yourls-api.php

<?php
/**
 * YOURLS API
 *
 * This file is the entry point for the YOURLS API. It handles all API requests
 * and returns the results in the requested format.
 *
 * @package YOURLS
 * @since 1.0
 */

define( 'YOURLS_API', true );
require_once( dirname( __FILE__ ) . '/includes/load-yourls.php' );
yourls_maybe_require_auth();

$action = $_REQUEST['action'] ?? null;

yourls_do_action( 'api', $action );

// Define standard API actions
$api_actions = array(
    'shorturl'  => 'yourls_api_action_shorturl',
    'stats'     => 'yourls_api_action_stats',
    'db-stats'  => 'yourls_api_action_db_stats',
    'url-stats' => 'yourls_api_action_url_stats',
    'expand'    => 'yourls_api_action_expand',
    'version'   => 'yourls_api_action_version',
    'delete'    => 'yourls_api_action_delete',
    'edit'      => 'yourls_api_action_edit',
    'search'    => 'yourls_api_action_search',
);
$api_actions = yourls_apply_filter( 'api_actions', $api_actions );

// Register API actions
foreach( (array) $api_actions as $_action => $_callback ) {
    yourls_add_filter( 'api_action_' . $_action, $_callback, 99 );        
}

// Try requested API method. Properly registered actions should return an array.
$return = yourls_apply_filter( 'api_action_' . $action, false );
if ( false === $return ) {
    $return = array(
        'errorCode' => '400',
        'message'   => 'Unknown or missing "action" parameter',
        'simple'    => 'Unknown or missing "action" parameter',
    );
}

if( isset( $_REQUEST['callback'] ) )
    $return['callback'] = $_REQUEST['callback'];
elseif ( isset( $_REQUEST['jsonp'] ) )
    $return['callback'] = $_REQUEST['jsonp'];

$format = $_REQUEST['format'] ?? 'xml';

yourls_api_output( $format, $return );

die();