import type { ImageDocument } from "@core/document";
import type { EditorState } from "@editor/state";

export type RenderFrame = {
  document: ImageDocument;
  editor: EditorState;
};

export type ImageRenderer = {
  render(frame: RenderFrame): void;
  dispose(): void;
};

export type RendererBackend = "webgl";

export function createRenderer(canvas: HTMLCanvasElement, backend: RendererBackend = "webgl"): ImageRenderer {
  if (backend !== "webgl") {
    throw new Error(`Unsupported renderer backend: ${backend}`);
  }

  const context = canvas.getContext("webgl2");
  if (!context) {
    throw new Error("WebGL2 is not available");
  }

  return {
    render(frame) {
      const { w, h } = frame.editor.viewport.size;

      if (canvas.width !== w) canvas.width = w;
      if (canvas.height !== h) canvas.height = h;

      context.viewport(0, 0, w, h);
      context.clearColor(0, 0, 0, 0);
      context.clear(context.COLOR_BUFFER_BIT);
    },
    dispose() {},
  };
}