// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Collections.Immutable;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Classification;
using Microsoft.CodeAnalysis.Text;

namespace Microsoft.CodeAnalysis.Host;

/// <summary>
/// excerpt some part of <see cref="Document"/>
/// </summary>
internal interface IDocumentExcerptService : IDocumentService
{
    /// <summary>
    /// return <see cref="ExcerptResult"/> of given <see cref="Document"/> and <see cref="TextSpan"/>
    /// 
    /// the result might not be an exact copy of the given source or contains more then given span
    /// </summary>
    Task<ExcerptResult?> TryExcerptAsync(Document document, TextSpan span, ExcerptMode mode, ClassificationOptions classificationOptions, CancellationToken cancellationToken);
}

/// <summary>
/// this mode shows intention not actual behavior. it is up to implementation how to interpret the intention.
/// </summary>
internal enum ExcerptMode
{
    SingleLine,
    Tooltip
}

/// <summary>
/// Result of excerpt
/// </summary>
internal readonly struct ExcerptResult(SourceText content, TextSpan mappedSpan, ImmutableArray<ClassifiedSpan> classifiedSpans, Document document, TextSpan span)
{
    /// <summary>
    /// excerpt content
    /// </summary>
    public readonly SourceText Content = content;

    /// <summary>
    /// span on <see cref="Content"/> that given <see cref="Span"/> got mapped to
    /// </summary>
    public readonly TextSpan MappedSpan = mappedSpan;

    /// <summary>
    /// classification information on the <see cref="Content"/>
    /// </summary>
    public readonly ImmutableArray<ClassifiedSpan> ClassifiedSpans = classifiedSpans;

    /// <summary>
    /// <see cref="Document"/> this excerpt is from
    /// 
    /// should be same document in <see cref="IDocumentExcerptService.TryExcerptAsync(Document, TextSpan, ExcerptMode, ClassificationOptions, CancellationToken)" />
    /// </summary>
    public readonly Document Document = document;

    /// <summary>
    /// span on <see cref="Document"/> this excerpt is from
    /// 
    /// should be same text span in <see cref="IDocumentExcerptService.TryExcerptAsync(Document, TextSpan, ExcerptMode, ClassificationOptions, CancellationToken)" />
    /// </summary>
    public readonly TextSpan Span = span;
}