/* Upload a file >2GB in javascript */

function Uploader(f)
{
	this.FileName=f.name;
	this.Size=f.size;
	this.f=f;
	this.PacketSize=1024*1024;	// 1MB
	this.TotalPackets=Math.ceil(this.Size/this.PacketSize);
	this.lastPacket=0;
	this.guid="";
	this.state=0;
	this.progress=null;
	this.cancelled=null;
	this.complete=null;
	this.fileno=0;
	this.nfiles=1;

	this.NewFile = function(f,idx) {
		this.FileName=f.name;
		this.Size=f.size;
		this.f=f;
		this.PacketSize=1024*1024;	// 1MB
		this.TotalPackets=Math.ceil(this.Size/this.PacketSize);
		this.lastPacket=0;
		this.state=0;
		this.fileno=idx;
	};

	this.Start = function(idx,n) {
		this.state=1;
		var obj=new Object();
		obj.filename=this.FileName;
		obj.filesize=this.Size;
		obj.totalpackets=this.TotalPackets;
		obj.packetsize=this.PacketSize;
		obj.fileno=idx;
		obj.nfiles=n;
		if ((this.guid) && (this.guid.length>0))
			obj.Guid=this.guid;
		var formData=JSON.stringify(obj);
		this.fileno=idx;
		this.nfiles=n;

        var obj = this;
        var xhr = new window.XMLHttpRequest();
        xhr.open('POST', API_URL("upload/startupload",0,true), true);
        xhr.setRequestHeader("Content-Type", "application/json");
        xhr.onload = function (e) {
            obj.onInitPacketArrival(this);
        };
        xhr.send(formData);
	};
	
	this.onInitPacketArrival = function(xmlHttpReq) {
		var resp=JSON.parse(xmlHttpReq.responseText);
		this.guid=resp.Guid;
		this.uploadPacket();
	};
	
	this.uploadPacket = function() {
		var packet=this.lastPacket+1;
		if (packet>this.TotalPackets)
			return;
		if (this.state==0)
			return;

   		var xhr = new window.XMLHttpRequest();
        var url = API_URL("upload/uploadpacket?guid=" + this.guid + "&packet=" + packet + "&total=" + this.TotalPackets,0,true);
        var obj = this;
        xhr.open('POST', url, true);
        xhr.onprogress = function (e) {
        };

        xhr.onload = function (e) {
	        obj.onPacketArrival(this);
        };
        xhr.send(this.getDataPacket(packet));
        if (this.progress)
        {
        	var pct=Math.ceil(100*packet/this.TotalPackets);
        	this.progress(pct);
        }
	};
	
	this.getDataPacket = function (packetNumber) {

		var startByte = (packetNumber - 1) * this.PacketSize;
		var endByte = startByte + this.PacketSize;
		var packet;

		// the HTML5 dirty part, FileReader API is not yet fully implemented
		//packet = this.file.slice(startByte, endByte);

		if ('mozSlice' in this.f) {
		    // mozilla
		    packet = this.f.mozSlice(startByte, endByte);
		} else if ('webkitSlice' in this.f) {
		        // webkit
		    packet = this.f.webkitSlice(startByte, endByte);
		} else {
		    // IE 10
		    packet = this.f.slice(startByte, endByte);
		}
		return packet;
	};

	this.onPacketArrival = function(xmlHttpReq) {
		if (this.state==0) return;
		var response = JSON.parse(xmlHttpReq.responseText);

        // if packet == -1 that means no retry possible
        if (response.Packet == -1) {
            //this.guid = "";
            this.lastPacket = 0;

            this.Start(this.fileno,this.nfiles);
            return;
        }
        if (response.Packet==-2) {
        	// cancel
        	this.guid="";
        	this.lastPacket=0;
			if (this.cancelled)
				this.cancelled();
        	return;
        }

        this.guid = response.Guid;
        this.lastPacket = response.Packet;

        // if last packet was received OK
        if (this.lastPacket == this.TotalPackets) {
            this.state = 0; // stoped
            if (this.complete)
            	this.complete();
        }
        else
        	this.uploadPacket();
	};
	
	this.cancel = function() {
        var xhr = new window.XMLHttpRequest();
        xhr.open('GET', API_URL("upload/cancel/"+this.guid,0,true), true);
        xhr.setRequestHeader("Content-Type", "application/json");
        xhr.send();

	};
}