package me.srvstr.shader;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import org.lwjgl.opengl.GL20C;

public class Shader
    implements AutoCloseable {
  private int shaderHandle;

  public Shader(String fileName, int shaderType) throws AssertionError {
    this.shaderHandle = GL20C.glCreateShader(shaderType);

    GL20C.glShaderSource(this.shaderHandle, getSource(fileName));
    GL20C.glCompileShader(this.shaderHandle);

    if (GL20C.glGetShaderi(this.shaderHandle, 35713) == 0) {

      System.err.println(GL20C.glGetShaderInfoLog(this.shaderHandle));
      throw new AssertionError("Could not compile Shader: " + fileName);
    }
  }

  private String getSource(String fileName) {
    try {
      BufferedReader reader = new BufferedReader(new InputStreamReader(getClass().getResource(fileName).openStream()));

      String result = reader.lines().reduce("", (A, B) -> String.valueOf(A) + B + System.lineSeparator());

      reader.close();

      return result;
    } catch (Exception e) {
      e.printStackTrace();
      return null;
    }
  }

  public final int getHandle() {
    return this.shaderHandle;
  }

  public void close() {
    GL20C.glDeleteShader(this.shaderHandle);
  }
}