/**
 * Clipboard module — copy canvas to system clipboard and paste images from it.
 *
 * Copy approach: snapshot the already-rendered canvas, then crop the visible
 * selection region in screen space. This preserves crop/flip/rotation/group
 * transforms exactly as the user sees them.
 */

import type { Viewport } from 'pixi-viewport';
import type { Application } from 'pixi.js';
import type { SceneManager, SceneItem } from './SceneManager';
import { uploadImage } from '../api';
import {
  renderCanvasSnapshot,
  renderNativeImageSelection,
  supportsNativeImageExport,
} from './snapshotRenderer';

/**
 * Write selected items (or full viewport) to system clipboard as PNG.
 * Selected items are rendered at their native size, not affected by zoom.
 */
export async function writeCanvasToClipboard(
  app: Application | null,
  viewport: Viewport | null,
  items?: SceneItem[],
): Promise<void> {
  if (!viewport) throw new Error('Viewport not available');
  if (!app) throw new Error('Renderer not available');

  let outputCanvas: HTMLCanvasElement;

  if (items && items.length > 0) {
    if (supportsNativeImageExport(items)) {
      outputCanvas = await renderNativeImageSelection(items, { background: null, paddingPx: 10 });
    } else {
      outputCanvas = renderCanvasSnapshot(app, viewport, items, { background: null, paddingPx: 12 });
    }
  } else {
    outputCanvas = renderCanvasSnapshot(app, viewport, undefined, { background: null });
  }

  const blob = await new Promise<Blob>((resolve, reject) => {
    outputCanvas.toBlob((b) => {
      if (b) resolve(b);
      else reject(new Error('toBlob returned null'));
    }, 'image/png');
  });

  await navigator.clipboard.write([
    new ClipboardItem({ 'image/png': blob }),
  ]);
}

/**
 * Paste an image from the system clipboard into the scene.
 * Reads the clipboard, uploads the first image found, and adds it at the viewport center.
 */
export async function pasteFromSystemClipboard(
  scene: SceneManager,
  viewport: Viewport,
  boardId: string,
  onChange: () => void,
): Promise<string> {
  const clipItems = await navigator.clipboard.read();
  for (const clipItem of clipItems) {
    for (const type of clipItem.types) {
      if (!type.startsWith('image/')) continue;
      const blob = await clipItem.getType(type);
      const file = new File([blob], `paste.${type.split('/')[1]}`, { type });
      const res = await uploadImage(boardId, file);
      const imgData = res.data.image || res.data;
      const assetKey = imgData.asset_key;
      const w = imgData.width || 400;
      const h = imgData.height || 300;
      // Display at native size — let user resize manually if needed
      const fw = w;
      const fh = h;
      if (assetKey) {
        const center = viewport.center;
        scene.addImageFromUpload(assetKey, fw, fh, center.x - fw / 2, center.y - fh / 2);
        onChange();
        return 'Pasted image';
      }
    }
  }
  return 'No image in clipboard';
}