WP api callback function

wp-api-callback-function.php

<?php

function wpc_somename_search_callback( $request_data ) {

	$parameters = $request_data->get_params();

	if( !isset( $parameters['keyword'] ) || empty($parameters['keyword']) )
		return array( 'error' => 'no_parameter_given' );

	$keyword = $parameters['keyword'];

	if( strlen( $keyword ) <= 3 )
		return array( 'error' => 'keyword_not_long_enough' );
    	
    	$output = wp_remote_get('https://thirdpartyapi.com/suggest/' . $keyword);

	if( $response = json_decode($output['body'], true) ) {
		if( isset( $response['error'] ) )
	    		return array( 'error' => 'error_when_retrieving_data' );
	
	    	return $response;
	} else {
	    	return array( 'error' => 'something_went_wrong_when_retrieving_data' );
	}

}