Add automatic extension download

README.md

@@ -18,12 +18,7 @@ Convert web articles to PDF using the [Reader View](https://chromewebstore.googl
 npm install
 ```
 
-Extract the Reader View extension (get it using [CRX Downloader](https://chromewebstore.google.com/detail/crx-extractordownloader/ajkhmmldknmfjnmeedkbkkojgobmljda)):
-
-```bash
-mkdir -p extension/reader-view
-unzip extension/Reader-View-Chrome-Web-Store.zip -d extension/reader-view
-```
+The Reader View extension is downloaded and extracted automatically on first run.
 
 ## Usage
 

src/browser.js

@@ -1,26 +1,31 @@
 import fs from 'node:fs'
 import path from 'node:path'
 import puppeteer from 'puppeteer'
+import { downloadExtension } from './download-extension.js'
 import logger from './logger.js'
 
 const EXTENSION_DIR = path.resolve('./extension/reader-view')
 const MANIFEST_PATH = path.join(EXTENSION_DIR, 'manifest.json')
 const READABILITY_PATH = path.join(EXTENSION_DIR, 'data/inject/Readability.js')
 
-export function checkExtension () {
+export async function checkExtension () {
   if (!fs.existsSync(MANIFEST_PATH)) {
-    logger.error(
-      `Extension not found at: "${EXTENSION_DIR}"\n` +
-        'Please extract the extension first:\n' +
-        '  mkdir -p extension/reader-view\n' +
-        '  unzip extension/Reader-View-Chrome-Web-Store.zip -d extension/reader-view'
-    )
+    logger.info('Extension not found. Downloading automatically...')
+    try {
+      await downloadExtension({ logger })
+    } catch (err) {
+      logger.error(`Failed to download extension: ${err.message}`)
       process.exit(1)
     }
+    if (!fs.existsSync(MANIFEST_PATH)) {
+      logger.error('Download completed but extension not found. Extraction may have failed.')
+      process.exit(1)
+    }
+  }
   if (!fs.existsSync(READABILITY_PATH)) {
     logger.error(
       `Readability.js not found at: "${READABILITY_PATH}"\n` +
-        'The extension may be incomplete. Please re-extract it.'
+        'The extension may be incomplete.'
     )
     process.exit(1)
   }

src/download-extension.js

@@ -0,0 +1,84 @@
+import fs from 'node:fs/promises'
+import path from 'node:path'
+import { execSync } from 'node:child_process'
+import { fileURLToPath } from 'node:url'
+import process from 'node:process'
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+const EXTENSION_DIR = path.resolve(__dirname, '..', 'extension')
+const EXTENSION_ID = 'ecabifbgmdmgdllomnfinbmaellmclnh'
+const CRX_PATH = path.join(EXTENSION_DIR, 'Reader-View-Chrome-Web-Store.crx')
+const ZIP_PATH = path.join(EXTENSION_DIR, 'Reader-View-Chrome-Web-Store.zip')
+const EXTRACT_DIR = path.join(EXTENSION_DIR, 'reader-view')
+
+export async function downloadExtension ({ logger } = {}) {
+  const log = logger || console
+
+  log.info('Downloading Reader View extension from Chrome Web Store...')
+
+  const url =
+    'https://clients2.google.com/service/update2/crx' +
+    '?response=redirect' +
+    '&prodversion=150.0.0.0' +
+    `&x=id%3D${EXTENSION_ID}%26installsource%3Dondemand%26uc` +
+    '&nacl_arch=arm' +
+    '&acceptformat=crx3'
+
+  const response = await fetch(url, { redirect: 'follow' })
+  if (!response.ok) {
+    throw new Error(`Failed to download CRX: HTTP ${response.status}`)
+  }
+
+  const crx = new Uint8Array(await response.arrayBuffer())
+  log.info(`Downloaded ${(crx.length / 1024).toFixed(0)} KB`)
+
+  if (crx[0] !== 0x43 || crx[1] !== 0x72 || crx[2] !== 0x32 || crx[3] !== 0x34) {
+    throw new Error('Not a valid CRX file (bad magic number)')
+  }
+
+  const view = new DataView(crx.buffer, crx.byteOffset, crx.byteLength)
+  const version = view.getUint32(4, true)
+
+  let zipOffset
+  if (version === 2) {
+    const publicKeyLength = view.getUint32(8, true)
+    const signatureLength = view.getUint32(12, true)
+    zipOffset = 16 + publicKeyLength + signatureLength
+  } else if (version === 3) {
+    const headerLength = view.getUint32(8, true)
+    zipOffset = 12 + headerLength
+  } else {
+    throw new Error(`Unsupported CRX version: ${version}`)
+  }
+
+  const zip = crx.slice(zipOffset)
+  if (zip[0] !== 0x50 || zip[1] !== 0x4b) {
+    throw new Error('Failed to locate ZIP payload in CRX')
+  }
+
+  await fs.mkdir(EXTENSION_DIR, { recursive: true })
+  await fs.writeFile(CRX_PATH, crx)
+  await fs.writeFile(ZIP_PATH, zip)
+
+  log.info('Extracting extension...')
+  await fs.mkdir(EXTRACT_DIR, { recursive: true })
+
+  try {
+    execSync(`unzip -o "${ZIP_PATH}" -d "${EXTRACT_DIR}"`, { stdio: 'pipe' })
+  } catch {
+    throw new Error(
+      'Failed to extract the extension. Make sure "unzip" is installed.\n' +
+        `You can manually extract it: unzip "${ZIP_PATH}" -d "${EXTRACT_DIR}"`
+    )
+  }
+
+  log.info('Extension ready.')
+}
+
+const __filename = fileURLToPath(import.meta.url)
+if (process.argv[1] && path.resolve(process.argv[1]) === __filename) {
+  downloadExtension().catch((err) => {
+    console.error('Download failed:', err.message)
+    process.exit(1)
+  })
+}

src/index.js

@@ -41,7 +41,7 @@ async function promptForInput () {
 async function main () {
   const { url, opts } = parseArgs()
 
-  checkExtension()
+  await checkExtension()
 
   let preferences = {}
   if (opts.prefs) {