package org.destr.jogl.mesh;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;

import javax.media.opengl.GL2;

public class MeshReader extends DataInputStream {

	public static int glTypeToSize(int glType) {
		switch(glType) {
		
			case GL2.GL_BYTE:	return	1;
			case GL2.GL_SHORT:	return	2;
			case GL2.GL_INT:	return	4;
			case GL2.GL_DOUBLE:	return	8;
			
			case GL2.GL_FLOAT:	return	4;
			
			default: return -1;
		}
	}
	
	public MeshReader(InputStream is) {
		super(is);
	}
	
	public BufferedMeshData readMesh() throws IOException {
		BufferedMeshData mesh = new BufferedMeshData();
		
		String version = readUTF();
		
		if(!version.equals("JMESH1.0")) {
			throw new IOException(String.format(
				"Invalis header \"%s\"", version
			));
		}
		
		String format = readUTF().toUpperCase();
		
		if(format.equals("VNC")) {
			
			mesh.count	= readInt();
			
			mesh.vGLType	= readInt();
			mesh.vSize	= readInt();
			mesh.vStride	= readInt();
			mesh.vOffset	= readLong();
			
			mesh.nUsed	= true;
			mesh.nGLType	= readInt();
			mesh.nStride	= readInt();
			mesh.nOffset	= readLong();
			
			mesh.tUsed	= true;
			mesh.tGLType	= readInt();
			mesh.tSize	= readInt();
			mesh.tStride	= readInt();
			mesh.tOffset	= readLong();
						
			int vBytes = mesh.vSize * glTypeToSize(mesh.vGLType);
			if(vBytes < 0) {
				throw new IOException(String.format(
					"Can not read vertex glType %d", mesh.vGLType
				));
			}
			
			int nBytes = 3 * glTypeToSize(mesh.nGLType);
			if(nBytes < 0) {
				throw new IOException(String.format(
					"Can not read normal glType %d", mesh.nGLType
				));
			}
			
			int tBytes = mesh.tSize * glTypeToSize(mesh.tGLType);
			if(tBytes < 0) {
				throw new IOException(String.format(
					"Can not read texture coord glType %d", mesh.tGLType
				));
			}
			
			mesh.data = new byte[mesh.count * (vBytes + nBytes + tBytes)];
			read(mesh.data);
			
		} else {
			throw new IOException(String.format(
				"Invalid format \"%s\"", format
			));
		}
		
		return mesh;
	}
	
}