import { GraphicsDevice } from './src/core/graphics-device.js'
import { PowerPreference, VertexFormat } from './src/enum.js'

async function main() {
  const canvas = /** @type {HTMLCanvasElement} */ (document.getElementById('webgpu-canvas'))

  if (!canvas) {
    console.error("Canvas element not found!")
    return
  }

  canvas.width = 800
  canvas.height = 600


  const graphicsDevice = await GraphicsDevice.build()
    .withCanvas(canvas)
    .withAdapter({ powerPreference: PowerPreference.HighPerformance })
    .build()

  const success = await graphicsDevice.initialize()

  if (!success) {
    console.error("Failed to initialize WebGPU.")
    document.body.innerHTML = "WebGPU initialization failed. Please use a supported browser and ensure hardware acceleration is enabled."
    return
  }

  const shaderSource = `
     @group(0) @binding(0)
     var<uniform> transform : mat4x4<f32>;

     @vertex
     fn vs_main(@location(0) in_pos : vec3<f32>) -> @builtin(position) vec4<f32> {
         return transform * vec4<f32>(in_pos, 1.0);
     }

     @fragment
     fn fs_main() -> @location(0) vec4<f32> {
         return vec4<f32>(0.0, 0.5, 1.0, 1.0);
     }
 `;

  const shaderModule = graphicsDevice.createShaderModule(
    shaderSource,
    'SquareShader',
  )

  const vertices = new Float32Array([
    -0.5, 0.5, 0.0,
    -0.5, -0.5, 0.0,
    0.5, 0.5, 0.0,

    0.5, 0.5, 0.0,
    -0.5, -0.5, 0.0,
    0.5, -0.5, 0.0
  ])

  const indices = new Uint16Array([
    0, 1, 2,
    3, 4, 5
  ])

  const indexBuffer = graphicsDevice.createBuffer({
    size: indices.byteLength,
    usage: GPUBufferUsage.INDEX | GPUBufferUsage.COPY_DST
  })

  indexBuffer.write(indices)

  const vertexBuffer = graphicsDevice.createBuffer(
    {
      label: 'TriangleVertexBuffer',
      size: vertices.byteLength,
      usage: GPUBufferUsage.VERTEX | GPUBufferUsage.COPY_DST,
    },
    vertices
  )

  const matrixSize = 4 * 4 * Float32Array.BYTES_PER_ELEMENT
  const matrixData = new Float32Array(16)

  matrixData[0] = 1
  matrixData[5] = 1
  matrixData[10] = 1
  matrixData[15] = 1

  const uniformBuffer = graphicsDevice.createBuffer(
    {
      label: 'SceneUniformsBuffer',
      size: matrixSize,
      usage: GPUBufferUsage.UNIFORM | GPUBufferUsage.COPY_DST,
    },
    matrixData
  )

  const material = graphicsDevice.createMaterial(
    { vertex: shaderModule },
  )


  const vertexBufferLayout = {
    arrayStride: 3 * 4,
    attributes: [
      { shaderLocation: 0, offset: 0, format: VertexFormat.Float32x3 }
    ]
  }

  const pipelineDescriptor = material.getRenderPipelineDescriptor({
    label: 'SquarePipeline',
    vertex: {
      buffers: [vertexBufferLayout]
    },
    fragment: {
      targets: [{ format: graphicsDevice.swapChain.format }]
    }
  })

  const pipeline = graphicsDevice.createRenderPipeline(pipelineDescriptor)

  /** @type {Array<import('./src/core/graphics-device.js').BindGroupEntry>} */
  const uniformBindings = [{
    binding: 0,
    resource: uniformBuffer
  }]

  const uniformBindGroup = graphicsDevice.createBindGroup(
    material.bindGroupLayouts[0],
    uniformBindings,
    'Uniforms'
  )

  async function frame() {
    if (!graphicsDevice.isInitialized) {
      return
    }

    graphicsDevice.queue.writeBuffer(uniformBuffer.handle, 0, matrixData)
    const commandRecorder = graphicsDevice.createCommandRecorder('FrameCommands')

    const passEncoder = commandRecorder.beginRenderPass()

    if (passEncoder) {
      passEncoder.setPipeline(pipeline.handle)
      passEncoder.setVertexBuffer(0, vertexBuffer.handle)
      passEncoder.setIndexBuffer(indexBuffer.handle, 'uint16')
      passEncoder.setBindGroup(0, uniformBindGroup.handle)
      passEncoder.drawIndexed(indices.length)

      commandRecorder.endRenderPass()
    }

    const commandBuffer = commandRecorder.finish()
    graphicsDevice.submitCommands([commandBuffer])
  }

  requestAnimationFrame(frame)

  // TODO: move to graphics device or somewhere else
  const resizeObserver = new ResizeObserver(entries => {
    for (let entry of entries) {
      const { width, height } = entry.contentRect
      if (graphicsDevice.isInitialized && width > 0 && height > 0) {
        graphicsDevice.swapChain.resize(width, height)
      }
    }
  })

  resizeObserver.observe(canvas)

  window.addEventListener('beforeunload', () => {
    resizeObserver.disconnect()
    graphicsDevice.destroy()
  })

}

if (document.readyState === 'loading') {
  document.addEventListener('DOMContentLoaded', main)
} else {
  main()
}