gui: Add explanation to options enabled or disabled per folder type

Currently, some options are automatically enabled or disabled depending
on the folder type. However, there is no explanation in the GUI on why
the options are like that. Thus, add short explanatory notes to each
case, where the option is either disabled or enabled according to the
current folder type.

Signed-off-by: Tomasz Wilczyński <twilczynski@naver.com>

gui/default/assets/lang/lang-en.json

@@ -27,6 +27,8 @@
     "Allowed Networks": "Allowed Networks",
     "Alphabetic": "Alphabetic",
     "Altered by ignoring deletes.": "Altered by ignoring deletes.",
+    "Always enabled when the folder type is \"{%foldertype%}\".": "Always enabled when the folder type is \"{{foldertype}}\".",
+    "Always turned on when the folder type is \"{%foldertype%}\".": "Always turned on when the folder type is \"{{foldertype}}\".",
     "An external command handles the versioning. It has to remove the file from the shared folder. If the path to the application contains spaces, it should be quoted.": "An external command handles the versioning. It has to remove the file from the shared folder. If the path to the application contains spaces, it should be quoted.",
     "Anonymous Usage Reporting": "Anonymous Usage Reporting",
     "Anonymous usage report format has changed. Would you like to move to the new format?": "Anonymous usage report format has changed. Would you like to move to the new format?",
@@ -52,6 +54,7 @@
     "Body:": "Body:",
     "Bugs": "Bugs",
     "Cancel": "Cancel",
+    "Cannot be enabled when the folder type is \"{%foldertype%}\".": "Cannot be enabled when the folder type is \"{{foldertype}}\".",
     "Changelog": "Changelog",
     "Clean out after": "Clean out after",
     "Cleaning Versions": "Cleaning Versions",

gui/default/syncthing/folder/editFolderModalView.html

@@ -251,6 +251,9 @@
               <select class="form-control" ng-if="currentFolder.type == 'sendonly'" disabled>
                 <option value="disabled" translate>Disabled</option>
               </select>
+              <p class="help-block" ng-if="currentFolder.type === 'sendonly'" translate translate-value-foldertype="{{'Send Only' | translate}}">
+                Cannot be enabled when the folder type is "{%foldertype%}".
+              </p>
             </div>
           </div>
 
@@ -282,6 +285,9 @@
               <p translate class="help-block">
                 Disables comparing and syncing file permissions. Useful on systems with nonexistent or custom permissions (e.g. FAT, exFAT, Synology, Android).
               </p>
+              <p class="help-block" ng-if="currentFolder._recvEnc" translate translate-value-foldertype="{{'Receive Encrypted' | translate}}">
+                Always turned on when the folder type is "{%foldertype%}".
+              </p>
             </div>
           </div>
 
@@ -297,12 +303,18 @@
               <p translate class="help-block">
                 Enables sending ownership information to other devices, and applying incoming ownership information. Typically requires running with elevated privileges.
               </p>
+              <p class="help-block" ng-if="has(['sendonly', 'receiveencrypted'], currentFolder.type)" translate translate-value-foldertype="{{currentFolder.type === 'sendonly' ? ('Send Only' | translate) : currentFolder.type === 'receiveencrypted' ? ('Receive Encrypted' | translate) : ''}}">
+                Cannot be enabled when the folder type is "{%foldertype%}".
+              </p>
               <label>
                 <input type="checkbox" ng-disabled="currentFolder.type == 'receiveonly' || currentFolder.type == 'receiveencrypted' || currentFolder.syncOwnership" ng-checked="currentFolder.sendOwnership || currentFolder.syncOwnership" ng-model="currentFolder.sendOwnership" /> <span translate>Send Ownership</span>
               </label>
               <p translate class="help-block">
                 Enables sending ownership information to other devices, but not applying incoming ownership information. This can have a significant performance impact. Always enabled when "Sync Ownership" is enabled.
               </p>
+              <p class="help-block" ng-if="has(['receiveonly', 'receiveencrypted'], currentFolder.type)" translate translate-value-foldertype="{{currentFolder.type === 'receiveonly' ? ('Receive Only' | translate) : currentFolder.type === 'receiveencrypted' ? ('Receive Encrypted' | translate) : ''}}">
+                Cannot be enabled when the folder type is "{%foldertype%}".
+              </p>
             </div>
             <div class="col-md-6 form-group">
               <p>
@@ -315,12 +327,18 @@
               <p translate class="help-block">
                 Enables sending extended attributes to other devices, and applying incoming extended attributes. May require running with elevated privileges.
               </p>
+              <p class="help-block" ng-if="has(['sendonly', 'receiveencrypted'], currentFolder.type)" translate translate-value-foldertype="{{currentFolder.type === 'sendonly' ? ('Send Only' | translate) : currentFolder.type === 'receiveencrypted' ? ('Receive Encrypted' | translate) : ''}}">
+                Cannot be enabled when the folder type is "{%foldertype%}".
+              </p>
               <label>
                 <input type="checkbox" ng-disabled="currentFolder.type == 'receiveonly' || currentFolder.type == 'receiveencrypted' || currentFolder.syncXattrs" ng-checked="currentFolder.sendXattrs || currentFolder.syncXattrs" ng-model="currentFolder.sendXattrs" /> <span translate>Send Extended Attributes</span>
               </label>
               <p translate class="help-block">
                 Enables sending extended attributes to other devices, but not applying incoming extended attributes. This can have a significant performance impact. Always enabled when "Sync Extended Attributes" is enabled.
               </p>
+              <p class="help-block" ng-if="has(['receiveonly', 'receiveencrypted'], currentFolder.type)" translate translate-value-foldertype="{{currentFolder.type === 'receiveonly' ? ('Receive Only' | translate) : currentFolder.type === 'receiveencrypted' ? ('Receive Encrypted' | translate) : ''}}">
+                Cannot be enabled when the folder type is "{%foldertype%}".
+              </p>
             </div>
           </div>