// Browser-only module worker: the one place react-pdf runs in the app. Not importable from Node tests.
import { installStreamAsyncIterator } from "../../lib/streamPolyfill";
import { initBrowserRendering } from "./browserInit";
import { runAssembleJob } from "./assembleJob";
import { renderInvoicePdf } from "./invoice";
import { registerJobFonts } from "./userFontJob";
import type { WorkerMessage, WorkerRequest } from "./jobs";

interface WorkerScope {
  onmessage: ((event: MessageEvent<WorkerRequest>) => void) | null;
  postMessage(message: WorkerMessage, options?: { transfer: Transferable[] }): void;
}
const scope = self as unknown as WorkerScope;

installStreamAsyncIterator();

const post = (message: WorkerMessage, transfer: Transferable[] = []) => scope.postMessage(message, { transfer });

const failure = (id: number | null, err: unknown): WorkerMessage => ({
  type: "error",
  id,
  message: err instanceof Error ? err.message : String(err),
  stack: err instanceof Error ? err.stack : undefined,
});

// Handing a buffer over instead of copying it only works when the view covers all of it.
const whole = (b: Uint8Array) => b.byteOffset === 0 && b.byteLength === b.buffer.byteLength;

const started = initBrowserRendering();

scope.onmessage = async (event) => {
  const request = event.data;
  if (request?.type === "assemble-images") {
    const { job } = request;
    try {
      const out = await runAssembleJob(job);
      const bytes = whole(out.bytes) ? out.bytes : out.bytes.slice();
      post({ type: "assembled", result: { ...out, bytes } }, [bytes.buffer]);
    } catch (err) {
      post(failure(job.id, err));
    }
    return;
  }
  if (request?.type !== "render") return;
  const { job } = request;
  try {
    await started.catch(() => initBrowserRendering());
    await registerJobFonts(job.prefs, job.userFonts);
    const t0 = performance.now();
    const out = await renderInvoicePdf({ model: job.model, prefs: job.prefs });
    const ms = Math.round(performance.now() - t0);
    const bytes = whole(out.bytes) ? out.bytes : out.bytes.slice();
    post(
      { type: "result", result: { id: job.id, bytes, pages: out.pages, issues: out.issues, fingerprint: out.fingerprint, ms } },
      [bytes.buffer],
    );
  } catch (err) {
    post(failure(job.id, err));
  }
};

started.then(
  () => post({ type: "ready" }),
  (err) => post(failure(null, err)),
);