//
// nsbtx.js
//--------------------
// Reads NSBTX files (or TEX0 sections) and provides canvases containing decoded texture data.
// by RHY3756547
//
// includes: gl-matrix.js (glMatrix 2.0)
// /formats/nitro.js
//

window.nsbtx = function(input, tex0, autogen) {
	var texDataSize, texInfoOff, texOffset, compTexSize, compTexInfoOff, 
		compTexOffset, compTexInfoDataOff /*wtf*/, palSize, palInfoOff, 
		palOffset, mainOff

	var textureInfo, paletteInfo, palData, texData, colourBuffer
	var thisObj = this;

	var bitDepths = [0, 8, 2, 4, 8, 2, 8, 16]

	if (input != null) {
		load(input, tex0, autogen);
	}
	this.load = load;
	this.readTexWithPal = readTexWithPal;

	this.scopeEval = function(code) {return eval(code)} //for debug purposes

	function load(input, tex0, autogen) {
		var colourBuffer = new Uint32Array(4);
		var view = new DataView(input);
		var header = null;
		var offset = 0;
		if (!tex0) { //nitro 3d header
			header = nitro.readHeader(view);
			if (header.stamp != "BTX0") throw "NSBTX invalid. Expected BTX0, found "+header.stamp;
			if (header.numSections > 1) throw "NSBTX invalid. Too many sections - should only have one.";
			offset = header.sectionOffsets[0];
		}

		mainOff = offset;

		var stamp = readChar(view, offset+0x0)+readChar(view, offset+0x1)+readChar(view, offset+0x2)+readChar(view, offset+0x3);
		if (stamp != "TEX0") throw "NSBTX invalid. Expected TEX0, found "+stamp;
		var size = view.getUint32(offset+0x04, true);
		var texDataSize = view.getUint16(offset+0x0C, true)<<8;
		var texInfoOff = view.getUint16(offset+0x0E, true);
		var texOffset = view.getUint16(offset+0x14, true);

		var compTexSize = view.getUint16(offset+0x1C, true)<<8;
		var compTexInfoOff = view.getUint16(offset+0x1E, true);
		var compTexOffset = view.getUint32(offset+0x24, true);
		var compTexInfoDataOff = view.getUint32(offset+0x28, true);

		var palSize = view.getUint32(offset+0x30, true)<<3;
		var palInfoOff = view.getUint32(offset+0x34, true);
		var palOffset = view.getUint32(offset+0x38, true);

		//read palletes, then textures.
		palData = input.slice(mainOff + palOffset, palSize);
		texData = input.slice(mainOff + texOffset, texDataSize);

		paletteInfo = nitro.read3dInfo(view, palInfoOff, palInfoHandler);
		textureInfo = nitro.read3dInfo(view, texInfoOff, texInfoHandler);

		if (autogen) {
			console.log(textureInfo.objectData.length)
			for (var i=0; i<textureInfo.objectData.length; i++) {
				var canvas = readTexWithPal(i, textureInfo.objectData[i].pal)
				document.body.appendChild(canvas);
				console.log("uh")
			}
		}

	}

	function readTexWithPal(textureId, palId) {
		palView = new DataView(palData);
		texView = new DataView(texData);
		var tex = textureInfo.objectData[textureId];
		var pal = paletteInfo.objectData[palId];

		var bit = bitDepths[pal.format]; //todo, compressed format whatever that is

		var canvas = document.createElement("canvas");
		canvas.width = tex.width;
		canvas.height = tex.height;
		var ctx = canvas.getContext("2d");
		var data = ctx.getImageData(0, 0, tex.width, tex.height);

		var off = tex.texOffset
		var palOff = pal.palOffset;

		var total = tex.width*tex.height;
		var databuf = texView.readUint8(off);
		for (var i=0; i<total; i++) {
			var col;
			if (bitDepths == 2) {
				col = readPalColour(palView, palOff, (databuf>>((i%4)*2))&3)
				if (i%4 == 3) databuf = texView.readUint8(++off);
			} else if (bitDepths == 4) {
				if (i%2 == 0) {
					col = readPalColour(palView, palOff, databuf&15)
				} else {
					col = readPalColour(palView, palOff, databuf>>4)
					databuf = texView.readUint8(++off);
				}
			} else if (bitDepths == 8) {
				col = readPalColour(palView, palOff, texView.readUint8(off))
				off += 1;
			} else if (bitDepths == 16) {
				col = readPalColour(palView, palOff, texView.readUint16(off, true))
				off += 2;
			}
			data.data.set(col, i*4);
		}
		return canvas;
	}

	function readPalColour(view, palOff, ind) {
		var col = palView.getUint16(palOff+ind*2, true);
		colourBuffer[0] = Math.round(((col&31)/31)*255)
		colourBuffer[1] = Math.round((((col>>5)&31)/31)*255)
		colourBuffer[2] = Math.round((((col>>10)&31)/31)*255)
		colourBuffer[3] = Math.round((col>>15)*255)
	}

	function palInfoHandler(view, offset) {
		var palOffset = view.getUint16(offset, true)<<3;
		var unknown = view.getUint16(offset+2, true);
		return {
			palOffset: palOffset,
			nextoff: offset+4
		}
	}

	function texInfoHandler(view, offset) {
		var texOffset = view.getUint16(offset, true)<<3;
		var flags = view.getUint16(offset+2, true);
		var width2 = view.getUint8(offset+4, true);
		var unknown = view.getUint8(offset+5, true);
		var height2 = view.getUint8(offset+6, true);
		var unknown2 = view.getUint8(offset+7, true);
		return {
			texOffset: texOffset,
			pal: (flags>>13),
			format: ((flags>>10)&7),
			height: ((flags>>7)&7)<<3,
			width: ((flags>>4)&7)<<3,

			nextoff: offset+8
		}
	}

	function readChar(view, offset) {
		return String.fromCharCode(view.getUint8(offset));
	}
}