import {glsl, Buffer} from '@luma.gl/core';
import {AnimationLoopTemplate, AnimationProps, Model} from '@luma.gl/engine';

const INFO_HTML = `
Have to start somewhere...
`;

const vs = `\
#version 300 es

in vec2 position;
in vec3 color;

out vec3 vColor;

void main() {
  vColor = color;
  gl_Position = vec4(position, 0.0, 1.0);
}
`;

const fs = glsl`\
#version 300 es

in vec3 vColor;
out vec4 fragColor;
void main() {
  fragColor = vec4(vColor, 1.0);
}
`;

// export const vs_wgsl = /* WGSL */`\
// struct VertexOutput {
// @builtin(position) Position : vec4<f32>;
// @location(0) fragColor : vec3<f32>;
// };

// @vertex
// fn main(@location(0) position : vec2<f32>, @location(1) color : vec3<f32>) -> VertexOutput {
//   var output : VertexOutput;
//   output.Position = uniforms.modelViewProjectionMatrix * position;
//   output.fragColor = color;
//   return output;
// }
// `;

// export const fs_wgsl = /* WGSL */`\
// @fragment
// fn main(@location(0) fragColor: vec3<f32>) -> @location(0) vec4<f32> {
//   return vec4<f32>(fragColor, 1.0);
// }
// `;

export default class AppAnimationLoopTemplate extends AnimationLoopTemplate {
  static info = INFO_HTML;

  model: Model;
  interleavedBuffer: Buffer;

  constructor({device}: AnimationProps) {
    super();

    // prettier-ignore
    const interleavedData = new Float32Array([
      // Offset
      0, 0,
      // vertex 1: 2D positions XY,  colors RGB
      -0.5, -0.5,  1, 0, 0,
      // vertex 2: 2D positions XY,  colors RGB
      0.5, -0.5,  0, 1, 0,
      // vertex 3: 2D positions XY,  colors RGB
      0.0, 0.5,  0, 0, 1
    ])
    this.interleavedBuffer = device.createBuffer(interleavedData);

    this.model = new Model(device, {
      id: 'triangle',
      vs,
      fs,
      bufferLayout: [
        {
          name: 'vertexData',
          byteStride: 20,
          attributes: [
            {attribute: 'position', format: 'float32x2', byteOffset: 8 + 0},
            {attribute: 'color', format: 'float32x3', byteOffset: 8 + 8}
          ]
        }
      ],
      attributes: {
        vertexData: this.interleavedBuffer
      },
      vertexCount: 3
    });
  }

  onFinalize() {
    this.model.destroy();
    this.interleavedBuffer.destroy();
  }

  onRender({device}: AnimationProps): void {
    const renderPass = device.beginRenderPass({clearColor: [0, 0, 0, 1]});
    this.model.draw(renderPass);
    renderPass.end();
  }
}