persistence layer integration

template-caching-handler.js

/*_________________________________________________________
 *
 *  @version 0.0.2
 */

( function( $ ) {

	const KEY                =   'template-name'
	const HTML_KEY           =   'html'
	const CONTAINER          =   '.container'

	const WP_API_PATH        =   ''

	let html;

	const request = ( function request( ) {

		let config = {
			method: 'GET'
		}

		let res = fetch( WP_API_PATH, config )

		let onerr = function onerr( err ) { }

		return {
			send: ( onresponse ) => res.then( onresponse ).catch( onerr )
		} 

	} )( )

	const store = ( function store() {

		return {
			get: ( key ) => localStorage.getItem( key )
			set: ( val ) => localStorage.setItem( KEY, JSON.stringify( val ) )
			keyExists: ( key ) => localStorage.getItem( key )
										? true
										: false 
		}

	} )( )

	const cookie = ( function() {
		return {
			get: ( name ) => cookies.get( { name: name } )
			set: ( obj ) => cookies.set( obj )
			exists: ( name ) => {}
		}

	} )( )


	let onresponse = function onresponse() {
		return function( res ) {

			store.set( KEY, res[ HTML_KEY ] )
			html = res[ HTML_KEY ]
		}
	}

	let extend = function( fn, middleware ) {

		if ( ! middleware ) {
			throw new Error( 'Bad Function Call' )

		}

		if ( ! Array.isArray( middleware ) ) {
			throw new Error(' Invalid Argument Type ')
		}

	    return ( res ) => {

		    for ( let i = 0; i < middleware.length; i++ ) {
		     	middleware[ i ].call(this, ...args )
		    }

		    cb.call( this, res )
	    }
	} 

	( function() {

		if ( ! cookie.exists( KEY ) ) {

			let noCookieResponse = extend( onresponse, [ ( res ) => {
				return ( res ) => {
					cookie.set( KEY, res[ HTML_KEY ] )
				}  
			} ] )

			request.send( noCookieResponse )
		}

		if ( ! store.keyExists( KEY ) ) {

			request.send( onresponse )

		}

		html = store.get( KEY )

	} )( )

	let container = document.querySelector( CONTAINER )
	
	// @todo implement eventual consistency

	container.innerHTML = html


} )( jQuery )