Add update post script to update user's app javascripts

lib/_update_javascripts.js

@@ -0,0 +1,85 @@
+const { Buffer } = require('buffer')
+const fs = require('fs').promises
+const https = require('https')
+const os = require('os')
+const path = require('path')
+
+const { projectDir, packageDir } = require('./path-utils')
+const updateDir = path.join(projectDir, 'update')
+
+async function fetchOriginal(filePath) {
+  const oldVersion = (await fs.readFile(path.join(projectDir, 'VERSION.txt'), 'utf8')).trim()
+  const remoteUrl = `https://raw.githubusercontent.com/alphagov/govuk-prototype-kit/v${oldVersion}/${filePath}`
+
+  let data = ''
+  return new Promise((resolve, reject) => {
+    https.get(remoteUrl, (response) => {
+      let error
+
+      if (response.statusCode !== 200) {
+        error = new Error(`could not fetch ${remoteUrl}: status code ${response.statusCode}`)
+        Object.assign(error, response)
+        response.resume()
+        reject(error)
+      }
+
+      response.setEncoding('utf8')
+
+      response.on('data', (chunk) => {
+        data += chunk
+      })
+
+      response.on('end', () => {
+        resolve(data)
+      })
+    })
+  })
+}
+
+async function removeKitJsFromApplicationJs () {
+  const assetPath = 'assets/javascripts/application.js'
+  const original = await fetchOriginal(path.posix.join('app', assetPath))
+  const theirs = await fs.readFile(path.resolve(projectDir, 'app', assetPath), 'utf8')
+
+  // If the user hasn't changed their application.js file we can just replace it completely
+  if (original === theirs) {
+    return fs.copyFile(path.join(packageDir, 'lib', assetPath), path.join(projectDir, 'app', assetPath))
+  }
+
+  // Otherwise, if the original code is contained as-is in their file, we can
+  // remove the shared lines, and add our hints
+  if (theirs.includes(original)) {
+    const ourLines = await fs.readFile(path.resolve(packageDir, 'app', assetPath), 'utf8').split('\n')
+
+    let merged
+    merged = theirs.replace(original, '\n')
+    merged = ourLines[0] + '\n' + merged
+    merged = merged + '\n' + ourLines[1:]
+    return fs.writeFile(path.resolve(projectDir, 'app', assetPath), merged, 'utf8')
+  }
+
+  // If the original code is not recognisable, we should give up, but not
+  // without giving a warning to the user
+  console.warn(
+    `WARNING: update.sh was not able to automatically update your ${assetPath} file.\n` +
+    'If you have issues when running your prototype please contact the GOV.UK Prototype Kit team for support,\n'
+    'using one of the methods listed at https://design-system.service.gov.uk/get-in-touch/'
+  )
+}
+
+async function removeKitJSFromAppJsPath () {
+  const appJsPath = path.join(projectDir, 'app', 'assets', 'javascripts')
+  await fs.unlink('auto-store-data.js').catch(() => {})
+  await fs.unlink('jquery-1.11.3.js').catch(() => {})
+  await fs.unlink('step-by-step-nav.js').catch(() => {})
+  await fs.unlink('step-by-step-navigation.js').catch(() => {})
+}
+
+async function main() {
+  await removeKitJsFromAppJsPath()
+  await removeKitJsFromApplicationJs()
+}
+
+if (require.main === module) {
+  main()
+}

update.sh

@@ -181,10 +181,12 @@ copy () {
 }
 
 post () {
-  # execute _update_scss if it exists in the update folder
-  if [ -d "update/lib/_update_scss" ]; then
-    node "update/lib/_update_scss"
-  fi
+	if [ -d "update/lib/_update_scss" ]; then
+		node "update/lib/_update_scss"
+	fi
+	if [ -f "update/lib/_update_javascripts.js" ]; then
+		node "update/lib/_update_javascripts"
+	fi
 }
 
 if [ "$0" == "${BASH_SOURCE:-$0}" ]