export default {
	/**
	 * Downloads file
	 * @param {*} filename
	 * @param {*} data
	 */
	download(filename, data) {
		var element = document.createElement("a");
		element.setAttribute("href", "data:text/plain;charset=utf-8," + encodeURIComponent(data));
		element.setAttribute("download", filename);

		element.style.display = "none";
		document.body.appendChild(element);

		element.click();

		document.body.removeChild(element);
	},

	/**
	 * Convert data of file selected in input to base64 string
	 * @param {*} input
	 */
	async toBase64(input) {
		return new Promise((resolve) => {
			if (input.files.length == 0){
				resolve(null)
			}
			else if (input.files.length == 1){
				this.fileToBase64(input.files[0]).then(resolve)
			}
			else				
				Promise.all(Array(...input.files).map(this.fileToBase64)).then(resolve)
			}
		);
	},

	/**
	 * Convert data of file selected in input to base64 string
	 * @param {*} input
	 */
	 async fileToBase64(file) {
		return new Promise((resolve, reject) => {
			var reader = new FileReader();			
			reader.readAsDataURL(file);

			reader.onload = function () {
				resolve(reader.result)
			};
			reader.onerror = function (error) {
				reject(error)
			};
		});
	},

	/**
	 * Read data of file/files selected in input as string
	 * @param {*} input
	 */
	 async read(input) {
		return new Promise((resolve) => {
			if (input.files.length == 0){
				resolve(null)
			}
			else if (input.files.length == 1){
				this.readFile(input.files[0]).then(resolve)
			}
			else				
				Promise.all(Array(...input.files).map(this.readFile)).then(resolve)
			}
		);
	},

	/**
	 * Read data of file/files selected in input as string
	 * @param {*} input
	 */
	 async readFile(file) {
		return new Promise((resolve, reject) => {
			var reader = new FileReader();			
			reader.readAsText(file);

			reader.onload = function () {
				resolve(reader.result)
			};
			reader.onerror = function (error) {
				reject(error)
			};
		});
	},	
};