// ==UserScript==
// @name        Crunchyroll HTML5 Manga Viewer
// @namespace   DoomTay
// @description Replaces Flash manga viewer with an HTML5 setup
// @require     https://cdn.jsdelivr.net/npm/vast-player@0.2/dist/vast-player.min.js
// @include     http://www.crunchyroll.com/comics*
// @version     0.4.0
// @grant       none
// @downloadURL none
// ==/UserScript==

var mangaObject = document.querySelector("object#showmedia_videoplayer_object");

var mangaConfig = {};
var pages = [];

var currentPage = 0;

if(mangaObject)
{
	var flashVars = parseFlashVars(mangaObject.querySelector("param[name='flashvars']").value);
	var authToken = flashVars.auth || null;

	var mangaDiv = document.createElement("div");
	mangaDiv.style.width = mangaObject.width;
	mangaDiv.style.height = mangaObject.height + "px";
	mangaDiv.style.position = "relative";

	var playerDiv = document.createElement("div");
	playerDiv.style.width = mangaObject.width;
	playerDiv.style.height = mangaObject.height;

	mangaObject.parentNode.replaceChild(playerDiv,mangaObject);

	var pageL = document.createElement("img");
	pageL.width = "460";
	pageL.height = "690";

	var pageR = document.createElement("img");
	pageR.width = "460";
	pageR.height = "690";

	var doubleSpread = document.createElement("img");
	doubleSpread.width = "920";
	doubleSpread.height = "690";
	doubleSpread.style.display = "none";

	mangaDiv.appendChild(pageL);
	mangaDiv.appendChild(pageR);
	mangaDiv.appendChild(doubleSpread);

	var leftButton = document.createElement("div");
	leftButton.style.position = "absolute";
	leftButton.style.top = "50%";
	leftButton.style.cursor = "pointer";
	leftButton.style.color = "white";
	leftButton.style.backgroundColor = "black";
	leftButton.innerHTML = "\u2b05";
	leftButton.onclick = function()
	{
		if(currentPage >= 0 && mangaConfig.pages[currentPage].is_spread) turnPage(currentPage + 1);
		else if(currentPage + 2 < mangaConfig.pages.length) turnPage(currentPage + 2);
	};
	mangaDiv.appendChild(leftButton);

	var rightButton = document.createElement("div");
	rightButton.style.position = "absolute";
	rightButton.style.top = "50%";
	rightButton.style.right = "0";
	rightButton.style.cursor = "pointer";
	rightButton.style.color = "white";
	rightButton.style.backgroundColor = "black";
	rightButton.innerHTML = "\u27a1";
	rightButton.onclick = function()
	{
		if(mangaConfig.pages[currentPage - 1].is_spread) turnPage(currentPage - 1);
		else if(currentPage - 1 >= 0) turnPage(currentPage - 2);
	};
	mangaDiv.appendChild(rightButton);

	getAdsConfig(flashVars.config_url).then(function(config)
	{
		var ads = Array.from(config.getElementsByTagName("manga:preload")[0].getElementsByTagName("adSlots")[0].getElementsByTagName("adSlot")[0].children,child => child.getAttribute("url"));

		if(ads.length > 0)
		{
			var currentAd = ads[ads.length - 1];

			var adPlayer = new window.VASTPlayer(playerDiv);

			adPlayer.once('AdStopped', startManga);

			adPlayer.load(currentAd).then(readyPlayer => readyPlayer.startAd());
		}
	});

	function startManga()
	{
		playerDiv.parentNode.replaceChild(mangaDiv,playerDiv);

		authenticate(authToken,flashVars.session_id,flashVars.seriesId).then(function(data)
		{
			return getJSON("http://" + flashVars.server + "/list_chapters?series%5Fid=" + flashVars.seriesId + (data ? ("&user%5Fid=" + data.user.user_id) : ""));
		}).then(function(config)
		{
			var chapterID = config.chapters.find(chapter => chapter.number == flashVars.chapterNumber).chapter_id;

			return getJSON("http://" + flashVars.server + "/list_chapter?chapter%5Fid=" + chapterID + "&session%5Fid=" + flashVars.session_id + "&auth=" + authToken);
		}).then(function(config)
		{
			mangaConfig = config;
			turnPage(0);
		});
	}

	function turnPage(newPage)
	{
		if(newPage < 0) newPage = 0;
		currentPage = newPage;
		pageL.style.display = "none";
		pageR.style.display = "none";
		doubleSpread.style.display = "none";
		setPage(pageL,"data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==");
		setPage(pageR,"data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==");
		setPage(doubleSpread,"data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==");

		var pageData = mangaConfig.pages[newPage];

		if(pageData.is_spread)
		{
			doubleSpread.style.display = "";
			if(pages[newPage]) setPage(doubleSpread,pages[newPage]);
			else getDecryptedImage(mangaConfig.pages[newPage].locale[flashVars.locale].encrypted_composed_image_url).then(function(pageURL)
			{
				pages[newPage] = pageURL;
				setPage(doubleSpread,pages[newPage]);
			})
		}
		else
		{
			pageL.style.display = "";
			pageR.style.display = "";

			if(pageData.page_number == 0 || pageData.page_number == 1)
			{
				if(pages[newPage]) setPage(pageR,pages[newPage]);
				else getDecryptedImage(mangaConfig.pages[newPage].locale[flashVars.locale].encrypted_composed_image_url).then(function(pageURL)
				{
					pages[newPage] = pageURL;
					setPage(pageR,pages[newPage]);
				})

				if(pages[newPage + 1]) setPage(pageL,pages[newPage + 1]);
				else if(newPage + 1 < mangaConfig.pages.length) getDecryptedImage(mangaConfig.pages[newPage + 1].locale[flashVars.locale].encrypted_composed_image_url).then(function(pageURL)
				{
					pages[newPage + 1] = pageURL;
					setPage(pageL,pages[newPage + 1]);
				})
			}
			else if(pageData.page_number == 2 || pageData.page_number == 6)
			{
				currentPage--;
				if(pages[newPage]) setPage(pageL,pages[newPage]);
				else getDecryptedImage(mangaConfig.pages[newPage].locale[flashVars.locale].encrypted_composed_image_url).then(function(pageURL)
				{
					pages[newPage] = pageURL;
					setPage(pageL,pages[newPage]);
				})
			}
		}

		function setPage(pageElement,image)
		{
			pageElement.src = image;
		}
	}
}

function authenticate(token,sessionId,seriesId)
{
	return new Promise(function(resolve)
	{
		if(!token) resolve(null);
		else getJSON("http://api-manga.crunchyroll.com/cr_authenticate?session%5Fid=" + sessionId + "&api%5Fver=1&device%5Ftype=com%2Ecrunchyroll%2Emanga%2Ewww&format=json&series%5Fid=" + seriesId + "&auth=" + token + "&version=0").then(data => resolve(data.data));
	})
}

function parseFlashVars(vars)
{
	var splitVars = vars.split("&");

	var parsed = {};

	for(var s = 0; s < splitVars.length; s++)
	{
		var split = splitVars[s].split("=");

		parsed[split[0]] = decodeURIComponent(split[1]);
	}

	return parsed;
}

function getDecryptedImage(imageURL)
{
	return new Promise(function(resolve,reject)
	{
		var config = new XMLHttpRequest();
		config.onload = function()
		{
			var buffer = this.response;

			var viewer = new DataView(buffer);
			for(var i = 0; i < buffer.byteLength; i++)
			{
				var originalByte = viewer.getUint8(i);
				viewer.setUint8(i,originalByte ^ 0x42);
			}

			resolve(URL.createObjectURL(new Blob([buffer], {type: "image/jpeg"})));
		};
		config.onerror = reject;
		config.open("GET", imageURL, true);
		config.responseType = "arraybuffer";
		config.send();
	});
}

function getAdsConfig(configURL)
{
	return new Promise(function(resolve,reject)
	{
		var config = new XMLHttpRequest();
		config.onload = function()
		{
			resolve(this.response);
		};
		config.onerror = reject;
		config.open("GET", configURL, true);
		config.responseType = "document";
		config.send();
	});
}

function getJSON(configURL)
{
	return new Promise(function(resolve,reject)
	{
		var jsonRequest = new XMLHttpRequest();
		jsonRequest.onload = function()
		{
			resolve(this.response);
		};
		jsonRequest.onerror = reject;
		jsonRequest.open("GET", configURL, true);
		jsonRequest.responseType = "json";
		jsonRequest.send();
	});
}