import type { Session, User } from '@supabase/supabase-js';
import { useRouter, useSegments } from 'expo-router';
import React, {
  createContext,
  useCallback,
  useContext,
  useEffect,
  useMemo,
  useState,
} from 'react';
import { supabase } from '@/services/supabase';

type AuthContextValue = {
  initialized: boolean;
  session: Session | null;
  user: User | null;
  signIn: (email: string, password: string) => Promise<{ error?: string }>;
  signUp: (params: {
    email: string;
    password: string;
    firstName: string;
    lastName: string;
  }) => Promise<{ error?: string }>;
  signOut: () => Promise<void>;
};

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

export function AuthProvider({ children }: { children: React.ReactNode }) {
  const [initialized, setInitialized] = useState(false);
  const [session, setSession] = useState<Session | null>(null);
  const segments = useSegments();
  const router = useRouter();

  useEffect(() => {
    let cancelled = false;
    void supabase.auth.getSession().then(({ data }) => {
      if (!cancelled) {
        setSession(data.session ?? null);
        setInitialized(true);
      }
    });
    const {
      data: { subscription },
    } = supabase.auth.onAuthStateChange((_event, nextSession) => {
      setSession(nextSession);
    });
    return () => {
      cancelled = true;
      subscription.unsubscribe();
    };
  }, []);

  useEffect(() => {
    if (!initialized) return;
    const root = segments[0];
    if (!session?.user && root === '(tabs)') {
      router.replace('/auth/login');
      return;
    }
    if (session?.user && root === 'auth') {
      router.replace('/(tabs)');
    }
  }, [initialized, session?.user, segments, router]);

  const signIn = useCallback(async (email: string, password: string) => {
    const { error } = await supabase.auth.signInWithPassword({ email, password });
    if (error) return { error: error.message };
    return {};
  }, []);

  const signUp = useCallback(
    async (params: {
      email: string;
      password: string;
      firstName: string;
      lastName: string;
    }) => {
      const { error } = await supabase.auth.signUp({
        email: params.email,
        password: params.password,
        options: {
          data: {
            first_name: params.firstName,
            last_name: params.lastName,
            full_name: `${params.firstName} ${params.lastName}`.trim(),
          },
        },
      });
      if (error) return { error: error.message };
      return {};
    },
    [],
  );

  const signOut = useCallback(async () => {
    await supabase.auth.signOut();
  }, []);

  const value = useMemo<AuthContextValue>(
    () => ({
      initialized,
      session,
      user: session?.user ?? null,
      signIn,
      signUp,
      signOut,
    }),
    [initialized, session, signIn, signUp, signOut],
  );

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

export function useAuth(): AuthContextValue {
  const ctx = useContext(AuthContext);
  if (!ctx) {
    throw new Error('useAuth doit être utilisé dans un AuthProvider');
  }
  return ctx;
}