//download.js v4.2, by dandavis; 2008-2016. [MIT] see http://danml.com/download.html for tests/usage
// v1 landed a FF+Chrome compat way of downloading strings to local un-named files, upgraded to use a hidden frame and optional mime
// v2 added named files via a[download], msSaveBlob, IE (10+) support, and window.URL support for larger+faster saves than dataURLs
// v3 added dataURL and Blob Input, bind-toggle arity, and legacy dataURL fallback was improved with force-download mime and base64 support. 3.1 improved safari handling.
// v4 adds AMD/UMD, commonJS, and plain browser support
// v4.1 adds url download capability via solo URL argument (same domain/CORS only)
// v4.2 adds semantic variable names, long (over 2MB) dataURL support, and hidden by default temp anchors
// https://github.com/rndme/download

export default function download(data, strFileName, strMimeType) {

	let self = window, // this script is only for browsers anyway...
		defaultMime = "application/octet-stream", // this default mime also triggers iframe downloads
		mimeType = strMimeType || defaultMime,
		payload = data,
		url = !strFileName && !strMimeType && payload,
		anchor = document.createElement("a"),
		toString = function(a) { return String(a); },
		myBlob = (self.Blob || self.MozBlob || self.WebKitBlob || toString),
		fileName = strFileName || "download",
		blob,
		reader;
	myBlob = myBlob.call ? myBlob.bind(self) : Blob;

	if (String(this) === "true") { //reverse arguments, allowing download.bind(true, "text/xml", "export.xml") to act as a callback
		payload = [payload, mimeType];
		mimeType = payload[0];
		payload = payload[1];
	}


	if (url && url.length < 2048) { // if no filename and no mime, assume a url was passed as the only argument
		fileName = url.split("/").pop().split("?")[0];
		anchor.href = url; // assign href prop to temp anchor
		if (anchor.href.indexOf(url) !== -1) { // if the browser determines that it's a potentially valid url path:
			let ajax = new XMLHttpRequest();
			ajax.open("GET", url, true);
			ajax.responseType = 'blob';
			ajax.onload = function(e) {
				download(e.target.response, fileName, defaultMime);
			};
			setTimeout(function() { ajax.send(); }, 0); // allows setting custom ajax headers using the return:
			return ajax;
		} // end if valid url?
	} // end if url?


	//go ahead and download dataURLs right away
	if (/^data:([\w+-]+\/[\w+.-]+)?[,;]/.test(payload)) {

		if (payload.length > (1024 * 1024 * 1.999) && myBlob !== toString) {
			payload = dataUrlToBlob(payload);
			mimeType = payload.type || defaultMime;
		} else {
			return navigator.msSaveBlob ? // IE10 can't do a[download], only Blobs:
				navigator.msSaveBlob(dataUrlToBlob(payload), fileName) :
				saver(payload); // everyone else can save dataURLs un-processed
		}

	} else { //not data url, is it a string with special needs?
		if (/([\x80-\xff])/.test(payload)) {
			let i = 0,
				tempUiArr = new Uint8Array(payload.length),
				mx = tempUiArr.length;
			for (i; i < mx; ++i) tempUiArr[i] = payload.charCodeAt(i);
			payload = new myBlob([tempUiArr], { type: mimeType });
		}
	}
	blob = payload instanceof myBlob ?
		payload :
		new myBlob([payload], { type: mimeType });


	function dataUrlToBlob(strUrl) {
		let parts = strUrl.split(/[:;,]/),
			type = parts[1],
			decoder = parts[2] == "base64" ? atob : decodeURIComponent,
			binData = decoder(parts.pop()),
			mx = binData.length,
			i = 0,
			uiArr = new Uint8Array(mx);

		for (i; i < mx; ++i) uiArr[i] = binData.charCodeAt(i);

		return new myBlob([uiArr], { type: type });
	}

	function saver(url, winMode) {

		if ('download' in anchor) { //html5 A[download]
			anchor.href = url;
			anchor.setAttribute("download", fileName);
			anchor.className = "download-js-link";
			anchor.innerHTML = "downloading...";
			anchor.style.display = "none";
			document.body.appendChild(anchor);
			setTimeout(function() {
				anchor.click();
				document.body.removeChild(anchor);
				if (winMode === true) { setTimeout(function() { self.URL.revokeObjectURL(anchor.href); }, 250); }
			}, 66);
			return true;
		}

		// handle non-a[download] safari as best we can:
		if (/(Version)\/(\d+)\.(\d+)(?:\.(\d+))?.*Safari\//.test(navigator.userAgent)) {
			if (/^data:/.test(url)) url = "data:" + url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
			if (!window.open(url)) { // popup blocked, offer direct download:
				if (confirm("Displaying New Document\n\nUse Save As... to download, then click back to return to this page.")) { location.href = url; }
			}
			return true;
		}

		//do iframe dataURL download (old ch+FF):
		let f = document.createElement("iframe");
		document.body.appendChild(f);

		if (!winMode && /^data:/.test(url)) { // force a mime that will download:
			url = "data:" + url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
		}
		f.src = url;
		setTimeout(function() { document.body.removeChild(f); }, 333);

	} //end saver




	if (navigator.msSaveBlob) { // IE10+ : (has Blob, but not a[download] or URL)
		return navigator.msSaveBlob(blob, fileName);
	}

	if (self.URL) { // simple fast and modern way using Blob and URL:
		saver(self.URL.createObjectURL(blob), true);
	} else {
		// handle non-Blob()+non-URL browsers:
		if (typeof blob === "string" || blob.constructor === toString) {
			try {
				return saver("data:" + mimeType + ";base64," + self.btoa(blob));
			} catch (y) {
				return saver("data:" + mimeType + "," + encodeURIComponent(blob));
			}
		}

		// Blob but not URL support:
		reader = new FileReader();
		reader.onload = function(e) {
			saver(this.result);
		};
		reader.readAsDataURL(blob);
	}
	return true;
}; /* end download() */