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;

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;
}

const bytes = readFileSync(CV_PATH);
const pdfDoc = await PDFDocument.load(bytes);
const title = pdfDoc.getTitle();
const author = pdfDoc.getAuthor();
const creator = pdfDoc.getCreator();
const page = pdfDoc.getPage(0);

if (pageHasPitchLink(page)) {
  console.log('Pitch link annotation already present; leaving CV.pdf unchanged.');
  process.exit(0);
}

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 (title) {
  pdfDoc.setTitle(title);
}
if (author) {
  pdfDoc.setAuthor(author);
}
if (creator) {
  pdfDoc.setCreator(creator);
}

const saved = await pdfDoc.save({ useObjectStreams: false });
writeFileSync(CV_PATH, saved);
console.log('Added visible pitch URL and link annotation to page 1 of CV.pdf.');