#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2010 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.IO;
using System.Threading;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Hive.Contracts;
using HeuristicLab.Hive.Contracts.BusinessObjects;
using HeuristicLab.Hive.Contracts.ResponseObjects;
using HeuristicLab.Hive.Slave.Common;
using HeuristicLab.Hive.Slave.Communication;
using HeuristicLab.Hive.Slave.Communication.SlaveFacade;
using HeuristicLab.Hive.Slave.Core.ConfigurationManager;
using HeuristicLab.Hive.Slave.Core.JobStorage;
using HeuristicLab.Hive.Slave.Core.SlaveConsoleService;
using HeuristicLab.Hive.Slave.ExecutionEngine;

namespace HeuristicLab.Hive.Slave.Core {
  /// <summary>
  /// The core component of the Hive Client
  /// </summary>
  public class Core : MarshalByRefObject {
    public static bool abortRequested { get; set; }

    public static ILog Log { get; set; }

    private Dictionary<Guid, Executor> engines = new Dictionary<Guid, Executor>();
    private Dictionary<Guid, AppDomain> appDomains = new Dictionary<Guid, AppDomain>();
    private Dictionary<Guid, JobDto> jobs = new Dictionary<Guid, JobDto>();

    private WcfService wcfService;
    private HeartbeatManager heartbeatManager;

    private bool currentlyFetching;
    private bool CurrentlyFetching {
      get {
        return currentlyFetching;
      }
      set {
        currentlyFetching = value;
        Logger.Debug("Set CurrentlyFetching to " + currentlyFetching);
      }
    }

    public Dictionary<Guid, Executor> ExecutionEngines {
      get { return engines; }
    }

    internal Dictionary<Guid, JobDto> Jobs {
      get { return jobs; }
    }

    /// <summary>
    /// Main Method for the client
    /// </summary>
    public void Start() {
      abortRequested = false;
      Logger.Info("Hive Slave started");
      SlaveConsoleServer server = new SlaveConsoleServer();
      server.Start();

      ConfigManager manager = ConfigManager.Instance;
      manager.Core = this;

      wcfService = WcfService.Instance;
      RegisterServiceEvents();

      RecoverSettings(); // recover server IP from the settings framework
      StartHeartbeats(); // Start heartbeats thread
      DispatchMessageQueue(); // dispatch messages until abortRequested

      DeRegisterServiceEvents();
      server.Close();
      Logger.Info("Program shutdown");
    }

    private void RecoverSettings() {
      ConnectionContainer cc = ConfigManager.Instance.GetServerIP();
      if (cc.IPAdress != String.Empty) {
        wcfService.ServerIp = cc.IPAdress;
      }
    }

    private void StartHeartbeats() {
      //Initialize the heartbeat
      heartbeatManager = new HeartbeatManager { Interval = new TimeSpan(0, 0, 10) };
      heartbeatManager.StartHeartbeat();
    }

    private void DispatchMessageQueue() {
      MessageQueue queue = MessageQueue.GetInstance();
      while (!abortRequested) {
        MessageContainer container = queue.GetMessage();
        DetermineAction(container);
      }
    }

    private void RegisterServiceEvents() {
      wcfService.GetJobCompleted += new EventHandler<GetJobCompletedEventArgs>(wcfService_GetJobCompleted);
      wcfService.GetFinishedJobResultCompleted += new EventHandler<StoreFinishedJobResultCompletedEventArgs>(wcfService_StoreFinishedJobResultCompleted);
      wcfService.ProcessSnapshotCompleted += new EventHandler<ProcessSnapshotCompletedEventArgs>(wcfService_ProcessSnapshotCompleted);
      wcfService.Connected += new EventHandler(wcfService_Connected);
    }

    private void DeRegisterServiceEvents() {
      wcfService.GetJobCompleted -= new EventHandler<GetJobCompletedEventArgs>(wcfService_GetJobCompleted);
      wcfService.GetFinishedJobResultCompleted -= new EventHandler<StoreFinishedJobResultCompletedEventArgs>(wcfService_StoreFinishedJobResultCompleted);
      wcfService.ProcessSnapshotCompleted -= new EventHandler<ProcessSnapshotCompletedEventArgs>(wcfService_ProcessSnapshotCompleted);
      wcfService.Connected -= new EventHandler(wcfService_Connected);
    }

    /// <summary>
    /// Reads and analyzes the Messages from the MessageQueue and starts corresponding actions
    /// </summary>
    /// <param name="container">The Container, containing the message</param>
    private void DetermineAction(MessageContainer container) {
      Logger.Info("Message: " + container.Message.ToString() + " for job: " + container.JobId);
      switch (container.Message) {
        //Server requests to abort a job
        case MessageContainer.MessageType.AbortJob:
          if (engines.ContainsKey(container.JobId))
            try {
              engines[container.JobId].Abort();
            }
            catch (AppDomainUnloadedException) {
              // appdomain already unloaded. Finishing job probably ongoing
            }
          else
            Logger.Error("AbortJob: Engine doesn't exist");
          break;

        //Job has been successfully aborted
        case MessageContainer.MessageType.JobAborted:
          Guid jobId = new Guid(container.JobId.ToString());
          KillAppDomain(jobId);
          break;

        //Request a Snapshot from the Execution Engine
        case MessageContainer.MessageType.RequestSnapshot:
          if (engines.ContainsKey(container.JobId))
            engines[container.JobId].RequestSnapshot();
          else
            Logger.Error("RequestSnapshot: Engine with Job doesn't exist");
          break;

        //Snapshot is ready and can be sent back to the Server
        case MessageContainer.MessageType.SnapshotReady:
          GetSnapshot(container.JobId);
          break;

        //Pull a Job from the Server
        case MessageContainer.MessageType.FetchJob:
          if (!CurrentlyFetching) {
            wcfService.GetJobAsync(ConfigManager.Instance.GetClientInfo().Id);
            CurrentlyFetching = true;
          } else
            Logger.Info("Currently fetching, won't fetch this time!");
          break;

        //A Job has finished and can be sent back to the server
        case MessageContainer.MessageType.FinishedJob:
          SendFinishedJob(container.JobId);
          break;

        //When the timeslice is up
        case MessageContainer.MessageType.UptimeLimitDisconnect:
          Logger.Info("Uptime Limit reached, storing jobs and sending them back");
          ShutdownRunningJobsAndSubmitSnapshots();
          break;

        //Fetch or Force Fetch Calendar!
        case MessageContainer.MessageType.FetchOrForceFetchCalendar:
          Logger.Info("Fetch Calendar from Server");
          FetchCalendarFromServer();
          break;

        //Hard shutdown of the client
        case MessageContainer.MessageType.Shutdown:
          Logger.Info("Shutdown Signal received");
          lock (engines) {
            Logger.Debug("engines locked");
            foreach (KeyValuePair<Guid, AppDomain> kvp in appDomains) {
              Logger.Debug("Shutting down Appdomain for " + kvp.Key);
              appDomains[kvp.Key].UnhandledException -= new UnhandledExceptionEventHandler(appDomain_UnhandledException);
              AppDomain.Unload(kvp.Value);
            }
          }
          Logger.Debug("Stopping heartbeat");
          abortRequested = true;
          heartbeatManager.StopHeartBeat();
          Logger.Debug("Logging out");
          WcfService.Instance.Logout(ConfigManager.Instance.GetClientInfo().Id);
          break;

        case MessageContainer.MessageType.AddChildJob:
          AddChildJob((MessageContainerWithJob)container);
          break;

        case MessageContainer.MessageType.PauseJob:
          // send the job back to hive
          PauseJob((MessageContainerWithJob)container);
          break;

        case MessageContainer.MessageType.GetChildJobs:
          GetChildJobs((MessageContainerWithCallback<SerializedJobList>)container);
          break;

        case MessageContainer.MessageType.DeleteChildJobs:
          wcfService.DeleteChildJobs(container.JobId);
          break;
      }
    }

    private void GetChildJobs(MessageContainerWithCallback<SerializedJobList> mc) {
      ResponseObject<SerializedJobList> response = wcfService.GetChildJobs(mc.JobId);
      if (response != null && response.StatusMessage == ResponseStatus.Ok) {
        mc.Callback(response.Obj);
      } else {
        if (response != null) {
          Logger.Error(string.Format("GetChildJobs failed: {0}", response.StatusMessage));
        } else {
          Logger.Error("GetChildJobs failed.");
        }
      }
    }

    private void PauseJob(MessageContainerWithJob mc) {
      ResponseObject<JobDto> response = wcfService.PauseJob(mc.SerializedJob);
      KillAppDomain(mc.JobId);
      if (response == null || response.StatusMessage != ResponseStatus.Ok) {
        Logger.Error("PauseJob failed: " + response.StatusMessage);
      }
    }

    private ResponseObject<JobDto> AddChildJob(MessageContainerWithJob mc) {
      ResponseObject<JobDto> response = wcfService.AddChildJob(mc.JobId, mc.SerializedJob);
      if (response == null || response.StatusMessage != ResponseStatus.Ok) {
        Logger.Error("AddChildJob failed: " + response.StatusMessage);
      }
      return response;
    }

    private void ShutdownRunningJobsAndSubmitSnapshots() {
      //check if there are running jobs
      if (engines.Count > 0) {
        //make sure there is no more fetching of jobs while the snapshots get processed
        CurrentlyFetching = true;
        //request a snapshot of each running job
        foreach (KeyValuePair<Guid, Executor> kvp in engines) {
          kvp.Value.RequestSnapshot();
        }
      }
    }

    //Asynchronous Threads for interaction with the Execution Engine
    #region Async Threads for the EE

    /// <summary>
    /// serializes the finished job and submits it to the server. If, at the time, a network connection is unavailable, the Job gets stored on the disk. 
    /// once the connection gets reestablished, the job gets submitted
    /// </summary>
    /// <param name="jobId"></param>
    private void SendFinishedJob(object jobId) {
      try {
        Guid jId = (Guid)jobId;
        Logger.Info("Getting the finished job with id: " + jId);
        if (!engines.ContainsKey(jId)) {
          Logger.Info("Engine doesn't exist");
          return;
        }

        byte[] sJob = engines[jId].GetFinishedJob();

        try {
          Logger.Info("Sending the finished job with id: " + jId);
          wcfService.GetFinishedJobResultAsync(ConfigManager.Instance.GetClientInfo().Id, jId, sJob, engines[jId].ExecutionTime, engines[jId].CurrentException, true);
        }
        catch (Exception e) {
          Logger.Info("Transmitting to server failed. Storing the finished job with id: " + jId + " to hdd (" + e.ToString() + ")");
          JobStorageManager.PersistObjectToDisc(wcfService.ServerIp, 0, jId, sJob); // [chn] Port is not unique anymore (since we need two ports for http and net.tcp-streaming). also the port is now specified only in app.config. use port 0 for the moment
        }
        finally {
          KillAppDomain(jId); // kill app-domain in every case
        }
      }
      catch (Exception e) {
        OnExceptionOccured(e);
      }
    }

    private void GetSnapshot(object jobId) {
      try {
        Logger.Info("Fetching a snapshot for job " + jobId);
        Guid jId = (Guid)jobId;
        byte[] obj = engines[jId].GetSnapshot();
        wcfService.ProcessSnapshotSync(ConfigManager.Instance.GetClientInfo().Id, jId, obj, engines[jId].ExecutionTime, null);

        //Uptime Limit reached, now is a good time to destroy this jobs.
        Logger.Debug("Checking if uptime limit is reached");
        if (!UptimeManager.Instance.IsAllowedToCalculate()) {
          Logger.Debug("Uptime limit reached");
          Logger.Debug("Killing Appdomain");
          KillAppDomain(jId);
          //Still anything running?  
          if (engines.Count == 0) {
            Logger.Info("All jobs snapshotted and sent back, disconnecting");
            WcfService.Instance.Disconnect();
          } else {
            Logger.Debug("There are still active Jobs in the Field, not disconnecting");
          }
        } else {
          Logger.Debug("Restarting the job" + jobId);
          engines[jId].StartOnlyJob();
          Logger.Info("Restarted the job" + jobId);
        }
      }
      catch (Exception e) {
        OnExceptionOccured(e);
      }
    }

    #endregion

    //Eventhandlers for the communication with the wcf Layer 
    #region wcfService Events
    /// <summary>
    /// Login has returned
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void wcfService_LoginCompleted(object sender, LoginCompletedEventArgs e) {
      if (e.Result.StatusMessage == ResponseStatus.Ok) {
        CurrentlyFetching = false;
        Logger.Info("Login completed to Hive Server @ " + DateTime.Now);
      } else
        Logger.Error("Error during login: " + e.Result.StatusMessage.ToString());
    }

    /// <summary>
    /// A new Job from the wcfService has been received and will be started within a AppDomain.
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void wcfService_GetJobCompleted(object sender, GetJobCompletedEventArgs e) {
      if (e.Result.StatusMessage != ResponseStatus.GetJob_NoJobsAvailable) {
        Logger.Info("Received new job with id " + e.Result.Obj.Id);
        Logger.Debug("Fetching plugins for job " + e.Result.Obj.Id);
        try {
          PluginCache.Instance.PreparePlugins(e.Result.Obj.PluginsNeeded);
          PluginCache.Instance.CopyPluginsForJob(e.Result.Obj.PluginsNeeded, e.Result.Obj.Id);

          Logger.Debug("Plugins fetched for job " + e.Result.Obj.Id);
          String pluginDir = Path.Combine(PluginCache.Instance.PluginRepositoryDir, e.Result.Obj.Id.ToString());

          AppDomain appDomain = HeuristicLab.PluginInfrastructure.Sandboxing.SandboxManager.CreateAndInitSandbox(pluginDir, null);
          appDomain.UnhandledException += new UnhandledExceptionEventHandler(appDomain_UnhandledException);
          lock (engines) {
            if (!jobs.ContainsKey(e.Result.Obj.Id)) {
              jobs.Add(e.Result.Obj.Id, e.Result.Obj);
              appDomains.Add(e.Result.Obj.Id, appDomain);
              Logger.Debug("Creating AppDomain");
              Executor engine = (Executor)appDomain.CreateInstanceAndUnwrap(typeof(Executor).Assembly.GetName().Name, typeof(Executor).FullName);
              Logger.Debug("Created AppDomain");
              engine.JobId = e.Result.Obj.Id;
              engine.Queue = MessageQueue.GetInstance();
              Logger.Debug("Starting Engine for job " + e.Result.Obj.Id);
              engine.Start(e.Data);
              engines.Add(e.Result.Obj.Id, engine);
              SlaveStatusInfo.JobsFetched++;
              Logger.Info("Increment FetchedJobs to:" + SlaveStatusInfo.JobsFetched);
            }
          }
          heartbeatManager.AwakeHeartBeatThread();
        }
        catch (Exception exception) {
          Logger.Error("Creating the Appdomain and loading the job failed for job " + e.Result.Obj.Id);
          Logger.Error("Error thrown is: ", exception);
          CurrentlyFetching = false;
          KillAppDomain(e.Result.Obj.Id);
          wcfService.StoreFinishedJobResultsSync(ConfigManager.Instance.GetClientInfo().Id, e.Result.Obj.Id, new byte[] { }, e.Result.Obj.ExecutionTime, exception.ToString(), true);
        }
      } else {
        Logger.Info("No more jobs left!");
      }
      CurrentlyFetching = false;
    }

    /// <summary>
    /// A finished job has been stored on the server
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void wcfService_StoreFinishedJobResultCompleted(object sender, StoreFinishedJobResultCompletedEventArgs e) {
      Logger.Info("Job submitted with id " + e.Result.JobId);
      KillAppDomain(e.Result.JobId);
      if (e.Result.StatusMessage == ResponseStatus.Ok) {
        SlaveStatusInfo.JobsProcessed++;
        Logger.Info("Increased ProcessedJobs to:" + SlaveStatusInfo.JobsProcessed);
        heartbeatManager.AwakeHeartBeatThread();
      } else {
        Logger.Error("Sending of job " + e.Result.JobId + " failed, job has been wasted. Message: " + e.Result.StatusMessage);
      }
    }

    /// <summary>
    /// A snapshot has been stored on the server
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void wcfService_ProcessSnapshotCompleted(object sender, ProcessSnapshotCompletedEventArgs e) {
      Logger.Info("Snapshot " + e.Result.JobId + " has been transmitted according to plan.");
    }


    /// <summary>
    /// Connnection to the server has been estabilshed => Login and Send the persistet Jobs from the harddisk.
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    void wcfService_Connected(object sender, EventArgs e) {
      Logger.Info("WCF Service got a connection");
      if (!UptimeManager.Instance.CalendarAvailable) {
        Logger.Info("No local calendar available, fetch it");
        FetchCalendarFromServer();
      }
      Logger.Info("CalendarAvailable is " + UptimeManager.Instance.CalendarAvailable + " and IsOnline is: " + UptimeManager.Instance.IsAllowedToCalculate());
      CurrentlyFetching = false;
      CheckRunningAppDomains();
      JobStorageManager.CheckAndSubmitJobsFromDisc();
    }

    private void FetchCalendarFromServer() {
      ResponseCalendar calres = wcfService.GetCalendarSync(ConfigManager.Instance.GetClientInfo().Id);
      if (calres.StatusMessage == ResponseStatus.Ok) {
        if (UptimeManager.Instance.SetAppointments(false, calres)) {
          Logger.Info("Remote calendar installed");
          wcfService.SetCalendarStatus(ConfigManager.Instance.GetClientInfo().Id, CalendarState.Fetched);
        } else {
          Logger.Info("Remote calendar installation failed, setting state to " + CalendarState.NotAllowedToFetch);
          wcfService.SetCalendarStatus(ConfigManager.Instance.GetClientInfo().Id, CalendarState.NotAllowedToFetch);
        }
      } else {
        Logger.Info("Remote calendar installation failed, setting state to " + CalendarState.NotAllowedToFetch);
        wcfService.SetCalendarStatus(ConfigManager.Instance.GetClientInfo().Id, CalendarState.NotAllowedToFetch);
      }
    }

    private void CheckRunningAppDomains() {
      foreach (KeyValuePair<Guid, Executor> execKVP in engines) {
        if (execKVP.Value.ExecutionState != ExecutionState.Started && execKVP.Value.CurrentMessage == MessageContainer.MessageType.NoMessage) {
          Logger.Info("Checking for JobId: " + execKVP.Value.JobId);
          Thread finThread = new Thread(new ParameterizedThreadStart(SendFinishedJob));
          finThread.Start(execKVP.Value.JobId);
        }
      }
    }

    #endregion

    public event EventHandler<EventArgs<Exception>> ExceptionOccured;
    private void OnExceptionOccured(Exception e) {
      Logger.Error("Error: " + e.ToString());
      var handler = ExceptionOccured;
      if (handler != null) handler(this, new EventArgs<Exception>(e));
    }

    void appDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e) {
      Logger.Error("Exception in AppDomain: " + e.ExceptionObject.ToString());
    }

    /// <summary>
    /// Kill a appdomain with a specific id.
    /// </summary>
    /// <param name="id">the GUID of the job</param>
    private void KillAppDomain(Guid id) {
      Logger.Debug("Shutting down Appdomain for Job " + id);
      lock (engines) {
        try {
          if (engines.ContainsKey(id))
            engines[id].Dispose();
          if (appDomains.ContainsKey(id)) {
            appDomains[id].UnhandledException -= new UnhandledExceptionEventHandler(appDomain_UnhandledException);

            int repeat = 5;
            while (repeat > 0) {
              try {
                AppDomain.Unload(appDomains[id]);
                repeat = 0;
              }
              catch (CannotUnloadAppDomainException) {
                Logger.Error("Could not unload AppDomain, will try again in 1 sec.");
                Thread.Sleep(1000);
                repeat--;
                if (repeat == 0) {
                  throw; // rethrow and let app crash
                }
              }
            }
            appDomains.Remove(id);
          }

          engines.Remove(id);
          jobs.Remove(id);
          PluginCache.Instance.DeletePluginsForJob(id);
          GC.Collect();
        }
        catch (Exception ex) {
          Logger.Error("Exception when unloading the appdomain: ", ex);
        }
      }
      GC.Collect();
    }
  }


}