using System;
using System.Drawing;
using System.IO;
using System.Reflection;
using System.Text;
using System.Threading;
using HeuristicLab.Common;
using HeuristicLab.Common.Resources;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Scripting.Python {
  [Item("Python Script", "An empty python script.")]
  [Creatable("Scripts")]
  [StorableClass]
  public sealed class PythonScript : NamedItem, IStorableContent {
    #region Constants
    private const string CodeTemplate =
@"# adding imports from some HeuristicLab namespaces
from HeuristicLab.Common import *
from HeuristicLab.Core import *
from HeuristicLab.Data import *
from HeuristicLab.MainForm import MainFormManager

# add paths to IronPython/Lib and further libraries
# import sys
# sys.path.append(r""path/to/lib"")

# use 'vars' to access global variables in the variable store

";
    #endregion

    #region Fields & Properties
    public string Filename { get; set; }

    public static new Image StaticItemImage {
      get { return VSImageLibrary.Script; }
    }

    [Storable]
    private VariableStore variableStore;
    public VariableStore VariableStore {
      get { return variableStore; }
    }

    [Storable]
    private string code;
    public string Code {
      get { return code; }
      set {
        if (value == code) return;
        code = value;
        OnCodeChanged();
      }
    }

    #endregion

    [StorableConstructor]
    private PythonScript(bool deserializing) : base(deserializing) { }
    private PythonScript(PythonScript original, Cloner cloner)
      : base(original, cloner) {
      code = original.code;
      variableStore = new VariableStore();
    }
    public PythonScript() {
      name = ItemName;
      description = ItemDescription;
      code = CodeTemplate;
      variableStore = new VariableStore();
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new PythonScript(this, cloner);
    }

    private Thread scriptThread;
    public void Execute() {
      scriptThread = new Thread(() => {
        Exception ex = null;
        try {
          var pyEngine = IronPython.Hosting.Python.CreateEngine();
          foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
            pyEngine.Runtime.LoadAssembly(assembly);

          using (var outputStream = new PyConsoleStream()) {
            outputStream.TextAdded += OutputStreamOnStreamChanged;
            pyEngine.Runtime.IO.SetOutput(outputStream, Encoding.UTF8);

            var pyScope = pyEngine.CreateScope();
            pyScope.SetVariable("vars", (dynamic)(new Variables(variableStore)));

            OnScriptExecutionStarted();
            pyEngine.CreateScriptSourceFromString(code).Compile().Execute(pyScope);
            outputStream.Close();
          }
        } catch (ThreadAbortException) {
          // the execution was cancelled by the user
        } catch (TargetInvocationException e) {
          ex = e.InnerException;
        } catch (Exception e) {
          ex = e;
        } finally {
          OnScriptExecutionFinished(ex);
        }
      });
      scriptThread.Start();
    }

    private void OutputStreamOnStreamChanged(object sender, EventArgs<string> args) {
      OnConsoleOutputChanged(args.Value);
    }

    public void Kill() {
      if (scriptThread != null && scriptThread.IsAlive)
        scriptThread.Abort();
    }


    public event EventHandler CodeChanged;
    private void OnCodeChanged() {
      var handler = CodeChanged;
      if (handler != null) handler(this, EventArgs.Empty);
    }

    public event EventHandler ScriptExecutionStarted;
    private void OnScriptExecutionStarted() {
      var handler = ScriptExecutionStarted;
      if (handler != null) handler(this, EventArgs.Empty);
    }

    public event EventHandler<EventArgs<Exception>> ScriptExecutionFinished;
    private void OnScriptExecutionFinished(Exception e) {
      var handler = ScriptExecutionFinished;
      if (handler != null) handler(this, new EventArgs<Exception>(e));
    }

    public event EventHandler<EventArgs<string>> ConsoleOutputChanged;
    private void OnConsoleOutputChanged(string args) {
      var handler = ConsoleOutputChanged;
      if (handler != null) handler(null, new EventArgs<string>(args));
    }

    class PyConsoleStream : Stream {
      public override void Flush() { }

      public override long Seek(long offset, SeekOrigin origin) {
        throw new NotSupportedException();
      }

      public override void SetLength(long value) {
        throw new NotSupportedException();
      }

      public override int Read(byte[] buffer, int offset, int count) {
        throw new NotSupportedException();
      }

      public override void Write(byte[] buffer, int offset, int count) {
        OnStreamChanged(Encoding.UTF8.GetString(buffer, offset, count));
      }

      public override bool CanRead {
        get { return false; }
      }

      public override bool CanSeek {
        get { return false; }
      }

      public override bool CanWrite {
        get { return true; }
      }

      public override long Length {
        get { return 0; }
      }

      public override long Position {
        get { return 0; }
        set { }
      }

      public event EventHandler<EventArgs<string>> TextAdded;
      private void OnStreamChanged(string text) {
        var handler = TextAdded;
        if (handler != null) handler(this, new EventArgs<string>(text));
      }
    }
  }
}