package com.persesgames.jogl.shader;

import java.util.HashMap;
import java.util.Map;

import javax.media.opengl.GL2ES2;

public abstract class Program {

    protected GL2ES2              gl;

    protected int                 program;

    private Map<String, Integer>  uniformLocations = new HashMap<>();
    private Map<String, Integer>  attribLocations = new HashMap<>();

    public Program(GL2ES2 gl) {
        this.gl = gl;
    }

    public int getUniformLocation(String uniform) {
        Integer result = uniformLocations.get(uniform);

        if (result == null) {
            result = gl.glGetUniformLocation(program, uniform);

            uniformLocations.put(uniform, result);
        }

        return result;
    }

    public int getAttribLocation(String attrib) {
        Integer result = attribLocations.get(attrib);

        if (result == null) {
            result = gl.glGetAttribLocation(program, attrib);

            attribLocations.put(attrib, result);
        }

        return result;
    }

    public void bindAttributeLocation(int location, String name) {
        gl.glBindAttribLocation(program, location, name);
    }

    public void begin() {
        gl.glUseProgram(program);
    }

    public void end() {
        gl.glUseProgram(0);
    }

    protected void dispose() {
        gl.glDeleteProgram(program);
    }

    protected int createAndCompileShader(int type, String shaderString) {
        int shader = gl.glCreateShader(type);

        String[] vlines = new String[]{shaderString};
        int[] vlengths = new int[]{vlines[0].length()};

        gl.glShaderSource(shader, vlines.length, vlines, vlengths, 0);
        gl.glCompileShader(shader);

        int[] compiled = new int[1];
        gl.glGetShaderiv(shader, GL2ES2.GL_COMPILE_STATUS, compiled, 0);

        if (compiled[0] == 0) {
            int[] logLength = new int[1];
            gl.glGetShaderiv(shader, GL2ES2.GL_INFO_LOG_LENGTH, logLength, 0);

            byte[] log = new byte[logLength[0]];
            gl.glGetShaderInfoLog(shader, logLength[0], (int[]) null, 0, log, 0);

            throw new IllegalStateException("Error compiling the shader: " + new String(log));
        }

        return shader;
    }

}