import React, { createContext, useContext, useState, useEffect } from 'react';
import { User, UserRole } from '../types';
import { authApi, clearSession, getSession, saveSession } from '../services/api';

interface AuthContextType {
  user: User | null;
  login: (email: string, password: string) => Promise<User | null>;
  register: (name: string, email: string, password: string) => Promise<User | null>;
  logout: () => void;
  isLoading: boolean;
}

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

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

  useEffect(() => {
    const restoreSession = async () => {
      const session = getSession();
      if (!session) {
        setIsLoading(false);
        return;
      }

      try {
        const { user: apiUser } = await authApi.me();
        const restoredUser = toFrontendUser(apiUser);
        saveSession({ ...session, user: apiUser });
        setUser(restoredUser);
      } catch {
        clearSession();
      } finally {
        setIsLoading(false);
      }
    };
    void restoreSession();
  }, []);

  const login = async (email: string, password: string): Promise<User | null> => {
    try {
      const session = await authApi.login(email, password);
      const signedInUser = toFrontendUser(session.user);
      saveSession(session);
      setUser(signedInUser);
      return signedInUser;
    } catch {
      return null;
    }
  };

  const register = async (name: string, email: string, password: string): Promise<User | null> => {
    try {
      const session = await authApi.register(name, email, password);
      const signedInUser = toFrontendUser(session.user);
      saveSession(session);
      setUser(signedInUser);
      return signedInUser;
    } catch {
      return null;
    }
  };

  const logout = () => {
    setUser(null);
    clearSession();
  };

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

const toFrontendUser = (user: { email: string; name: string; role: string }): User => ({
  email: user.email,
  name: user.name,
  role: user.role === 'student' ? 'student' : 'professor',
});

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