import { createContext, useContext, useState, useEffect } from 'react'
import { auth, signInWithEmailAndPassword, signOut as firebaseSignOut, onAuthStateChanged } from '../firebase'
import { db, collection, getDocs, doc, setDoc, updateDoc } from 'firebase/firestore'

const StorageContext = createContext(null)

const CITIES = [
  'Алматы', 'Астана', 'Шымкент', 'Караганда', 'Актобе', 'Тараз', 'Павлодар',
  'Усть-Каменогорск', 'Семей', 'Атырау', 'Орал', 'Кызылорда', 'Костанай',
  'Петропавловск', 'Актау', 'Темиртау', 'Другой'
]

const DEFAULT_DATA = {
  program: {
    title: 'Адаптационная программа стажёров',
    description: 'Программа профессиональной адаптации для новых сотрудников',
    startDate: '',
    endDate: '',
    collectionOpen: false,
    groupsFormed: false,
    examEnabled: false,
    numberOfGroups: 2
  },
  trainers: [
    { id: 1, name: 'Тренер 1', login: 'trainer1', password: 'pass1' },
    { id: 2, name: 'Тренер 2', login: 'trainer2', password: 'pass2' }
  ],
  programRules: 'Правила программы:\n1. Посещаемость обязательна\n2. Домашние задания сдавать вовремя\n3. Активно участвовать в обсуждениях',
  examRules: 'Правила экзамена:\n1. 10 вопросов\n2. Порог сдачи: 9 правильных ответов (90%)\n3. Время выполнения: 60 минут',
  sessions: [],
  trainees: []
}

export function StorageProvider({ children }) {
  const [user, setUser] = useState(null)
  const [data, setData] = useState(DEFAULT_DATA)
  const [loading, setLoading] = useState(true)

  useEffect(() => {
    const unsubscribe = onAuthStateChanged(auth, (user) => {
      setUser(user)
      setLoading(false)
    })
    return unsubscribe
  }, [])

  useEffect(() => {
    loadData()
  }, [])

  const loadData = async () => {
    try {
      const stored = localStorage.getItem('internAdaptationData')
      if (stored) {
        setData(JSON.parse(stored))
      }
    } catch (error) {
      console.error('Error loading data:', error)
    }
  }

  const saveData = (newData) => {
    setData(newData)
    localStorage.setItem('internAdaptationData', JSON.stringify(newData))
  }

  const updateProgram = (updates) => {
    const newData = { ...data, program: { ...data.program, ...updates } }
    saveData(newData)
  }

  const updateTrainers = (trainers) => {
    const newData = { ...data, trainers }
    saveData(newData)
  }

  const updateProgramRules = (rules) => {
    const newData = { ...data, programRules: rules }
    saveData(newData)
  }

  const updateExamRules = (rules) => {
    const newData = { ...data, examRules: rules }
    saveData(newData)
  }

  const addSession = (session) => {
    const newSessions = [...data.sessions, { ...session, id: Date.now() }]
    const newData = { ...data, sessions: newSessions }
    saveData(newData)
  }

  const removeSession = (sessionId) => {
    const newSessions = data.sessions.filter(s => s.id !== sessionId)
    const newData = { ...data, sessions: newSessions }
    saveData(newData)
  }

  const addTrainee = (trainee) => {
    const newTrainees = [...data.trainees, { ...trainee, id: Date.now(), groupId: null, attendance: {}, homeworkStatus: {}, examScore: null }]
    const newData = { ...data, trainees: newTrainees }
    saveData(newData)
  }

  const updateTrainee = (id, updates) => {
    const newTrainees = data.trainees.map(t => t.id === id ? { ...t, ...updates } : t)
    const newData = { ...data, trainees: newTrainees }
    saveData(newData)
  }

  const deleteTrainee = (id) => {
    const newTrainees = data.trainees.filter(t => t.id !== id)
    const newData = { ...data, trainees: newTrainees }
    saveData(newData)
  }

  const formGroups = () => {
    const { numberOfGroups } = data.program
    const trainees = [...data.trainees]
    
    // Группировка по подразделениям и городам
    const groups = Array.from({ length: numberOfGroups }, () => [])
    
    // Сортировка для равномерного распределения
    trainees.sort((a, b) => {
      if (a.division !== b.division) return a.division.localeCompare(b.division)
      return a.city.localeCompare(b.city)
    })

    // Распределение по группам
    trainees.forEach((trainee, index) => {
      groups[index % numberOfGroups].push(trainee.id)
    })

    // Обновление trainees с groupId
    const updatedTrainees = data.trainees.map(t => {
      const groupIndex = groups.findIndex(g => g.includes(t.id))
      return { ...t, groupId: groupIndex >= 0 ? groupIndex + 1 : null }
    })

    const newData = {
      ...data,
      trainees: updatedTrainees,
      program: { ...data.program, groupsFormed: true, collectionOpen: false }
    }
    saveData(newData)
  }

  const resetGroups = () => {
    const updatedTrainees = data.trainees.map(t => ({
      ...t,
      groupId: null,
      attendance: {},
      homeworkStatus: {},
      examScore: null
    }))
    const newData = {
      ...data,
      trainees: updatedTrainees,
      program: { ...data.program, groupsFormed: false, examEnabled: false }
    }
    saveData(newData)
  }

  const login = async (login, password) => {
    const trainer = data.trainers.find(t => t.login === login && t.password === password)
    if (!trainer) {
      throw new Error('Неверный логин или пароль')
    }
    // Используем демо-режим с localStorage
    localStorage.setItem('demoUser', JSON.stringify(trainer))
    window.dispatchEvent(new Event('storage'))
  }

  const logout = () => {
    localStorage.removeItem('demoUser')
    window.dispatchEvent(new Event('storage'))
  }

  const value = {
    user,
    data,
    loading,
    CITIES,
    updateProgram,
    updateTrainers,
    updateProgramRules,
    updateExamRules,
    addSession,
    removeSession,
    addTrainee,
    updateTrainee,
    deleteTrainee,
    formGroups,
    resetGroups,
    login,
    logout
  }

  return (
    <StorageContext.Provider value={value}>
      {children}
    </StorageContext.Provider>
  )
}

export function useStorage() {
  const context = useContext(StorageContext)
  if (!context) {
    throw new Error('useStorage must be used within StorageProvider')
  }
  return context
}

export function useAuth() {
  const [demoUser, setDemoUser] = useState(null)

  useEffect(() => {
    const user = localStorage.getItem('demoUser')
    if (user) {
      setDemoUser(JSON.parse(user))
    }

    const handler = () => {
      const user = localStorage.getItem('demoUser')
      setDemoUser(user ? JSON.parse(user) : null)
    }

    window.addEventListener('storage', handler)
    return () => window.removeEventListener('storage', handler)
  }, [])

  return { user: demoUser, loading: false }
}