feat: add pdf to the central invoice system

apps/edr-freight-api/src/modules/billing/documents/documents.module.ts

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+import { Module } from "@nestjs/common";
+
+import { InvoiceDocumentService } from "./invoice-document.service";
+import { PdfRenderService } from "./pdf-render.service";
+
+/**
+ * Standalone document infrastructure — generic HTML→PDF plus the shared
+ * invoice/receipt renderer. Has no domain dependencies, so any module (billing,
+ * warehouses, …) can import it to print invoices without coupling to the
+ * billing payment graph.
+ */
+@Module({
+  providers: [PdfRenderService, InvoiceDocumentService],
+  exports: [PdfRenderService, InvoiceDocumentService],
+})
+export class DocumentsModule {}

apps/edr-freight-api/src/modules/billing/documents/invoice-document.service.ts

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+import { Injectable } from "@nestjs/common";
+
+import { PdfRenderService } from "./pdf-render.service";
+
+export type InvoiceDocumentKind = "INVOICE" | "RECEIPT";
+
+/** One billed line on the document (charge type / fee type agnostic). */
+export interface InvoiceDocumentLine {
+  description: string | null;
+  /** Optional categorisation column (e.g. "Fee type" / "Charge type"). */
+  category?: string | null;
+  quantity?: number | null;
+  unitRate?: number | null;
+  amount?: number | null;
+  currency?: string | null;
+}
+
+/** A labelled total row in the totals box; mark `grand` for the headline total. */
+export interface InvoiceDocumentTotal {
+  label: string;
+  amount: number;
+  grand?: boolean;
+}
+
+/**
+ * Source-agnostic description of a printable invoice/receipt. Each billing
+ * source maps its own entity onto this shape; the renderer owns the layout so
+ * every EDR invoice document looks identical regardless of source.
+ */
+export interface InvoiceDocumentModel {
+  kind: InvoiceDocumentKind;
+  /** Document heading, e.g. "Warehouse Fee Invoice" / "Freight Invoice". */
+  title: string;
+  documentNumber: string;
+  issuedAt?: Date | string | null;
+  status: string;
+  currency: string;
+  /** Free-form summary grid (label/value pairs). */
+  summary: Array<{ label: string; value: string | null }>;
+  /** Header for the line-item category column; column hidden when omitted. */
+  categoryHeader?: string;
+  lines: InvoiceDocumentLine[];
+  totals: InvoiceDocumentTotal[];
+  /** Override the round seal text; defaults from kind/status. */
+  sealText?: string;
+}
+
+/**
+ * Central invoice/receipt PDF renderer shared by every billing source. Turns a
+ * {@link InvoiceDocumentModel} into the sealed EDR document HTML and renders it
+ * via {@link PdfRenderService}. Previously this layout lived (warehouse-only) in
+ * `WarehouseInvoiceService`; it now serves all invoices.
+ */
+@Injectable()
+export class InvoiceDocumentService {
+  constructor(private readonly pdf: PdfRenderService) {}
+
+  async render(
+    model: InvoiceDocumentModel,
+  ): Promise<{ filename: string; buffer: Buffer }> {
+    const html = this.buildHtml(model);
+    const kindLabel = model.kind === "RECEIPT" ? "receipt" : "invoice";
+    return {
+      filename: `${this.safeFilename(model.documentNumber)}-${kindLabel}.pdf`,
+      buffer: await this.pdf.htmlToPdfBuffer(html, { label: `${model.title} ${kindLabel}` }),
+    };
+  }
+
+  buildHtml(model: InvoiceDocumentModel): string {
+    const esc = (value: unknown) =>
+      String(value ?? "-")
+        .replace(/&/g, "&amp;")
+        .replace(/</g, "&lt;")
+        .replace(/>/g, "&gt;")
+        .replace(/"/g, "&quot;")
+        .replace(/'/g, "&#39;");
+    const money = (amount: unknown, currency = model.currency) =>
+      `${Number(amount ?? 0).toLocaleString()} ${currency === "ETB" ? "Birr (ETB)" : currency}`;
+    const date = (value: unknown) =>
+      value ? new Date(value as string | Date).toLocaleDateString("en-GB") : "-";
+
+    const showCategory = Boolean(model.categoryHeader);
+    const sealText =
+      model.sealText ?? (model.kind === "RECEIPT" || model.status === "PAID" ? "EDR PAID" : "EDR");
+
+    const summaryRows = model.summary
+      .map((row) => `<div><span>${esc(row.label)}</span>${esc(row.value)}</div>`)
+      .join("");
+
+    const itemRows = model.lines
+      .map(
+        (item) => `<tr>
+              <td>${esc(item.description)}</td>
+              ${showCategory ? `<td>${esc((item.category ?? "").replace(/_/g, " "))}</td>` : ""}
+              <td class="num">${esc(item.quantity ?? 0)}</td>
+              <td class="num">${esc(money(item.unitRate, item.currency ?? model.currency))}</td>
+              <td class="num">${esc(money(item.amount, item.currency ?? model.currency))}</td>
+            </tr>`,
+      )
+      .join("");
+
+    const totalRows = model.totals
+      .map(
+        (total) =>
+          `<div class="total-row${total.grand ? " grand" : ""}"><span>${esc(total.label)}</span><strong>${esc(money(total.amount))}</strong></div>`,
+      )
+      .join("");
+
+    return `<!doctype html>
+<html>
+<head>
+  <meta charset="utf-8" />
+  <title>${esc(model.title)} ${model.kind === "RECEIPT" ? "Receipt" : "Invoice"}</title>
+  <style>
+    body { font-family: Arial, sans-serif; color: #0f172a; margin: 0; }
+    .doc { padding: 16px 8px; position: relative; }
+    .top { display: flex; justify-content: space-between; gap: 24px; border-bottom: 3px solid #0f766e; padding-bottom: 16px; }
+    .brand { font-size: 13px; color: #475569; text-transform: uppercase; letter-spacing: .08em; }
+    h1 { margin: 8px 0 0; font-size: 30px; }
+    .meta { text-align: right; font-size: 12px; color: #475569; }
+    .meta strong { display: block; color: #0f172a; font-size: 17px; margin-top: 5px; }
+    .seal { position: absolute; right: 28px; top: 118px; width: 116px; height: 116px; border: 4px double #0f766e; border-radius: 999px; color: #0f766e; display: flex; align-items: center; justify-content: center; text-align: center; font-weight: 800; font-size: 18px; transform: rotate(-14deg); opacity: .82; }
+    .summary { display: grid; grid-template-columns: 1fr 1fr; gap: 12px 28px; margin: 24px 150px 16px 0; font-size: 13px; }
+    .summary div { border-bottom: 1px solid #e2e8f0; padding: 7px 0; }
+    .summary span { color: #64748b; display: block; font-size: 11px; margin-bottom: 3px; }
+    table { width: 100%; border-collapse: collapse; margin-top: 18px; }
+    th { text-align: left; background: #f8fafc; color: #475569; }
+    th, td { border: 1px solid #cbd5e1; padding: 9px 10px; font-size: 12px; }
+    td.num, th.num { text-align: right; }
+    .totals { margin-left: auto; width: 330px; margin-top: 18px; }
+    .total-row { display: flex; justify-content: space-between; border-bottom: 1px solid #e2e8f0; padding: 8px 0; font-size: 13px; }
+    .grand { font-size: 16px; font-weight: 800; }
+    .footer { margin-top: 34px; display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
+    .line { border-top: 1px solid #334155; padding-top: 8px; font-size: 12px; color: #475569; }
+  </style>
+</head>
+<body>
+  <div class="doc">
+    <div class="top">
+      <div>
+        <div class="brand">Ethio-Djibouti Railway S.C.</div>
+        <h1>${esc(model.title)} ${model.kind === "RECEIPT" ? "Receipt" : "Invoice"}</h1>
+      </div>
+      <div class="meta">
+        Document no.
+        <strong>${esc(model.documentNumber)}</strong>
+        Issued: ${esc(date(model.issuedAt))}
+      </div>
+    </div>
+    <div class="seal">${esc(sealText)}</div>
+    <div class="summary">${summaryRows}</div>
+    <table>
+      <thead>
+        <tr>
+          <th>Description</th>
+          ${showCategory ? `<th>${esc(model.categoryHeader)}</th>` : ""}
+          <th class="num">Qty</th>
+          <th class="num">Rate</th>
+          <th class="num">Amount</th>
+        </tr>
+      </thead>
+      <tbody>
+        ${itemRows}
+      </tbody>
+    </table>
+    <div class="totals">${totalRows}</div>
+    <div class="footer">
+      <div class="line">Prepared by EDR finance</div>
+      <div class="line">Authorized seal / signature</div>
+    </div>
+  </div>
+</body>
+</html>`;
+  }
+
+  safeFilename(value: string): string {
+    return value.replace(/[^a-zA-Z0-9_-]+/g, "-");
+  }
+}

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");
+  }
+}