<?php
session_start();

header('Content-Type: application/json');

require __DIR__ . '/vendor/autoload.php'; // Composer Autoloader

use Kreait\Firebase\Factory;
use Kreait\Firebase\Exception\Auth\InvalidToken;

$response = ['status' => 'error', 'message' => 'Invalid request'];

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $input = json_decode(file_get_contents('php://input'), true);

    $action = $input['action'] ?? '';
    $idToken = $input['idToken'] ?? '';

    // Initialize Firebase Admin SDK
    // IMPORTANT: Replace 'path/to/your/serviceAccountKey.json' with the actual path to your Firebase service account key file.
    // This file contains your project's credentials and should be kept secure.
    // You can download it from Firebase Console -> Project settings -> Service accounts -> Generate new private key.
    try {
        $factory = (new Factory())->withServiceAccount(__DIR__ . '/firebase-service-account.json');
        $auth = $factory->createAuth();
    } catch (\Exception $e) {
        error_log('Firebase Admin SDK initialization error: ' . $e->getMessage());
        $response = ['status' => 'error', 'message' => 'Server configuration error.'];
        echo json_encode($response);
        exit;
    }


    if ($action === 'signin' && !empty($idToken)) {
        try {
            $verifiedIdToken = $auth->verifyIdToken($idToken);
            $uid = $verifiedIdToken->claims()->get('sub');
            $email = $verifiedIdToken->claims()->get('email');
            $displayName = $verifiedIdToken->claims()->get('name');

            $_SESSION['user_id'] = $uid;
            $_SESSION['user_email'] = $email;
            $_SESSION['user_name'] = $displayName;
            $_SESSION['is_logged_in'] = true;

            $response = ['status' => 'success', 'message' => 'Sign-in successful.', 'user' => ['uid' => $uid, 'email' => $email, 'name' => $displayName]];
        } catch (InvalidToken $e) {
            $response = ['status' => 'error', 'message' => 'Invalid Firebase ID token.'];
            error_log('Firebase ID token verification failed: ' . $e->getMessage());
        } catch (\Exception $e) {
            $response = ['status' => 'error', 'message' => 'Authentication failed.'];
            error_log('General authentication error: ' . $e->getMessage());
        }
    } else if ($action === 'signout') {
        session_unset();
        session_destroy();
        $response = ['status' => 'success', 'message' => 'Sign-out successful. Session destroyed.'];
    }
}

echo json_encode($response);
?>