import React, { createContext, useCallback, useContext, useEffect, useMemo, useState } from 'react';
import { api, ApiError, AUTH_UNAUTHORIZED_EVENT } from '../services/apiClient.ts';
import type { User } from '../types/api.ts';

type AuthContextValue = {
  user: User | null;
  loading: boolean;
  login: (userName: string, password: string) => Promise<void>;
  logout: () => Promise<void>;
};

const AuthContext = createContext<AuthContextValue | null>(null);

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

  useEffect(() => {
    const onUnauthorized = () => setUser(null);
    window.addEventListener(AUTH_UNAUTHORIZED_EVENT, onUnauthorized);
    return () => window.removeEventListener(AUTH_UNAUTHORIZED_EVENT, onUnauthorized);
  }, []);

  useEffect(() => {
    let cancelled = false;
    (async () => {
      try {
        const me = await api.auth.me();
        if (!cancelled) setUser(me);
      } catch (err) {
        if (
          !cancelled &&
          !(err instanceof ApiError && (err.status === 401 || err.status === 403))
        ) {
          console.error(err);
        }
        if (!cancelled) setUser(null);
      } finally {
        if (!cancelled) setLoading(false);
      }
    })();
    return () => {
      cancelled = true;
    };
  }, []);

  const login = useCallback(async (userName: string, password: string) => {
    await api.auth.csrf();
    const next = await api.auth.login(userName, password);
    setUser(next);
  }, []);

  const logout = useCallback(async () => {
    try {
      await api.auth.logout();
    } finally {
      setUser(null);
    }
  }, []);

  const value = useMemo(() => ({ user, loading, login, logout }), [user, loading, login, logout]);

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

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