background.js

(function() {

	"use strict";

	var imagesWaiting,
		windowId,
		openTabs,
		openTabsCount,
		autoDownload;

	function cleanBeforeLoad() {

		imagesWaiting = [];
		openTabs = {};
		openTabsCount = 0;
	}

	function openNextImage() {

		if( imagesWaiting.length > 0 ) {

			// Not too many waiting or not auto downloading?
			if( openTabsCount < 5 || !autoDownload ) {

				chrome.tabs.create({
					windowId: windowId,
					url: imagesWaiting.shift(),
					active: false
				}, tabOpened);
			}

		} else {
			stopListeningForTabClose();
		}
	}

	function tabOpened(tab) {

		if( tab ) {
			openTabs[ tab.id ] = true;
			openTabsCount++;
			openNextImage();
		}
	}

	function listenForTabClose() {
		stopListeningForTabClose();
		chrome.tabs.onRemoved.addListener(tabClosed);
	}

	function stopListeningForTabClose() {
		chrome.tabs.onRemoved.removeListener(tabClosed);
	}

	function tabClosed(tabId, removeInfo) {

		if( openTabs[tabId] === true ) {

			delete openTabs[tabId];
			openTabsCount--;
			openNextImage();
		}
	}

	//////////////////////

	function newDownloadNext() {

		if( imagesWaiting.length > 0 && openTabsCount < 5 ) {
			openTabsCount++;
			callDownload(imagesWaiting.shift(), true);
			newDownloadNext();
		}
	}

	function callDownload(image, canRetry) {

		chrome.downloads.download(image, function(downloadId) {
			if( downloadId ) {
				openTabs[downloadId] = true;
			} else if(canRetry) {
				// Couldn't download? Try removing title from name and fallback to original.
				delete image.filename;
				callDownload(image, false);
			}
		});
	}

	chrome.downloads.onChanged.addListener(function(delta) {

		if( delta.state && delta.state.current === "complete" && openTabs[delta.id] === true ) {
			delete openTabs[delta.id];
			openTabsCount--;
			newDownloadNext();
		}
	});

	//////////////////////

	// Listen for request to open all photos
	chrome.extension.onRequest.addListener( function(request, sender, sendResponse)
	{
		if (request.msg === "openAllPhotos")
		{
			cleanBeforeLoad();
			imagesWaiting = request.imgs;

			if( imagesWaiting.length === 1 ) {
				imagesWaiting[0].saveAs = true;
			}

			newDownloadNext();

			// if( confirm("Are you sure you want to open " + request.imgs.length + " tab(s)? It may take a while to load everything.") )
			// {
			// 	// Open a new window with a blank page
			// 	chrome.windows.create({url: "about:blank"}, function(win) {

			// 		cleanBeforeLoad();

			// 		windowId = win.id;
			// 		autoDownload = request.autoDownload;
			// 		imagesWaiting = request.imgs;

			// 		if( autoDownload ) {
			// 			listenForTabClose();
			// 		}

			// 		openNextImage();
			// 	});
			// }
		}
	});

})();