using System;
using System.Collections.Generic;
using System.ComponentModel.Composition;
using System.Windows.Media;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Classification;
using Microsoft.VisualStudio.Utilities;

namespace Cosmos.VS.XSharp {
  /// This class causes a classifier to be added to the set of classifiers. Since 
  /// the content type is set to "text", this classifier applies to all text files
  [Export(typeof(IClassifierProvider))]
  [ContentType("XSharp")]
  internal class XSharpProvider : IClassifierProvider {
    /// Import the classification registry to be used for getting a reference
    /// to the custom classification type later.
    [Import]
    internal IClassificationTypeRegistryService ClassificationRegistry = null; // Set via MEF

    public IClassifier GetClassifier(ITextBuffer buffer) {
      return buffer.Properties.GetOrCreateSingletonProperty<XSharp>(delegate { return new XSharp(ClassificationRegistry); });
    }
  }

  // Classifier that classifies all text as an instance of the OrinaryClassifierType
  class XSharp : IClassifier {
    IClassificationType _classificationType;

    internal XSharp(IClassificationTypeRegistryService registry) {
      _classificationType = registry.GetClassificationType("XSharp");
    }

    /// This method scans the given SnapshotSpan for potential matches for this classification.
    /// In this instance, it classifies everything and returns each span as a new ClassificationSpan.
    /// <param name="trackingSpan">The span currently being classified</param>
    /// <returns>A list of ClassificationSpans that represent spans identified to be of this classification</returns>
    public IList<ClassificationSpan> GetClassificationSpans(SnapshotSpan span) {
      //create a list to hold the results
      var classifications = new List<ClassificationSpan>();
      classifications.Add(new ClassificationSpan(new SnapshotSpan(span.Snapshot, new Span(span.Start, span.Length)),
                                                     _classificationType));
      return classifications;
    }

#pragma warning disable 67
    // This event gets raised if a non-text change would affect the classification in some way,
    // for example typing /* would cause the classification to change in C# without directly
    // affecting the span.
    public event EventHandler<ClassificationChangedEventArgs> ClassificationChanged;
#pragma warning restore 67
  }
}