// Copyright (C) 2008 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 static com.google.gerrit.common.PageLinks.ADMIN_CREATE_GROUP;
import static com.google.gerrit.common.PageLinks.ADMIN_CREATE_PROJECT;
import static com.google.gerrit.common.PageLinks.ADMIN_GROUPS;
import static com.google.gerrit.common.PageLinks.ADMIN_PLUGINS;
import static com.google.gerrit.common.PageLinks.ADMIN_PROJECTS;
import static com.google.gerrit.common.PageLinks.DASHBOARDS;
import static com.google.gerrit.common.PageLinks.MINE;
import static com.google.gerrit.common.PageLinks.PROJECTS;
import static com.google.gerrit.common.PageLinks.QUERY;
import static com.google.gerrit.common.PageLinks.REGISTER;
import static com.google.gerrit.common.PageLinks.SETTINGS;
import static com.google.gerrit.common.PageLinks.SETTINGS_AGREEMENTS;
import static com.google.gerrit.common.PageLinks.SETTINGS_CONTACT;
import static com.google.gerrit.common.PageLinks.SETTINGS_HTTP_PASSWORD;
import static com.google.gerrit.common.PageLinks.SETTINGS_MYGROUPS;
import static com.google.gerrit.common.PageLinks.SETTINGS_NEW_AGREEMENT;
import static com.google.gerrit.common.PageLinks.SETTINGS_PREFERENCES;
import static com.google.gerrit.common.PageLinks.SETTINGS_PROJECTS;
import static com.google.gerrit.common.PageLinks.SETTINGS_SSHKEYS;
import static com.google.gerrit.common.PageLinks.SETTINGS_WEBIDENT;
import static com.google.gerrit.common.PageLinks.op;
import static com.google.gerrit.common.PageLinks.toChangeQuery;

import com.google.gerrit.client.account.MyAgreementsScreen;
import com.google.gerrit.client.account.MyContactInformationScreen;
import com.google.gerrit.client.account.MyGroupsScreen;
import com.google.gerrit.client.account.MyIdentitiesScreen;
import com.google.gerrit.client.account.MyPasswordScreen;
import com.google.gerrit.client.account.MyPreferencesScreen;
import com.google.gerrit.client.account.MyProfileScreen;
import com.google.gerrit.client.account.MySshKeysScreen;
import com.google.gerrit.client.account.MyWatchedProjectsScreen;
import com.google.gerrit.client.account.NewAgreementScreen;
import com.google.gerrit.client.account.RegisterScreen;
import com.google.gerrit.client.account.ValidateEmailScreen;
import com.google.gerrit.client.admin.AccountGroupInfoScreen;
import com.google.gerrit.client.admin.AccountGroupMembersScreen;
import com.google.gerrit.client.admin.AccountGroupScreen;
import com.google.gerrit.client.admin.CreateGroupScreen;
import com.google.gerrit.client.admin.CreateProjectScreen;
import com.google.gerrit.client.admin.GroupListScreen;
import com.google.gerrit.client.admin.PluginListScreen;
import com.google.gerrit.client.admin.ProjectAccessScreen;
import com.google.gerrit.client.admin.ProjectBranchesScreen;
import com.google.gerrit.client.admin.ProjectDashboardsScreen;
import com.google.gerrit.client.admin.ProjectInfoScreen;
import com.google.gerrit.client.admin.ProjectListScreen;
import com.google.gerrit.client.admin.ProjectScreen;
import com.google.gerrit.client.api.ExtensionScreen;
import com.google.gerrit.client.change.ChangeScreen2;
import com.google.gerrit.client.changes.AccountDashboardScreen;
import com.google.gerrit.client.changes.ChangeScreen;
import com.google.gerrit.client.changes.CustomDashboardScreen;
import com.google.gerrit.client.changes.PatchTable;
import com.google.gerrit.client.changes.ProjectDashboardScreen;
import com.google.gerrit.client.changes.PublishCommentScreen;
import com.google.gerrit.client.changes.QueryScreen;
import com.google.gerrit.client.dashboards.DashboardInfo;
import com.google.gerrit.client.dashboards.DashboardList;
import com.google.gerrit.client.diff.DisplaySide;
import com.google.gerrit.client.diff.SideBySide2;
import com.google.gerrit.client.documentation.DocScreen;
import com.google.gerrit.client.groups.GroupApi;
import com.google.gerrit.client.groups.GroupInfo;
import com.google.gerrit.client.patches.PatchScreen;
import com.google.gerrit.client.rpc.GerritCallback;
import com.google.gerrit.client.rpc.RestApi;
import com.google.gerrit.client.ui.Screen;
import com.google.gerrit.common.PageLinks;
import com.google.gerrit.common.data.PatchSetDetail;
import com.google.gerrit.reviewdb.client.Account;
import com.google.gerrit.reviewdb.client.AccountGeneralPreferences;
import com.google.gerrit.reviewdb.client.AccountGeneralPreferences.DiffView;
import com.google.gerrit.reviewdb.client.AccountGroup;
import com.google.gerrit.reviewdb.client.Change;
import com.google.gerrit.reviewdb.client.Patch;
import com.google.gerrit.reviewdb.client.PatchSet;
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.user.client.Cookies;
import com.google.gwt.user.client.Window;
import com.google.gwtorm.client.KeyUtil;

public class Dispatcher {
  public static final String COOKIE_CS2 = "gerrit_cs2";
  public static boolean changeScreen2;

  public static String toPatchSideBySide(final Patch.Key id) {
    return toPatch("", null, id);
  }

  public static String toPatchSideBySide(PatchSet.Id diffBase, Patch.Key id) {
    return toPatch("", diffBase, id);
  }

  public static String toSideBySide(PatchSet.Id diffBase,
      PatchSet.Id revision, String fileName) {
    return toPatch("", diffBase, revision, fileName, null, 0);
  }

  public static String toSideBySide(PatchSet.Id diffBase,
      PatchSet.Id revision, String fileName, DisplaySide side, int line) {
    return toPatch("", diffBase, revision, fileName, side, line);
  }

  public static String toUnified(PatchSet.Id diffBase,
      PatchSet.Id revision, String fileName) {
    return toPatch("unified", diffBase, revision, fileName, null, 0);
  }

  public static String toPatchUnified(final Patch.Key id) {
    return toPatch("unified", null, id);
  }

  public static String toPatchUnified(PatchSet.Id diffBase, Patch.Key id) {
    return toPatch("unified", diffBase, id);
  }

  private static String toPatch(String type, PatchSet.Id diffBase, Patch.Key id) {
    return toPatch(type, diffBase, id.getParentKey(), id.get(), null, 0);
  }

  private static String toPatch(String type, PatchSet.Id diffBase,
      PatchSet.Id revision, String fileName, DisplaySide side, int line) {
    Change.Id c = revision.getParentKey();
    StringBuilder p = new StringBuilder();
    p.append("/c/").append(c).append("/");
    if (diffBase != null) {
      p.append(diffBase.get()).append("..");
    }
    p.append(revision.get()).append("/").append(KeyUtil.encode(fileName));
    if (type != null && !type.isEmpty()) {
      p.append(",").append(type);
    }
    if (side == DisplaySide.A && line > 0) {
      p.append("@a").append(line);
    } else if (line > 0) {
      p.append("@").append(line);
    }
    return p.toString();
  }

  public static String toPatch(final PatchScreen.Type type, final Patch.Key id) {
    if (type == PatchScreen.Type.SIDE_BY_SIDE) {
      return toPatchSideBySide(id);
    } else {
      return toPatchUnified(id);
    }
  }

  public static String toPublish(PatchSet.Id ps) {
    Change.Id c = ps.getParentKey();
    return "/c/" + c + "/" + ps.get() + ",publish";
  }

  public static String toGroup(final AccountGroup.Id id) {
    return ADMIN_GROUPS + id.toString();
  }

  public static String toGroup(AccountGroup.Id id, String panel) {
    return ADMIN_GROUPS + id.toString() + "," + panel;
  }

  public static String toGroup(AccountGroup.UUID uuid) {
    return PageLinks.toGroup(uuid);
  }

  public static String toGroup(AccountGroup.UUID uuid, String panel) {
    return toGroup(uuid) + "," + panel;
  }

  public static String toProject(Project.NameKey n) {
    return toProjectAdmin(n, ProjectScreen.getSavedPanel());
  }

  public static String toProjectAdmin(Project.NameKey n, String panel) {
    if (panel == null || ProjectScreen.INFO.equals(panel)) {
      return ADMIN_PROJECTS + n.toString();
    }
    return ADMIN_PROJECTS + n.toString() + "," + panel;
  }

  static final String RELOAD_UI = "/reload-ui/";
  private static boolean wasStartedByReloadUI;

  void display(String token) {
    assert token != null;
    try {
      try {
        if (matchPrefix(RELOAD_UI, token)) {
          wasStartedByReloadUI = true;
          token = skip(token);
        }
        select(token);
      } finally {
        wasStartedByReloadUI = false;
      }
    } catch (RuntimeException err) {
      GWT.log("Error parsing history token: " + token, err);
      Gerrit.display(token, new NotFoundScreen());
    }
  }

  private static void select(final String token) {
    if (matchPrefix(QUERY, token)) {
      query(token);

    } else if (matchPrefix("/Documentation/", token)) {
      docSearch(token);

    } else if (matchPrefix("/c/", token)) {
      change(token);

    } else if (matchPrefix("/x/", token)) {
      extension(token);

    } else if (matchExact(MINE, token)) {
      Gerrit.display(token, mine(token));

    } else if (matchPrefix("/dashboard/", token)) {
      dashboard(token);

    } else if (matchPrefix(PROJECTS, token)) {
      projects(token);

    } else if (matchExact(SETTINGS, token) //
        || matchPrefix("/settings/", token) //
        || matchExact("register", token) //
        || matchExact(REGISTER, token) //
        || matchPrefix("/register/", token) //
        || matchPrefix("/VE/", token) || matchPrefix("VE,", token) //
        || matchPrefix("/SignInFailure,", token)) {
      settings(token);

    } else if (matchPrefix("/admin/", token)) {
      admin(token);

    } else if (/* DEPRECATED URL */matchPrefix("/c2/", token)) {
      changeScreen2 = true;
      change(token);
    } else if (/* LEGACY URL */matchPrefix("all,", token)) {
      redirectFromLegacyToken(token, legacyAll(token));
    } else if (/* LEGACY URL */matchPrefix("mine,", token)
        || matchExact("mine", token)) {
      redirectFromLegacyToken(token, legacyMine(token));
    } else if (/* LEGACY URL */matchPrefix("project,", token)) {
      redirectFromLegacyToken(token, legacyProject(token));
    } else if (/* LEGACY URL */matchPrefix("change,", token)) {
      redirectFromLegacyToken(token, legacyChange(token));
    } else if (/* LEGACY URL */matchPrefix("patch,", token)) {
      redirectFromLegacyToken(token, legacyPatch(token));
    } else if (/* LEGACY URL */matchPrefix("admin,", token)) {
      redirectFromLegacyToken(token, legacyAdmin(token));
    } else if (/* LEGACY URL */matchPrefix("settings,", token)
        || matchPrefix("register,", token)
        || matchPrefix("q,", token)) {
      redirectFromLegacyToken(token, legacySettings(token));

    } else {
      Gerrit.display(token, new NotFoundScreen());
    }
  }

  private static void redirectFromLegacyToken(String oldToken, String newToken) {
    if (newToken != null) {
      Window.Location.replace(Window.Location.getPath() + "#" + newToken);
    } else {
      Gerrit.display(oldToken, new NotFoundScreen());
    }
  }

  private static String legacyMine(final String token) {
    if (matchExact("mine", token)) {
      return MINE;
    }

    if (matchExact("mine,starred", token)) {
      return toChangeQuery("is:starred");
    }

    if (matchExact("mine,drafts", token)) {
      return toChangeQuery("is:draft");
    }

    if (matchExact("mine,comments", token)) {
      return toChangeQuery("has:draft");
    }

    if (matchPrefix("mine,watched,", token)) {
      return toChangeQuery("is:watched status:open");
    }

    return null;
  }

  private static String legacyAll(final String token) {
    if (matchPrefix("all,abandoned,", token)) {
      return toChangeQuery("status:abandoned");
    }

    if (matchPrefix("all,merged,", token)) {
      return toChangeQuery("status:merged");
    }

    if (matchPrefix("all,open,", token)) {
      return toChangeQuery("status:open");
    }

    return null;
  }

  private static String legacyProject(final String token) {
    if (matchPrefix("project,open,", token)) {
      final String s = skip(token);
      final int c = s.indexOf(',');
      Project.NameKey proj = Project.NameKey.parse(s.substring(0, c));
      return toChangeQuery("status:open " + op("project", proj.get()));
    }

    if (matchPrefix("project,merged,", token)) {
      final String s = skip(token);
      final int c = s.indexOf(',');
      Project.NameKey proj = Project.NameKey.parse(s.substring(0, c));
      return toChangeQuery("status:merged " + op("project", proj.get()));
    }

    if (matchPrefix("project,abandoned,", token)) {
      final String s = skip(token);
      final int c = s.indexOf(',');
      Project.NameKey proj = Project.NameKey.parse(s.substring(0, c));
      return toChangeQuery("status:abandoned " + op("project", proj.get()));
    }

    return null;
  }

  private static String legacyChange(final String token) {
    final String s = skip(token);
    final String t[] = s.split(",", 2);
    if (t.length > 1 && matchPrefix("patchset=", t[1])) {
      return PageLinks.toChange(PatchSet.Id.parse(t[0] + "," + skip(t[1])));
    }
    return PageLinks.toChange(Change.Id.parse(t[0]));
  }

  private static String legacyPatch(String token) {
    if (/* LEGACY URL */matchPrefix("patch,sidebyside,", token)) {
      return toPatchSideBySide(Patch.Key.parse(skip(token)));
    }

    if (/* LEGACY URL */matchPrefix("patch,unified,", token)) {
      return toPatchUnified(Patch.Key.parse(skip(token)));
    }

    return null;
  }

  private static String legacyAdmin(String token) {
    if (matchPrefix("admin,group,", token)) {
      return ADMIN_GROUPS + skip(token);
    }

    if (matchPrefix("admin,project,", token)) {
      String rest = skip(token);
      int c = rest.indexOf(',');
      String panel;
      Project.NameKey k;
      if (0 < c) {
        panel = rest.substring(c + 1);
        k = Project.NameKey.parse(rest.substring(0, c));
      } else {
        panel = ProjectScreen.INFO;
        k = Project.NameKey.parse(rest);
      }
      return toProjectAdmin(k, panel);
    }

    return null;
  }

  private static String legacySettings(String token) {
    int c = token.indexOf(',');
    if (0 < c) {
      return "/" + token.substring(0, c) + "/" + token.substring(c + 1);
    }
    return null;
  }

  private static void query(String token) {
    String s = skip(token);
    int c = s.indexOf(',');
    Screen screen;
    if (c >= 0) {
      String prefix = s.substring(0, c);
      if (s.substring(c).equals(",n,z")) {
        // Respect legacy token with max sortkey.
        screen = new QueryScreen(prefix, 0);
      } else {
        screen = new QueryScreen(prefix, Integer.parseInt(s.substring(c + 1)));
      }
    } else {
      screen = new QueryScreen(s, 0);
    }
    Gerrit.display(token, screen);
  }

  private static Screen mine(final String token) {
    if (Gerrit.isSignedIn()) {
      return new AccountDashboardScreen(Gerrit.getUserAccount().getId());

    } else {
      Screen r = new AccountDashboardScreen(null);
      r.setRequiresSignIn(true);
      return r;
    }
  }

  private static void dashboard(final String token) {
    String rest = skip(token);
    if (rest.matches("[0-9]+")) {
      Gerrit.display(token, new AccountDashboardScreen(Account.Id.parse(rest)));
      return;
    }

    if (rest.startsWith("?")) {
      Gerrit.display(token, new CustomDashboardScreen(rest.substring(1)));
      return;
    }

    Gerrit.display(token, new NotFoundScreen());
  }

  private static void projects(final String token) {
    String rest = skip(token);
    int c = rest.indexOf(DASHBOARDS);
    if (0 <= c) {
      final String project = URL.decodePathSegment(rest.substring(0, c));
      rest = rest.substring(c);
      if (matchPrefix(DASHBOARDS, rest)) {
        final String dashboardId = skip(rest);
        GerritCallback<DashboardInfo> cb = new GerritCallback<DashboardInfo>() {
          @Override
          public void onSuccess(DashboardInfo result) {
            if (matchPrefix("/dashboard/", result.url())) {
              String params = skip(result.url()).substring(1);
              ProjectDashboardScreen dash = new ProjectDashboardScreen(
                  new Project.NameKey(project), params);
              Gerrit.display(token, dash);
            }
          }

          @Override
          public void onFailure(Throwable caught) {
            if ("default".equals(dashboardId) && RestApi.isNotFound(caught)) {
              Gerrit.display(toChangeQuery(
                  PageLinks.projectQuery(new Project.NameKey(project))));
            } else {
              super.onFailure(caught);
            }
          }
        };
        if ("default".equals(dashboardId)) {
          DashboardList.getDefault(new Project.NameKey(project), cb);
          return;
        }
        c = dashboardId.indexOf(":");
        if (0 <= c) {
          final String ref = URL.decodeQueryString(dashboardId.substring(0, c));
          final String path = URL.decodeQueryString(dashboardId.substring(c + 1));
          DashboardList.get(new Project.NameKey(project), ref + ":" + path, cb);
          return;
        }
      }
    }

    Gerrit.display(token, new NotFoundScreen());
  }

  private static void change(final String token) {
    String rest = skip(token);
    int c = rest.lastIndexOf(',');
    String panel = null;
    if (0 <= c) {
      panel = rest.substring(c + 1);
      rest = rest.substring(0, c);
    }

    Change.Id id;
    int s = rest.indexOf('/');
    if (0 <= s) {
      id = Change.Id.parse(rest.substring(0, s));
      rest = rest.substring(s + 1);
    } else {
      id = Change.Id.parse(rest);
      rest = "";
    }

    if (rest.isEmpty()) {
      Gerrit.display(token, panel== null
          ? (isChangeScreen2()
              ? new ChangeScreen2(id, null, null, false)
              : new ChangeScreen(id))
          : new NotFoundScreen());
      return;
    }

    String psIdStr;
    s = rest.indexOf('/');
    if (0 <= s) {
      psIdStr = rest.substring(0, s);
      rest = rest.substring(s + 1);
    } else {
      psIdStr = rest;
      rest = "";
    }

    PatchSet.Id base;
    PatchSet.Id ps;
    int dotdot = psIdStr.indexOf("..");
    if (1 <= dotdot) {
      base = new PatchSet.Id(id, Integer.parseInt(psIdStr.substring(0, dotdot)));
      ps = new PatchSet.Id(id, Integer.parseInt(psIdStr.substring(dotdot + 2)));
    } else {
      base = null;
      ps = new PatchSet.Id(id, Integer.parseInt(psIdStr));
    }

    if (!rest.isEmpty()) {
      DisplaySide side = DisplaySide.B;
      int line = 0;
      int at = rest.lastIndexOf('@');
      if (at > 0) {
        String l = rest.substring(at+1);
        if (l.startsWith("a")) {
          side = DisplaySide.A;
          l = l.substring(1);
        }
        line = Integer.parseInt(l);
        rest = rest.substring(0, at);
      }
      Patch.Key p = new Patch.Key(ps, KeyUtil.decode(rest));
      patch(token, base, p, side, line, 0,
          null, null, null, panel);
    } else {
      if (panel == null) {
        Gerrit.display(token, isChangeScreen2()
            ? new ChangeScreen2(id,
                base != null
                    ? String.valueOf(base.get())
                    : null,
                String.valueOf(ps.get()), false)
            : new ChangeScreen(id));
      } else if ("publish".equals(panel)) {
        publish(ps);
      } else {
        Gerrit.display(token, new NotFoundScreen());
      }
    }
  }

  private static void extension(final String token) {
    ExtensionScreen view = new ExtensionScreen(skip(token));
    if (view.isFound()) {
      Gerrit.display(token, view);
    } else {
      Gerrit.display(token, new NotFoundScreen());
    }
  }

  public static boolean isChangeScreen2() {
    if (!Gerrit.getConfig().getNewFeatures()) {
      return false;
    } else if (changeScreen2) {
      return true;
    }

    AccountGeneralPreferences.ChangeScreen ui = null;
    if (Gerrit.isSignedIn()) {
      ui = Gerrit.getUserAccount()
          .getGeneralPreferences()
          .getChangeScreen();
    }
    String v = Cookies.getCookie(Dispatcher.COOKIE_CS2);
    if (v != null) {
      changeScreen2 = "1".equals(v);
      return changeScreen2;
    }
    if (ui == null) {
      ui = Gerrit.getConfig().getChangeScreen();
    }
    return ui == AccountGeneralPreferences.ChangeScreen.CHANGE_SCREEN2;
  }

  private static void publish(final PatchSet.Id ps) {
    String token = toPublish(ps);
    new AsyncSplit(token) {
      public void onSuccess() {
        Gerrit.display(token, select());
      }

      private Screen select() {
        return new PublishCommentScreen(ps);
      }
    }.onSuccess();
  }

  public static void patch(String token, PatchSet.Id base, Patch.Key id,
      int patchIndex, PatchSetDetail patchSetDetail,
      PatchTable patchTable, PatchScreen.TopView topView) {
    patch(token, base, id, null, 0, patchIndex,
        patchSetDetail, patchTable, topView, null);
  }

  public static void patch(String token, final PatchSet.Id baseId, final Patch.Key id,
      final DisplaySide side, final int line,
      final int patchIndex, final PatchSetDetail patchSetDetail,
      final PatchTable patchTable, final PatchScreen.TopView topView,
      final String panelType) {
    final PatchScreen.TopView top =  topView == null ?
        Gerrit.getPatchScreenTopView() : topView;

    GWT.runAsync(new AsyncSplit(token) {
      public void onSuccess() {
        Gerrit.display(token, select());
      }

      private Screen select() {
        if (id != null) {
          String panel = panelType;
          if (panel == null) {
            int c = token.lastIndexOf(',');
            panel = 0 <= c ? token.substring(c + 1) : "";
          }

          if ("".equals(panel)) {
            if (isChangeScreen2()) {
              if (Gerrit.isSignedIn()
                  && DiffView.UNIFIED_DIFF.equals(Gerrit.getUserAccount()
                      .getGeneralPreferences().getDiffView())) {
                return new PatchScreen.Unified(id, patchIndex, patchSetDetail,
                    patchTable, top, baseId);
              }
              return new SideBySide2(baseId, id.getParentKey(), id.get(),
                  side, line);
            }
            return new PatchScreen.SideBySide( //
                id, //
                patchIndex, //
                patchSetDetail, //
                patchTable, //
                top, //
                baseId //
            );
          } else if ("unified".equals(panel)) {
            return new PatchScreen.Unified( //
                id, //
                patchIndex, //
                patchSetDetail, //
                patchTable, //
                top, //
                baseId //
            );
          } else if ("cm".equals(panel) && Gerrit.getConfig().getNewFeatures()) {
            if (Gerrit.isSignedIn()
                && DiffView.UNIFIED_DIFF.equals(Gerrit.getUserAccount()
                    .getGeneralPreferences().getDiffView())) {
              return new PatchScreen.Unified( //
                  id, //
                  patchIndex, //
                  patchSetDetail, //
                  patchTable, //
                  top, //
                  baseId //
              );
            }
            return new SideBySide2(baseId, id.getParentKey(), id.get(),
                side, line);
          } else if ("".equals(panel) || "sidebyside".equals(panel)) {
            return new PatchScreen.SideBySide(//
                id, //
                patchIndex,//
                patchSetDetail,//
                patchTable,//
                top,//
                baseId);//
          }
        }

        return new NotFoundScreen();
      }
    });
  }

  private static void settings(String token) {
    GWT.runAsync(new AsyncSplit(token) {
      public void onSuccess() {
        Gerrit.display(token, select());
      }

      private Screen select() {
        if (matchExact(SETTINGS, token)) {
          return new MyProfileScreen();
        }

        if (matchExact(SETTINGS_PREFERENCES, token)) {
          return new MyPreferencesScreen();
        }

        if (matchExact(SETTINGS_PROJECTS, token)) {
          return new MyWatchedProjectsScreen();
        }

        if (matchExact(SETTINGS_CONTACT, token)) {
          return new MyContactInformationScreen();
        }

        if (matchExact(SETTINGS_SSHKEYS, token)) {
          return new MySshKeysScreen();
        }

        if (matchExact(SETTINGS_WEBIDENT, token)) {
          return new MyIdentitiesScreen();
        }

        if (matchExact(SETTINGS_HTTP_PASSWORD, token)) {
          return new MyPasswordScreen();
        }

        if (matchExact(SETTINGS_MYGROUPS, token)) {
          return new MyGroupsScreen();
        }

        if (matchExact(SETTINGS_AGREEMENTS, token)
            && Gerrit.getConfig().isUseContributorAgreements()) {
          return new MyAgreementsScreen();
        }

        if (matchExact(REGISTER, token)
            || matchExact("/register/", token)
            || matchExact("register", token)) {
          return new RegisterScreen(MINE);
        } else if (matchPrefix("/register/", token)) {
          return new RegisterScreen("/" + skip(token));
        }

        if (matchPrefix("/VE/", token) || matchPrefix("VE,", token))
          return new ValidateEmailScreen(skip(token));

        if (matchExact(SETTINGS_NEW_AGREEMENT, token))
          return new NewAgreementScreen();

        if (matchPrefix(SETTINGS_NEW_AGREEMENT + "/", token)) {
          return new NewAgreementScreen(skip(token));
        }

        return new NotFoundScreen();
      }
    });
  }

  private static void admin(String token) {
    GWT.runAsync(new AsyncSplit(token) {
      public void onSuccess() {
        if (matchExact(ADMIN_GROUPS, token)
            || matchExact("/admin/groups", token)) {
          Gerrit.display(token, new GroupListScreen());

        } else if (matchPrefix(ADMIN_GROUPS, token)) {
          String rest = skip(token);
          if (rest.startsWith("?")) {
            Gerrit.display(token, new GroupListScreen(rest.substring(1)));
          } else {
            group();
          }

        } else if (matchPrefix("/admin/groups", token)) {
          String rest = skip(token);
          if (rest.startsWith("?")) {
            Gerrit.display(token, new GroupListScreen(rest.substring(1)));
          }

        } else if (matchExact(ADMIN_PROJECTS, token)
            || matchExact("/admin/projects", token)) {
          Gerrit.display(token, new ProjectListScreen());

        } else if (matchPrefix(ADMIN_PROJECTS, token)) {
            String rest = skip(token);
            if (rest.startsWith("?")) {
              Gerrit.display(token, new ProjectListScreen(rest.substring(1)));
            } else {
              Gerrit.display(token, selectProject());
            }

        } else if (matchPrefix("/admin/projects", token)) {
          String rest = skip(token);
          if (rest.startsWith("?")) {
            Gerrit.display(token, new ProjectListScreen(rest.substring(1)));
          }

        } else if (matchPrefix(ADMIN_PLUGINS, token)
            || matchExact("/admin/plugins", token)) {
          Gerrit.display(token, new PluginListScreen());

        } else if (matchExact(ADMIN_CREATE_PROJECT, token)
            || matchExact("/admin/create-project", token)) {
          Gerrit.display(token, new CreateProjectScreen());

        } else if (matchExact(ADMIN_CREATE_GROUP, token)
            || matchExact("/admin/create-group", token)) {
          Gerrit.display(token, new CreateGroupScreen());

        } else {
          Gerrit.display(token, new NotFoundScreen());
        }
      }

      private void group() {
        final String panel;
        final String group;

        if (matchPrefix("/admin/groups/uuid-", token)) {
          String p = skip(token);
          int c = p.indexOf(',');
          if (c < 0) {
            group = p;
            panel = null;
          } else {
            group = p.substring(0, c);
            panel = p.substring(c + 1);
          }
        } else if (matchPrefix(ADMIN_GROUPS, token)) {
          String p = skip(token);
          int c = p.indexOf(',');
          if (c < 0) {
            group = p;
            panel = null;
          } else {
            group = p.substring(0, c);
            panel = p.substring(c + 1);
          }
        } else {
          Gerrit.display(token, new NotFoundScreen());
          return;
        }

        GroupApi.getGroupDetail(group, new GerritCallback<GroupInfo>() {
          @Override
          public void onSuccess(GroupInfo group) {
            if (panel == null || panel.isEmpty()) {
              // The token does not say which group screen should be shown,
              // as default for internal groups show the members, as default
              // for external and system groups show the info screen (since
              // for external and system groups the members cannot be
              // shown in the web UI).
              //
              if (AccountGroup.isInternalGroup(group.getGroupUUID())) {
                Gerrit.display(toGroup(group.getGroupId(), AccountGroupScreen.MEMBERS),
                    new AccountGroupMembersScreen(group, token));
              } else {
                Gerrit.display(toGroup(group.getGroupId(), AccountGroupScreen.INFO),
                    new AccountGroupInfoScreen(group, token));
              }
            } else if (AccountGroupScreen.INFO.equals(panel)) {
              Gerrit.display(token, new AccountGroupInfoScreen(group, token));
            } else if (AccountGroupScreen.MEMBERS.equals(panel)) {
              Gerrit.display(token, new AccountGroupMembersScreen(group, token));
            } else {
              Gerrit.display(token, new NotFoundScreen());
            }
          }
        });
      }

      private Screen selectProject() {
        if (matchPrefix(ADMIN_PROJECTS, token)) {
          String rest = skip(token);
          int c = rest.lastIndexOf(',');
          if (c < 0) {
            return new ProjectInfoScreen(Project.NameKey.parse(rest));
          } else if (c == 0) {
            return new NotFoundScreen();
          }

          Project.NameKey k = Project.NameKey.parse(rest.substring(0, c));
          String panel = rest.substring(c + 1);

          if (ProjectScreen.INFO.equals(panel)) {
            return new ProjectInfoScreen(k);
          }

          if (ProjectScreen.BRANCH.equals(panel)) {
            return new ProjectBranchesScreen(k);
          }

          if (ProjectScreen.ACCESS.equals(panel)) {
            return new ProjectAccessScreen(k);
          }

          if (ProjectScreen.DASHBOARDS.equals(panel)) {
            return new ProjectDashboardsScreen(k);
          }
        }
        return new NotFoundScreen();
      }
    });
  }

  private static boolean matchExact(String want, String token) {
    return token.equals(want);
  }

  private static int prefixlen;

  private static boolean matchPrefix(String want, String token) {
    if (token.startsWith(want)) {
      prefixlen = want.length();
      return true;
    } else {
      return false;
    }
  }

  private static String skip(String token) {
    return token.substring(prefixlen);
  }

  private static abstract class AsyncSplit implements RunAsyncCallback {
    private final boolean isReloadUi;
    protected final String token;

    protected AsyncSplit(String token) {
      this.isReloadUi = wasStartedByReloadUI;
      this.token = token;
    }

    public final void onFailure(Throwable reason) {
      if (!isReloadUi
          && "HTTP download failed with status 404".equals(reason.getMessage())) {
        // The server was upgraded since we last download the main script,
        // so the pointers to the splits aren't valid anymore.  Force the
        // page to reload itself and pick up the new code.
        //
        Gerrit.upgradeUI(token);
      } else {
        new ErrorDialog(reason).center();
      }
    }
  }

  private static void docSearch(final String token) {
    GWT.runAsync(new AsyncSplit(token) {
      public void onSuccess() {
        Gerrit.display(token, new DocScreen(skip(token)));
      }
    });
  }
}