-- 文件下载器

local FileDownloader = class("FileDownloader")

-- urls : 下载地址
-- fileName ：保存在本地的文件名
-- onFinishCallback ： 完成后的回调
function FileDownloader:ctor(urls, atts, onFinishCallback)
	self.urls = urls
	self.atts = atts
	self.onFinishCallback = onFinishCallback;
end

-- 开启下载
function FileDownloader:start()
	
	local priority = 0
	local startPos = self.atts.offset or 0
	local dataSize = self.atts.compressedSize or 0
	
	local timebegin;
	
	local index = 0;
	local function downloadFileFromUrl()
		local function onUpdateFirst(status , data)
			if status == "successed" then
				-- 打印下载文件的耗时
				local timeEnd = os.time()
				logI(string.format("FileDownloader() cost time = %4s , size = %8s , file = %s", timeEnd - timebegin, dataSize, self.atts.name))
				
				-- 下载成功后将数据保存为本地文件
				self:onDownloadSuccessed(data);
			else
				-- 下载失败后再次请求下载
				downloadFileFromUrl()				
			end
		end	
	
		index = index + 1
		if not self.urls[index] then
			logE("FileDownloader:start() url is nil")
			return
		end
		timebegin = os.time()
		self.task = cc.CURLManager:getInstance():createTask(self.urls[index], onUpdateFirst , priority , startPos , dataSize);
	end
	downloadFileFromUrl();	
end

-- 取消下载
function FileDownloader:cancel()
	if self.task then
		cc.CURLManager:getInstance():cancelTask(self.task);
		self.task = nil
	end
end

function FileDownloader:onDownloadSuccessed(data)
	local targetFilename = cc.FileUtils:getInstance():getWritablePath() .. self.atts.md5
	
	local uncompressData = lzma.uncompress(data);
	
	-- 解压成功
	if uncompressData then
		local targetFile = io.open(targetFilename , "wb");
		if targetFile == nil then
			return;
		end
		targetFile:write(uncompressData);
		targetFile:close();
	else
		logE("文件解压失败：" , self.atts.name , "压缩文件大小：" , #data , "/" , self.atts.compressedSize) ;
		return;
	end
	
	-- win32平台下面文件系统是不会起作用的
	if not isWin32Platform() then
		-- 加到文件系统中
		self:addFile();
		
		--[[
		-- 检查MD5	
		local md5Result = cc.FilePackage:calcFileMd5(targetFilename);
		if md5Result ~= self.atts.md5 then
			logE("文件下载完毕，但是文件的md5跟服务器上面记录的md5不一致，删除本地文件：", targetFilename)
			os.remove(targetFilename);
			return;
		end
		--]]
	end
	
	self:onFinish()
end

-- 添加文件信息到打包文件系统中
function FileDownloader:addFile()
	
	local info = 
	{
		isRomFile = false;
		origin = self.atts.origin;
		name = self.atts.name;		
		md5 = self.atts.md5;
		size = tonumber(self.atts.size),
		realFilePath = getWritableFullName(self.atts.md5);
	};

	print("加到文件系统" , info.realFilePath , self.atts.md5 , self.atts.name);

	cc.FilePackage:getInstance():addFile(info);
end

-- 下载完成
function FileDownloader:onFinish()
	if self.onFinishCallback then
		self.onFinishCallback()
	end
end

return FileDownloader