/// <reference no-default-lib="true" />
/// <reference lib="esnext" />
/// <reference lib="dom" />

import type {
  getDocument,
  GlobalWorkerOptions,
} from "https://raw.githubusercontent.com/takker99/deno-pdfjs-dist-types/0.1.0/mod.d.ts";

declare global {
  interface Window {
    pdfjsLib?: {
      getDocument: typeof getDocument;
      GlobalWorkerOptions: typeof GlobalWorkerOptions;
    };
  }
}

export type PDFjsLib = Required<Window>["pdfjsLib"];

const ensurePDFjsLib = (): Promise<PDFjsLib>  => new Promise<PDFjsLib>((resolve) => {
  if (window.pdfjsLib) resolve(window.pdfjsLib);
  const timer = setInterval(() => {
    if (!window.pdfjsLib) return;
    clearInterval(timer);
    resolve(window.pdfjsLib);
  }, 1000);
});

export const load = async (version: string): Promise<PDFjsLib> => {
  const src = `//cdnjs.cloudflare.com/ajax/libs/pdf.js/${version}/pdf.min.js`;
  
  if (!document.querySelector(`script[src="${src}"]`)) {
    const script = document.createElement("script");
    script.src = src;
    
    await new Promise<void>((resolve, reject) => {
      script.addEventListener("load", () => resolve());
      script.addEventListener("error", reject);
      document.body.append(script);
    });
    
    const pdfjsLib = await ensurePDFjsLib();
    pdfjsLib.GlobalWorkerOptions.workerSrc =
      `//cdnjs.cloudflare.com/ajax/libs/pdf.js/${version}/pdf.worker.min.js`;
    return pdfjsLib;
  }
    
  return await ensurePDFjsLib();
};