/*
 * Copyright 2017 Cisco Systems, Inc.
 *
 * 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.cisco.gerrit.plugins.slack;

import com.cisco.gerrit.plugins.slack.client.WebhookClient;
import com.cisco.gerrit.plugins.slack.config.ProjectConfig;
import com.cisco.gerrit.plugins.slack.message.MessageGenerator;
import com.cisco.gerrit.plugins.slack.message.MessageGeneratorFactory;
import com.google.gerrit.extensions.annotations.Listen;
import com.google.gerrit.server.config.PluginConfigFactory;
import com.google.gerrit.server.events.ChangeMergedEvent;
import com.google.gerrit.server.events.CommentAddedEvent;
import com.google.gerrit.server.events.Event;
import com.google.gerrit.server.events.EventListener;
import com.google.gerrit.server.events.PatchSetCreatedEvent;
import com.google.gerrit.server.events.ReviewerAddedEvent;
import com.google.gerrit.server.events.WorkInProgressStateChangedEvent;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** Listens for Gerrit change events and publishes messages to Slack. */
@Listen
@Singleton
public class PublishEventListener implements EventListener {
  private static final Logger LOGGER = LoggerFactory.getLogger(PublishEventListener.class);

  private static final String ALL_PROJECTS = "All-Projects";

  @Inject private PluginConfigFactory configFactory;

  @Override
  public void onEvent(Event event) {
    try {
      ProjectConfig config;
      MessageGenerator messageGenerator;

      if (event instanceof PatchSetCreatedEvent) {
        PatchSetCreatedEvent patchSetCreatedEvent;
        patchSetCreatedEvent = (PatchSetCreatedEvent) event;

        config = new ProjectConfig(configFactory, patchSetCreatedEvent.change.get().project);

        messageGenerator = MessageGeneratorFactory.newInstance(patchSetCreatedEvent, config);
      } else if (event instanceof ChangeMergedEvent) {
        ChangeMergedEvent changeMergedEvent;
        changeMergedEvent = (ChangeMergedEvent) event;

        config = new ProjectConfig(configFactory, changeMergedEvent.change.get().project);

        messageGenerator = MessageGeneratorFactory.newInstance(changeMergedEvent, config);
      } else if (event instanceof CommentAddedEvent) {
        CommentAddedEvent commentAddedEvent;
        commentAddedEvent = (CommentAddedEvent) event;

        config = new ProjectConfig(configFactory, commentAddedEvent.change.get().project);

        messageGenerator = MessageGeneratorFactory.newInstance(commentAddedEvent, config);
      } else if (event instanceof ReviewerAddedEvent) {
        ReviewerAddedEvent reviewerAddedEvent;
        reviewerAddedEvent = (ReviewerAddedEvent) event;

        config = new ProjectConfig(configFactory, reviewerAddedEvent.change.get().project);

        messageGenerator = MessageGeneratorFactory.newInstance(reviewerAddedEvent, config);
      } else if (event instanceof WorkInProgressStateChangedEvent) {
        WorkInProgressStateChangedEvent wipStateChangedEvent;
        wipStateChangedEvent = (WorkInProgressStateChangedEvent) event;

        config = new ProjectConfig(configFactory, wipStateChangedEvent.change.get().project);

        messageGenerator = MessageGeneratorFactory.newInstance(wipStateChangedEvent, config);
      } else {
        LOGGER.debug("Event " + event + " not currently supported");

        config = new ProjectConfig(configFactory, ALL_PROJECTS);

        messageGenerator = MessageGeneratorFactory.newInstance(event, config);
      }

      if (messageGenerator.shouldPublish()) {
        WebhookClient client;
        client = new WebhookClient(config);

        client.publish(messageGenerator.generate(), config.getWebhookUrl());
      }
    } catch (Throwable e) {
      LOGGER.error("Event " + event + " processing failed", e);
    }
  }
}