// 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.
 
namespace Roslyn.LanguageServer.Protocol;
 
using System.Text.Json.Serialization;
 
/// <summary>
/// Class representing the signature of something callable. This class is returned from the textDocument/signatureHelp request.
/// <para>
/// See the <see href="https://microsoft.github.io/language-server-protocol/specifications/specification-current/#signatureHelp">Language Server Protocol specification</see> for additional information.
/// </para>
/// </summary>
internal sealed class SignatureHelp
{
    /// <summary>
    /// One or more signatures.
    /// <para>
    /// If no signatures are available the signature help
    /// request should return <see langword="null"/>.
    /// </para>
    /// </summary>
    [JsonPropertyName("signatures")]
    [JsonRequired]
    public SignatureInformation[] Signatures
    {
        get;
        set;
    }
 
    /// <summary>
    /// The active signature.
    /// <para>
    /// </para>
    /// If omitted or the value lies outside the range of <see cref="Signatures"/> the
    /// value defaults to zero or is ignored if the <see cref="SignatureHelp"/> has no signatures.
    /// <para>
    /// Whenever possible implementors should make an active decision about
    /// the active signature and shouldn't rely on a default value.
    /// </para>
    /// <para>
    /// In a future version of the protocol this property might become
    /// mandatory to better express this.
    /// </para>
    /// </summary>
    [JsonPropertyName("activeSignature")]
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public int? ActiveSignature
    {
        get;
        set;
    }
 
    /// <summary>
    /// The active parameter of the active signature.
    /// <para>
    /// If omitted or the value lies outside the range of <c>Signatures[ActiveSignature].Parameters</c>
    /// it defaults to 0 if the active signature has parameters.
    /// If the active signature has no parameters it is ignored.
    /// </para>
    /// <para>
    /// In a future version of the protocol this property might become
    /// mandatory to better express the active parameter if the active
    /// signature has any parameters.
    /// </para>
    /// </summary>
    [JsonPropertyName("activeParameter")]
    [JsonIgnore(Condition = JsonIgnoreCondition.WhenWritingNull)]
    public int? ActiveParameter
    {
        get;
        set;
    }
}