export default class DataUtils {
	//--------------------------
	// constructor
	//--------------------------
	constructor() {}
	//--------------------------
	// methods
	//--------------------------

	imgLoad(url) {
		'use strict';
		// Create new promise with the Promise() constructor;
		// This has as its argument a function with two parameters, resolve and reject
		return new Promise(function(resolve, reject) {
			// Standard XHR to load an image
			var request = new XMLHttpRequest();
			request.open('GET', url);
			request.responseType = 'blob';
			// When the request loads, check whether it was successful
			request.onload = function() {
				if (request.status === 200) {
					// If successful, resolve the promise by passing back the request response
					resolve(request.response);
				} else {
					// If it fails, reject the promise with a error message
					reject(
						new Error(
							"Image didn't load successfully; error code:" + request.statusText
						)
					);
				}
			};
			request.onerror = function() {
				// Also deal with the case when the entire request fails to begin with
				// This is probably a network error, so reject the promise with an appropriate message
				reject(new Error('There was a network error.'));
			};
			// Send the request
			request.send();
		});
	}
	loadImage(src) {
		'use strict';
		let self = this;
		return new Promise(function(resolve, reject) {
			// Get a reference to the body element, and create a new image object
			var myImage = new Image();
			myImage.crossOrigin = ''; // or "anonymous"
			// Call the function with the URL we want to load, but then chain the
			// promise then() method on to the end of it. This contains two callbacks
			self.imgLoad(src).then(
				function(response) {
					// The first runs when the promise resolves, with the request.reponse specified within the resolve() method.
					var imageURL = window.URL.createObjectURL(response);
					resolve(imageURL);
					//$('background-content').setStyle('background-image', 'url('+imageURL+')') //myImage.src = imageURL;
					//console.log(imageURL);
					//body.appendChild(myImage);
					// The second runs when the promise is rejected, and logs the Error specified with the reject() method.
				},
				function(Error) {
					reject(Error);
				}
			);
		});
	}

	/**
	 * Create a function to convert the serialize and convert the form data to JSON
	 * @param : $('#form_example');
	 * @return a JSON Stringify
	 */
	formDataToJSON(form) {
		let object = {};
		let formData = new FormData(form);
		formData.forEach((value, key) => {
			if (!object.hasOwnProperty(key)) {
				object[key] = value;
				return;
			}
			if (!Array.isArray(object[key])) {
				object[key] = [object[key]];
			}
			object[key].push(value);
		});
		//let json = JSON.stringify(object);
		return object;
	}
	//--------------------------
	// event handlers
	//--------------------------
}
