import { createContext, useContext, useState, useEffect } from 'react';
import { useRouter } from 'next/router';

type User = {
  id: string;
  username: string;
  name: string;
  role: string;
};

type AuthContextType = {
  user: User | null;
  isLoading: boolean;
  login: (username: string, password: string) => Promise<void>;
  logout: () => void;
  isAdmin: () => boolean;
};

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

export function AuthProvider({ children }: { children: React.ReactNode }) {
  const [user, setUser] = useState<User | null>(null);
  const [isLoading, setIsLoading] = useState(true);
  const router = useRouter();

  useEffect(() => {
    // ページ読み込み時にセッションを確認
    checkSession();
  }, []);

  const checkSession = async () => {
    try {
      const response = await fetch('/api/auth/session');
      if (response.ok) {
        const data = await response.json();
        setUser(data.user);
      }
    } catch (error) {
      console.error('セッション確認エラー:', error);
    } finally {
      setIsLoading(false);
    }
  };

  const login = async (username: string, password: string) => {
    try {
      const response = await fetch('/api/auth/login', {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
        },
        body: JSON.stringify({ username, password }),
      });

      const data = await response.json();

      if (!response.ok) {
        throw new Error(data.message);
      }

      setUser(data.user);
      router.push('/projects');
    } catch (error) {
      throw error;
    }
  };

  const logout = async () => {
    try {
      await fetch('/api/auth/logout', {
        method: 'POST',
      });
      setUser(null);
      router.push('/login');
    } catch (error) {
      console.error('ログアウトエラー:', error);
    }
  };

  const isAdmin = () => {
    return user?.role === 'admin';
  };

  return (
    <AuthContext.Provider value={{ user, isLoading, login, logout, isAdmin }}>
      {children}
    </AuthContext.Provider>
  );
}

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