package destr.jogl.pointer;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import javax.media.opengl.GL;

public abstract class Pointer {
	
	private static byte[] makeMD5(ByteBuffer data) throws NoSuchAlgorithmException {
		MessageDigest md5 = MessageDigest.getInstance("MD5");			
		md5.update(data);
        return md5.digest();
	}
	
	private static String Bytes2HexStr(byte[] data) {
		StringBuilder result = new StringBuilder();
        for(int i = 0; i < data.length; ++i)
        	result.append(Integer.toString((data[i] & 0xff) + 0x100, 16).substring(1));
        return result.toString();
	}
	
	private String md5Str;
	protected int id, bytes, glType;
	public Pointer(int id){
		this.id = id;
	}
	
	public Pointer(GL gl){
		int glID[] = new int[1];
		gl.glGenBuffers(1, glID, 0);
		id = glID[0];
	}
	
	public void load(GL gl, float[] data){
		ByteBuffer buffer = ByteBuffer.allocateDirect(data.length * Float.SIZE);
		buffer.order(ByteOrder.nativeOrder());
		buffer.asFloatBuffer().put(data).position(0);
		load(gl, buffer, Float.SIZE);
	}
	
	//TODO загрузка остальных типов
	
	public void load(GL gl, ByteBuffer buffer, int glType) { // Все загрузки ведут сюда
		this.glType = glType;
		
		bytes = buffer.capacity();
		gl.glBindBuffer(GL.GL_ARRAY_BUFFER, id);
		gl.glBufferData(GL.GL_ARRAY_BUFFER, bytes, buffer, getUsage());
		gl.glBindBuffer(GL.GL_ARRAY_BUFFER, 0);
		
		try {
			buffer.mark();
			md5Str = Bytes2HexStr(makeMD5(buffer));
			buffer.reset();
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			md5Str = "[no MD5hash: "+this.hashCode()+"]";
		}
	}
	
	public void free(GL gl){
		gl.glDeleteBuffers(1, new int[]{id}, 0);
	}
	
	public String hashMD5(){
		return md5Str;
	}
	
	public abstract void bind(GL gl);  // Наследник устанавливает нужный тип буфера
	public abstract void unBind(GL gl);
	protected abstract int getUsage();
	/* Specifies the expected usage pattern of the data store. The symbolic constant must be:
	 * GL_STREAM_DRAW
	 * GL_STREAM_READ
	 * GL_STREAM_COPY
	 * GL_STATIC_DRAW
	 * GL_STATIC_READ
	 * GL_STATIC_COPY
	 * GL_DYNAMIC_DRAW
	 * GL_DYNAMIC_READ
	 * GL_DYNAMIC_COPY
	 */
}