import fs from 'fs';
import os from 'os';
import path from 'path';
import { execFileSync } from 'child_process';

const root = process.cwd();
const sourcePdf = path.join(root, 'Patentes', 'SOLICITUD_PATENTE_OEPM_FARMAFINDER.pdf');
const outDir = path.join(root, 'Patentes');

function ensureExists(file) {
  if (!fs.existsSync(file)) {
    throw new Error(`Missing file: ${file}`);
  }
}

function run(cmd, args) {
  execFileSync(cmd, args, { stdio: 'inherit' });
}

function mergePages(output, pages) {
  const tmp = fs.mkdtempSync(path.join(os.tmpdir(), 'farmafinder-clean-'));
  run('pdfseparate', [sourcePdf, path.join(tmp, 'page-%d.pdf')]);
  const inputs = pages.map((n) => path.join(tmp, `page-${n}.pdf`));
  run('pdfunite', [...inputs, output]);
}

function esc(s) {
  return String(s).replace(/\\/g, '\\\\').replace(/\(/g, '\\(').replace(/\)/g, '\\)');
}

function latin1(s) {
  return Buffer.from(s, 'latin1').toString('latin1');
}

function wrapText(text, widthChars) {
  const words = String(text).split(/\s+/);
  const lines = [];
  let line = '';
  for (const word of words) {
    const candidate = line ? `${line} ${word}` : word;
    if (candidate.length > widthChars && line) {
      lines.push(line);
      line = word;
    } else {
      line = candidate;
    }
  }
  if (line) lines.push(line);
  return lines;
}

function writeDrawingsPdf(output) {
  const PAGE_W = 595.28;
  const PAGE_H = 841.89;
  const MARGIN_L = 56;
  const MARGIN_R = 56;
  const MARGIN_T = 56;
  const MARGIN_B = 54;
  const CONTENT_W = PAGE_W - MARGIN_L - MARGIN_R;

  const lines = [
    { type: 'title', text: 'Dibujos' },
    { type: 'subtitle', text: 'Bloque limpio para la presentación de la solicitud' },
    { type: 'spacer', lines: 1 },
    { type: 'heading', text: 'Breve descripción de los dibujos' },
    { type: 'paragraph', text: 'Figura 1. Diagrama de bloques general del sistema.' },
    { type: 'paragraph', text: 'Figura 2. Flujo de captura y validación del escaneo de la TSI.' },
    { type: 'paragraph', text: 'Figura 3. Flujo de contraste entre necesidad terapéutica y stock de farmacias.' },
    { type: 'paragraph', text: 'Figura 4. Flujo de acción cuando no existe stock disponible.' },
    { type: 'spacer', lines: 1 },
    { type: 'heading', text: 'Nota' },
    { type: 'paragraph', text: 'El documento fuente contiene referencias esquemáticas a las figuras, pero no incluye láminas técnicas dibujadas de forma separada. Si la Oficina requiere placas gráficas, habrá que añadirlas antes de la presentación definitiva.' },
  ];

  const objects = [''];
  const add = (body) => {
    objects.push(body);
    return objects.length - 1;
  };
  const fontReg = add('<< /Type /Font /Subtype /Type1 /BaseFont /Times-Roman /Encoding /WinAnsiEncoding >>');
  const fontBold = add('<< /Type /Font /Subtype /Type1 /BaseFont /Times-Bold /Encoding /WinAnsiEncoding >>');
  const fontIt = add('<< /Type /Font /Subtype /Type1 /BaseFont /Times-Italic /Encoding /WinAnsiEncoding >>');
  const pagesTree = add('');

  const ops = [];
  let y = PAGE_H - MARGIN_T;
  const write = (txt, x, size, font = 'F1') => {
    ops.push(`BT /${font} ${size} Tf ${x} ${y} Td (${esc(latin1(txt))}) Tj ET`);
    y -= size * 1.25;
  };
  const ensure = (needed) => y - needed > MARGIN_B;
  for (const item of lines) {
    if (item.type === 'title') {
      for (const line of wrapText(item.text, 26)) write(line, MARGIN_L + 175, 18, 'F2');
      continue;
    }
    if (item.type === 'subtitle') {
      for (const line of wrapText(item.text, 40)) write(line, MARGIN_L + 45, 11.5, 'F3');
      y -= 6;
      continue;
    }
    if (item.type === 'spacer') {
      y -= (item.lines || 1) * 12;
      continue;
    }
    if (item.type === 'heading') {
      if (!ensure(20)) break;
      write(item.text, MARGIN_L, 13, 'F2');
      y -= 2;
      ops.push(`0.3 w ${MARGIN_L} ${y} m ${PAGE_W - MARGIN_R} ${y} l S`);
      y -= 8;
      continue;
    }
    if (item.type === 'paragraph') {
      const wrapped = wrapText(item.text, 80);
      if (!ensure(wrapped.length * 14 + 6)) break;
      for (const line of wrapped) write(line, MARGIN_L, 11.5, 'F1');
      y -= 2;
    }
  }
  ops.push(`BT /F1 9 Tf ${PAGE_W - 100} ${24} Td (Page 1) Tj ET`);
  const content = ops.join('\n');
  const contentObj = add(`<< /Length ${Buffer.byteLength(content, 'latin1')} >>\nstream\n${content}\nendstream`);
  const pageObj = add(`<< /Type /Page /Parent ${pagesTree} 0 R /MediaBox [0 0 ${PAGE_W} ${PAGE_H}] /Resources << /Font << /F1 ${fontReg} 0 R /F2 ${fontBold} 0 R /F3 ${fontIt} 0 R >> >> /Contents ${contentObj} 0 R >>`);
  objects[pagesTree] = `<< /Type /Pages /Kids [${pageObj} 0 R] /Count 1 >>`;
  const catalog = add(`<< /Type /Catalog /Pages ${pagesTree} 0 R >>`);

  let pdf = '%PDF-1.4\n';
  const offsets = [0];
  for (let i = 1; i < objects.length; i += 1) {
    offsets[i] = Buffer.byteLength(pdf, 'latin1');
    pdf += `${i} 0 obj\n${objects[i]}\nendobj\n`;
  }
  const xref = Buffer.byteLength(pdf, 'latin1');
  pdf += `xref\n0 ${objects.length}\n`;
  pdf += '0000000000 65535 f \n';
  for (let i = 1; i < objects.length; i += 1) {
    pdf += `${String(offsets[i]).padStart(10, '0')} 00000 n \n`;
  }
  pdf += `trailer << /Size ${objects.length} /Root ${catalog} 0 R >>\nstartxref\n${xref}\n%%EOF\n`;
  fs.writeFileSync(output, Buffer.from(pdf, 'latin1'));
}

ensureExists(sourcePdf);
mergePages(path.join(outDir, 'SOLICITUD_PATENTE_OEPM_FARMAFINDER_descripcion_limpia.pdf'), [2, 3, 4]);
mergePages(path.join(outDir, 'SOLICITUD_PATENTE_OEPM_FARMAFINDER_reivindicaciones_limpia.pdf'), [5]);
mergePages(path.join(outDir, 'SOLICITUD_PATENTE_OEPM_FARMAFINDER_resumen_limpia.pdf'), [6]);
writeDrawingsPdf(path.join(outDir, 'SOLICITUD_PATENTE_OEPM_FARMAFINDER_dibujos_limpia.pdf'));

console.log('Clean section PDFs generated.');