using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using HeuristicLab.Hive.Server.Core.InternalInterfaces;
using HeuristicLab.Hive.Contracts.BusinessObjects;
using HeuristicLab.Hive.Server.DataAccess;
using System.Threading;
using HeuristicLab.DataAccess.Interfaces;

namespace HeuristicLab.Hive.Server.Core {
  internal class DefaultScheduler : IScheduler {
    //private ISessionFactory factory;

    private static Mutex jobLock =
      new Mutex();

    #region IScheduler Members

    public DefaultScheduler() {
      //factory = ServiceLocator.GetSessionFactory();
    }

    public bool ExistsJobForClient(HeuristicLab.Hive.Contracts.BusinessObjects.HeartBeatData hbData) {
      List<JobDto> allOfflineJobsForClient =
        new List<JobDto>(DaoLocator.JobDao.FindFittingJobsForClient(State.offline, hbData.FreeCores, hbData.FreeMemory,
                                                                    hbData.ClientId));
      return (allOfflineJobsForClient != null && allOfflineJobsForClient.Count > 0);
    }

    public HeuristicLab.Hive.Contracts.BusinessObjects.JobDto GetNextJobForClient(Guid clientId) {
      /// Critical section ///
      jobLock.WaitOne();

      ClientDto client = DaoLocator.ClientDao.FindById(clientId);
      LinkedList<JobDto> allOfflineJobsForClient =
        new LinkedList<JobDto>(DaoLocator.JobDao.FindFittingJobsForClient(State.offline, client.NrOfFreeCores,
                                                                          client.FreeMemory, client.Id));

      JobDto jobToCalculate = null;
      if (allOfflineJobsForClient != null && allOfflineJobsForClient.Count > 0) {
        jobToCalculate = allOfflineJobsForClient.First.Value;
        jobToCalculate.State = State.calculating;
        jobToCalculate.Client = client;
        jobToCalculate.Client.State = State.calculating;
        jobToCalculate.DateCalculated = DateTime.Now;
        DaoLocator.JobDao.AssignClientToJob(client.Id, jobToCalculate.Id);
        DaoLocator.JobDao.Update(jobToCalculate);
        DaoLocator.ClientDao.Update(jobToCalculate.Client);
      }
      jobLock.ReleaseMutex();
      /// End Critical section ///

      return jobToCalculate;
    }

    #endregion
  }
}