import { useEffect } from 'react'
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
import { api } from '../utils/api'
import { useAppStore } from '../store/useAppStore'

export function useAuth() {
  const queryClient = useQueryClient()
  const token = useAppStore((state) => state.token)
  const setToken = useAppStore((state) => state.setToken)
  const openAuth = useAppStore((state) => state.openAuth)
  const closeAuth = useAppStore((state) => state.closeAuth)
  const addToast = useAppStore((state) => state.addToast)
  const authMode = useAppStore((state) => state.authMode)
  const activeModal = useAppStore((state) => state.activeModal)
  const startNewChat = useAppStore((state) => state.startNewChat)

  useEffect(() => {
    if (typeof window === 'undefined') return
    const params = new URLSearchParams(window.location.search)
    const accessToken = params.get('access_token')
    if (accessToken) {
      setToken(accessToken)
      window.history.replaceState({}, '', window.location.pathname)
    }
  }, [setToken])

  const meQuery = useQuery({
    queryKey: ['auth', 'me', token],
    queryFn: () => api.get('/auth/me', { token }),
    enabled: Boolean(token),
    retry: false,
    staleTime: 60_000,
  })

  useEffect(() => {
    if (!token || !meQuery.isError) return
    setToken(null)
  }, [meQuery.isError, setToken, token])

  const loginMutation = useMutation({
    mutationFn: ({ username, password }) => api.post('/auth/login', { username, password }),
    onSuccess: (data) => {
      setToken(data.access_token)
      closeAuth()
      addToast({
        title: 'Welcome back',
        description: 'You are signed in and ready to chat.',
        variant: 'success',
      })
      queryClient.invalidateQueries({ queryKey: ['auth', 'me'] })
    },
    onError: (error) => {
      addToast({
        title: 'Sign in failed',
        description: error.message,
        variant: 'danger',
      })
    },
  })

  const registerMutation = useMutation({
    mutationFn: async ({ username, name, password }) => {
      await api.post('/auth/register', { username, name, password })
      return api.post('/auth/login', { username, password })
    },
    onSuccess: (data) => {
      setToken(data.access_token)
      closeAuth()
      addToast({
        title: 'Account created',
        description: 'Your workspace is ready.',
        variant: 'success',
      })
      queryClient.invalidateQueries({ queryKey: ['auth', 'me'] })
    },
    onError: (error) => {
      addToast({
        title: 'Registration failed',
        description: error.message,
        variant: 'danger',
      })
    },
  })

  const logout = () => {
    setToken(null)
    startNewChat()
    queryClient.removeQueries({ queryKey: ['auth'] })
    queryClient.removeQueries({ queryKey: ['history'] })
    queryClient.removeQueries({ queryKey: ['sessions'] })
    addToast({
      title: 'Signed out',
      description: 'Your local session has been cleared.',
      variant: 'info',
    })
  }

  const loginWithGoogle = () => {
    window.location.href = '/auth/google/login'
  }

  const requireAuth = (callback) => {
    if (!meQuery.data) {
      openAuth('login')
      return false
    }
    callback?.()
    return true
  }

  return {
    token,
    user: meQuery.data || null,
    isAuthLoading: Boolean(token) && meQuery.isLoading,
    isAuthenticated: Boolean(meQuery.data),
    authMode,
    isAuthDialogOpen: activeModal === 'auth',
    openAuth,
    closeAuth,
    login: loginMutation.mutateAsync,
    register: registerMutation.mutateAsync,
    loginPending: loginMutation.isPending,
    registerPending: registerMutation.isPending,
    logout,
    loginWithGoogle,
    requireAuth,
  }
}