Add a syntax highlight dropdown, if pygments is enabled.

Summary:
- Add a default list of supported languages to default.conf.php
  and make the initial/default value customizable.
- Store a '' in the database to infer the language from the filename/title.

Test Plan:
Tested in my sandbox with pygments enabled and disabled and various
combinations of filename/extension/dropdown selection.

Reviewers:
epriestley

CC:

Differential Revision: 587

src/applications/paste/controller/create/PhabricatorPasteCreateController.php

@@ -31,6 +31,16 @@ class PhabricatorPasteCreateController extends PhabricatorPasteController {
     if ($request->isFormPost()) {
       $errors = array();
       $title = $request->getStr('title');
+
+      $language = $request->getStr('language');
+      if ($language == 'infer') {
+        // If it's infer, store an empty string. Otherwise, store the
+        // language name. We do this so we can refer to 'infer' elsewhere
+        // in the code (such as default value) while retaining backwards
+        // compatibility with old posts with no language stored.
+        $language = '';
+      }
+
       $text = $request->getStr('text');
 
       if (!strlen($text)) {
@@ -41,6 +51,7 @@ class PhabricatorPasteCreateController extends PhabricatorPasteController {
       }
 
       $paste->setTitle($title);
+      $paste->setLanguage($language);
 
       if (!$errors) {
         $paste_file = PhabricatorFile::newFromFileData(
@@ -76,6 +87,26 @@ class PhabricatorPasteCreateController extends PhabricatorPasteController {
     }
 
     $form = new AphrontFormView();
+
+    // If we're coming back from an error and the language was already defined,
+    // use that. Otherwise, ask the config for the default.
+    if ($paste->getLanguage()) {
+      $language_default = $paste->getLanguage();
+    } else {
+      $language_default = PhabricatorEnv::getEnvConfig(
+        'pygments.dropdown-default');
+    }
+
+    $available_languages = PhabricatorEnv::getEnvConfig(
+      'pygments.dropdown-choices');
+    asort($available_languages);
+
+    $language_select = id(new AphrontFormSelectControl())
+      ->setLabel('Language')
+      ->setName('language')
+      ->setValue($language_default)
+      ->setOptions($available_languages);
+
     $form
       ->setUser($user)
       ->setAction($request->getRequestURI()->getPath())
@@ -84,6 +115,7 @@ class PhabricatorPasteCreateController extends PhabricatorPasteController {
           ->setLabel('Title')
           ->setValue($paste->getTitle())
           ->setName('title'))
+      ->appendChild($language_select)
       ->appendChild(
         id(new AphrontFormTextAreaControl())
           ->setLabel('Text')

src/applications/paste/controller/create/__init__.php

@@ -10,7 +10,9 @@ phutil_require_module('phabricator', 'aphront/response/redirect');
 phutil_require_module('phabricator', 'applications/files/storage/file');
 phutil_require_module('phabricator', 'applications/paste/controller/base');
 phutil_require_module('phabricator', 'applications/paste/storage/paste');
+phutil_require_module('phabricator', 'infrastructure/env');
 phutil_require_module('phabricator', 'view/form/base');
+phutil_require_module('phabricator', 'view/form/control/select');
 phutil_require_module('phabricator', 'view/form/control/submit');
 phutil_require_module('phabricator', 'view/form/control/text');
 phutil_require_module('phabricator', 'view/form/control/textarea');