<?php
require_once __DIR__ . '/vendor/autoload.php';
require_once __DIR__ . '/db/config.php';
require_once __DIR__ . '/ai/config.php';

session_start();

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $credential = $_POST['credential'];
    $client = new Google_Client(['client_id' => GOOGLE_CLIENT_ID]);
    $payload = $client->verifyIdToken($credential);

    if ($payload) {
        $google_id = $payload['sub'];
        $email = $payload['email'];

        try {
            $pdo = db();
            $stmt = $pdo->prepare("SELECT * FROM users WHERE google_id = ?");
            $stmt->execute([$google_id]);
            $user = $stmt->fetch();

            if ($user) {
                // User found with google_id, log them in
                $_SESSION['user_id'] = $user['id'];
                $_SESSION['user_email'] = $user['email'];
                header("Location: index.php");
                exit;
            } else {
                // No user with this google_id, check by email
                $stmt = $pdo->prepare("SELECT * FROM users WHERE email = ?");
                $stmt->execute([$email]);
                $user = $stmt->fetch();

                if ($user) {
                    // User with this email exists, link google_id
                    $update_stmt = $pdo->prepare("UPDATE users SET google_id = ? WHERE id = ?");
                    $update_stmt->execute([$google_id, $user['id']]);
                    $_SESSION['user_id'] = $user['id'];
                    $_SESSION['user_email'] = $user['email'];
                    header("Location: index.php");
                    exit;
                } else {
                    // No user with this email, create a new user
                    $password = bin2hex(random_bytes(16)); // Create a random password
                    $hashed_password = password_hash($password, PASSWORD_DEFAULT);
                    $insert_stmt = $pdo->prepare("INSERT INTO users (email, password, google_id) VALUES (?, ?, ?)");
                    $insert_stmt->execute([$email, $hashed_password, $google_id]);
                    $user_id = $pdo->lastInsertId();
                    $_SESSION['user_id'] = $user_id;
                    $_SESSION['user_email'] = $email;
                    header("Location: index.php");
                    exit;
                }
            }
        } catch (PDOException $e) {
            // Handle DB error
            header("Location: login.php?error=db_error");
            exit;
        }
    } else {
        // Invalid token
        header("Location: login.php?error=invalid_token");
        exit;
    }
} else {
    header("Location: login.php");
    exit;
}
?>