Add an 'initial' element to the Drupal Scaffold 'extras' section, to allow files to be scaffolded iff the target file does not yet exist (e.g. to copy from a default file to the user-customized file on first install only).

Author: greg-1-anderson

README.md

@@ -38,6 +38,10 @@ of your root `composer.json`.
       "includes": [
         "sites/default/example.settings.my.php"
       ],
+      "initial": {
+        "sites/default/default.services.yml": "sites/default/services.yml",
+        "sites/default/default.settings.php": "sites/default/settings.php"
+      },
       "omit-defaults": false
     }
   }
@@ -77,6 +81,10 @@ listed in the `excludes` and `includes` options will be considered. If
 `omit-defaults` is `false` (the default), then any items listed in `excludes`
 or `includes` will be in addition to the usual defaults.
 
+The `initial` hash lists files that should be copied over only if they do not
+exist in the destination. The key specifies the path to the source file, and
+the value indicates the path to the destination file.
+
 ## Limitation
 
 When using Composer to install or update the Drupal development branch, the

src/FileFetcher.php

@@ -17,6 +17,10 @@ class FileFetcher {
    */
   protected $remoteFilesystem;
 
+  protected $source;
+  protected $filenames;
+  protected $fs;
+
   public function __construct(RemoteFilesystem $remoteFilesystem, $source, $filenames = []) {
     $this->remoteFilesystem = $remoteFilesystem;
     $this->source = $source;

src/Handler.php

@@ -114,9 +114,14 @@ public function downloadScaffold() {
       $version = substr($version, 0, -4);
     }
 
-    $fetcher = new FileFetcher(new RemoteFilesystem($this->io), $options['source'], $files);
+    $remoteFs = new RemoteFilesystem($this->io);
+
+    $fetcher = new FileFetcher($remoteFs, $options['source'], $files);
     $fetcher->fetch($version, $webroot);
 
+    $initialFileFetcher = new InitialFileFetcher($remoteFs, $options['source'], $this->getInitial());
+    $initialFileFetcher->fetch($version, $webroot);
+
     // Call post-scaffold scripts.
     $dispatcher->dispatch(self::POST_DRUPAL_SCAFFOLD_CMD);
   }
@@ -239,6 +244,15 @@ protected function getIncludes() {
     return $this->getNamedOptionList('includes', 'getIncludesDefault');
   }
 
+  /**
+   * Retrieve list of initial files from optional "extra" configuration.
+   *
+   * @return array
+   */
+  protected function getInitial() {
+    return $this->getNamedOptionList('initial', 'getInitialDefault');
+  }
+
   /**
    * Retrieve a named list of options from optional "extra" configuration.
    * Respects 'omit-defaults', and either includes or does not include the
@@ -268,6 +282,7 @@ protected function getOptions() {
       'omit-defaults' => FALSE,
       'excludes' => [],
       'includes' => [],
+      'initial' => [],
       'source' => 'http://cgit.drupalcode.org/drupal/plain/{path}?h={version}',
       // Github: https://raw.githubusercontent.com/drupal/drupal/{version}/{path}
     ];
@@ -304,4 +319,11 @@ protected function getIncludesDefault() {
     ];
   }
 
+  /**
+   * Holds default initial files.
+   */
+  protected function getInitialDefault() {
+    return [];
+  }
+
 }

src/InitialFileFetcher.php

@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * @file
+ * Contains \DrupalComposer\DrupalScaffold\FileFetcher.
+ */
+
+namespace DrupalComposer\DrupalScaffold;
+
+use Composer\Util\Filesystem;
+use Composer\Util\RemoteFilesystem;
+
+class InitialFileFetcher extends FileFetcher {
+  public function fetch($version, $destination) {
+    array_walk($this->filenames, function ($filename, $sourceFilename) use ($version, $destination) {
+      $target = "$destination/$filename";
+      if (!file_exists($target)) {
+        $url = $this->getUri($sourceFilename, $version);
+        $this->fs->ensureDirectoryExists($destination . '/' . dirname($filename));
+        $this->remoteFilesystem->copy($url, $url, $target);
+      }
+    });
+  }
+}

tests/FetcherTest.php

@@ -11,6 +11,7 @@
 use Composer\Util\Filesystem;
 use Composer\Util\RemoteFilesystem;
 use DrupalComposer\DrupalScaffold\FileFetcher;
+use DrupalComposer\DrupalScaffold\InitialFileFetcher;
 
 class FetcherTest extends \PHPUnit_Framework_TestCase {
 
@@ -67,4 +68,9 @@ public function testFetch() {
     $this->assertFileExists($this->tmpDir . '/sites/default/default.settings.php');
   }
 
+  public function testInitialFetch() {
+    $fetcher = new InitialFileFetcher(new RemoteFilesystem(new NullIO()), 'http://cgit.drupalcode.org/drupal/plain/{path}?h={version}', ['sites/default/default.settings.php' => 'sites/default/settings.php']);
+    $fetcher->fetch('8.1.1', $this->tmpDir);
+    $this->assertFileExists($this->tmpDir . '/sites/default/settings.php');
+  }
 }