask.getStatusAsync();
      return status || BackgroundTask.BackgroundTaskStatus.Restricted;
    } catch (error) {
      console.error('获取后台任务状态失败:', error);
      return BackgroundTask.BackgroundTaskStatus.Restricted;
    }
  }

  /**
   * 检查后台任务状态
   */
  async checkStatus(): Promise<string> {
    const status = await this.getStatus();

    switch (status) {
      case BackgroundTask.BackgroundTaskStatus.Available:
        return '可用';
      case BackgroundTask.BackgroundTaskStatus.Restricted:
        return '受限制';
      default:
        return '未知';
    }
  }

  async triggerTaskForTesting(): Promise<void> {
    await BackgroundTask.triggerTaskWorkerForTestingAsync();
  }


  /**
   * 测试后台任务
   */
  async testBackgroundTask(): Promise<void> {
    console.log('开始测试后台任务...');

    try {
      // 手动触发后台任务执行
      await executeBackgroundTasks();
      console.log('后台任务测试完成');
    } catch (error) {
      console.error('后台任务测试失败:', error);
    }
  }


  /**
   * 获取最后一次后台检查时间
   */
  async getLastBackgroundCheckTime(): Promise<number | null> {
    try {
      const lastCheck = await AsyncStorage.getItem('@last_background_water_check');
      return lastCheck ? parseInt(lastCheck) : null;
    } catch (error) {
      console.error('获取最后后台检查时间失败:', error);
      return null;
    }
  }
}

/**
 * 后台任务事件类型
 */
export interface BackgroundTaskEvent {
  taskId: string;
  timestamp: number;
  success: boolean;
  error?: string;
}