feat: add pdf to the central invoice system

apps/edr-freight-api/src/modules/billing/documents/pdf-render.service.ts

@@ -0,0 +1,160 @@
+import { existsSync } from "fs";
+
+import { Injectable, InternalServerErrorException, Logger } from "@nestjs/common";
+
+const MIN_VALID_PDF_BYTES = 2_000;
+
+const PDF_PRINT_STYLES = `
+<style id="edr-pdf-print-fix">
+  @media print {
+    html, body {
+      background: #fff !important;
+      -webkit-print-color-adjust: exact;
+      print-color-adjust: exact;
+    }
+  }
+</style>`;
+
+export interface PdfRenderOptions {
+  /** Label used in logs to identify the document kind. */
+  label?: string;
+  /**
+   * Degraded renderer used when Chromium is unavailable. Receives the
+   * print-prepared HTML and must return a valid PDF buffer (≥ 2KB, `%PDF-`
+   * header). When omitted, a generic single-page fallback is produced.
+   */
+  fallback?: (preparedHtml: string) => Buffer;
+}
+
+/**
+ * Generic HTML → PDF renderer shared by every document producer (invoices,
+ * receipts, warehouse release orders). Renders via headless Chromium when
+ * available and degrades to a caller-supplied (or generic) hand-built PDF
+ * otherwise. This is pure infrastructure — it knows nothing about invoices.
+ */
+@Injectable()
+export class PdfRenderService {
+  private readonly logger = new Logger(PdfRenderService.name);
+
+  async htmlToPdfBuffer(html: string, opts: PdfRenderOptions = {}): Promise<Buffer> {
+    const label = opts.label ?? "document";
+    const preparedHtml = this.injectPdfPrintStyles(html);
+    const executablePath = this.resolveExecutablePath();
+
+    try {
+      const puppeteer = await import("puppeteer");
+      const launchOptions: import("puppeteer").LaunchOptions = {
+        headless: true,
+        args: ["--no-sandbox", "--disable-setuid-sandbox", "--disable-dev-shm-usage"],
+        ...(executablePath ? { executablePath } : {}),
+      };
+
+      const browser = await puppeteer.default.launch(launchOptions);
+      try {
+        const page = await browser.newPage();
+        await page.setViewport({ width: 794, height: 1123, deviceScaleFactor: 1 });
+        await page.setContent(preparedHtml, { waitUntil: "load", timeout: 60_000 });
+        await page.emulateMediaType("print");
+        await new Promise((resolve) => setTimeout(resolve, 250));
+
+        const pdf = await page.pdf({
+          format: "A4",
+          printBackground: true,
+          margin: { top: "16mm", bottom: "18mm", left: "14mm", right: "14mm" },
+        });
+
+        const buffer = Buffer.from(pdf);
+        if (!this.isValidPdf(buffer)) {
+          throw new Error(`Puppeteer produced invalid ${label} PDF (${buffer.length} bytes)`);
+        }
+        this.logger.log(
+          `${label} PDF rendered (${buffer.length} bytes) via ${executablePath ?? "bundled Chromium"}`,
+        );
+        return buffer;
+      } finally {
+        await browser.close();
+      }
+    } catch (error) {
+      this.logger.error(`${label} PDF failed (executable=${executablePath ?? "default"}): ${error}`);
+      const fallback = (opts.fallback ?? ((h) => this.genericFallbackPdf(h)))(preparedHtml);
+      if (this.isValidPdf(fallback)) {
+        this.logger.warn(
+          `Using ${label} PDF fallback (${fallback.length} bytes). Install Chromium or set PUPPETEER_EXECUTABLE_PATH for full layout rendering.`,
+        );
+        return fallback;
+      }
+      throw new InternalServerErrorException(
+        `${label} PDF could not be generated. Ensure Chromium is installed or set PUPPETEER_EXECUTABLE_PATH.`,
+      );
+    }
+  }
+
+  private injectPdfPrintStyles(html: string): string {
+    if (html.includes("edr-pdf-print-fix")) return html;
+    if (html.includes("</head>")) {
+      return html.replace("</head>", `${PDF_PRINT_STYLES}</head>`);
+    }
+    return `${PDF_PRINT_STYLES}${html}`;
+  }
+
+  private resolveExecutablePath(): string | undefined {
+    const fromEnv = process.env.PUPPETEER_EXECUTABLE_PATH?.trim();
+    if (fromEnv && existsSync(fromEnv)) return fromEnv;
+
+    const candidates = [
+      "/usr/bin/chromium",
+      "/usr/bin/chromium-browser",
+      "/usr/bin/google-chrome-stable",
+      "/usr/bin/google-chrome",
+    ];
+    return candidates.find((path) => existsSync(path));
+  }
+
+  isValidPdf(buffer: Buffer): boolean {
+    return buffer.length >= MIN_VALID_PDF_BYTES && buffer.subarray(0, 5).toString("ascii") === "%PDF-";
+  }
+
+  /** Minimal valid one-page PDF carrying a plain-text rendering of the document. */
+  private genericFallbackPdf(html: string): Buffer {
+    const text = html
+      .replace(/<script[\s\S]*?<\/script>/gi, "")
+      .replace(/<style[\s\S]*?<\/style>/gi, "")
+      .replace(/<[^>]+>/g, " ")
+      .replace(/&nbsp;/gi, " ")
+      .replace(/&amp;/gi, "&")
+      .replace(/&lt;/gi, "<")
+      .replace(/&gt;/gi, ">")
+      .replace(/[^\x20-\x7e]/g, " ")
+      .replace(/\s+/g, " ")
+      .trim()
+      .slice(0, 900);
+
+    const escape = (value: string) => value.replace(/\\/g, "\\\\").replace(/\(/g, "\\(").replace(/\)/g, "\\)");
+    const lines = (text.match(/.{1,90}/g) ?? ["Document"]).slice(0, 40);
+    const stream =
+      "BT\n/F1 10 Tf\n36 800 Td\n12 TL\n" +
+      lines.map((line, i) => `${i === 0 ? "" : "T*\n"}(${escape(line)}) Tj\n`).join("") +
+      "ET";
+
+    const objects = [
+      "<< /Type /Catalog /Pages 2 0 R >>",
+      "<< /Type /Pages /Kids [3 0 R] /Count 1 >>",
+      "<< /Type /Page /Parent 2 0 R /MediaBox [0 0 595 842] /Resources << /Font << /F1 4 0 R >> >> /Contents 5 0 R >>",
+      "<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>",
+      `<< /Length ${Buffer.byteLength(stream, "latin1")} >>\nstream\n${stream}\nendstream`,
+    ];
+
+    let pdf = "%PDF-1.4\n";
+    const offsets: number[] = [];
+    objects.forEach((object, index) => {
+      offsets.push(Buffer.byteLength(pdf, "latin1"));
+      pdf += `${index + 1} 0 obj\n${object}\nendobj\n`;
+    });
+    while (Buffer.byteLength(pdf, "latin1") < MIN_VALID_PDF_BYTES) pdf += "% pad\n";
+    const xrefOffset = Buffer.byteLength(pdf, "latin1");
+    pdf += `xref\n0 ${objects.length + 1}\n0000000000 65535 f \n`;
+    for (const offset of offsets) pdf += `${String(offset).padStart(10, "0")} 00000 n \n`;
+    pdf += `trailer\n<< /Size ${objects.length + 1} /Root 1 0 R >>\nstartxref\n${xrefOffset}\n%%EOF\n`;
+    return Buffer.from(pdf, "latin1");
+  }
+}