import 'dart:html';
import 'dart:web_gl';

class ShaderProgramBuilderWithShaders {
  final RenderingContext _gl;
  final Shader _vertexShader, _fragmentShader;

  ShaderProgramBuilderWithShaders(this._gl, this._vertexShader, this._fragmentShader);

  Program build() {
    var program = _gl.createProgram();

    _gl.attachShader(program, _vertexShader);
    _gl.attachShader(program, _fragmentShader);
    _gl.linkProgram(program);

    var success = _gl.getProgramParameter(program, RenderingContext.LINK_STATUS);
    if (success != null)
      return program;

    window.console.error(_gl.getProgramInfoLog(program));
    _gl.deleteProgram(program);
    throw new Exception('Error while creating program');
  }
}

class ShaderProgramBuilder {
  final RenderingContext _gl;

  ShaderProgramBuilder(this._gl);

  ShaderProgramBuilderWithVertexShader addVertexShader(String source) {
    var shader = _gl.createShader(RenderingContext.VERTEX_SHADER);

    _gl.shaderSource(shader, source);
    _gl.compileShader(shader);

    var success = _gl.getShaderParameter(shader, RenderingContext.COMPILE_STATUS);
    if (success != null)
      return new ShaderProgramBuilderWithVertexShader(_gl, shader);

    window.console.error(_gl.getShaderInfoLog(shader));
    _gl.deleteShader(shader);
    throw new Exception('Unable to compile vertex shader');
  }
}

class ShaderProgramBuilderWithVertexShader {
  final RenderingContext _gl;
  final Shader _vertexShader;

  ShaderProgramBuilderWithVertexShader(this._gl, this._vertexShader);

  ShaderProgramBuilderWithShaders addFragmentShader(String source) {
    var shader = _gl.createShader(RenderingContext.FRAGMENT_SHADER);

    _gl.shaderSource(shader, source);
    _gl.compileShader(shader);

    var success = _gl.getShaderParameter(shader, RenderingContext.COMPILE_STATUS);
    if (success != null)
      return new ShaderProgramBuilderWithShaders(_gl, _vertexShader, shader);

    window.console.error(_gl.getShaderInfoLog(shader));
    _gl.deleteShader(shader);
    throw new Exception('Unable to compile fragment shader');
  }
}