content.js

let running = false;
let autoScrolling = true;
let status;
let albumZip;


// run receiver: extension is triggered by a message from background.js
chrome.runtime.onMessage.addListener(
	function(request, sender, sendResponse) {
		if (request.run == 'true') {
			if (running) {
				alert('There is a download already in progress!');
			} else {
				running = true;
				init();
			}
		}
	}
);


function init() {
	const compatCheck = (document.getElementById('meta_og_site_name').content.toUpperCase() == 'PIXIESET');

	if (!compatCheck) {
		alert("This doesn't look like a Pixieset website.");
		running = false;
	} else {
		if (!document.getElementById('statusText')) {
			// add status text to navbar
			let nav = document.evaluate(
				'//div[@id="nav-icon-buttons" and @class="pull-right"]',
				document, null, XPathResult.ANY_TYPE, null
			);
			if (nav) {
				nav = nav.iterateNext();

				let div = document.createElement('div');
				div.className = 'nav-buy-photos__container';
				div.innerHTML = `
					<a id="statusText" title="pixieDownloader" style="cursor: default; font-weight: bold; font-size: 15px" class="nav-buy-photos">Ready</a></div>
					<span class="f-24 spacer-right-15 spacer-left-15 bl o-20"></span>
				`;
				nav.insertBefore(div, nav.firstChild);
				status = document.getElementById('statusText');
			}
		}

		if (autoScrolling) {
			// scroll to the bottom to load all images in the current album
			let lastScrollHeight = 0;
			function autoScroll() {
				let scrollHeight = document.documentElement.scrollHeight;
				if (scrollHeight != lastScrollHeight) {
					lastScrollHeight = scrollHeight;
					document.documentElement.scrollTop = scrollHeight;
				}
			}
			window.setInterval(autoScroll, 50);
		}

		// initialize JSZip object
		albumZip = new JSZip();

		// give it some time to (hopefully) finish completely scrolling/loading first
		setTimeout(() => { zip() }, 2000);
	}
}


// helper function to update navbar status text
function setStatus(text, color = null) {
	status.style.color = color;
	status.innerText = text;
}


function zip() {
	setStatus('Preparing...', '#45b0e6');

	// locate all <img> elements
	const container = document.getElementById('gamma-container');
	const imgElements = container.getElementsByTagName('img');

	const re_imgUrl = /(.*images.pixieset.*-)(.*)(.jpg)/;

	// JSON data structure to store { URL, filename, base64 encoding } of each image
	let imgObjects = [];

	for (let i = 0; i < imgElements.length; i++) {
		const currEle = imgElements[i];
		const currSrc = currEle.currentSrc;

		// filter out irrelevant images (i.e. site assets)
		if (currSrc.match(re_imgUrl)) {
			// obtain largest size available ('xxlarge')
			const newUrl = currSrc.replace(re_imgUrl, '$1xxlarge$3');
			// obtain original filename
			const origName = currEle.alt;

			imgObjects.push({ url: newUrl, name: origName, base64: '' });
		}
	}

	// set default ZIP filename — combination of window title and current album
	let albumName = window.location.pathname.split('/');
	albumName = albumName.pop() || albumName.pop();
	let zipName = document.title + ' - ' + albumName;

	setStatus('Downloading...', '#eca142');

	chrome.runtime.sendMessage(
		{ array: imgObjects },
		array => {
			// add all images to ZIP
			array.forEach(obj => albumZip.file(
				obj.name,
				obj.base64,
				{ base64: true }
			));

			// serve ZIP to user
			download(albumZip, zipName, true);
		}
	);
}


function download(zip, name, ask) {
	zip.generateAsync({ type:'blob' }).then(blob => {
		if (ask) {
			name = prompt('What should the name of the ZIP file be?', name);
			if (name === null) {
				setStatus('Cancelled', '#e71d1d');
				running = false;
				return;
			};
		}

		// https://stackoverflow.com/a/9834261
		const url = window.URL.createObjectURL(blob);
		const a = document.createElement('a');
		a.style.display = 'none';
		a.href = url;
		a.download = name + '.zip';
		document.body.appendChild(a);
		a.click();
		window.URL.revokeObjectURL(url);

		setStatus('Finished', '#37ae3d');
		running = false;
	});
}