#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2019 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.Drawing;
using System.Threading;
using System.Threading.Tasks;
using HeuristicLab.Common;
using HEAL.Attic;

namespace HeuristicLab.Core {
  [Item("Executable", "A base class for executables.")]
  [StorableType("17DFB815-4CF8-49EB-BC4A-98059064DB31")]
  public abstract class Executable : Item, IExecutable {
    public static new Image StaticItemImage {
      get { return HeuristicLab.Common.Resources.VSImageLibrary.Event; }
    }
    public override Image ItemImage {
      get {
        if (ExecutionState == ExecutionState.Prepared) return HeuristicLab.Common.Resources.VSImageLibrary.ExecutablePrepared;
        else if (ExecutionState == ExecutionState.Started) return HeuristicLab.Common.Resources.VSImageLibrary.ExecutableStarted;
        else if (ExecutionState == ExecutionState.Paused) return HeuristicLab.Common.Resources.VSImageLibrary.ExecutablePaused;
        else if (ExecutionState == ExecutionState.Stopped) return HeuristicLab.Common.Resources.VSImageLibrary.ExecutableStopped;
        else return base.ItemImage;
      }
    }

    [Storable]
    private ExecutionState executionState;
    public ExecutionState ExecutionState {
      get { return executionState; }
      private set {
        if (executionState != value) {
          executionState = value;
          OnExecutionStateChanged();
          OnItemImageChanged();
        }
      }
    }

    [Storable]
    private TimeSpan executionTime;
    public TimeSpan ExecutionTime {
      get { return executionTime; }
      protected set {
        executionTime = value;
        OnExecutionTimeChanged();
      }
    }

    [StorableConstructor]
    protected Executable(StorableConstructorFlag _) : base(_) { }
    protected Executable(Executable original, Cloner cloner)
      : base(original, cloner) {
      executionState = original.executionState;
      executionTime = original.executionTime;
    }
    protected Executable() {
      executionState = ExecutionState.Stopped;
      executionTime = TimeSpan.Zero;
    }

    public virtual void Prepare() {
      if ((ExecutionState != ExecutionState.Prepared) && (ExecutionState != ExecutionState.Paused) && (ExecutionState != ExecutionState.Stopped))
        throw new InvalidOperationException(string.Format("Prepare not allowed in execution state \"{0}\".", ExecutionState));
      ExecutionTime = TimeSpan.Zero;
    }
    public virtual void Start() {
      Start(CancellationToken.None);
    }
    public virtual void Start(CancellationToken cancellationToken) {
      if ((ExecutionState != ExecutionState.Prepared) && (ExecutionState != ExecutionState.Paused))
        throw new InvalidOperationException(string.Format("Start not allowed in execution state \"{0}\".", ExecutionState));
    }
    public virtual async Task StartAsync() { await StartAsync(CancellationToken.None); }
    public virtual async Task StartAsync(CancellationToken cancellationToken) {
      await AsyncHelper.DoAsync(Start, cancellationToken);
    }
    public virtual void Pause() {
      if (ExecutionState != ExecutionState.Started)
        throw new InvalidOperationException(string.Format("Pause not allowed in execution state \"{0}\".", ExecutionState));
    }
    public virtual void Stop() {
      if ((ExecutionState != ExecutionState.Started) && (ExecutionState != ExecutionState.Paused))
        throw new InvalidOperationException(string.Format("Stop not allowed in execution state \"{0}\".", ExecutionState));
    }

    public event EventHandler ExecutionStateChanged;
    protected virtual void OnExecutionStateChanged() {
      EventHandler handler = ExecutionStateChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler ExecutionTimeChanged;
    protected virtual void OnExecutionTimeChanged() {
      EventHandler handler = ExecutionTimeChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler Prepared;
    protected virtual void OnPrepared() {
      ExecutionState = ExecutionState.Prepared;
      EventHandler handler = Prepared;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler Started;
    protected virtual void OnStarted() {
      ExecutionState = ExecutionState.Started;
      EventHandler handler = Started;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler Paused;
    protected virtual void OnPaused() {
      ExecutionState = ExecutionState.Paused;
      EventHandler handler = Paused;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler Stopped;
    protected virtual void OnStopped() {
      ExecutionState = ExecutionState.Stopped;
      EventHandler handler = Stopped;
      if (handler != null) handler(this, EventArgs.Empty);
    }
    public event EventHandler<EventArgs<Exception>> ExceptionOccurred;
    protected virtual void OnExceptionOccurred(Exception exception) {
      EventHandler<EventArgs<Exception>> handler = ExceptionOccurred;
      if (handler != null) handler(this, new EventArgs<Exception>(exception));
    }
  }
}