// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.

using System;
using System.ComponentModel.Composition;
using dnSpy.Roslyn.EditorFeatures.Editor;
using dnSpy.Roslyn.EditorFeatures.Host;
using dnSpy.Roslyn.EditorFeatures.TextStructureNavigation;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.VisualStudio.Text;
using Microsoft.VisualStudio.Text.Operations;
using Microsoft.VisualStudio.Utilities;

namespace dnSpy.Roslyn.CSharp.EditorFeatures.TextStructureNavigation
{
    [Export(typeof(ITextStructureNavigatorProvider))]
    [ContentType(ContentTypeNames.CSharpContentType)]
    internal class TextStructureNavigatorProvider : AbstractTextStructureNavigatorProvider
    {
        [ImportingConstructor]
        internal TextStructureNavigatorProvider(
            ITextStructureNavigatorSelectorService selectorService,
            IContentTypeRegistryService contentTypeService,
            IWaitIndicator waitIndicator)
            : base(selectorService, contentTypeService, waitIndicator)
        {
        }

        protected override bool ShouldSelectEntireTriviaFromStart(SyntaxTrivia trivia)
        {
            return trivia.IsRegularOrDocComment();
        }

        protected override bool IsWithinNaturalLanguage(SyntaxToken token, int position)
        {
            switch (token.Kind())
            {
                case SyntaxKind.StringLiteralToken:
                    // This, in combination with the override of GetExtentOfWordFromToken() below, treats the closing
                    // quote as a separate token.  This maintains behavior with VS2013.
                    if (position == token.Span.End - 1 && token.Text.EndsWith("\"", StringComparison.Ordinal))
                    {
                        return false;
                    }

                    return true;

                case SyntaxKind.CharacterLiteralToken:
                    // Before the ' is considered outside the character
                    return position != token.SpanStart;

                case SyntaxKind.InterpolatedStringTextToken:
                case SyntaxKind.XmlTextLiteralToken:
                    return true;
            }

            return false;
        }

        protected override TextExtent GetExtentOfWordFromToken(SyntaxToken token, SnapshotPoint position)
        {
            if (token.Kind() == SyntaxKind.StringLiteralToken && position.Position == token.Span.End - 1 && token.Text.EndsWith("\"", StringComparison.Ordinal))
            {
                // Special case to treat the closing quote of a string literal as a separate token.  This allows the
                // cursor to stop during word navigation (Ctrl+LeftArrow, etc.) immediately before AND after the
                // closing quote, just like it did in VS2013 and like it currently does for interpolated strings.
                var span = new Span(position.Position, 1);
                return new TextExtent(new SnapshotSpan(position.Snapshot, span), isSignificant: true);
            }
            else
            {
                return base.GetExtentOfWordFromToken(token, position);
            }
        }
    }
}