import {
  ClampToEdgeWrapping,
  LinearFilter,
  Material,
  RawShaderMaterial,
  RenderTargetOptions,
  SRGBColorSpace,
  ShaderMaterialParameters,
  UnsignedByteType,
  WebGLRenderTarget,
} from "three"
import { FullScreenQuad } from "three/examples/jsm/postprocessing/Pass.js"
import blitFrag from "../../shaders/postprocessing/blitFrag.glsl?raw"
import blitVert from "../../shaders/postprocessing/blitVert.glsl?raw"
import { Properties } from "../utils/properties"

/* -------------------------------------------------------------------------- */
/*                                    main                                    */
/* -------------------------------------------------------------------------- */
export class FBOHelper {
  static fsQuad: FullScreenQuad

  // prescision
  static precisionPrefix = ""

  static init() {
    // fullscreen quad used to drive every GPGPU pass
    this.fsQuad = new FullScreenQuad()

    // get precision
    this.precisionPrefix = `precision ${Properties.gl?.capabilities.precision} float;\n`
  }

  static render(material: Material, renderTarget: WebGLRenderTarget | null) {
    if (!Properties.gl || !this.fsQuad) return

    this.fsQuad.material = material

    Properties.gl.setRenderTarget(renderTarget)
    this.fsQuad.render(Properties.gl)
    Properties.gl.setRenderTarget(null)
  }

  /* ----------------------------- render targets ----------------------------- */
  static createRenderTarget(width: number, height: number, options?: RenderTargetOptions) {
    return new WebGLRenderTarget(width, height, {
      wrapS: ClampToEdgeWrapping,
      wrapT: ClampToEdgeWrapping,
      magFilter: LinearFilter,
      minFilter: LinearFilter,
      type: UnsignedByteType,
      anisotropy: 0,
      colorSpace: SRGBColorSpace,
      stencilBuffer: false,
      ...options,
    })
  }

  /* -------------------------------- materials ------------------------------- */
  static createRawShaderMaterial(
    options: ShaderMaterialParameters & { vertexShaderPrefix?: string; fragmentShaderPrefix?: string }
  ) {
    const _options = {
      vertexShader: blitVert,
      fragmentShader: blitFrag,
      ...options,
    }

    _options.vertexShader =
      (_options.vertexShaderPrefix !== undefined ? _options.vertexShaderPrefix : this.precisionPrefix) +
      _options.vertexShader

    _options.fragmentShader =
      (_options.fragmentShaderPrefix !== undefined ? _options.fragmentShaderPrefix : this.precisionPrefix) +
      _options.fragmentShader

    delete _options.vertexShaderPrefix
    delete _options.fragmentShaderPrefix

    return new RawShaderMaterial(_options)
  }
}