/**
 * Next.js instrumentation hook — runs once before any route handler.
 * Polyfills browser globals required by pdfjs-dist at module load time.
 * @napi-rs/canvas normally provides these but may be absent in some server
 * environments (e.g. linux/amd64 Docker image on ARM build host).
 * Text extraction never actually calls these — pdfjs needs the classes defined.
 */
export async function register() {
  if (process.env.NEXT_RUNTIME === 'nodejs') {
    if (typeof globalThis.DOMMatrix === 'undefined') {
      // @ts-expect-error minimal stub
      globalThis.DOMMatrix = class DOMMatrix { constructor() { return this; } };
    }
    if (typeof globalThis.ImageData === 'undefined') {
      // @ts-expect-error minimal stub
      globalThis.ImageData = class ImageData { constructor() { return this; } };
    }
    if (typeof globalThis.Path2D === 'undefined') {
      // @ts-expect-error minimal stub
      globalThis.Path2D = class Path2D { constructor() { return this; } };
    }
  }
}