using System;
using System.Text.RegularExpressions;
using HeuristicLab.Common;
using HeuristicLab.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;

namespace HeuristicLab.Parameters {

  [Item("ScopePathLookupParameter", "Start parameter lookup after freely navigating the scope tree using a path string.")]
  [StorableClass]
  public class ScopePathLookupParameter<T> : LookupParameter<T>, ILookupParameter<T> where T : class, IItem {

    #region Properties

    public static Regex ValidPathRegex = new Regex("|(..|[a-zA-Z0-9_ ]+|\\{[0-9]+\\})(/(..|[a-zA-Z0-9_ ]+|\\{[0-9]+\\}))?");

    [Storable]
    private string path;
    public string Path {
      get { return path; }
      set {
        if (!ValidPathRegex.IsMatch(value))
          throw new ArgumentException("Invalid Path");
        if (value != null) {
          path = value;
          OnPathChanged();
          OnToStringChanged();
        }
      }
    }

    #endregion

    #region Constructors & Cloning

    [StorableConstructor]
    protected ScopePathLookupParameter(bool deserializing) : base(deserializing) { }
    protected ScopePathLookupParameter(ScopePathLookupParameter<T> original, Cloner cloner)
      : base(original, cloner) {
      path = original.path;
    }
    public ScopePathLookupParameter()
      : base() {
      path = "";
    }
    public ScopePathLookupParameter(string name)
      : base(name) {
      path = "";
    }
    public ScopePathLookupParameter(string name, string description)
      : base(name, description) {
      path = "";
    }
    public ScopePathLookupParameter(string name, string description, string actualName)
      : base(name, description, actualName) {
      path = "";
    }

    public override IDeepCloneable Clone(Cloner cloner) {
      return new ScopePathLookupParameter<T>(this, cloner);
    }

    #endregion

    public static IScope NavigateScope(IScope scope, string path) {
      foreach (var dir in path.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries)) {
        if (dir == "..")
          scope = scope.Parent;
        else if (dir.StartsWith("{")) {
          scope = scope.SubScopes[int.Parse(dir.Substring(1, dir.Length-2))];
        } else {
          scope = scope.SubScopes.Find(s => s.Name == dir);
        }
      }
      return scope;
    }

    protected override IItem GetActualValue() {
      var originalContext = ExecutionContext as ExecutionContext;
      ExecutionContext = new ExecutionContext(originalContext.Parent, originalContext.Operator, NavigateScope(originalContext.Scope, Path));
      IItem result = base.GetActualValue();
      ExecutionContext = originalContext;
      return result;
    }

    protected override void SetActualValue(IItem value) {
      var originalContext = ExecutionContext as ExecutionContext;
      ExecutionContext = new ExecutionContext(originalContext.Parent, originalContext.Operator, NavigateScope(originalContext.Scope, Path));
      base.SetActualValue(value);
      ExecutionContext = originalContext;
    }

    public event EventHandler PathChanged;
    protected virtual void OnPathChanged() {
      EventHandler handler = PathChanged;
      if (handler != null)
        handler(this, EventArgs.Empty);
    }

    public override string ToString() {
      return string.Format("{0} [{1}]", base.ToString(), Path);
    }
  }  
}