using System;
using HeuristicLab.Collections;
using HeuristicLab.Core;
using HeuristicLab.MainForm;
using HeuristicLab.MainForm.WindowsForms;

namespace HeuristicLab.Problems.DataAnalysis.Symbolic.Views {
  [View("ParsedConstraint View")]
  [Content(typeof(ParsedConstraint), true)]
  public partial class ParsedConstraintView : AsynchronousContentView {
    private CheckedItemList<IntervalConstraint> intervalConstraints;
    public new ParsedConstraint Content {
      get => (ParsedConstraint)base.Content;
      set => base.Content = value;
    }

    public ParsedConstraintView() {
      InitializeComponent();
      errorOutput.Text = "";
      intervalConstraints = new CheckedItemList<IntervalConstraint>();
      intervalConstraints.CheckedItemsChanged += constraints_CheckedItemsChanged;
    }

    protected override void OnContentChanged() {
      base.OnContentChanged();
      UpdateControl();
    }

    private CheckedItemList<IntervalConstraint> ParseConstraints(string input) {
      CheckedItemList<IntervalConstraint> constraints = new CheckedItemList<IntervalConstraint>(IntervalConstraintsParser.ParseInput(input, Content.ProblemData.TargetVariable, Content.ProblemData.AllowedInputVariables));
      return constraints;
    }

    private void parseBtn_Click(object sender, EventArgs e) {
      if (constraintsInput.Text != null) {
        intervalConstraints = ParseConstraints(constraintsInput.Text);
        intervalConstraints.CheckedItemsChanged += constraints_CheckedItemsChanged;
        constraintsOutput.Content = intervalConstraints;
        Content.Constraints = intervalConstraints;
        Content.Input = constraintsInput.Text;
        errorOutput.Text = "";
      } else {
        errorOutput.Text = "No constraints were found!";
      }
    }

    private void UpdateControl() {
      if (Content == null) {
        ClearConstraints();
        constraintsInput.Text = string.Empty;
        errorOutput.Text = string.Empty;
        constraintsOutput.Content = intervalConstraints;
      } else {
        constraintsInput.Text = Content.Input;
        foreach (var constraint in Content.Constraints) {
          constraint.Changed += new EventHandler(Content_Changed);
          intervalConstraints.Add(constraint, constraint.IsChecked);
        }
      }
      constraintsOutput.Content = intervalConstraints;
    }

    private void constraintsInput_TextChanged(object sender, EventArgs e) {
      errorOutput.Text = "Unparsed changes! Press parse button to save changes.";
    }

    private void Content_Changed(object sender, EventArgs e) {
      var constraint = (IntervalConstraint) sender;
      intervalConstraints.SetItemCheckedState(constraint, constraint.IsChecked);
      constraintsOutput.Content = intervalConstraints;
    }

    private void constraints_CheckedItemsChanged(object sender,
      CollectionItemsChangedEventArgs<IndexedItem<IntervalConstraint>> e) {
      var checkedItemList = (ICheckedItemList<IntervalConstraint>) sender;
      foreach (var indexedItem in e.Items) {
        indexedItem.Value.IsChecked = checkedItemList.ItemChecked(indexedItem.Value);
      }
    }

    private void ClearConstraints() {
      foreach (var constraint in intervalConstraints) {
        constraint.Changed -= new EventHandler(Content_Changed);
      }
      intervalConstraints.Clear();
    }

  }
}