khanat-opennel-code/code/web/private_php/ams/autoload/rest_api.php

<?php

/**
 * REST API class  
 * 
 * Request for the given url using cURL  
 * and send the AccessToken for authentication 
 * to make public access for the user
 * 
 * @author Shubham Meena, mentored by Matthew Lagoe 
 */

class Rest_Api {
    
    /**
     * Makes a request using cURL with authentication headers and returns the response.
     * 
     * @param  $url where request is to be sent
     * @param  $applicationKey user generated key
     * @param  $host host for the website
     * @return URL response.
     */
    public function request( $url , $applicationKey, $host , $data )
     {
        // Check the referer is the host website
        $referer = $_SERVER['HTTP_REFERER'];
         $referer_parse = parse_url( $referer );
         if ( $referer_parse['host'] == $host ) {
            
            // Initialize the cURL session with the request URL
            $session = curl_init( $url );
            
             // Tell cURL to return the request data
            curl_setopt( $session, CURLOPT_RETURNTRANSFER, true );
            
             // Set the HTTP request authentication headers
            $headers = array( 
                'AppKey: ' . $applicationKey,
                 'Timestamp: ' . date( 'Ymd H:i:s', time() ),
                 'Accept: application/json',
                 'Content-Type: application/json'
                 );
             curl_setopt( $session, CURLOPT_HTTPHEADER, $headers );
             curl_setopt( $session, CURLOPT_CUSTOMREQUEST, "POST" );
             curl_setopt( $session, CURLOPT_POSTFIELDS, $data );
             // Execute cURL on the session handle
            $response = curl_exec( $session );
            
             if ( curl_errno( $session ) ) {
                // if request is not sent
                die( 'Couldn\'t send request: ' . curl_error( $session ) );
                 } else {
                // check the HTTP status code of the request
                $resultStatus = curl_getinfo( $session, CURLINFO_HTTP_CODE );
                 if ( $resultStatus == 200 ) {
                    // everything went fine return response
                    return $response;
                    
                     } else {
                    // the request did not complete as expected. common errors are 4xx
                    // (not found, bad request, etc.) and 5xx (usually concerning
                    // errors/exceptions in the remote script execution)
                    die( 'Request failed: HTTP status code: ' . $resultStatus );
                     } 
                } 
            curl_close( $session );
             } 
        else {
            return null;
             } 
        } 
    }