import { readFileSync, writeFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';
import { PDFDocument, PDFName, PDFString, rgb, StandardFonts } from 'pdf-lib';

const ROOT = join(dirname(fileURLToPath(import.meta.url)), '..');
const CV_PATH = join(ROOT, 'CV.pdf');
const PITCH_URI = 'https://antoniolede.de/pitch';
const VISIBLE_TEXT = 'antoniolede.de/pitch';
const TEXT_X = 59.6;
const TEXT_Y = 215.4;
const FONT_SIZE = 10.5;
const PADDING = 2;
const ORIGINAL_TITLE = 'CV';
const ORIGINAL_CREATOR = 'Pages';
// Producer from the unmodified Pages/Quartz export of CV.pdf.
const ORIGINAL_PRODUCER = 'macOS Version 26.5.2 (Build 25F84) Quartz PDFContext';

function asString(value) {
  if (!value) {
    return '';
  }

  if (typeof value.decodeText === 'function') {
    return value.decodeText();
  }

  return String(value);
}

function annotationUri(annotation) {
  const action = annotation.lookup(PDFName.of('A'));
  if (!action || typeof action.lookup !== 'function') {
    return '';
  }

  const uri = action.lookup(PDFName.of('URI'));
  return asString(uri);
}

function pageHasPitchLink(page) {
  const annots = page.node.lookup(PDFName.of('Annots'));
  if (!annots || typeof annots.size !== 'function') {
    return false;
  }

  for (let index = 0; index < annots.size(); index += 1) {
    const annotation = annots.lookup(index);
    if (annotationUri(annotation) === PITCH_URI) {
      return true;
    }
  }

  return false;
}

function hasOriginalMetadata(pdfDoc) {
  return (
    pdfDoc.getTitle() === ORIGINAL_TITLE &&
    pdfDoc.getCreator() === ORIGINAL_CREATOR &&
    pdfDoc.getProducer() === ORIGINAL_PRODUCER
  );
}

const bytes = readFileSync(CV_PATH);
const pdfDoc = await PDFDocument.load(bytes, { updateMetadata: false });
const page = pdfDoc.getPage(0);
const needsLink = !pageHasPitchLink(page);
const needsMetadata = !hasOriginalMetadata(pdfDoc);

if (!needsLink && !needsMetadata) {
  console.log('Pitch link and original metadata already present; leaving CV.pdf unchanged.');
  process.exit(0);
}

if (needsLink) {
  const font = await pdfDoc.embedFont(StandardFonts.Helvetica);
  const textWidth = font.widthOfTextAtSize(VISIBLE_TEXT, FONT_SIZE);

  page.drawText(VISIBLE_TEXT, {
    x: TEXT_X,
    y: TEXT_Y,
    size: FONT_SIZE,
    font,
    color: rgb(54 / 255, 125 / 255, 162 / 255),
  });

  const link = pdfDoc.context.register(
    pdfDoc.context.obj({
      Type: 'Annot',
      Subtype: 'Link',
      Rect: [
        TEXT_X - PADDING,
        TEXT_Y - PADDING,
        TEXT_X + textWidth + PADDING,
        TEXT_Y + FONT_SIZE + PADDING,
      ],
      Border: [0, 0, 0],
      A: {
        S: 'URI',
        URI: PDFString.of(PITCH_URI),
      },
    }),
  );
  page.node.addAnnot(link);
}

if (needsMetadata) {
  pdfDoc.setTitle(ORIGINAL_TITLE);
  pdfDoc.setCreator(ORIGINAL_CREATOR);
  pdfDoc.setProducer(ORIGINAL_PRODUCER);
}

const saved = await pdfDoc.save({ useObjectStreams: false });
writeFileSync(CV_PATH, saved);

if (needsLink && needsMetadata) {
  console.log('Added the pitch link and restored the original CV.pdf metadata.');
} else if (needsLink) {
  console.log('Added visible pitch URL and link annotation to page 1 of CV.pdf.');
} else {
  console.log('Restored the original Title, Creator and Producer on CV.pdf.');
}