// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import type {FramebufferProps} from '@luma.gl/core';
import {Framebuffer} from '@luma.gl/core';
import {GL} from '@luma.gl/webgl/constants';
import {WebGLDevice} from '../webgl-device';
import {WEBGLTexture} from './webgl-texture';
import {WEBGLTextureView} from './webgl-texture-view';
import {getDepthStencilAttachmentWebGL} from '../converters/webgl-texture-table';

export type Attachment = WEBGLTextureView | WEBGLTexture; // | WEBGLRenderbuffer;

/** luma.gl Framebuffer, WebGL implementation  */
export class WEBGLFramebuffer extends Framebuffer {
  readonly device: WebGLDevice;
  gl: WebGL2RenderingContext;
  readonly handle: WebGLFramebuffer;

  colorAttachments: WEBGLTextureView[] = [];
  depthStencilAttachment: WEBGLTextureView | null = null;

  constructor(device: WebGLDevice, props: FramebufferProps) {
    super(device, props);

    // WebGL default framebuffer handle is null
    const isDefaultFramebuffer = props.handle === null;

    this.device = device;
    this.gl = device.gl;
    this.handle =
      this.props.handle || isDefaultFramebuffer ? this.props.handle : this.gl.createFramebuffer();

    if (!isDefaultFramebuffer) {
      // default framebuffer handle is null, so we can't set debug metadata...
      device._setWebGLDebugMetadata(this.handle, this, {spector: this.props});

      // Auto create textures for attachments if needed
      this.autoCreateAttachmentTextures();

      this.updateAttachments();
    }
  }

  /** destroys any auto created resources etc. */
  override destroy(): void {
    super.destroy(); // destroys owned resources etc.
    if (!this.destroyed && this.handle !== null) {
      this.gl.deleteFramebuffer(this.handle);
      // this.handle = null;
    }
  }

  protected updateAttachments(): void {
    /** Attach from a map of attachments */
    // @ts-expect-error native bindFramebuffer is overridden by our state tracker
    const prevHandle: WebGLFramebuffer | null = this.gl.bindFramebuffer(
      GL.FRAMEBUFFER,
      this.handle
    );

    // Walk the attachments
    for (let i = 0; i < this.colorAttachments.length; ++i) {
      const attachment = this.colorAttachments[i];
      if (attachment) {
        const attachmentPoint = GL.COLOR_ATTACHMENT0 + i;
        this._attachTextureView(attachmentPoint, attachment);
      }
    }

    if (this.depthStencilAttachment) {
      const attachmentPoint = getDepthStencilAttachmentWebGL(
        this.depthStencilAttachment.props.format
      );
      this._attachTextureView(attachmentPoint, this.depthStencilAttachment);
    }

    /** Check the status */
    if (this.device.props.debug) {
      const status = this.gl.checkFramebufferStatus(GL.FRAMEBUFFER) as GL;
      if (status !== GL.FRAMEBUFFER_COMPLETE) {
        throw new Error(`Framebuffer ${_getFrameBufferStatus(status)}`);
      }
    }

    this.gl.bindFramebuffer(GL.FRAMEBUFFER, prevHandle);
  }

  // PRIVATE

  /** In WebGL we must use renderbuffers for depth/stencil attachments (unless we have extensions) */
  // protected override createDepthStencilTexture(format: TextureFormat): Texture {
  //   // return new WEBGLRenderbuffer(this.device, {
  //   return new WEBGLTexture(this.device, {
  //     id: `${this.id}-depth-stencil`,
  //     format,
  //     width: this.width,
  //     height: this.height,
  //     mipmaps: false
  //   });
  // }

  /**
   * @param attachment
   * @param texture
   * @param layer = 0 - index into WEBGLTextureArray and Texture3D or face for `TextureCubeMap`
   * @param level = 0 - mipmapLevel
   */
  protected _attachTextureView(attachment: GL, textureView: WEBGLTextureView): void {
    const {gl} = this.device;
    const {texture} = textureView;
    const level = textureView.props.baseMipLevel;
    const layer = textureView.props.baseArrayLayer;

    gl.bindTexture(texture.glTarget, texture.handle);

    switch (texture.glTarget) {
      case GL.TEXTURE_2D_ARRAY:
      case GL.TEXTURE_3D:
        gl.framebufferTextureLayer(GL.FRAMEBUFFER, attachment, texture.handle, level, layer);
        break;

      case GL.TEXTURE_CUBE_MAP:
        // layer must be a cubemap face (or if index, converted to cube map face)
        const face = mapIndexToCubeMapFace(layer);
        gl.framebufferTexture2D(GL.FRAMEBUFFER, attachment, face, texture.handle, level);
        break;

      case GL.TEXTURE_2D:
        gl.framebufferTexture2D(GL.FRAMEBUFFER, attachment, GL.TEXTURE_2D, texture.handle, level);
        break;

      default:
        throw new Error('Illegal texture type');
    }

    gl.bindTexture(texture.glTarget, null);
  }

  /** Default framebuffer resize is managed by canvas size and should be a no-op. */
  protected override resizeAttachments(width: number, height: number): void {
    if (this.handle === null) {
      this.width = width;
      this.height = height;
      return;
    }

    super.resizeAttachments(width, height);
  }
}

// Helper functions

// Map an index to a cube map face constant
function mapIndexToCubeMapFace(layer: number | GL): GL {
  // TEXTURE_CUBE_MAP_POSITIVE_X is a big value (0x8515)
  // if smaller assume layer is index, otherwise assume it is already a cube map face constant
  return layer < (GL.TEXTURE_CUBE_MAP_POSITIVE_X as number)
    ? layer + GL.TEXTURE_CUBE_MAP_POSITIVE_X
    : layer;
}

// Helper METHODS
// Get a string describing the framebuffer error if installed
function _getFrameBufferStatus(status: GL) {
  switch (status) {
    case GL.FRAMEBUFFER_COMPLETE:
      return 'success';
    case GL.FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
      return 'Mismatched attachments';
    case GL.FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
      return 'No attachments';
    case GL.FRAMEBUFFER_INCOMPLETE_DIMENSIONS:
      return 'Height/width mismatch';
    case GL.FRAMEBUFFER_UNSUPPORTED:
      return 'Unsupported or split attachments';
    // WebGL2
    case GL.FRAMEBUFFER_INCOMPLETE_MULTISAMPLE:
      return 'Samples mismatch';
    // OVR_multiview2 extension
    // case GL.FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR: return 'baseViewIndex mismatch';
    default:
      return `${status}`;
  }
}

/**
 * Attachment resize is expected to be a noop if size is same
 *
protected override resizeAttachments(width: number, height: number): this {
  // for default framebuffer, just update the stored size
  if (this.handle === null) {
    // assert(width === undefined && height === undefined);
    this.width = this.gl.drawingBufferWidth;
    this.height = this.gl.drawingBufferHeight;
    return this;
  }

  if (width === undefined) {
    width = this.gl.drawingBufferWidth;
  }
  if (height === undefined) {
    height = this.gl.drawingBufferHeight;
  }

  // TODO Not clear that this is better than default destroy/create implementation

  for (const colorAttachment of this.colorAttachments) {
    colorAttachment.texture.clone({width, height});
  }
  if (this.depthStencilAttachment) {
    this.depthStencilAttachment.texture.resize({width, height});
  }
  return this;
}
*/