#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2008 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Text;
using HeuristicLab.Core;
using System.Threading;
using System.IO;
using System.Xml;
using System.IO.Compression;
using HeuristicLab.Common;
using HeuristicLab.Hive.JobBase;
using HeuristicLab.Hive.Contracts.Interfaces;
using HeuristicLab.Hive.Contracts;
using HeuristicLab.PluginInfrastructure;
using HeuristicLab.Hive.Contracts.BusinessObjects;
using HeuristicLab.Tracing;

namespace HeuristicLab.Hive.Engine {
  /// <summary>
  /// Represents an engine that executes its operator-graph on the hive.
  /// in parallel.
  /// </summary>
  public class HiveEngine : ItemBase, IEngine, IEditable {
    private const int SNAPSHOT_POLLING_INTERVAL_MS = 1000;
    private const int RESULT_POLLING_INTERVAL_MS = 10000;
    private const int MAX_SNAPSHOT_RETRIES = 20;
    private Guid jobId;
    private Job job;
    private object locker = new object();
    private volatile bool abortRequested;

    public string HiveServerUrl { get; set; }

    public HiveEngine() {
      job = new Job();
      abortRequested = false;
      Priority = ThreadPriority.Lowest;
    }

    #region IEngine Members

    public IOperatorGraph OperatorGraph {
      get { return job.Engine.OperatorGraph; }
    }

    public IScope GlobalScope {
      get { return job.Engine.GlobalScope; }
    }

    public TimeSpan ExecutionTime {
      get { return job.Engine.ExecutionTime; }
    }

    public ThreadPriority Priority {
      get { return job.Engine.Priority; }
      set { job.Engine.Priority = value; }
    }

    public bool Running {
      get { return job.Engine.Running; }
    }

    public bool Canceled {
      get { return job.Engine.Canceled; }
    }

    public bool Terminated {
      get { return job.Engine.Terminated; }
    }

    public void Execute() {
      var jobObj = CreateJobObj();
      IExecutionEngineFacade executionEngineFacade = ServiceLocator.CreateExecutionEngineFacade(HiveServerUrl);
      ResponseObject<Contracts.BusinessObjects.Job> res = executionEngineFacade.AddJob(jobObj);
      jobId = res.Obj.Id;

      StartResultPollingThread();
    }

    private void StartResultPollingThread() {
      // start a backgroud thread to poll the final result of the job
      Thread t = new Thread(() => {
        IExecutionEngineFacade executionEngineFacade = ServiceLocator.CreateExecutionEngineFacade(HiveServerUrl);
        ResponseObject<SerializedJobResult> response = null;
        Job restoredJob = null;
        do {
          Thread.Sleep(RESULT_POLLING_INTERVAL_MS);
          lock (locker) {
            HiveLogger.Debug("HiveEngine: Results-polling - GetLastResult");
            response = executionEngineFacade.GetLastSerializedResult(jobId, false);
            HiveLogger.Debug("HiveEngine: Results-polling - Server: " + response.StatusMessage + " success: " + response.Success);
            // loop while 
            // 1. the user doesn't request an abort 
            // 2. there is a problem with server communication (success==false)
            // 3. no result for the job is available yet (response.Obj==null)
            // 4. the result that we get from the server is a snapshot and not the final result
            if (abortRequested) return;
            if (response.Success && response.Obj != null) {
              HiveLogger.Debug("HiveEngine: Results-polling - Got result!");
              restoredJob = (Job)PersistenceManager.RestoreFromGZip(response.Obj.SerializedJobResultData);
              HiveLogger.Debug("HiveEngine: Results-polling - IsSnapshotResult: " + (restoredJob.Progress<1.0));
            }
          }
        } while (restoredJob == null || (restoredJob.Progress < 1.0));

        job = restoredJob;
        PluginManager.ControlManager.ShowControl(job.Engine.CreateView());
        OnChanged();
        OnFinished();
      });
      HiveLogger.Debug("HiveEngine: Starting results-polling thread");
      t.Start();
    }

    public void RequestSnapshot() {
      IExecutionEngineFacade executionEngineFacade = ServiceLocator.CreateExecutionEngineFacade(HiveServerUrl);
      int retryCount = 0;
      ResponseObject<SerializedJobResult> response;
      lock (locker) {
        HiveLogger.Debug("HiveEngine: Abort - RequestSnapshot");
        Response snapShotResponse = executionEngineFacade.RequestSnapshot(jobId);
        if (snapShotResponse.StatusMessage == ApplicationConstants.RESPONSE_JOB_IS_NOT_BEEING_CALCULATED) {
          // job is finished already
          HiveLogger.Debug("HiveEngine: Abort - GetLastResult(false)");
          response = executionEngineFacade.GetLastSerializedResult(jobId, false);
          HiveLogger.Debug("HiveEngine: Abort - Server: " + response.StatusMessage + " success: " + response.Success);
        } else {
          // server sent snapshot request to client
          // poll until snapshot is ready
          do {
            Thread.Sleep(SNAPSHOT_POLLING_INTERVAL_MS);
            HiveLogger.Debug("HiveEngine: Abort - GetLastResult(true)");
            response = executionEngineFacade.GetLastSerializedResult(jobId, true);
            HiveLogger.Debug("HiveEngine: Abort - Server: " + response.StatusMessage + " success: " + response.Success);
            retryCount++;
            // loop while
            // 1. problem with communication with server
            // 2. job result not yet ready
          } while (
            (retryCount < MAX_SNAPSHOT_RETRIES) && (
            !response.Success ||
            response.StatusMessage == ApplicationConstants.RESPONSE_JOB_RESULT_NOT_YET_HERE)
            );
        }
      }
      SerializedJobResult jobResult = response.Obj;
      if (jobResult != null) {
        HiveLogger.Debug("HiveEngine: Results-polling - Got result!");
        job = (Job)PersistenceManager.RestoreFromGZip(jobResult.SerializedJobResultData);
        PluginManager.ControlManager.ShowControl(job.Engine.CreateView());
      }
      //HiveLogger.Debug("HiveEngine: Results-polling - Exception!");
      //Exception ex = new Exception(response.Obj.Exception.Message);
      //ThreadPool.QueueUserWorkItem(delegate(object state) { OnExceptionOccurred(ex); });
    }

    public void ExecuteStep() {
      throw new NotSupportedException();
    }

    public void ExecuteSteps(int steps) {
      throw new NotSupportedException();
    }

    public void Abort() {
      abortRequested = true;
      // RequestSnapshot();
      IExecutionEngineFacade executionEngineFacade = ServiceLocator.CreateExecutionEngineFacade(HiveServerUrl);
      executionEngineFacade.AbortJob(jobId);
      OnChanged();
      OnFinished();
    }

    public void Reset() {
      abortRequested = false;
      job.Engine.Reset();
      jobId = Guid.NewGuid();
      OnInitialized();
    }

    private HeuristicLab.Hive.Contracts.BusinessObjects.SerializedJob CreateJobObj() {
      HeuristicLab.Hive.Contracts.BusinessObjects.Job jobObj =
        new HeuristicLab.Hive.Contracts.BusinessObjects.Job();

      MemoryStream memStream = new MemoryStream();
      GZipStream stream = new GZipStream(memStream, CompressionMode.Compress, true);
      XmlDocument document = PersistenceManager.CreateXmlDocument();
      Dictionary<Guid, IStorable> dictionary = new Dictionary<Guid, IStorable>();
      XmlNode rootNode = document.CreateElement("Root");
      document.AppendChild(rootNode);
      rootNode.AppendChild(PersistenceManager.Persist(job, document, dictionary));
      document.Save(stream);
      stream.Close();

      HeuristicLab.Hive.Contracts.BusinessObjects.SerializedJob executableJobObj =
        new HeuristicLab.Hive.Contracts.BusinessObjects.SerializedJob();
      executableJobObj.JobInfo = jobObj;
      executableJobObj.SerializedJobData = memStream.ToArray();

      DiscoveryService service = new DiscoveryService();
      List<PluginInfo> plugins = new List<PluginInfo>();

      foreach (IStorable storeable in dictionary.Values) {
        PluginInfo pluginInfo = service.GetDeclaringPlugin(storeable.GetType());
        if (!plugins.Contains(pluginInfo)) {
          plugins.Add(pluginInfo);
          foreach (var dependency in pluginInfo.Dependencies) {
            if (!plugins.Contains(dependency)) plugins.Add(dependency);
          }
        }
      }

      List<HivePluginInfo> pluginsNeeded =
        new List<HivePluginInfo>();
      foreach (PluginInfo uniquePlugin in plugins) {
        HivePluginInfo pluginInfo =
          new HivePluginInfo();
        pluginInfo.Name = uniquePlugin.Name;
        pluginInfo.Version = uniquePlugin.Version.ToString();
        pluginInfo.BuildDate = uniquePlugin.BuildDate;
        pluginsNeeded.Add(pluginInfo);
      }

      jobObj.CoresNeeded = 1;
      jobObj.PluginsNeeded = pluginsNeeded;
      jobObj.State = HeuristicLab.Hive.Contracts.BusinessObjects.State.offline;
      return executableJobObj;
    }

    public event EventHandler Initialized;
    /// <summary>
    /// Fires a new <c>Initialized</c> event.
    /// </summary>
    protected virtual void OnInitialized() {
      if (Initialized != null)
        Initialized(this, new EventArgs());
    }

    public event EventHandler<EventArgs<IOperation>> OperationExecuted;
    /// <summary>
    /// Fires a new <c>OperationExecuted</c> event.
    /// </summary>
    /// <param name="operation">The operation that has been executed.</param>
    protected virtual void OnOperationExecuted(IOperation operation) {
      if (OperationExecuted != null)
        OperationExecuted(this, new EventArgs<IOperation>(operation));
    }

    public event EventHandler<EventArgs<Exception>> ExceptionOccurred;
    /// <summary>
    /// Aborts the execution and fires a new <c>ExceptionOccurred</c> event.
    /// </summary>
    /// <param name="exception">The exception that was thrown.</param>
    protected virtual void OnExceptionOccurred(Exception exception) {
      Abort();
      if (ExceptionOccurred != null)
        ExceptionOccurred(this, new EventArgs<Exception>(exception));
    }

    public event EventHandler ExecutionTimeChanged;
    /// <summary>
    /// Fires a new <c>ExecutionTimeChanged</c> event.
    /// </summary>
    protected virtual void OnExecutionTimeChanged() {
      if (ExecutionTimeChanged != null)
        ExecutionTimeChanged(this, new EventArgs());
    }

    public event EventHandler Finished;
    /// <summary>
    /// Fires a new <c>Finished</c> event.
    /// </summary>
    protected virtual void OnFinished() {
      if (Finished != null)
        Finished(this, new EventArgs());
    }

    #endregion

    public override IView CreateView() {
      return new HiveEngineEditor(this);
    }

    #region IEditable Members

    public IEditor CreateEditor() {
      return new HiveEngineEditor(this);
    }
    #endregion

    public override System.Xml.XmlNode GetXmlNode(string name, System.Xml.XmlDocument document, IDictionary<Guid, IStorable> persistedObjects) {
      XmlNode node = base.GetXmlNode(name, document, persistedObjects);
      XmlAttribute attr = document.CreateAttribute("HiveServerUrl");
      attr.Value = HiveServerUrl;
      node.Attributes.Append(attr);
      node.AppendChild(PersistenceManager.Persist("Job", job, document, persistedObjects));
      return node;
    }

    public override void Populate(System.Xml.XmlNode node, IDictionary<Guid, IStorable> restoredObjects) {
      base.Populate(node, restoredObjects);
      HiveServerUrl = node.Attributes["HiveServerUrl"].Value;
      job = (Job)PersistenceManager.Restore(node.SelectSingleNode("Job"), restoredObjects);
    }
  }
}