// Copyright (C) 2020 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.change;

import static com.google.gerrit.server.mail.send.AttentionSetChangeEmailDecorator.AttentionSetChange.USER_REMOVED;
import static java.util.Objects.requireNonNull;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.gerrit.common.Nullable;
import com.google.gerrit.entities.Account;
import com.google.gerrit.entities.AttentionSetUpdate;
import com.google.gerrit.entities.AttentionSetUpdate.Operation;
import com.google.gerrit.entities.Change;
import com.google.gerrit.extensions.restapi.RestApiException;
import com.google.gerrit.server.notedb.ChangeUpdate;
import com.google.gerrit.server.query.change.ChangeData;
import com.google.gerrit.server.update.BatchUpdateOp;
import com.google.gerrit.server.update.ChangeContext;
import com.google.gerrit.server.update.PostUpdateContext;
import com.google.gerrit.server.util.AttentionSetEmail;
import com.google.inject.Inject;
import com.google.inject.assistedinject.Assisted;
import java.util.Optional;

/** Remove a specified user from the attention set. */
public class RemoveFromAttentionSetOp implements BatchUpdateOp {
  public interface Factory {
    RemoveFromAttentionSetOp create(Account.Id attentionUserId, String reason, boolean notify);
  }

  private final ChangeData.Factory changeDataFactory;
  private final AttentionSetEmail.Factory attentionSetEmailFactory;

  private final Account.Id attentionUserId;
  private final String reason;

  private Change change;
  private boolean notify;
  @Nullable private AttentionSetUpdateCondition condition;

  /**
   * Remove a specified user from the attention set.
   *
   * @param attentionUserId the id of the user we want to add to the attention set.
   * @param reason the reason for adding that user.
   * @param notify whether or not to send emails if the operation is successful.
   */
  @Inject
  RemoveFromAttentionSetOp(
      ChangeData.Factory changeDataFactory,
      AttentionSetEmail.Factory attentionSetEmailFactory,
      @Assisted Account.Id attentionUserId,
      @Assisted String reason,
      @Assisted boolean notify) {
    this.changeDataFactory = changeDataFactory;
    this.attentionSetEmailFactory = attentionSetEmailFactory;
    this.attentionUserId = requireNonNull(attentionUserId, "user");
    this.reason = requireNonNull(reason, "reason");
    this.notify = notify;
  }

  /** Sets a condition for performing this attention set update. */
  @CanIgnoreReturnValue
  public RemoveFromAttentionSetOp setCondition(AttentionSetUpdateCondition condition) {
    this.condition = condition;
    return this;
  }

  @Override
  public boolean updateChange(ChangeContext ctx) throws RestApiException {
    if (condition != null && !condition.check()) {
      return false;
    }

    ChangeData changeData = changeDataFactory.create(ctx.getNotes());
    Optional<AttentionSetUpdate> existingEntry =
        changeData.attentionSet().stream()
            .filter(u -> u.account().equals(attentionUserId))
            .findAny();
    if (!existingEntry.isPresent() || existingEntry.get().operation() == Operation.REMOVE) {
      // We still need to perform this update to ensure that we don't add the user in a follow-up
      // operation, but no need to send an email about it.
      notify = false;
    }

    change = ctx.getChange();

    ChangeUpdate changeUpdate = ctx.getUpdate(ctx.getChange().currentPatchSetId());
    changeUpdate.addToPlannedAttentionSetUpdates(
        AttentionSetUpdate.createForWrite(attentionUserId, Operation.REMOVE, reason));
    return true;
  }

  @Override
  public void postUpdate(PostUpdateContext ctx) {
    if (!notify) {
      return;
    }
    attentionSetEmailFactory.create(USER_REMOVED, ctx, change, reason, attentionUserId).sendAsync();
  }
}