/**
 * Copyright 2011 Google 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 org.waveprotocol.box.server.robots.agent;

import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.name.Named;
import com.google.inject.name.Names;
import com.google.wave.api.AbstractRobot;

import org.waveprotocol.box.server.CoreSettings;
import org.waveprotocol.box.server.account.AccountData;
import org.waveprotocol.box.server.persistence.AccountStore;
import org.waveprotocol.box.server.persistence.PersistenceException;
import org.waveprotocol.box.server.robots.util.RobotsUtil;
import org.waveprotocol.box.server.robots.util.RobotsUtil.RobotRegistrationException;
import org.waveprotocol.wave.model.id.TokenGenerator;
import org.waveprotocol.wave.model.wave.InvalidParticipantAddress;
import org.waveprotocol.wave.model.wave.ParticipantId;

import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * The base for robot agents that run on the WIAB server.
 * 
 * @author yurize@apache.org (Yuri Zelikov)
 */
@SuppressWarnings("serial")
public abstract class AbstractBaseRobotAgent extends AbstractRobot {

  static class ServerFrontendAddressHolder {

    private final List<String> addresses;

    @Inject
    ServerFrontendAddressHolder(
        @Named(CoreSettings.HTTP_FRONTEND_ADDRESSES) List<String> addresses) {
      this.addresses = addresses;
    }

    List<String> getAddresses() {
      return addresses;
    }
  }

  public static final String AGENT_PREFIX_URI = "/agent";
  private static final Logger LOG = Logger.getLogger(AbstractBaseRobotAgent.class.getName());

  /** The wave server domain. */
  private final String waveDomain;

  /** Account store with user and robot accounts. */
  private final AccountStore accountStore;
  
  private final ServerFrontendAddressHolder frontendAddressHolder;

  /**
   * Constructor. Initializes the agent to serve on the URI provided by
   * {@link #getRobotUri()} and ensures that the agent is registered in the
   * Account store.
   * 
   * @param injector the injector instance.
   */
  public AbstractBaseRobotAgent(Injector injector) {
    this(injector.getInstance(Key.get(String.class, Names.named(CoreSettings.WAVE_SERVER_DOMAIN))),
        injector.getInstance(AccountStore.class), injector.getInstance(TokenGenerator.class),
        injector.getInstance(ServerFrontendAddressHolder.class));
  }

  /**
   * Constructor. Initializes the agent to serve on the URI provided by
   * {@link #getRobotUri()} and ensures that the agent is registered in the
   * Account store.
   */
  AbstractBaseRobotAgent(String waveDomain, AccountStore accountStore, TokenGenerator tokenGenerator,
      ServerFrontendAddressHolder frontendAddressHolder) {
    this.waveDomain = waveDomain;
    this.accountStore = accountStore;
    this.frontendAddressHolder = frontendAddressHolder;
    ensureRegistered(tokenGenerator, getFrontEndAddress());
  }

  /**
   * Ensures that the robot agent is registered in the {@link AccountStore}.
   */
  private void ensureRegistered(TokenGenerator tokenGenerator, String serverFrontendAddress) {
    ParticipantId robotId = null;
    try {
      robotId = ParticipantId.of(getRobotId() + "@" + waveDomain);
    } catch (InvalidParticipantAddress e) {
      LOG.log(Level.SEVERE, "Failed to register the agent:" + getRobotId(), e);
      return;
    }
    try {
      String location = "http://" + serverFrontendAddress + getRobotUri();
      // Register this agent in the account store. The registration is forced
      // in order to re-register the agents if the server frontend address has
      // changed.
      AccountData account = accountStore.getAccount(robotId);
      if ((account == null || ( account != null && !account.asRobot().getUrl().equals(location)))) {
        RobotsUtil.registerRobotUri(location, robotId, accountStore, tokenGenerator, true);
      }
    
    } catch (RobotRegistrationException e) {
      LOG.log(Level.SEVERE, "Failed to register the agent:" + getRobotId(), e);
    } catch (PersistenceException e) {
      LOG.log(Level.SEVERE, "Failed to register the agent:" + getRobotId(), e);
    }
  }

  @Override
  protected String getRobotProfilePageUrl() {
    return null;
  }

  /**
   * Returns the wave domain.
   */
  public String getWaveDomain() {
    return waveDomain;
  }
  
  public String getFrontEndAddress() {
    return frontendAddressHolder.getAddresses().get(0);
  }

  /**
   * Returns the account store.
   */
  protected AccountStore getAccountStore() {
    return accountStore;
  }

  /**
   * Returns the robot URI.
   */
  public abstract String getRobotUri();

  /**
   * Returns the robot participant id.
   */
  public abstract String getRobotId();
}