// luma.gl, MIT license
// Copyright (c) vis.gl contributors

import test from 'tape-promise/tape';
import {getWebGLTestDevices} from '@luma.gl/test-utils';
import {TextureTransform} from '@luma.gl/engine';
import {Device, Texture} from '@luma.gl/core';

/** Creates a minimal, no-op transform. */
test('TextureTransform#constructor', async t => {
  for (const device of getWebGLTestDevices()) {
    if (device.isWebGL1) {
      t.comment('TextureTransform aggregation not yet supported in WebGL1');
    } else {
      const targetTexture = device.createTexture({
        data: new Float32Array([201, 202, 203, 1.0]),
        width: 1,
        height: 1,
        format: 'rgba32float',
      });
      const transform = new TextureTransform(device, {
        vs: BASIC_VS,
        topology: 'point-list',
        targetTexture,
        targetTextureChannels: 1,
        targetTextureVarying: 'vSrc',
        vertexCount: 1,
      });
      t.ok(transform, 'creates transform');
    }
  }
  t.end();
});

/** Computes a sum over vertex attribute values by writing to framebuffer. */
test('TextureTransform#attribute', async t => {
  for (const device of getWebGLTestDevices()) {
    if (device.isWebGL1) {
      t.comment('TextureTransform aggregation not yet supported in WebGL1');
    } else {
      const src = device.createBuffer({data: new Float32Array([10, 20, 30, 70, 80, 90])});
      const targetTexture = device.createTexture({
        data: new Float32Array([201, 202, 203, 1.0]),
        width: 1,
        height: 1,
        format: 'rgba32float',
      });
      const transform = new TextureTransform(device, {
        vs: SUM_VS,
        attributes: {src},
        bufferLayout: [{name: 'src', format: 'float32'}],
        topology: 'point-list',
        targetTexture,
        targetTextureChannels: 1,
        targetTextureVarying: 'vSrc',
        vertexCount: 6,
        parameters: {
          depthCompare: 'always',
          blendColorOperation: 'add',
          blendColorSrcFactor: 'one',
          blendColorDstFactor: 'one',
        },
      });
      const source = transform.getTargetTexture();
    
      // TODO(donmccurdy): Consider having Transform inherit from Model, or at
      // least mimic its API by accepting a RenderPass in .run().
      transform.run({clearColor: [0, 0, 0, 0]});

      const sum = await readF32(device, source, 16);
      t.is(sum[0], 300, 'computes sum');

      transform.destroy();
    }
  }
  t.end();
});

/** Computes a sum over texture pixels by writing to framebuffer. */
test('TextureTransform#texture', async t => {
  for (const device of getWebGLTestDevices()) {
    if (device.isWebGL1) {
      t.comment('TextureTransform aggregation not yet supported in WebGL1');
    } else {
      const srcData = new Uint8Array([2, 10, 255, 255]);
      const dstData = new Uint8Array([8, 40, 255, 255]); // src x 4
      const dstOffsetData = new Uint8Array([108, 140, 255, 255]); // src x 4 + 100

      const inputTexture = device.createTexture({
        data: srcData,
        width: 1,
        height: 1,
        format: 'rgba8unorm',
      });
      const targetTexture = device.createTexture({
        data: new Uint8Array([0, 0, 0, 1]),
        width: 1,
        height: 1,
        format: 'rgba8unorm',
      });
      const transform = new TextureTransform(device, {
        vs: BLEND_VS,
        fs: BLEND_FS,
        topology: 'point-list',
        vertexCount: 4,
        targetTexture,
        targetTextureChannels: 4,
        targetTextureVarying: 'vUv',
        bindings: {uSampler: inputTexture},
        parameters: {
          depthCompare: 'always',
          blendColorOperation: 'add',
          blendColorSrcFactor: 'one',
          blendColorDstFactor: 'one',
        },
      });

      // TODO(donmccurdy): Consider having Transform inherit from Model, or at
      // least mimic its API by accepting a RenderPass in .run().
      transform.run({clearColor: [0, 0, 0, 0]});
      let blend = await readU8(device, targetTexture, 4);
      t.deepEqual(Array.from(blend), Array.from(dstData), 'computes blend');

      const offset = 100 / 255;
      transform.run({clearColor: [offset, offset, offset, 1]});
      blend = await readU8(device, targetTexture, 4);
      t.deepEqual(Array.from(blend), Array.from(dstOffsetData), 'computes blend');

      transform.destroy();
      inputTexture.destroy();
      targetTexture.destroy();
    }
  }
  t.end();
});

async function readF32(device: Device, source: Texture, byteLength: number): Promise<Float32Array> {
  const bytes = await readU8(device, source, byteLength);
  return new Float32Array(bytes.buffer, bytes.byteOffset, bytes.byteLength / 4);
}

async function readU8(device: Device, source: Texture, byteLength: number): Promise<Uint8Array> {
  const destination = device.createBuffer({byteLength});
  try {
    const cmd = device.createCommandEncoder();
    cmd.copyTextureToBuffer({source, destination});
    cmd.finish();
    return destination.readAsync();
  } finally {
    destination.destroy();
  }
}

const BASIC_VS = `\
#version 300 es
#define SHADER_NAME texture-transform-basic
precision highp float;
out float vSrc;

void main()
{
  vSrc = 1.0;
  gl_PointSize = 1.0;
}
`;

const SUM_VS = `\
#version 300 es
#define SHADER_NAME texture-transform-sum
precision highp float;
in float src;
out float vSrc;

void main()
{
  vSrc = src;
  gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
  gl_PointSize = 1.0;
}
`;

const BLEND_VS = `\
#version 300 es
#define SHADER_NAME texture-transform-blend
precision highp float;
out vec2 vUv;

void main()
{
  vUv = vec2(0.5, 0.5);
  gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
  gl_PointSize = 1.0;
}
`;

const BLEND_FS = `\
#version 300 es
#define SHADER_NAME texture-transform-blend
precision highp float;
in vec2 vUv;
out vec4 fragColor;
uniform sampler2D uSampler;

void main()
{
  fragColor = texture(uSampler, vUv);
}
`;