Allow admins to configure URL aliases

This allows to map plugin screens into the Gerrit URL namespace, e.g.:

  [urlAlias "MyPluginScreen"]
    match = /myscreen/(.*)
    token = /x/myplugin/myscreen/$1

This can also be used to replace Gerrit screens with plugin screens,
e.g. to replace change screen:

  [urlAlias "MyChangeScreen"]
    match = /c/(.*)
    token = /x/myplugin/c/$1

Defining URL aliases is similar to defining comment links. This is why
a similar representation in the gerrit.config was chosen.

Change-Id: Ie4a3b69703629051f7627eeb0c479dfc964f27ae
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

Documentation/config-gerrit.txt

@@ -3767,6 +3767,46 @@ on the server. One or more groups can be set.
 If no groups are added, any user will be allowed to execute
 'upload-pack' on the server.
 
+[[urlAlias]]
+=== Section urlAlias
+
+URL aliases define regular expressions for URL tokens that are mapped
+to target URL tokens.
+
+Each URL alias must be specified in its own subsection. The subsection
+name should be a descriptive name. It must be unique, but is not
+interpreted in any way.
+
+The URL aliases are applied in no particular order. The first matching
+URL alias is used and further matches are ignored.
+
+URL aliases can be used to map plugin screens into the Gerrit URL
+namespace, or to replace Gerrit screens by plugin screens.
+
+Example:
+
+----
+[urlAlias "MyPluginScreen"]
+  match = /myscreen/(.*)
+  token = /x/myplugin/myscreen/$1
+[urlAlias "MyChangeScreen"]
+  match = /c/(.*)
+  token = /x/myplugin/c/$1
+----
+
+[[urlAlias.match]]urlAlias.match::
++
+A regular expression for a URL token.
++
+The matched URL token is replaced by `urlAlias.token`.
+
+[[urlAlias.token]]urlAlias.token::
++
+The target URL token.
++
+It can contain placeholders for the groups matched by the
+`urlAlias.match` regular expression: `$1` for the first matched group,
+`$2` for the second matched group, etc.
 
 [[submodule]]
 === Section submodule

Documentation/dev-plugins.txt

@@ -1788,6 +1788,10 @@ public class MyPlugin extends PluginEntryPoint {
 }
 ----
 
+By defining an link:config-gerrit.html#urlAlias[urlAlias] Gerrit
+administrators can map plugin screens into the Gerrit URL namespace or
+even replace Gerrit screens by plugin screens.
+
 [[settings-screen]]
 == Plugin Settings Screen
 

Documentation/rest-api-config.txt

@@ -1352,6 +1352,11 @@ entity. Not set if SSHD is disabled.
 Information about the configuration from the
 link:config-gerrit.html#suggest[suggest] section as link:#suggest-info[
 SuggestInfo] entity.
+|`url_aliases`             |optional|
+A map of URL aliases, where a regular expression for an URL token is
+mapped to a target URL token. The target URL token can contain
+placeholders for the groups matched by the regular expression: `$1` for
+the first matched group, `$2` for the second matched group, etc.
 |`user`                    ||
 Information about the configuration from the
 link:config-gerrit.html#user[user] section as link:#user-config-info[

gerrit-gwtui/src/main/java/com/google/gerrit/client/Dispatcher.java

@@ -96,6 +96,8 @@ import com.google.gerrit.reviewdb.client.Project;
 import com.google.gwt.core.client.GWT;
 import com.google.gwt.core.client.RunAsyncCallback;
 import com.google.gwt.http.client.URL;
+import com.google.gwt.regexp.shared.MatchResult;
+import com.google.gwt.regexp.shared.RegExp;
 import com.google.gwt.user.client.Window;
 import com.google.gwtorm.client.KeyUtil;
 
@@ -204,7 +206,9 @@ public class Dispatcher {
     }
   }
 
-  private static void select(final String token) {
+  private static void select(String token) {
+    token = Gerrit.getUrlAliasMatcher().replace(token);
+
     if (matchPrefix(QUERY, token)) {
       query(token);
 

gerrit-gwtui/src/main/java/com/google/gerrit/client/Gerrit.java

@@ -112,6 +112,7 @@ public class Gerrit implements EntryPoint {
   private static String myHost;
   private static ServerInfo myServerInfo;
   private static AccountPreferencesInfo myPrefs;
+  private static UrlAliasMatcher urlAliasMatcher;
   private static boolean hasDocumentation;
   private static String docUrl;
   private static HostPageData.Theme myTheme;
@@ -294,6 +295,10 @@ public class Gerrit implements EntryPoint {
     return myServerInfo;
   }
 
+  public static UrlAliasMatcher getUrlAliasMatcher() {
+    return urlAliasMatcher;
+  }
+
   /** Site theme information (site specific colors)/ */
   public static HostPageData.Theme getTheme() {
     return myTheme;
@@ -446,6 +451,7 @@ public class Gerrit implements EntryPoint {
       @Override
       public void onSuccess(ServerInfo info) {
         myServerInfo = info;
+        urlAliasMatcher = new UrlAliasMatcher(info.urlAliases());
         String du = info.gerrit().docUrl();
         if (du != null && !du.isEmpty()) {
           hasDocumentation = true;

gerrit-gwtui/src/main/java/com/google/gerrit/client/UrlAliasMatcher.java

@@ -0,0 +1,43 @@
+// Copyright (C) 2015 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.client;
+
+import com.google.gwt.regexp.shared.RegExp;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class UrlAliasMatcher {
+  private final Map<RegExp, String> globalUrlAliases;
+
+  UrlAliasMatcher(Map<String, String> globalUrlAliases) {
+    this.globalUrlAliases = new HashMap<>();
+    if (globalUrlAliases != null) {
+      for (Map.Entry<String, String> e : globalUrlAliases.entrySet()) {
+        this.globalUrlAliases.put(RegExp.compile(e.getKey()), e.getValue());
+      }
+    }
+  }
+
+  public String replace(String token) {
+    for (Map.Entry<RegExp, String> e : globalUrlAliases.entrySet()) {
+      RegExp pat = e.getKey();
+      if (pat.exec(token) != null) {
+        return pat.replace(token, e.getValue());
+      }
+    }
+    return token;
+  }
+}

gerrit-gwtui/src/main/java/com/google/gerrit/client/config/ServerInfo.java

@@ -14,8 +14,15 @@
 
 package com.google.gerrit.client.config;
 
+import com.google.gerrit.client.rpc.NativeMap;
+import com.google.gerrit.client.rpc.NativeString;
+import com.google.gerrit.client.rpc.Natives;
 import com.google.gwt.core.client.JavaScriptObject;
 
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Set;
+
 public class ServerInfo extends JavaScriptObject {
   public final native AuthInfo auth() /*-{ return this.auth; }-*/;
   public final native ChangeConfigInfo change() /*-{ return this.change; }-*/;
@@ -29,6 +36,18 @@ public class ServerInfo extends JavaScriptObject {
   public final native UserConfigInfo user() /*-{ return this.user; }-*/;
   public final native ReceiveInfo receive() /*-{ return this.receive; }-*/;
 
+  public final Map<String, String> urlAliases() {
+    Map<String, String> urlAliases = new HashMap<>();
+    for (String k : Natives.keys(_urlAliases())) {
+      urlAliases.put(k, urlAliasToken(k));
+    }
+    return urlAliases;
+  }
+
+  public final native String urlAliasToken(String n) /*-{ return this.url_aliases[n]; }-*/;
+  private final native NativeMap<NativeString> _urlAliases() /*-{ return this.url_aliases; }-*/;
+
+
   public final boolean hasContactStore() {
     return contactStore() != null;
   }

gerrit-server/src/main/java/com/google/gerrit/server/config/GetServerInfo.java

@@ -47,6 +47,10 @@ import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 public class GetServerInfo implements RestReadView<ConfigResource> {
+  private final static String URL_ALIAS = "urlAlias";
+  private final static String KEY_MATCH = "match";
+  private final static String KEY_TOKEN = "token";
+
   private final Config config;
   private final AuthConfig authConfig;
   private final Realm realm;
@@ -102,6 +106,10 @@ public class GetServerInfo implements RestReadView<ConfigResource> {
     info.plugin = getPluginInfo();
     info.sshd = getSshdInfo(config);
     info.suggest = getSuggestInfo(config);
+
+    Map<String, String> urlAliases = getUrlAliasesInfo(config);
+    info.urlAliases = !urlAliases.isEmpty() ? urlAliases : null;
+
     info.user = getUserInfo(anonymousCowardName);
     info.receive = getReceiveInfo(config);
     return info;
@@ -267,6 +275,15 @@ public class GetServerInfo implements RestReadView<ConfigResource> {
     return info;
   }
 
+  private Map<String, String> getUrlAliasesInfo(Config cfg) {
+    Map<String, String> urlAliases = new HashMap<>();
+    for (String subsection : cfg.getSubsections(URL_ALIAS)) {
+      urlAliases.put(cfg.getString(URL_ALIAS, subsection, KEY_MATCH),
+         cfg.getString(URL_ALIAS, subsection, KEY_TOKEN));
+    }
+    return urlAliases;
+  }
+
   private SshdInfo getSshdInfo(Config cfg) {
     String[] addr = cfg.getStringList("sshd", null, "listenAddress");
     if (addr.length == 1 && isOff(addr[0])) {
@@ -313,6 +330,7 @@ public class GetServerInfo implements RestReadView<ConfigResource> {
     public PluginConfigInfo plugin;
     public SshdInfo sshd;
     public SuggestInfo suggest;
+    public Map<String, String> urlAliases;
     public UserConfigInfo user;
     public ReceiveInfo receive;
   }