import * as pdfjs from 'pdfjs-dist/legacy/build/pdf.mjs';

interface ExtractOptions {
  pages?: number[];
  maxSize?: number;
  quality?: number;
  fit?: 'inside' | 'outside';
}

async function extractImages(pdfBuffer: Buffer, options: ExtractOptions) {
  const loadingTask = pdfjs.getDocument({
    data: new Uint8Array(pdfBuffer),
    cMapUrl: '/opt/nodejs/node_modules/pdfjs-dist/cmaps/',
    cMapPacked: true,
    standardFontDataUrl: '/opt/nodejs/node_modules/pdfjs-dist/standard_fonts/',
    // enableHWA: true,
    // verbosity: pdfjs.VerbosityLevel.INFOS,
  });
  const pdfDocument = await loadingTask.promise;

  // if no pages are specified, use [0, ..., numPages - 1]
  const pages = options?.pages || new Array(pdfDocument.numPages).fill(0).map((_, i) => i + 1);

  const images: Buffer[] = [];

  for (const index of pages) {
    console.log('Rendering page', index, 'of', pages[pages.length - 1], '...');

    const page = await pdfDocument.getPage(index);

    // calculate viewport scale based on max dimension
    const maxDimension = options?.maxSize || 4096;
    const initialViewport = page.getViewport({ scale: 1.0 });
    if (!initialViewport.width || !initialViewport.height) {
      throw new Error('Invalid viewport dimensions');
    }

    const scale = (options?.fit === 'outside' ? Math.max : Math.min)(
      maxDimension / initialViewport.width,
      maxDimension / initialViewport.height,
    );
    const viewport = page.getViewport({ scale });

    // render page
    const canvasAndContext = (pdfDocument.canvasFactory as any).create(viewport.width, viewport.height);
    const renderTask = page.render({
      canvas: canvasAndContext.canvas,
      canvasContext: canvasAndContext.context,
      viewport: viewport,
      intent: 'print',
    });
    await renderTask.promise;
    page.cleanup();

    // retrieve image
    const image = canvasAndContext.canvas.toBuffer('image/jpeg', {
      quality: (options?.quality || 80) / 100,
    });

    images.push(image);
  }

  void pdfDocument.cleanup();
  return images;
}