96 lines
3.9 KiB
TypeScript
96 lines
3.9 KiB
TypeScript
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import { execFile } from 'node:child_process';
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import { existsSync } from 'node:fs';
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import { mkdtemp, readFile, rm, writeFile } from 'node:fs/promises';
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import { tmpdir } from 'node:os';
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import { join } from 'node:path';
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import { pathToFileURL } from 'node:url';
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import { Injectable, Logger, ServiceUnavailableException } from '@nestjs/common';
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import { AppConfigService } from '../config/app-config.service.js';
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/** Dónde suele estar Chrome o Chromium (macOS, Linux y Windows). */
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const CANDIDATES = [
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'/Applications/Google Chrome.app/Contents/MacOS/Google Chrome',
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'/Applications/Chromium.app/Contents/MacOS/Chromium',
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'/usr/bin/google-chrome',
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'/usr/bin/google-chrome-stable',
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'/usr/bin/chromium',
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'/usr/bin/chromium-browser',
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'/snap/bin/chromium',
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'C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe',
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'C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe',
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];
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/**
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* Convierte el HTML de un reporte en PDF con Chrome sin pantalla (`--print-to-pdf`): el mismo motor que imprime el navegador,
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* pero con el tamaño de papel y los márgenes de la plantilla (`@page`) fijos, sin depender del cuadro de impresión de cada
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* usuario. No descarga nada: usa el Chrome o Chromium instalado (`CHROME_BIN`). Cola propia (`HTML_PDF_MAX_CONCURRENCY`).
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*/
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@Injectable()
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export class HtmlPdfService {
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private readonly logger = new Logger(HtmlPdfService.name);
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private active = 0;
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private readonly waiting: (() => void)[] = [];
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constructor(private readonly config: AppConfigService) {}
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/** Ruta de Chrome: la de `CHROME_BIN` o la primera instalada que se encuentre. */
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chrome(): string | null {
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const wanted = this.config.get('CHROME_BIN');
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if (wanted) return existsSync(wanted) ? wanted : null;
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return CANDIDATES.find((c) => existsSync(c)) ?? null;
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}
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private async turn<T>(work: () => Promise<T>): Promise<T> {
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if (this.active >= this.config.get('HTML_PDF_MAX_CONCURRENCY')) await new Promise<void>((go) => this.waiting.push(go));
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this.active++;
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try {
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return await work();
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} finally {
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this.active--;
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this.waiting.shift()?.();
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}
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}
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/** Ejecuta Chrome (separado para poder simularlo en las pruebas). */
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protected run(bin: string, args: string[], timeoutMs: number): Promise<void> {
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return new Promise((done, fail) => {
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execFile(bin, args, { timeout: timeoutMs, maxBuffer: 1024 * 1024 }, (err, _stdout, stderr) => {
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if (err) fail(new Error(`Chrome no pudo generar el PDF: ${(stderr || err.message).toString().slice(0, 300)}`));
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else done();
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});
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});
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}
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async toPdf(html: string): Promise<Buffer> {
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const bin = this.chrome();
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if (!bin) throw new ServiceUnavailableException('No hay Chrome o Chromium instalado para generar el PDF (indique su ruta en CHROME_BIN)');
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return this.turn(async () => {
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const dir = await mkdtemp(join(tmpdir(), 'reporte-'));
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try {
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const input = join(dir, 'reporte.html');
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const output = join(dir, 'reporte.pdf');
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await writeFile(input, html, 'utf8');
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const args = [
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'--headless=new',
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'--disable-gpu',
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'--no-pdf-header-footer',
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'--disable-dev-shm-usage',
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`--user-data-dir=${join(dir, 'perfil')}`,
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// como administrador (contenedores) Chrome exige desactivar su sandbox
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...(process.getuid?.() === 0 ? ['--no-sandbox'] : []),
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`--print-to-pdf=${output}`,
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pathToFileURL(input).href,
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];
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await this.run(bin, args, this.config.get('HTML_PDF_TIMEOUT') * 1000);
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const pdf = await readFile(output);
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if (pdf.subarray(0, 4).toString('latin1') !== '%PDF') throw new Error('Chrome no devolvió un PDF');
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return pdf;
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} catch (e) {
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this.logger.error(`No se pudo generar el PDF: ${e instanceof Error ? e.message : String(e)}`);
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throw e;
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} finally {
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await rm(dir, { recursive: true, force: true });
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}
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});
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}
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}
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