// 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_GROUPS;
import static com.google.gerrit.common.PageLinks.ADMIN_PROJECTS;
import static com.google.gerrit.common.PageLinks.MINE;
import static com.google.gerrit.common.PageLinks.MINE_DRAFTS;
import static com.google.gerrit.common.PageLinks.MINE_STARRED;
import static com.google.gerrit.common.PageLinks.REGISTER;
import static com.google.gerrit.common.PageLinks.SETTINGS;
import static com.google.gerrit.common.PageLinks.SETTINGS_NEW_AGREEMENT;
import static com.google.gerrit.common.PageLinks.SETTINGS_WEBIDENT;
import static com.google.gerrit.common.PageLinks.TOP;

import com.google.gerrit.client.account.AccountSettings;
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.AccountGroupScreen;
import com.google.gerrit.client.admin.GroupListScreen;
import com.google.gerrit.client.admin.ProjectAdminScreen;
import com.google.gerrit.client.admin.ProjectListScreen;
import com.google.gerrit.client.auth.openid.OpenIdSignInDialog;
import com.google.gerrit.client.auth.userpass.UserPassSignInDialog;
import com.google.gerrit.client.changes.AccountDashboardScreen;
import com.google.gerrit.client.changes.AllAbandonedChangesScreen;
import com.google.gerrit.client.changes.AllMergedChangesScreen;
import com.google.gerrit.client.changes.AllOpenChangesScreen;
import com.google.gerrit.client.changes.ByProjectAbandonedChangesScreen;
import com.google.gerrit.client.changes.ByProjectMergedChangesScreen;
import com.google.gerrit.client.changes.ByProjectOpenChangesScreen;
import com.google.gerrit.client.changes.ChangeQueryResultsScreen;
import com.google.gerrit.client.changes.ChangeScreen;
import com.google.gerrit.client.changes.MineDraftsScreen;
import com.google.gerrit.client.changes.MineStarredScreen;
import com.google.gerrit.client.changes.PatchTable;
import com.google.gerrit.client.changes.PublishCommentScreen;
import com.google.gerrit.client.patches.PatchScreen;
import com.google.gerrit.client.ui.Screen;
import com.google.gerrit.common.PageLinks;
import com.google.gerrit.common.auth.SignInMode;
import com.google.gerrit.reviewdb.Account;
import com.google.gerrit.reviewdb.AccountGroup;
import com.google.gerrit.reviewdb.Change;
import com.google.gerrit.reviewdb.Patch;
import com.google.gerrit.reviewdb.PatchSet;
import com.google.gerrit.reviewdb.Project;
import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.RunAsyncCallback;
import com.google.gwtorm.client.KeyUtil;

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

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

  public static String toPatch(final String type, final Patch.Key id) {
    return "patch," + type + "," + id.toString();
  }

  public static String toAccountGroup(final AccountGroup.Id id) {
    return "admin,group," + id.toString();
  }

  public static String toProjectAdmin(final Project.NameKey n, final String tab) {
    return "admin,project," + n.toString() + "," + tab;
  }

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

  void display(String token) {
    assert token != null;
    try {
      try {
        if (token.startsWith(RELOAD_UI)) {
          wasStartedByReloadUI = true;
          token = skip(RELOAD_UI, 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 (token.startsWith("patch,")) {
      patch(token, null, 0, null);

    } else if (token.startsWith("change,publish,")) {
      publish(token);

    } else if (MINE.equals(token) || token.startsWith("mine,")) {
      Gerrit.display(token, mine(token));

    } else if (token.startsWith("all,")) {
      Gerrit.display(token, all(token));

    } else if (token.startsWith("project,")) {
      Gerrit.display(token, project(token));

    } else if (SETTINGS.equals(token) //
        || REGISTER.equals(token) //
        || token.startsWith("settings,") //
        || token.startsWith("register,") //
        || token.startsWith("VE,") //
        || token.startsWith("SignInFailure,")) {
      settings(token);

    } else if (token.startsWith("admin,")) {
      admin(token);

    } else {
      Gerrit.display(token, core(token));
    }
  }

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

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

    } else if (MINE_STARRED.equals(token)) {
      return new MineStarredScreen();

    } else if (MINE_DRAFTS.equals(token)) {
      return new MineDraftsScreen();

    } else {
      return new NotFoundScreen();
    }
  }

  private static Screen all(final String token) {
    String p;

    p = "all,abandoned,";
    if (token.startsWith(p)) {
      return new AllAbandonedChangesScreen(skip(p, token));
    }

    p = "all,merged,";
    if (token.startsWith(p)) {
      return new AllMergedChangesScreen(skip(p, token));
    }

    p = "all,open,";
    if (token.startsWith(p)) {
      return new AllOpenChangesScreen(skip(p, token));
    }
    return new NotFoundScreen();
  }

  private static Screen project(final String token) {
    String p;

    p = "project,open,";
    if (token.startsWith(p)) {
      final String s = skip(p, token);
      final int c = s.indexOf(',');
      return new ByProjectOpenChangesScreen(Project.NameKey.parse(s.substring(
          0, c)), s.substring(c + 1));
    }

    p = "project,merged,";
    if (token.startsWith(p)) {
      final String s = skip(p, token);
      final int c = s.indexOf(',');
      return new ByProjectMergedChangesScreen(Project.NameKey.parse(s
          .substring(0, c)), s.substring(c + 1));
    }

    p = "project,abandoned,";
    if (token.startsWith(p)) {
      final String s = skip(p, token);
      final int c = s.indexOf(',');
      return new ByProjectAbandonedChangesScreen(Project.NameKey.parse(s
          .substring(0, c)), s.substring(c + 1));
    }
    return new NotFoundScreen();
  }

  private static Screen core(final String token) {
    String p;

    p = "change,";
    if (token.startsWith(p))
      return new ChangeScreen(Change.Id.parse(skip(p, token)));

    p = "dashboard,";
    if (token.startsWith(p))
      return new AccountDashboardScreen(Account.Id.parse(skip(p, token)));

    p = "q,";
    if (token.startsWith(p)) {
      final String s = skip(p, token);
      final int c = s.indexOf(',');
      return new ChangeQueryResultsScreen(s.substring(0, c), s.substring(c + 1));
    }

    return new NotFoundScreen();
  }

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

      private Screen select() {
        String p = "change,publish,";
        if (token.startsWith(p))
          return new PublishCommentScreen(PatchSet.Id.parse(skip(p, token)));
        return new NotFoundScreen();
      }
    }.onSuccess();
  }

  public static void patch(String token, final Patch.Key id,
      final int patchIndex, final PatchTable patchTable) {
    GWT.runAsync(new AsyncSplit(token) {
      public void onSuccess() {
        Gerrit.display(token, select());
      }

      private Screen select() {
        String p;

        p = "patch,sidebyside,";
        if (token.startsWith(p)) {
          return new PatchScreen.SideBySide( //
              id != null ? id : Patch.Key.parse(skip(p, token)), //
              patchIndex, //
              patchTable //
          );
        }

        p = "patch,unified,";
        if (token.startsWith(p)) {
          return new PatchScreen.Unified( //
              id != null ? id : Patch.Key.parse(skip(p, token)), //
              patchIndex, //
              patchTable //
          );
        }

        return new NotFoundScreen();
      }
    });
  }

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

      private Screen select() {
        String p;

        p = "register,";
        if (token.startsWith(p)) {
          return new RegisterScreen(skip(p, token));
        } else if (REGISTER.equals(token)) {
          return new RegisterScreen(MINE);
        }

        p = "VE,";
        if (token.startsWith(p))
          return new ValidateEmailScreen(skip(p, token));

        p = "SignInFailure,";
        if (token.startsWith(p)) {
          final String[] args = skip(p, token).split(",");
          final SignInMode mode = SignInMode.valueOf(args[0]);
          final String msg = KeyUtil.decode(args[1]);
          final String to = PageLinks.MINE;
          switch (Gerrit.getConfig().getAuthType()) {
            case OPENID:
              new OpenIdSignInDialog(mode, to, msg).center();
              break;
            case LDAP:
            case LDAP_BIND:
              new UserPassSignInDialog(to, msg).center();
              break;
            default:
              return null;
          }
          switch (mode) {
            case SIGN_IN:
              return new AllOpenChangesScreen(TOP);
            case LINK_IDENTIY:
              return new AccountSettings(SETTINGS_WEBIDENT);
          }
        }

        if (SETTINGS_NEW_AGREEMENT.equals(token))
          return new NewAgreementScreen();

        p = SETTINGS_NEW_AGREEMENT + ",";
        if (token.startsWith(p)) {
          return new NewAgreementScreen(skip(p, token));
        }

        return new AccountSettings(token);
      }
    });
  }

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

      private Screen select() {
        String p;

        p = "admin,group,";
        if (token.startsWith(p))
          return new AccountGroupScreen(AccountGroup.Id.parse(skip(p, token)));

        p = "admin,project,";
        if (token.startsWith(p)) {
          p = skip(p, token);
          final int c = p.indexOf(',');
          final String idstr = p.substring(0, c);
          return new ProjectAdminScreen(Project.NameKey.parse(idstr), token);
        }

        if (ADMIN_GROUPS.equals(token)) {
          return new GroupListScreen();
        }

        if (ADMIN_PROJECTS.equals(token)) {
          return new ProjectListScreen();
        }

        return new NotFoundScreen();
      }
    });
  }

  private static String skip(final String prefix, final String in) {
    return in.substring(prefix.length());
  }

  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();
      }
    }
  }
}