/**
  * Initializes the WebGL Shader program
  */
export function initializeShaderProgram(gl, vertexShaderSource, fragmentShaderSource) {

  const vertexShader = loadShader(gl, gl.VERTEX_SHADER, vertexShaderSource);
  const fragmentShader = loadShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource);

  const shaderProgram = gl.createProgram();
  gl.attachShader(shaderProgram, vertexShader);
  gl.attachShader(shaderProgram, fragmentShader);

  gl.linkProgram(shaderProgram);

  if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
    console.error(`Unable to initialize shader program: ${gl.getProgramInfoLog(shaderProgram)}`);
    return null;
  }

  return shaderProgram;
}

/**
  * Initializes the buffers
  */
export function initializeBuffers(gl) {

  const positionBuffer = gl.createBuffer();

  gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);

  return {
    position: positionBuffer
  };
}


/**
  * Loads and compiles a shader
  */
function loadShader(gl, type, source) {

  const shader = gl.createShader(type);
  gl.shaderSource(shader, source);
  gl.compileShader(shader);

  if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
    console.error(`Unable to compile shader: ${gl.getShaderInfoLog(shader)}`);
    gl.deleteShader(shader);
    return null;
  }

  return shader;
}