<?php
// Initialize the session
session_start();

//Login in with Facebook
require ("XXXXXXXXXXXXXXX");

if(isset($_GET['state'])) {
    $_SESSION['FBRLH_state'] = $_GET['state'];
}
/*Step 1: Enter Credentials*/
$fb = new \Facebook\Facebook([
    'app_id' => 'XXXXXXXXXXXX',
    'app_secret' => 'XXXXXXXXXXXXXXXXXXX',
    'default_graph_version' => 'v3.3',
    //'default_access_token' => '{access-token}', // optional
]);

/*Step 3 : Get Access Token*/
$access_token = $fb->getRedirectLoginHelper()->getAccessToken();
/*Step 4: Get the graph user*/
if(isset($access_token)) {
    try {
        $response = $fb->get('/me',$access_token);
        $fb_user = $response->getGraphUser();
        echo  $fb_user->getName();
        //  var_dump($fb_user);
    } catch (\Facebook\Exceptions\FacebookResponseException $e) {
        echo  'Graph returned an error: ' . $e->getMessage();
    } catch (\Facebook\Exceptions\FacebookSDKException $e) {
        // When validation fails or other local issues
        echo 'Facebook SDK returned an error: ' . $e->getMessage();
    }
}

// Check if the user is already logged in, if yes then redirect him to welcome page
if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
    header("location: myaccount.php");
    exit;
}

// Include config file
require_once "config.php";

// Define variables and initialize with empty values
$login = $username = $email = $password = "";
$login_err = $username_err = $email_err = $password_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){

    // Check if username/email is empty
    if(empty(trim($_POST["login"]))){
        $login_err = "Please enter username or email";
    } else{
        $login = trim($_POST["login"]);
    }

    // Check if password is empty
    if(empty(trim($_POST["password"]))){
        $password_err = "Please enter your password.";
    } else{
        $password = trim($_POST["password"]);
    }

    // Validate credentials
    if(empty($username_err) && empty($email_err) && empty($password_err)){
        // Prepare a select statement
        $sql = "SELECT id, username, email, password FROM users WHERE username = '$login' OR email = '$login'";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "ss", $param_username, $param_email);

            // Set parameters
            $param_username = $username;
			$param_email = $email;

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Store result
                mysqli_stmt_store_result($stmt);

                // Check if username exists, if yes then verify password
                if(mysqli_stmt_num_rows($stmt) == 1){
                    // Bind result variables
                    mysqli_stmt_bind_result($stmt, $id, $username, $email, $hashed_password);
                    if(mysqli_stmt_fetch($stmt)){
                        if(password_verify($password, $hashed_password)){
                            // Password is correct, so start a new session
                            session_start();

                            // Store data in session variables
                            $_SESSION["loggedin"] = true;
                            $_SESSION["id"] = $id;
                            $_SESSION["username"] = $username;
							$_SESSION["email"] = $email;

                            // Redirect user to welcome page
                            header("location: myaccount.php");
                        } else{
                            // Display an error message if password is not valid
                            $password_err = "The password you entered was not valid.";
                        }
                    }
                } else{
                    // Display an error message if username doesn't exist
                    $login_err = $username_err = $email_err = "No account found with that username/email";
                }
            } else{
                echo "Oops! Something went wrong. Please try again later.";
            }
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($link);
}
?>