Pien-Studio/apps/web/lib/effects/registry.ts

import type { LayerEffect } from "@pien-studio/types";
import type { EffectRenderer, EffectRenderContext } from "./types";
import { faceBlurRenderer } from "./face-blur";

const renderers: EffectRenderer[] = [faceBlurRenderer];

const effectRendererRegistry = new Map<string, EffectRenderer>(
  renderers.map((r) => [r.kind, r]),
);

export function getEffectRenderer(kind: string): EffectRenderer | undefined {
  return effectRendererRegistry.get(kind);
}

/** Draws a layer image applying all its effects in order. */
export function renderLayerWithEffects(
  ctx: CanvasRenderingContext2D,
  image: HTMLImageElement,
  effects: LayerEffect[],
  targetWidth: number,
  targetHeight: number,
): void {
  const activeEffects = effects.filter((e) => {
    if (e.enabled === false) return false;
    return effectRendererRegistry.get(e.kind) !== undefined;
  });

  if (activeEffects.length === 0) {
    ctx.drawImage(image, 0, 0, targetWidth, targetHeight);
    return;
  }

  const context: EffectRenderContext = { ctx, image, targetWidth, targetHeight };

  // The first effect owns the full layer render (draws base image + applies itself)
  const first = activeEffects[0];
  const firstRenderer = effectRendererRegistry.get(first.kind);
  firstRenderer?.renderLayer(context, first);

  // Subsequent effects render on top (overlay only, no re-draw of base)
  for (let i = 1; i < activeEffects.length; i++) {
    const effect = activeEffects[i];
    const renderer = effectRendererRegistry.get(effect.kind);
    renderer?.render(context, effect);
  }
}