import { FASTING_PLANS, FastingPlan, getPlanById } from '@/constants/Fasting';
import { calculateFastingWindow, getFastingPhase } from '@/utils/fasting';
import { createSlice, PayloadAction } from '@reduxjs/toolkit';
import dayjs from 'dayjs';
import type { RootState } from './index';

export type FastingScheduleOrigin = 'manual' | 'recommended' | 'quick-start' | 'auto';

// 保持向后兼容的单次断食计划
export type FastingSchedule = {
  planId: string;
  startISO: string;
  endISO: string;
  createdAtISO: string;
  updatedAtISO: string;
  origin: FastingScheduleOrigin;
};

// 新的周期性断食计划
export type FastingCycle = {
  planId: string;
  startHour: number;
  startMinute: number;
  enabled: boolean;
  createdAtISO: string;
  lastUpdatedISO: string;
};

// 周期性断食的单次会话
export type FastingCycleSession = {
  planId: string;
  startISO: string;
  endISO: string;
  cycleDate: string; // YYYY-MM-DD
  completed: boolean;
};

type FastingState = {
  // 保持向后兼容的单次计划
  activeSchedule: FastingSchedule | null;
  history: FastingSchedule[];
  
  // 新的周期性计划
  activeCycle: FastingCycle | null;
  currentCycleSession: FastingCycleSession | null;
  cycleHistory: FastingCycleSession[];
};

const initialState: FastingState = {
  activeSchedule: null,
  history: [],
  activeCycle: null,
  currentCycleSession: null,
  cycleHistory: [],
};

const fastingSlice = createSlice({
  name: 'fasting',
  initialState,
  reducers: {
    hydrateActiveSchedule: (
      state,
      action: PayloadAction<FastingSchedule | null>
    ) => {
      const incoming = action.payload;
      if (!incoming) {
        state.activeSchedule = null;
        return;
      }

      if (state.activeSchedule) {
        const currentUpdated = dayjs(state.activeSchedule.updatedAtISO ?? state.activeSchedule.startISO);
        const incomingUpdated = dayjs(incoming.updatedAtISO ?? incoming.startISO);
        if (currentUpdated.isSame(incomingUpdated) || currentUpdated.isAfter(incomingUpdated)) {
          return;
        }
      }

      state.activeSchedule = incoming;
    },
    scheduleFastingPlan: (
      state,
      action: PayloadAction<{ planId: string; start: string; origin?: FastingScheduleOrigin }>
    ) => {
      const plan = getPlanById(action.payload.planId);
      if (!plan) return;

      const startDate = new Date(action.payload.start);
      const { start, end } = calculateFastingWindow(startDate, plan.fastingHours);
      const nowISO = new Date().toISOString();
      state.activeSchedule = {
        planId: plan.id,
        startISO: start.toISOString(),
        endISO: end.toISOString(),
        createdAtISO: nowISO,
        updatedAtISO: nowISO,
        origin: action.payload.origin ?? 'manual',
      };
    },
    rescheduleActivePlan: (
      state,
      action: PayloadAction<{ start: string; origin?: FastingScheduleOrigin }>
    ) => {
      if (!state.activeSchedule) return;
      const plan = getPlanById(state.activeSchedule.planId);
      if (!plan) return;

      const startDate = new Date(action.payload.start);
      const { start, end } = calculateFastingWindow(startDate, plan.fastingHours);
      state.activeSchedule = {
        ...state.activeSchedule,
        startISO: start.toISOString(),
        endISO: end.toISOString(),
        updatedAtISO: new Date().toISOString(),
        origin: action.payload.origin ?? state.activeSchedule.origin,
      };
    },
    setRecommendedSchedule: (
      state,
      action: PayloadAction<{ planId: string; recommendedStart: string }>
    ) => {
      const plan = getPlanById(action.payload.planId);
      if (!plan) return;
      const startDate = new Date(action.payload.recommendedStart);
      const { start, end } = calculateFastingWindow(startDate, plan.fastingHours);
      const nowISO = new Date().toISOString();
      state.activeSchedule = {
        planId: plan.id,
        startISO: start.toISOString(),
        endISO: end.toISOString(),
        createdAtISO: nowISO,
        updatedAtISO: nowISO,
        origin: 'recommended',
      };
    },
    completeActiveSchedule: (state) => {
      if (!state.activeSchedule) return;
      const phase = getFastingPhase(
        new Date(state.activeSchedule.startISO),
        new Date(state.activeSchedule.endISO)
      );

      if (phase === 'fasting') {
        // Allow manual completion only when fasting window已经结束
        state.activeSchedule = {
          ...state.activeSchedule,
          endISO: dayjs().toISOString(),
          updatedAtISO: new Date().toISOString(),
        };
      }

      state.history.unshift(state.activeSchedule);
      state.activeSchedule = null;
    },
    clearActiveSchedule: (state) => {
      state.activeSchedule = null;
    },
    
    // 周期性断食计划相关的 actions
    startFastingCycle: (
      state,
      action: PayloadAction<{
        planId: string;
        startHour: number;
        startMinute: number;
      }>
    ) => {
      const plan = getPlanById(action.payload.planId);
      if (!plan) return;
      
      const nowISO = new Date().toISOString();
      state.activeCycle = {
        planId: plan.id,
        startHour: action.payload.startHour,
        startMinute: action.payload.startMinute,
        enabled: true,
        createdAtISO: nowISO,
        lastUpdatedISO: nowISO,
      };
      
      // 创建今天的断食会话，增加最小提前时间检查
      const today = dayjs();
      const todayStart = today.hour(action.payload.startHour).minute(action.payload.startMinute).second(0).millisecond(0);
      
      // 要求至少提前10分钟设置周期性断食
      const minAdvanceTime = 10; // 分钟
      const minStartTime = today.add(minAdvanceTime, 'minute');
      
      // 如果今天的开始时间已过或太接近，则从明天开始
      const sessionStart = todayStart.isBefore(minStartTime)
        ? todayStart.add(1, 'day')
        : todayStart;
      
      const { start, end } = calculateFastingWindow(sessionStart.toDate(), plan.fastingHours);
      
      state.currentCycleSession = {
        planId: plan.id,
        startISO: start.toISOString(),
        endISO: end.toISOString(),
        cycleDate: sessionStart.format('YYYY-MM-DD'),
        completed: false,
      };
    },
    
    pauseFastingCycle: (state) => {
      if (state.activeCycle) {
        state.activeCycle.enabled = false;
        state.activeCycle.lastUpdatedISO = new Date().toISOString();
      }
    },
    
    resumeFastingCycle: (state) => {
      if (state.activeCycle) {
        state.activeCycle.enabled = true;
        state.activeCycle.lastUpdatedISO = new Date().toISOString();
      }
    },
    
    stopFastingCycle: (state) => {
      // 完成当前会话
      if (state.currentCycleSession) {
        state.cycleHistory.unshift(state.currentCycleSession);
      }
      
      // 清除周期性计划
      state.activeCycle = null;
      state.currentCycleSession = null;
    },
    
    updateFastingCycleTime: (
      state,
      action: PayloadAction<{ startHour: number; startMinute: number }>
    ) => {
      if (!state.activeCycle) return;
      
      state.activeCycle.startHour = action.payload.startHour;
      state.activeCycle.startMinute = action.payload.startMinute;
      state.activeCycle.lastUpdatedISO = new Date().toISOString();
    },
    
    completeCurrentCycleSession: (state) => {
      if (!state.currentCycleSession) return;
      
      // 标记当前会话为已完成
      state.currentCycleSession.completed = true;
      
      // 添加到历史记录
      state.cycleHistory.unshift(state.currentCycleSession);
      
      // 创建下一个周期的会话
      if (state.activeCycle && state.activeCycle.enabled) {
        const plan = getPlanById(state.activeCycle.planId);
        if (plan) {
          const nextDate = dayjs(state.currentCycleSession.cycleDate).add(1, 'day');
          const nextStart = nextDate.hour(state.activeCycle.startHour).minute(state.activeCycle.startMinute).second(0).millisecond(0);
          const { start, end } = calculateFastingWindow(nextStart.toDate(), plan.fastingHours);
          
          state.currentCycleSession = {
            planId: plan.id,
            startISO: start.toISOString(),
            endISO: end.toISOString(),
            cycleDate: nextDate.format('YYYY-MM-DD'),
            completed: false,
          };
        }
      } else {
        state.currentCycleSession = null;
      }
    },
    
    hydrateFastingCycle: (
      state,
      action: PayloadAction<{
        activeCycle: FastingCycle | null;
        currentCycleSession: FastingCycleSession | null;
        cycleHistory: FastingCycleSession[];
      }>
    ) => {
      state.activeCycle = action.payload.activeCycle;
      state.currentCycleSession = action.payload.currentCycleSession;
      state.cycleHistory = action.payload.cycleHistory;
    },
  },
});

export const {
  hydrateActiveSchedule,
  scheduleFastingPlan,
  rescheduleActivePlan,
  setRecommendedSchedule,
  completeActiveSchedule,
  clearActiveSchedule,
  // 周期性断食相关的 actions
  startFastingCycle,
  pauseFastingCycle,
  resumeFastingCycle,
  stopFastingCycle,
  updateFastingCycleTime,
  completeCurrentCycleSession,
  hydrateFastingCycle,
} = fastingSlice.actions;

export default fastingSlice.reducer;

export const selectFastingRoot = (state: RootState) => state.fasting;
export const selectActiveFastingSchedule = (state: RootState) => state.fasting.activeSchedule;
export const selectFastingPlans = () => FASTING_PLANS;
export const selectActiveFastingPlan = (state: RootState): FastingPlan | undefined => {
  const schedule = state.fasting.activeSchedule;
  if (!schedule) return undefined;
  return getPlanById(schedule.planId);
};

// 周期性断食相关的 selectors
export const selectActiveFastingCycle = (state: RootState) => state.fasting.activeCycle;
export const selectCurrentCycleSession = (state: RootState) => state.fasting.currentCycleSession;
export const selectCycleHistory = (state: RootState) => state.fasting.cycleHistory;
export const selectActiveCyclePlan = (state: RootState): FastingPlan | undefined => {
  const cycle = state.fasting.activeCycle;
  if (!cycle) return undefined;
  return getPlanById(cycle.planId);
};
export const selectCurrentCyclePlan = (state: RootState): FastingPlan | undefined => {
  const session = state.fasting.currentCycleSession;
  if (!session) return undefined;
  return getPlanById(session.planId);
};

// 获取当前应该显示的断食信息（优先显示周期性，其次显示单次）
export const selectCurrentFastingPlan = (state: RootState): FastingPlan | undefined => {
  // 优先显示周期性断食
  const cyclePlan = selectCurrentCyclePlan(state);
  if (cyclePlan) return cyclePlan;
  
  // 其次显示单次断食
  return selectActiveFastingPlan(state);
};

// 获取当前应该显示的断食时间
export const selectCurrentFastingTimes = (state: RootState) => {
  // 优先显示周期性断食
  const cycleSession = state.fasting.currentCycleSession;
  if (cycleSession) {
    return {
      startISO: cycleSession.startISO,
      endISO: cycleSession.endISO,
    };
  }
  
  // 其次显示单次断食
  const schedule = state.fasting.activeSchedule;
  if (schedule) {
    return {
      startISO: schedule.startISO,
      endISO: schedule.endISO,
    };
  }
  
  return null;
};

// 判断是否处于周期性断食模式
export const selectIsInCycleMode = (state: RootState) => {
  return !!state.fasting.activeCycle;
};