package me.srvstr.shader;

import org.lwjgl.opengl.GL20C;

public class ShaderProgram
    implements AutoCloseable {
  protected int program;
  private Shader vertexShader;
  private Shader fragmentShader;

  public ShaderProgram(String shaderName) throws AssertionError {
    this.program = GL20C.glCreateProgram();

    this.vertexShader = new Shader(String.valueOf(shaderName) + ".vsh.glsl", 35633);
    this.fragmentShader = new Shader(String.valueOf(shaderName) + ".fsh.glsl", 35632);

    GL20C.glAttachShader(this.program, this.vertexShader.getHandle());
    GL20C.glAttachShader(this.program, this.fragmentShader.getHandle());

    GL20C.glBindAttribLocation(this.program, 0, "vertexPosition");

    GL20C.glLinkProgram(this.program);
    if (GL20C.glGetProgrami(this.program, 35714) == 0) {

      System.err.println(GL20C.glGetProgramInfoLog(this.program));
      throw new AssertionError("Unable to create shader program");
    }

    GL20C.glValidateProgram(this.program);
    if (GL20C.glGetProgrami(this.program, 35715) == 0) {

      System.err.println(GL20C.glGetProgramInfoLog(this.program));
      throw new AssertionError("Unable to create shader program");
    }
  }

  public void bind() {
    GL20C.glUseProgram(this.program);
  }

  public void close() {
    GL20C.glDeleteProgram(this.program);

    this.vertexShader.close();
    this.fragmentShader.close();
  }

  public void unbind() {
    GL20C.glUseProgram(0);
  }
}