import { createContext, useCallback, useContext, useEffect, useState } from 'react'
import type { ReactNode } from 'react'
import * as authApi from '../api/auth'
import { setAuthFailureHandler, tokenStorage } from '../api/client'
import type { User } from '../api/types'

interface AuthContextValue {
  user: User | null
  loading: boolean
  login: (email: string, password: string) => Promise<void>
  register: (email: string, username: string, password: string) => Promise<void>
  logout: () => void
  refreshUser: () => Promise<void>
}

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

export function AuthProvider({ children }: { children: ReactNode }) {
  const [user, setUser] = useState<User | null>(null)
  const [loading, setLoading] = useState(true)

  const refreshMe = useCallback(async () => {
    if (!tokenStorage.getAccess()) {
      setUser(null)
      setLoading(false)
      return
    }
    try {
      setUser(await authApi.getMe())
    } catch {
      tokenStorage.clear()
      setUser(null)
    } finally {
      setLoading(false)
    }
  }, [])

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

  // Fires when a request's 401 survives a refresh attempt (refresh token
  // missing/expired/revoked) — drop back to logged-out state so
  // ProtectedRoute sends the user to /login instead of the app silently
  // failing every request.
  useEffect(() => {
    setAuthFailureHandler(() => setUser(null))
    return () => setAuthFailureHandler(() => {})
  }, [])

  const login = async (email: string, password: string) => {
    await authApi.login(email, password)
    await refreshMe()
  }

  const register = async (email: string, username: string, password: string) => {
    await authApi.register(email, username, password)
    await refreshMe()
  }

  const logout = () => {
    authApi.logout()
    setUser(null)
  }

  return (
    <AuthContext.Provider value={{ user, loading, login, register, logout, refreshUser: refreshMe }}>
      {children}
    </AuthContext.Provider>
  )
}

export function useAuth(): AuthContextValue {
  const ctx = useContext(AuthContext)
  if (!ctx) throw new Error('useAuth must be used within AuthProvider')
  return ctx
}