Add support to retrieve the account diff preferences via REST

The diff preferences of a user can now be retrieved by GET on
'/accounts/*/preferences.diff'.

Change-Id: Ica4014496b8ced4d0d0f34804a8dc4efcdd694a1

Documentation/rest-api-accounts.txt

@@ -257,6 +257,41 @@ The response redirects to the URL of the avatar image.
   Location: https://profiles/avatar/john_doe.jpeg?s=20x20
 ----
 
+[[get-diff-preferences]]
+Get Diff Preferences
+~~~~~~~~~~~~~~~~~~~~
+[verse]
+'GET /accounts/link:#account-id[\{account-id\}]/preferences.diff'
+
+Retrieves the diff preferences of a user.
+
+.Request
+----
+  GET /a/accounts/self/preferences.diff HTTP/1.0
+----
+
+As result the diff preferences of the user are returned as a
+link:#diff-preferences-info[DiffPreferencesInfo] entity.
+
+.Response
+----
+  HTTP/1.1 200 OK
+  Content-Disposition: attachment
+  Content-Type: application/json;charset=UTF-8
+
+  )]}'
+  {
+    "context": 10,
+    "ignore_whitespace": "IGNORE_ALL_SPACE",
+    "intraline_difference": true,
+    "line_length": 100,
+    "show_tabs": true,
+    "show_whitespace_errors": true,
+    "syntax_highlighting": true,
+    "tab_size": 8
+  }
+----
+
 
 [[ids]]
 IDs
@@ -349,6 +384,52 @@ link:access-control.html#capability_startReplication[Start Replication]
 capability.
 |=================================
 
+[[diff-preferences-info]]
+DiffPreferencesInfo
+~~~~~~~~~~~~~~~~~~~
+The `DiffPreferencesInfo` entity contains information about the diff
+preferences of a user.
+
+[options="header",width="50%",cols="1,^1,5"]
+|=====================================
+|Field Name              ||Description
+|`context`               ||
+The number of lines of context when viewing a patch.
+|`expand_all_comments`   |not set if `false`|
+Whether all inline comments should be automatically expanded.
+|`ignore_whitespace`     ||
+Whether whitespace changes should be ignored and if yes, which
+whitespace changes should be ignored. +
+Allowed values are `IGNORE_NONE`, `IGNORE_SPACE_AT_EOL`,
+`IGNORE_SPACE_CHANGE`, `IGNORE_ALL_SPACE`.
+|`intraline_difference`  |not set if `false`|
+Whether intraline differences should be highlighted.
+|`line_length`           ||
+Number of characters that should be displayed in one line.
+|`manual_review`         |not set if `false`|
+Whether the 'Reviewed' flag should not be set automatically on a patch
+when it is viewed.
+|`retain_header`         |not set if `false`|
+Whether the header that is displayed above the patch (that either shows
+the commit message, the diff preferences, the patch sets or the files)
+should be retained on file switch.
+|`show_line_endings`     |not set if `false`|
+Whether Windows EOL/Cr-Lf should be displayed as '\r' in a dotted-line
+box.
+|`show_tabs`             |not set if `false`|
+Whether tabs should be shown.
+|`show_whitespace_errors`|not set if `false`|
+Whether whitespace errors should be shown.
+|`skip_deleted`          |not set if `false`|
+Whether deleted files should be skipped on file switch.
+|`skip_uncommented`      |not set if `false`|
+Whether uncommented files should be skipped on file switch.
+|`syntax_highlighting`   |not set if `false`|
+Whether syntax highlighting should be enabled.
+|`tab_size`              ||
+Number of spaces that should be used to display one tab.
+|=====================================
+
 [[query-limit-info]]
 QueryLimitInfo
 ~~~~~~~~~~~~~~

gerrit-server/src/main/java/com/google/gerrit/server/account/GetDiffPreferences.java

@@ -0,0 +1,78 @@
+// Copyright (C) 2013 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.account;
+
+import com.google.gerrit.extensions.restapi.AuthException;
+import com.google.gerrit.extensions.restapi.RestReadView;
+import com.google.gerrit.reviewdb.client.AccountDiffPreference;
+import com.google.gerrit.reviewdb.client.AccountDiffPreference.Whitespace;
+import com.google.gerrit.server.CurrentUser;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+
+public class GetDiffPreferences implements RestReadView<AccountResource> {
+
+  private final Provider<CurrentUser> self;
+
+  @Inject
+  GetDiffPreferences(Provider<CurrentUser> self) {
+    this.self = self;
+  }
+
+  @Override
+  public DiffPreferencesInfo apply(AccountResource rsrc) throws AuthException {
+    if (self.get() != rsrc.getUser()
+        && !self.get().getCapabilities().canAdministrateServer()) {
+      throw new AuthException("restricted to administrator");
+    }
+    return DiffPreferencesInfo.parse(rsrc.getUser().getAccountDiffPreference());
+  }
+
+  static class DiffPreferencesInfo {
+    static DiffPreferencesInfo parse(AccountDiffPreference p) {
+      DiffPreferencesInfo info = new DiffPreferencesInfo();
+      info.context = p.getContext();
+      info.expandAllComments = p.isExpandAllComments() ? true : null;
+      info.ignoreWhitespace = p.getIgnoreWhitespace();
+      info.intralineDifference = p.isIntralineDifference() ? true : null;
+      info.lineLength = p.getLineLength();
+      info.manualReview = p.isManualReview() ? true : null;
+      info.retainHeader = p.isRetainHeader() ? true : null;
+      info.showLineEndings = p.isShowLineEndings() ? true : null;
+      info.showTabs = p.isShowTabs() ? true : null;
+      info.showWhitespaceErrors = p.isShowWhitespaceErrors() ? true : null;
+      info.skipDeleted = p.isSkipDeleted() ? true : null;
+      info.skipUncommented = p.isSkipUncommented() ? true : null;
+      info.syntaxHighlighting = p.isSyntaxHighlighting() ? true : null;
+      info.tabSize = p.getTabSize();
+      return info;
+    }
+
+    short context;
+    Boolean expandAllComments;
+    Whitespace ignoreWhitespace;
+    Boolean intralineDifference;
+    int lineLength;
+    Boolean manualReview;
+    Boolean retainHeader;
+    Boolean showLineEndings;
+    Boolean showTabs;
+    Boolean showWhitespaceErrors;
+    Boolean skipDeleted;
+    Boolean skipUncommented;
+    Boolean syntaxHighlighting;
+    int tabSize;
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/account/Module.java

@@ -33,6 +33,7 @@ public class Module extends RestApiModule {
     get(ACCOUNT_KIND, "avatar").to(GetAvatar.class);
     child(ACCOUNT_KIND, "capabilities").to(Capabilities.class);
     get(ACCOUNT_KIND, "groups").to(GetGroups.class);
+    get(ACCOUNT_KIND, "preferences.diff").to(GetDiffPreferences.class);
     get(CAPABILITY_KIND).to(GetCapabilities.CheckOne.class);
   }
 }