import {
  createContext,
  useCallback,
  useContext,
  useMemo,
  useState,
  type ReactNode,
} from 'react'
import type { User } from '../types'
import { authApi } from '../api'

interface AuthState {
  token: string | null
  user: User | null
  login: (username: string, password: string) => Promise<void>
  logout: () => void
  refreshProfile: () => Promise<void>
  isAdmin: boolean
}

const AuthContext = createContext<AuthState | null>(null)

function loadUser(): User | null {
  try {
    const raw = localStorage.getItem('user')
    return raw ? (JSON.parse(raw) as User) : null
  } catch {
    return null
  }
}

export function AuthProvider({ children }: { children: ReactNode }) {
  const [token, setToken] = useState<string | null>(() => localStorage.getItem('token'))
  const [user, setUser] = useState<User | null>(() => loadUser())

  const login = useCallback(async (username: string, password: string) => {
    const result = await authApi.login(username, password)
    localStorage.setItem('token', result.token)
    localStorage.setItem('user', JSON.stringify(result.user))
    setToken(result.token)
    setUser(result.user)
  }, [])

  const logout = useCallback(() => {
    localStorage.removeItem('token')
    localStorage.removeItem('user')
    setToken(null)
    setUser(null)
  }, [])

  const refreshProfile = useCallback(async () => {
    const profile = await authApi.profile()
    localStorage.setItem('user', JSON.stringify(profile))
    setUser(profile)
  }, [])

  const value = useMemo(
    () => ({
      token,
      user,
      login,
      logout,
      refreshProfile,
      isAdmin: user?.role === 'admin',
    }),
    [token, user, login, logout, refreshProfile],
  )

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

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