This file is an implementation of oauth for SkyMake4

skymake-oauth.php

<?php
session_name("SkyMakeSessionStorage");
session_start();
include_once "../SkyMakeDatabaseConnector/SkyMakeDBconfig.php";
include_once "../SkyMakeConfiguration.php";
include_once "../SkyMakeFunctionSet/Operation-Requirements/MainFunctions.php";
include "../classes/user.php";

$client_id = '';
$client_secret = '';
$redirect_uri = '';
$idp_uri = '';

if(!isset($_SESSION["oauth_authcode"]) and !isset($_GET["code"])){
    header("location: ".$idp_uri."oauth/authorize?client_id=".$client_id."&redirect_uri=".$redirect_uri."&response_type=code");
}
if(isset($_GET["code"])){
    $_SESSION["oauth_authcode"] = $_GET["code"];
    //echo "Requesting Authorization Code";
    $url = $idp_uri."oauth/token";
    $data = array(
        'grant_type' => 'authorization_code', 
        'code' => $_SESSION["oauth_authcode"],
        'client_id' => $client_id,
        'client_secret' => $client_secret,
        'redirect_uri' => $redirect_uri
    );
    
    $options = array(
        'http' => array(
            'header'  => "Content-type: application/x-www-form-urlencoded\r\n",
            'method'  => 'POST',
            'content' => http_build_query($data)
        )
    );
    //var_dump($options);
    $context  = stream_context_create($options);
    $result = file_get_contents($url, false, $context);
    if ($result === FALSE) {
        session_destroy();
        die("Token has expired. Please try again. If authorization takes longr than a few seconds try using a better connection"); 
    }
    echo(json_decode($result,true)["access_token"]);
    $_SESSION["oauth_bearer"] = json_decode($result,true)["access_token"];
}

if(isset($_SESSION["oauth_bearer"])){
    //echo "Requesting Credidentals";
    $result = file_get_contents($idp_uri."?oauth=me&access_token=".$_SESSION["oauth_bearer"], false);
    $username = json_decode($result,true)["user_email"];
    $sql = "SELECT id FROM skymake_users WHERE username = ?";

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

        // Set parameters
        $param_username = trim($username);

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

            if (mysqli_stmt_num_rows($stmt) != 1) {
                //Register user
                $param_password = md5(uniqid(rand(), true));
                $sql = "INSERT INTO skymake_users (username, password) VALUES (?, ?)";

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

                    // Set parameters
                    $param_username = trim($username);
                    
                    $param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash

                    // Attempt to execute the prepared statement
                    if (mysqli_stmt_execute($stmt)) {
                        // Redirect to login page
                        header("location: /oauth/");
                    } else {
                        die("Something went wrong. Please try again later.".mysqli_stmt_error($stmt));
                    }

                    // Close statement
                    mysqli_stmt_close($stmt);
                }
            } else {
               //Login user
                $sql = "SELECT id, username, password FROM skymake_users WHERE username = ?";

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

                    // Set parameters
                    $param_username = $username;

                    // 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, $hashed_password);
                            if (mysqli_stmt_fetch($stmt)) {
                                    session_start();

                                    //prevent unathorized updates
                                    $_SESSION["UPDATE_AUTHORIZED"] = false;

                                    // Store data in session variables
                                    $_SESSION["loggedin"] = true;
                                    $_SESSION["id"] = $id;
                                    $_SESSION["username"] = $username;
                                    //get assigned class
                                    $_SESSION["classid"] = SMUser::getStudentClassID($link,$_SESSION["username"]);
                                    $_SESSION["dm"] = "off";
                                    // Redirect user to welcome page
                                    // Logged in successfully.
                                        header("Location: /home");
                            }
                        } else {
                            // Display an error message if username doesn't exist
                            $username_err = "No account found with that username.";
                        }
                    } else {
                        // ANY OTHER ERROR - Will need an update in a future build.
                        die("Oops! Something went wrong. Please try again later.");
                    }

                    // Close statement
                    mysqli_stmt_close($stmt);
                }
            }
        } else {
            die(_("Oops! Something went wrong. Please try again later."). mysqli_stmt_error($stmt));
        }

        // Close statement
        mysqli_stmt_close($stmt);
    }
}