event_request/server/plugins/available_plugins/file_stream_handler_plugin.js

A Backend Server

'use strict';

const PluginInterface	= require( '../plugin_interface' );
const fileStreamHandler	= require( '../../components/file_streams/file_stream_handler' );

/**
 * @brief	File stream handler responsible for attaching FileStreams to the eventRequest
 */
class FileStreamHandlerPlugin extends PluginInterface {
	/**
	 * @brief	Attaches the function stream file to the event
	 *
	 * @param	{EventRequest} event
	 */
	attachFunctions( event ) {
		/**
		 * @brief	Streams files
		 *
		 * @details	The file must be the absolute path to the file to be streamed
		 *
		 * @param	{String} file
		 * @param	{Object} [options={}]
		 *
		 * @return	{ReadStream|null}
		 */
		event.getFileStream	= function( file, options = {} ) {
			const fileStream	= this.fileStreamHandler.getFileStreamerForType( file );

			if ( fileStream !== null )
				return fileStream.getFileStream( event, file, options );
			else
				return null;
		};

		/**
		 * @brief	Streams files
		 *
		 * @details	The file must be the absolute path to the file to be streamed
		 *
		 * @param	{String} file
		 * @param	{Object} [options={}]
		 * @param	{Function} [errCallback=null]
		 */
		event.streamFile	= function( file, options = {}, errCallback = null ) {
			const fileStream	= event.getFileStream( file, options );

			if ( fileStream !== null )
				fileStream.pipe( event.response );
			else
				if ( typeof errCallback !== 'function' )
					this.next( 'Could not find a FileStream that supports that format', 400 );
				else
					errCallback();
		};
	}

	/**
	 * @brief	Gets the plugin middlewares to attach to the event request
	 *
	 * @return	{Array}
	 */
	getPluginMiddleware() {
		return [{
			handler	: ( event ) => {
				event.fileStreamHandler	= fileStreamHandler;

				this.attachFunctions( event );

				event.on( 'cleanUp', () => {
					event.fileStreamHandler	= undefined;
					event.getFileStream		= undefined;
					event.streamFile		= undefined;
				} );

				event.next();
			}
		}];
	}
}

module.exports	= FileStreamHandlerPlugin;