From 352c09d292775fa66543a3d29f09590f2b5fd092 Mon Sep 17 00:00:00 2001
From: CanadaHonk <oj@oojmed.com>
Date: Sun, 29 Jan 2023 19:22:36 +0000
Subject: [PATCH] api/page: add printToPDF

---
 gluon.d.ts             | 122 +++++++++++++++++++++++++++++++++++++++++
 src/launcher/inject.js |  22 ++++++++
 2 files changed, 144 insertions(+)

diff --git a/gluon.d.ts b/gluon.d.ts
index f2d8a35..1c26bfc 100644
--- a/gluon.d.ts
+++ b/gluon.d.ts
@@ -53,6 +53,107 @@ type V8CacheApi = {
   ): Promise<boolean>
 };
 
+type PrintToPDFOptions = {
+  /**
+   * Paper orientation.
+   * @default false
+   */
+  landscape?: boolean,
+
+  /**
+   * Display header and footer.
+   * @default false
+   */
+  displayHeaderFooter?: boolean,
+
+  /**
+   * Print background graphics.
+   * @default false
+   */
+  printBackground?: boolean,
+
+  /**
+   * Scale of the webpage rendering.
+   * @default 1
+   */
+  scale?: number,
+
+  /**
+   * Paper width in inches.
+   * @default 8.5
+   */
+  paperWidth?: number,
+
+  /**
+   * Paper height in inches.
+   * @default 11
+   */
+  paperHeight?: number,
+
+  /**
+   * Top margin in inches.
+   * @default 0.4
+   */
+  marginTop?: number,
+
+  /**
+   * Bottom margin in inches.
+   * @default 0.4
+   */
+  marginBottom?: number,
+
+  /**
+   * Left margin in inches.
+   * @default 0.4
+   */
+  marginLeft?: number,
+
+  /**
+   * Right margin in inches.
+   * @default 0.4
+   */
+  marginRight?: number,
+
+  /**
+   * Paper ranges to print, one based, (eg '1-5, 8, 11-13').
+   * Pages are printed in the document order, not in the order specified, and no more than once.
+   * Defaults to an empty string, which implies all pages available are printed.
+   * @default ''
+   */
+  pageRanges?: string,
+
+  /**
+   * HTML template for the print header.
+   * You can use the following classes which will have the relevant print data injected into the contents:
+   * - `date` - formatted print date
+   * - `title` - document title
+   * - `url` - document location
+   * - `pageNumber` - current page number
+   * - `totalPages` - total pages in the document
+   * @example `<span class=title></span>` would create a span containing the document title.
+   */
+  headerTemplate?: string,
+
+  /**
+   * HTML template for the print footer.
+   * You can use the following classes which will have the relevant print data injected into the contents:
+   * - `date` - formatted print date
+   * - `title` - document title
+   * - `url` - document location
+   * - `pageNumber` - current page number
+   * - `totalPages` - total pages in the document
+   * @example `<span class=title></span>` would create a span containing the document title.
+   */
+  footerTemplate?: string,
+
+  /**
+   * Prefer the page size defined by the page's CSS.
+   * When set to false, it will scale to fit the paper size.
+   * @default false
+   */
+  preferCSSPageSize?: boolean,
+};
+
 type PageApi = {
   /**
    * Evaluate a string or function in the web context.
@@ -85,6 +186,27 @@ type PageApi = {
     */
     ignoreCache?: boolean
   ): Promise<void>,
+
+  /**
+   * Print (save) the page as a PDF, optionally to a file.
+   * @returns Buffer of PDF data.
+   */
+  printToPDF(
+    /** Optional print options (based on Chromium's headless standard). */
+    options?: PrintToPDFOptions
+  ): Promise<Buffer>,
+
+  /**
+   * Print (save) the page as a PDF to a file.
+   * @returns Buffer of PDF data.
+   */
+  printToPDF(
+    /** Path to save the PDF to. Do not include to just get a Buffer. */
+    path: string,
+
+    /** Optional print options (based on Chromium's headless standard). */
+    options?: PrintToPDFOptions
+  ): Promise<Buffer>
 };
 
 type IPCStoreApi = {
diff --git a/src/launcher/inject.js b/src/launcher/inject.js
index a3717b3..6b431fb 100644
--- a/src/launcher/inject.js
+++ b/src/launcher/inject.js
@@ -1,3 +1,4 @@
+import { writeFile } from 'fs/promises';
 import { log } from '../lib/logger.js';
 
 import IPCApi from '../lib/ipc.js';
@@ -114,6 +115,27 @@ export default async (CDP, proc, injectionType = 'browser', { dataPath, browserN
         await Window.cdp.send('Page.reload', {
           ignoreCache
         });
+      },
+
+      printToPDF: async (...args) => {
+        let path, options;
+
+        if (args.length === 1) {
+          if (typeof args[0] === 'string') path = args[0];
+            else options = args[0];
+        }
+
+        if (args.length === 2) {
+          [ path, options ] = args;
+        }
+
+
+        const { data } = await CDP.send('Page.printToPDF', options);
+        const buffer = Buffer.from(data, 'base64');
+
+        if (path) await writeFile(path, buffer);
+
+        return buffer;
       }
     },