// 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.Threading;
using Microsoft.CodeAnalysis.Text;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Host;
using System;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.Editor
{
    /// <summary>
    /// An indentation result represents where the indent should be placed.  It conveys this through
    /// a pair of values.  A position in the existing document where the indent should be relative,
    /// and the number of columns after that the indent should be placed at.  
    /// 
    /// This pairing provides flexibility to the implementor to compute the indentation results in
    /// a variety of ways.  For example, one implementation may wish to express indentation of a 
    /// newline as being four columns past the start of the first token on a previous line.  Another
    /// may wish to simply express the indentation as an absolute amount from the start of the 
    /// current line.  With this tuple, both forms can be expressed, and the implementor does not
    /// have to convert from one to the other.
    /// </summary>
    internal readonly struct FSharpIndentationResult
    {
        /// <summary>
        /// The base position in the document that the indent should be relative to.  This position
        /// can occur on any line (including the current line, or a previous line).
        /// </summary>
        public int BasePosition { get; }
 
        /// <summary>
        /// The number of columns the indent should be at relative to the BasePosition's column.
        /// </summary>
        public int Offset { get; }
 
        public FSharpIndentationResult(int basePosition, int offset)
        {
            BasePosition = basePosition;
            Offset = offset;
        }
    }
 
    [Obsolete("Use IFSharpIndentationService instead")]
    internal interface IFSharpSynchronousIndentationService
    {
        /// <summary>
        /// Determines the desired indentation of a given line.  May return <see langword="null"/> if the
        /// <paramref name="document"/> does not want any sort of automatic indentation.  May also return
        /// <see langword="null"/> if the line in question is not blank and thus indentation should
        /// be deferred to the formatting command handler to handle.
        /// </summary>
        FSharpIndentationResult? GetDesiredIndentation(Document document, int lineNumber, CancellationToken cancellationToken);
    }
 
    internal interface IFSharpIndentationService
    {
        /// <summary>
        /// Determines the desired indentation of a given line.  May return <see langword="null"/> if the
        /// no automatic indentation is desired.  May also return <see langword="null"/> if the line in
        /// question is not blank and thus indentation should be deferred to the formatting command handler to handle.
        /// </summary>
        FSharpIndentationResult? GetDesiredIndentation(HostLanguageServices services, SourceText text, DocumentId documentId, string path, int lineNumber, FSharpIndentationOptions options);
    }
 
    internal readonly record struct FSharpIndentationOptions(int TabSize, FormattingOptions.IndentStyle IndentStyle);
}