// Copyright (C) 2017 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.schema;

import static com.google.gerrit.server.group.SystemGroupBackend.REGISTERED_USERS;

import com.google.gerrit.common.data.AccessSection;
import com.google.gerrit.common.data.Permission;
import com.google.gerrit.common.data.PermissionRule;
import com.google.gerrit.common.data.PermissionRule.Action;
import com.google.gerrit.reviewdb.client.RefNames;
import com.google.gerrit.reviewdb.server.ReviewDb;
import com.google.gerrit.server.GerritPersonIdent;
import com.google.gerrit.server.config.AllUsersName;
import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
import com.google.gerrit.server.git.GitRepositoryManager;
import com.google.gerrit.server.git.meta.MetaDataUpdate;
import com.google.gerrit.server.group.SystemGroupBackend;
import com.google.gerrit.server.project.ProjectConfig;
import com.google.gerrit.server.project.RefPattern;
import com.google.gwtorm.server.OrmException;
import com.google.inject.Inject;
import com.google.inject.Provider;
import java.io.IOException;
import java.sql.SQLException;
import java.util.Optional;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.lib.PersonIdent;
import org.eclipse.jgit.lib.Repository;

/** Make default Label-Code-Review permission on user branches exclusive. */
public class Schema_165 extends SchemaVersion {
  private static final String COMMIT_MSG =
      "Make default Label-Code-Review permission on user branches exclusive";

  private final GitRepositoryManager repoManager;
  private final AllUsersName allUsersName;
  private final SystemGroupBackend systemGroupBackend;
  private final PersonIdent serverUser;

  @Inject
  Schema_165(
      Provider<Schema_164> prior,
      GitRepositoryManager repoManager,
      AllUsersName allUsersName,
      SystemGroupBackend systemGroupBackend,
      @GerritPersonIdent PersonIdent serverUser) {
    super(prior);
    this.repoManager = repoManager;
    this.allUsersName = allUsersName;
    this.systemGroupBackend = systemGroupBackend;
    this.serverUser = serverUser;
  }

  @Override
  protected void migrateData(ReviewDb db, UpdateUI ui) throws OrmException, SQLException {
    try (Repository git = repoManager.openRepository(allUsersName);
        MetaDataUpdate md = new MetaDataUpdate(GitReferenceUpdated.DISABLED, allUsersName, git)) {
      ProjectConfig config = ProjectConfig.read(md);
      Optional<Permission> permission = findDefaultPermission(config);
      if (!permission.isPresent()) {
        // the default permission was not found, hence it cannot be fixed
        return;
      }

      permission.get().setExclusiveGroup(true);

      md.getCommitBuilder().setAuthor(serverUser);
      md.getCommitBuilder().setCommitter(serverUser);
      md.setMessage(COMMIT_MSG);
      config.commit(md);
    } catch (IOException | ConfigInvalidException e) {
      throw new OrmException(
          "Failed to make default Label-Code-Review permission on user branches exclusive", e);
    }
  }

  /**
   * Searches for the default "Label-Code-Review" permission on the user branch and returns it if it
   * was found. If it was not found (e.g. because it was removed or modified) {@link
   * Optional#empty()} is returned.
   */
  private Optional<Permission> findDefaultPermission(ProjectConfig config) {
    AccessSection users =
        config.getAccessSection(
            RefNames.REFS_USERS + "${" + RefPattern.USERID_SHARDED + "}", false);
    if (users == null) {
      // default permission was removed
      return Optional.empty();
    }

    Permission permission = users.getPermission(Permission.LABEL + "Code-Review", false);
    return isDefaultPermissionUntouched(permission) ? Optional.of(permission) : Optional.empty();
  }

  /**
   * Checks whether the given permission matches the default "Label-Code-Review" permission on the
   * user branch that was initially setup by {@link AllUsersCreator}.
   */
  private boolean isDefaultPermissionUntouched(Permission permission) {
    if (permission == null) {
      // default permission was removed
      return false;
    } else if (permission.getExclusiveGroup()) {
      // default permission was modified
      return false;
    }

    if (permission.getRules().size() != 1) {
      // default permission was modified
      return false;
    }

    PermissionRule rule = permission.getRule(systemGroupBackend.getGroup(REGISTERED_USERS));
    if (rule == null) {
      // default permission was removed
      return false;
    }

    if (rule.getAction() != Action.ALLOW
        || rule.getForce()
        || rule.getMin() != -2
        || rule.getMax() != 2) {
      // default permission was modified
      return false;
    }

    return true;
  }
}