'use client'

import React, { createContext, useContext, useEffect, useState, ReactNode } from 'react'
import { authService, User } from '@/lib/services/auth'

interface AuthState {
  user: User | null
  token: string | null
  isAuthenticated: boolean
  isLoading: boolean
}

interface AuthContextType extends AuthState {
  login: (email: string, password: string) => Promise<{ success: boolean; error?: string }>
  register: (username: string, email: string, password: string) => Promise<{ success: boolean; error?: string }>
  logout: () => void
  checkAuth: () => Promise<boolean>
  updateUser: (updatedUser: Partial<User>) => void
}

const AuthContext = createContext<AuthContextType | undefined>(undefined)

export const useAuth = () => {
  const context = useContext(AuthContext)
  if (context === undefined) {
    throw new Error('useAuth must be used within an AuthProvider')
  }
  return context
}

interface AuthProviderProps {
  children: ReactNode
}

export const AuthProvider: React.FC<AuthProviderProps> = ({ children }) => {
  const [state, setState] = useState<AuthState>({
    user: null,
    token: null,
    isAuthenticated: false,
    isLoading: true,
  })

  // 初始化時檢查認證狀態
  useEffect(() => {
    const initAuth = async () => {
      const token = authService.getToken()
      const user = authService.getUser()

      if (token && user) {
        // 驗證 token 是否仍然有效
        const isValid = await authService.checkAuthStatus()
        if (isValid) {
          setState({
            user,
            token,
            isAuthenticated: true,
            isLoading: false,
          })
        } else {
          // Token 無效，清除本地存儲
          authService.logout()
          setState({
            user: null,
            token: null,
            isAuthenticated: false,
            isLoading: false,
          })
        }
      } else {
        setState({
          user: null,
          token: null,
          isAuthenticated: false,
          isLoading: false,
        })
      }
    }

    initAuth()
  }, [])

  const login = async (email: string, password: string) => {
    try {
      const response = await authService.login({ email, password })

      if (response.success && response.data) {
        setState({
          user: response.data.user,
          token: response.data.token,
          isAuthenticated: true,
          isLoading: false,
        })
        return { success: true }
      } else {
        return { success: false, error: response.error || '登入失敗' }
      }
    } catch (error) {
      return { success: false, error: '網路錯誤，請稍後再試' }
    }
  }

  const register = async (username: string, email: string, password: string) => {
    try {
      const response = await authService.register({ username, email, password })

      if (response.success && response.data) {
        setState({
          user: response.data.user,
          token: response.data.token,
          isAuthenticated: true,
          isLoading: false,
        })
        return { success: true }
      } else {
        return { success: false, error: response.error || '註冊失敗' }
      }
    } catch (error) {
      return { success: false, error: '網路錯誤，請稍後再試' }
    }
  }

  const logout = () => {
    authService.logout()
    setState({
      user: null,
      token: null,
      isAuthenticated: false,
      isLoading: false,
    })
    // 立即跳轉到登入頁面
    window.location.href = '/login'
  }

  const checkAuth = async (): Promise<boolean> => {
    if (!state.token) return false

    const isValid = await authService.checkAuthStatus()
    if (!isValid) {
      logout()
      return false
    }
    return true
  }

  const updateUser = (updatedUser: Partial<User>) => {
    if (!state.user) return

    const newUser = { ...state.user, ...updatedUser }

    setState(prev => ({
      ...prev,
      user: newUser
    }))

    // 同時更新 localStorage 中的用戶資料
    localStorage.setItem('user_data', JSON.stringify(newUser))
  }

  const contextValue: AuthContextType = {
    ...state,
    login,
    register,
    logout,
    checkAuth,
    updateUser,
  }

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