feat(brandkit): permitir subir PDF y DOCX como fuentes
Extrae texto del PDF/DOCX en Fuentes del kit de marca para no depender de pegar el contenido a mano. Co-authored-by: Cursor <cursoragent@cursor.com>
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4Ventures
270
src/lib/extract-document-text.ts
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270
src/lib/extract-document-text.ts
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/**
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* Extract plain text from brandbook source uploads (txt/md/csv/json/pdf/docx).
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* No heavy native deps — PDF via FlateDecode streams; DOCX via zip + document.xml.
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*/
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import { inflateRawSync, inflateSync } from 'zlib';
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const MAX_CHARS = 200_000;
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function decodePdfStringLiteral(raw: string): string {
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// PDF literal strings: \( \) \\ \n \r \t \b \f \ddd octal
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let out = '';
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for (let i = 0; i < raw.length; i++) {
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const c = raw[i];
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if (c !== '\\') {
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out += c;
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continue;
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}
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const n = raw[i + 1];
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if (n === 'n') {
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out += '\n';
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i++;
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} else if (n === 'r') {
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out += '\r';
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i++;
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} else if (n === 't') {
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out += '\t';
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i++;
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} else if (n === 'b' || n === 'f') {
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i++;
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} else if (n === '(' || n === ')' || n === '\\') {
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out += n;
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i++;
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} else if (n && /[0-7]/.test(n)) {
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let oct = n;
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i++;
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if (raw[i + 1] && /[0-7]/.test(raw[i + 1])) {
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oct += raw[i + 1];
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i++;
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}
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if (raw[i + 1] && /[0-7]/.test(raw[i + 1])) {
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oct += raw[i + 1];
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i++;
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}
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out += String.fromCharCode(parseInt(oct, 8));
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} else if (n) {
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out += n;
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i++;
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}
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}
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return out;
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}
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function decodePdfHexString(hex: string): string {
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const clean = hex.replace(/[^0-9a-fA-F]/g, '');
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let out = '';
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for (let i = 0; i + 1 < clean.length; i += 2) {
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const code = parseInt(clean.slice(i, i + 2), 16);
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if (code >= 32 && code !== 127) out += String.fromCharCode(code);
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else if (code === 10 || code === 13) out += '\n';
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}
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return out;
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}
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function extractTextFromPdfContent(content: string): string {
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const parts: string[] = [];
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// Tj / ' / " operators with literal or hex strings
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const re =
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/(\((?:\\.|[^\\)])*\))\s*Tj|(\((?:\\.|[^\\)])*\))\s*'|\[((?:[^\[\]]|\[[^\]]*\])*)\]\s*TJ|<([0-9A-Fa-f\s]+)>\s*Tj/g;
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let m: RegExpExecArray | null;
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while ((m = re.exec(content))) {
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if (m[1] || m[2]) {
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const lit = (m[1] || m[2]).slice(1, -1);
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parts.push(decodePdfStringLiteral(lit));
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} else if (m[3]) {
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const arr = m[3];
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const inner = /\((?:\\.|[^\\)])*\)|<([0-9A-Fa-f\s]+)>/g;
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let im: RegExpExecArray | null;
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while ((im = inner.exec(arr))) {
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if (im[0].startsWith('(')) {
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parts.push(decodePdfStringLiteral(im[0].slice(1, -1)));
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} else if (im[1]) {
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parts.push(decodePdfHexString(im[1]));
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}
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}
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parts.push(' ');
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} else if (m[4]) {
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parts.push(decodePdfHexString(m[4]));
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}
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}
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return parts.join('');
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}
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function inflatePdfStream(data: Buffer): Buffer | null {
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try {
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return inflateSync(data);
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} catch {
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try {
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return inflateRawSync(data);
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} catch {
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return null;
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}
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}
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}
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/** Best-effort text extraction from PDF bytes. */
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export function extractTextFromPdf(buffer: Buffer): string {
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const latin = buffer.toString('latin1');
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const chunks: string[] = [];
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// Stream objects: ... stream\nDATA\nendstream
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const streamRe = /stream\r?\n([\s\S]*?)endstream/g;
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let sm: RegExpExecArray | null;
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while ((sm = streamRe.exec(latin))) {
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const before = latin.slice(Math.max(0, sm.index - 400), sm.index);
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const isFlate = /\/Filter\s*\/FlateDecode|\/Filter\s*\[\s*\/FlateDecode/i.test(
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before
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);
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const raw = Buffer.from(sm[1], 'latin1');
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// Trim possible trailing \r\n that belongs to endstream delimiter
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let payload = raw;
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if (payload.length >= 2 && payload[payload.length - 2] === 0x0d) {
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payload = payload.subarray(0, payload.length - 2);
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} else if (payload.length >= 1 && payload[payload.length - 1] === 0x0a) {
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payload = payload.subarray(0, payload.length - 1);
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}
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let content = '';
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if (isFlate) {
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const inflated = inflatePdfStream(payload);
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if (!inflated) continue;
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content = inflated.toString('latin1');
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} else {
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content = payload.toString('latin1');
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}
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const text = extractTextFromPdfContent(content);
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if (text.trim()) chunks.push(text);
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}
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// Also scan uncompressed page content outside streams (rare)
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const direct = extractTextFromPdfContent(latin);
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if (direct.trim().length > 40) chunks.push(direct);
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const joined = chunks
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.join('\n')
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.replace(/\r/g, '\n')
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.replace(/[ \t]+\n/g, '\n')
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.replace(/\n{3,}/g, '\n\n')
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.replace(/[^\S\n]{2,}/g, ' ')
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.trim();
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return joined.slice(0, MAX_CHARS);
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}
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/** Minimal ZIP local-file reader (enough for DOCX document.xml). */
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function zipReadFile(buffer: Buffer, pathInZip: string): Buffer | null {
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let offset = 0;
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while (offset + 30 <= buffer.length) {
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if (buffer.readUInt32LE(offset) !== 0x04034b50) break;
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const method = buffer.readUInt16LE(offset + 8);
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const compSize = buffer.readUInt32LE(offset + 18);
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const nameLen = buffer.readUInt16LE(offset + 26);
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const extraLen = buffer.readUInt16LE(offset + 28);
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const name = buffer
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.subarray(offset + 30, offset + 30 + nameLen)
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.toString('utf8');
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const dataStart = offset + 30 + nameLen + extraLen;
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const data = buffer.subarray(dataStart, dataStart + compSize);
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offset = dataStart + compSize;
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if (name !== pathInZip) continue;
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if (method === 0) return Buffer.from(data);
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if (method === 8) {
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try {
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return inflateRawSync(data);
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} catch {
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return null;
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}
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}
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return null;
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}
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return null;
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}
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export function extractTextFromDocx(buffer: Buffer): string {
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const xml = zipReadFile(buffer, 'word/document.xml');
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if (!xml) {
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throw new Error(
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'No se pudo leer el DOCX (¿archivo corrupto o protegido?). Prueba a pegar el texto.'
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);
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}
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const raw = xml.toString('utf8');
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const text = raw
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.replace(/<w:tab\/>/g, '\t')
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.replace(/<w:br\/>/g, '\n')
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.replace(/<\/w:p>/g, '\n\n')
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.replace(/<[^>]+>/g, '')
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.replace(/&/g, '&')
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.replace(/</g, '<')
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.replace(/>/g, '>')
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.replace(/"/g, '"')
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.replace(/&#(\d+);/g, (_, n) => String.fromCharCode(Number(n)))
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.replace(/[ \t]+\n/g, '\n')
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.replace(/\n{3,}/g, '\n\n')
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.trim();
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return text.slice(0, MAX_CHARS);
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}
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export type ExtractableExt = 'txt' | 'md' | 'csv' | 'json' | 'pdf' | 'docx';
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export function detectSourceExt(filename: string, mime?: string): ExtractableExt | null {
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const lower = filename.toLowerCase();
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if (lower.endsWith('.pdf') || mime === 'application/pdf') return 'pdf';
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if (
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lower.endsWith('.docx') ||
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mime ===
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'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
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)
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return 'docx';
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if (lower.endsWith('.txt') || mime === 'text/plain') return 'txt';
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if (lower.endsWith('.md') || mime === 'text/markdown') return 'md';
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if (lower.endsWith('.csv') || mime === 'text/csv') return 'csv';
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if (lower.endsWith('.json') || mime === 'application/json') return 'json';
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return null;
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}
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export async function extractSourceText(opts: {
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filename: string;
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mime?: string;
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buffer?: Buffer;
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textFallback?: string;
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}): Promise<{ text: string; filename: string }> {
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const ext = detectSourceExt(opts.filename, opts.mime);
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const filename = opts.filename || `fuente.${ext || 'txt'}`;
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if (!ext || ext === 'txt' || ext === 'md' || ext === 'csv' || ext === 'json') {
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if (opts.textFallback != null) {
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return { text: opts.textFallback.slice(0, MAX_CHARS), filename };
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}
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if (opts.buffer) {
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return {
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text: opts.buffer.toString('utf8').slice(0, MAX_CHARS),
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filename,
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};
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}
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throw new Error('Sin texto');
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}
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if (!opts.buffer) throw new Error('Falta el archivo');
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if (ext === 'pdf') {
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const text = extractTextFromPdf(opts.buffer);
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if (!text.trim() || text.trim().length < 20) {
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throw new Error(
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'No se pudo extraer texto del PDF (puede ser escaneado o protegido). Copia el texto y pégalo en el campo.'
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);
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}
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return { text, filename };
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}
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if (ext === 'docx') {
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const text = extractTextFromDocx(opts.buffer);
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if (!text.trim()) {
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throw new Error(
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'El DOCX no contiene texto legible. Copia el contenido y pégalo en el campo.'
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);
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}
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return { text, filename };
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}
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throw new Error('Formato no soportado');
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}
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