using System.Linq;
using HeuristicLab.Collections;
using HeuristicLab.Core;
using HeuristicLab.Core.Views;
using HeuristicLab.MainForm;

namespace HeuristicLab.Problems.ProgramSynthesis {
  [View("ERC Options")]
  [Content(typeof(ErcOptions), true)]
  public partial class ErcOptionsView : NamedItemView {
    private const string PERCENTAGE_FORMAT = "0%";
    private CheckedItemCollection<IErcItem> ercItems;

    public ErcOptionsView() {
      InitializeComponent();

      possibilityTextBox.Validating += PossibilityTextBoxValidating;
      possibilityTextBox.KeyDown += PossibilityTextBoxKeyDown;
    }

    private void PossibilityTextBoxKeyDown(object sender, System.Windows.Forms.KeyEventArgs e) {
      if (e.KeyCode == System.Windows.Forms.Keys.Enter) {
        Validate();
      }
    }

    private void PossibilityTextBoxValidating(object sender, System.ComponentModel.CancelEventArgs e) {
      var text = possibilityTextBox.Text.Trim();
      if (text.EndsWith("%")) {
        text = text.Substring(0, text.Length - 1);
      }

      double value;
      if (double.TryParse(text, out value)) {
        if (value > 1) value /= 100.0;
        possibilityTextBox.Text = value.ToString(PERCENTAGE_FORMAT);
      } else {
        possibilityTextBox.Text = "0%";
        e.Cancel = true;
      }

      Content.ErcProbability = value;
    }

    public new ErcOptions Content {
      get { return (ErcOptions)base.Content; }
      set {
        ClearOldContent();
        base.Content = value;
      }
    }

    protected override void OnReadOnlyChanged() {
      base.OnReadOnlyChanged();

      possibilityTextBox.ReadOnly = ReadOnly;
    }

    protected override void OnContentChanged() {
      if (Content == null)
        return;

      nameTextBox.Text = Content.Name;
      possibilityTextBox.Text = Content.ErcProbability.ToString(PERCENTAGE_FORMAT);

      var ercOptions = typeof(ErcOptions)
        .GetProperties()
        .Where(p => typeof(IErcItem).IsAssignableFrom(p.PropertyType))
        .Select(p => (IErcItem)p.GetValue(Content))
        .ToArray();

      ercItems = new CheckedItemCollection<IErcItem>(ercOptions);

      ercItems.ForEach(item => {
        item.EnabledChanged += OptionEnabledChanged;
        ercItems.SetItemCheckedState(item, item.IsEnabled);
      });

      ercItems.CheckedItemsChanged += ErcItemsCheckedItemsChanged;
      ErcOptionListView.Content = new ReadOnlyCheckedItemCollection<IErcItem>(ercItems);
    }

    private void ClearOldContent() {
      if (ercItems != null) {
        ercItems.ForEach(item => item.EnabledChanged -= OptionEnabledChanged);
        ercItems.CheckedItemsChanged -= ErcItemsCheckedItemsChanged;
        ercItems = null;
      }
    }

    private void ErcItemsCheckedItemsChanged(object sender, Collections.CollectionItemsChangedEventArgs<IErcItem> e) {
      foreach (var item in e.Items)
        item.IsEnabled = ercItems.ItemChecked(item);
    }

    private void OptionEnabledChanged(object sender, bool state) {
      var item = (IErcItem)sender;

      // avoid unnecessary state change events
      if (ercItems.ItemChecked(item) != state)
        ercItems.SetItemCheckedState(item, state);
    }
  }
}