#!/usr/bin/env node
/**
 * Generates a labelled training set of randomized valid/damaged PDFs
 * for the pdf-damage-classifier model.
 *
 * Usage: node gen_training.js [outputDir] [variantsPerClass]
 * Output: <outputDir>/*.pdf and <outputDir>/labels.csv  (file,label)
 */
const fs = require('fs');
const path = require('path');
const { PDFDocument, rgb, StandardFonts } = require('pdf-lib');
const { scenarios, toLatin1, fromLatin1 } = require('./generate');

const IMG = 'iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAYAAABytg0kAAAAFElEQVQIW2NkwAJGDjACU2M4wAgAJu4BCHgB5hQAAAAASUVORK5CYII=';

// Small seeded PRNG so the dataset is reproducible.
function rng(seed) {
  let s = seed >>> 0;
  return () => {
    s = (s + 0x6d2b79f5) >>> 0;
    let t = s;
    t = Math.imul(t ^ (t >>> 15), t | 1);
    t ^= t + Math.imul(t ^ (t >>> 7), t | 61);
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296;
  };
}

const WORDS = 'alpha beta gamma delta report invoice summary table chart data page section total value note draft final review'.split(' ');

async function randomPdf(r) {
  const doc = await PDFDocument.create();
  const font = await doc.embedFont(r() < 0.5 ? StandardFonts.Helvetica : StandardFonts.TimesRoman);
  const pages = 1 + Math.floor(r() * 8);
  const png = r() < 0.6 ? await doc.embedPng(Buffer.from(IMG, 'base64')) : null;
  for (let p = 0; p < pages; p++) {
    const page = doc.addPage([r() < 0.8 ? 595 : 612, r() < 0.8 ? 842 : 792]);
    const lines = 1 + Math.floor(r() * 40);
    for (let i = 0; i < lines; i++) {
      const n = 3 + Math.floor(r() * 12);
      const text = Array.from({ length: n }, () => WORDS[Math.floor(r() * WORDS.length)]).join(' ');
      page.drawText(text, { x: 40, y: 800 - i * 14, size: 8 + Math.floor(r() * 5), font, color: rgb(r(), r(), r()) });
    }
    if (png && r() < 0.5) page.drawImage(png, { x: 60, y: 100, width: 40 + r() * 100, height: 40 + r() * 100 });
  }
  return doc.save({ useObjectStreams: false });
}

async function main() {
  const outDir = path.resolve(process.argv[2] || path.join(__dirname, 'training'));
  const perClass = parseInt(process.argv[3] || '200', 10);
  fs.mkdirSync(outDir, { recursive: true });
  const r = rng(42);
  const rows = ['file,label'];
  const classes = ['valid', ...scenarios.filter((s) => !s.id.startsWith('truncated')).map((s) => s.id), 'truncated'];

  for (const label of classes) {
    for (let i = 0; i < perClass; i++) {
      const base = await randomPdf(r);
      const text = toLatin1(base);
      let out;
      if (label === 'valid') out = base;
      else if (label === 'truncated') out = base.slice(0, Math.floor(base.length * (0.3 + r() * 0.6)));
      else out = scenarios.find((s) => s.id === label).apply(base, text);
      const name = `${label}_${String(i).padStart(4, '0')}.pdf`;
      fs.writeFileSync(path.join(outDir, name), out);
      rows.push(`${name},${label}`);
    }
    console.log(`${label}: ${perClass}`);
  }
  fs.writeFileSync(path.join(outDir, 'labels.csv'), rows.join('\n') + '\n');
  console.log(`labels.csv written to ${outDir}`);
}

main().catch((e) => {
  console.error(e);
  process.exit(1);
});