/*
 * Copyright 2012 LinkedIn Corp.
 *
 * 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 azkaban.scheduler;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Logger;
import org.joda.time.DateTimeZone;
import org.joda.time.ReadablePeriod;
import org.joda.time.format.DateTimeFormat;
import org.joda.time.format.DateTimeFormatter;

import azkaban.executor.ExecutionOptions;
import azkaban.sla.SlaOption;
import azkaban.trigger.TriggerAgent;
import azkaban.trigger.TriggerStatus;
import azkaban.utils.Pair;
import azkaban.utils.Props;

/**
 * The ScheduleManager stores and executes the schedule. It uses a single thread
 * instead and waits until correct loading time for the flow. It will not remove
 * the flow from the schedule when it is run, which can potentially allow the
 * flow to and overlap each other.
 */
public class ScheduleManager implements TriggerAgent {
  private static Logger logger = Logger.getLogger(ScheduleManager.class);

  public static final String triggerSource = "SimpleTimeTrigger";
  private final DateTimeFormatter _dateFormat = DateTimeFormat
      .forPattern("MM-dd-yyyy HH:mm:ss:SSS");
  private ScheduleLoader loader;

  private Map<Integer, Schedule> scheduleIDMap =
      new LinkedHashMap<Integer, Schedule>();
  private Map<Pair<Integer, String>, Schedule> scheduleIdentityPairMap =
      new LinkedHashMap<Pair<Integer, String>, Schedule>();

  /**
   * Give the schedule manager a loader class that will properly load the
   * schedule.
   * 
   * @param loader
   */
  public ScheduleManager(ScheduleLoader loader) {
    this.loader = loader;
  }

  @Override
  public void start() throws ScheduleManagerException {
    List<Schedule> scheduleList = null;
    try {
      scheduleList = loader.loadSchedules();
    } catch (ScheduleManagerException e) {
      // TODO Auto-generated catch block
      logger.error("Failed to load schedules" + e.getCause() + e.getMessage());
      e.printStackTrace();
    }

    for (Schedule sched : scheduleList) {
      if (sched.getStatus().equals(TriggerStatus.EXPIRED.toString())) {
        onScheduleExpire(sched);
      } else {
        internalSchedule(sched);
      }
    }

  }

  // only do this when using external runner
  public synchronized void updateLocal() throws ScheduleManagerException {
    List<Schedule> updates = loader.loadUpdatedSchedules();
    for (Schedule s : updates) {
      if (s.getStatus().equals(TriggerStatus.EXPIRED.toString())) {
        onScheduleExpire(s);
      } else {
        internalSchedule(s);
      }
    }
  }

  private void onScheduleExpire(Schedule s) {
    removeSchedule(s);
  }

  /**
   * Shutdowns the scheduler thread. After shutdown, it may not be safe to use
   * it again.
   */
  public void shutdown() {

  }

  /**
   * Retrieves a copy of the list of schedules.
   * 
   * @return
   * @throws ScheduleManagerException
   */
  public synchronized List<Schedule> getSchedules()
      throws ScheduleManagerException {

    updateLocal();
    return new ArrayList<Schedule>(scheduleIDMap.values());
  }

  /**
   * Returns the scheduled flow for the flow name
   * 
   * @param id
   * @return
   * @throws ScheduleManagerException
   */

  public Schedule getSchedule(int projectId, String flowId)
      throws ScheduleManagerException {
    updateLocal();
    return scheduleIdentityPairMap.get(new Pair<Integer, String>(projectId,
        flowId));
  }

  /**
   * Returns the scheduled flow for the scheduleId
   * 
   * @param id
   * @return
   * @throws ScheduleManagerException
   */
  public Schedule getSchedule(int scheduleId) throws ScheduleManagerException {
    updateLocal();
    return scheduleIDMap.get(scheduleId);
  }

  /**
   * Removes the flow from the schedule if it exists.
   * 
   * @param id
   * @throws ScheduleManagerException
   */

  public synchronized void removeSchedule(int projectId, String flowId)
      throws ScheduleManagerException {
    Schedule sched = getSchedule(projectId, flowId);
    if (sched != null) {
      removeSchedule(sched);
    }
  }

  /**
   * Removes the flow from the schedule if it exists.
   * 
   * @param id
   */
  public synchronized void removeSchedule(Schedule sched) {
    Pair<Integer, String> identityPairMap = sched.getScheduleIdentityPair();

    Schedule schedule = scheduleIdentityPairMap.get(identityPairMap);
    if (schedule != null) {
      scheduleIdentityPairMap.remove(identityPairMap);
    }

    scheduleIDMap.remove(sched.getScheduleId());

    try {
      loader.removeSchedule(sched);
    } catch (ScheduleManagerException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
  }

  public Schedule scheduleFlow(final int scheduleId, final int projectId,
      final String projectName, final String flowName, final String status,
      final long firstSchedTime, final DateTimeZone timezone,
      final ReadablePeriod period, final long lastModifyTime,
      final long nextExecTime, final long submitTime, final String submitUser) {
    return scheduleFlow(scheduleId, projectId, projectName, flowName, status,
        firstSchedTime, timezone, period, lastModifyTime, nextExecTime,
        submitTime, submitUser, null, null);
  }

  public Schedule scheduleFlow(final int scheduleId, final int projectId,
      final String projectName, final String flowName, final String status,
      final long firstSchedTime, final DateTimeZone timezone,
      final ReadablePeriod period, final long lastModifyTime,
      final long nextExecTime, final long submitTime, final String submitUser,
      ExecutionOptions execOptions, List<SlaOption> slaOptions) {
    Schedule sched =
        new Schedule(scheduleId, projectId, projectName, flowName, status,
            firstSchedTime, timezone, period, lastModifyTime, nextExecTime,
            submitTime, submitUser, execOptions, slaOptions);
    logger
        .info("Scheduling flow '" + sched.getScheduleName() + "' for "
            + _dateFormat.print(firstSchedTime) + " with a period of " + period == null ? "(non-recurring)"
            : period);

    insertSchedule(sched);
    return sched;
  }

  /**
   * Schedules the flow, but doesn't save the schedule afterwards.
   * 
   * @param flow
   */
  private synchronized void internalSchedule(Schedule s) {
    scheduleIDMap.put(s.getScheduleId(), s);
    scheduleIdentityPairMap.put(s.getScheduleIdentityPair(), s);
  }

  /**
   * Adds a flow to the schedule.
   * 
   * @param flow
   */
  public synchronized void insertSchedule(Schedule s) {
    // boolean exist = s.getScheduleId() != -1;
    Schedule exist = scheduleIdentityPairMap.get(s.getScheduleIdentityPair());
    if (s.updateTime()) {
      try {
        if (exist == null) {
          loader.insertSchedule(s);
          internalSchedule(s);
        } else {
          s.setScheduleId(exist.getScheduleId());
          loader.updateSchedule(s);
          internalSchedule(s);
        }
      } catch (ScheduleManagerException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
    } else {
      logger
          .error("The provided schedule is non-recurring and the scheduled time already passed. "
              + s.getScheduleName());
    }
  }

  @Override
  public void loadTriggerFromProps(Props props) throws ScheduleManagerException {
    throw new ScheduleManagerException("create " + getTriggerSource()
        + " from json not supported yet");
  }

  @Override
  public String getTriggerSource() {
    return triggerSource;
  }
}
