// 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.
 
#nullable disable
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.ExternalAccess.FSharp.SignatureHelp;
 
internal class FSharpSignatureHelpParameter
{
    /// <summary>
    /// The name of this parameter.
    /// </summary>
    public string Name { get; }
 
    /// <summary>
    /// Documentation for this parameter.  This should normally be presented to the user when
    /// this parameter is selected.
    /// </summary>
    public Func<CancellationToken, IEnumerable<TaggedText>> DocumentationFactory { get; }
 
    /// <summary>
    /// Display parts to show before the normal display parts for the parameter.
    /// </summary>
    public IList<TaggedText> PrefixDisplayParts { get; }
 
    /// <summary>
    /// Display parts to show after the normal display parts for the parameter.
    /// </summary>
    public IList<TaggedText> SuffixDisplayParts { get; }
 
    /// <summary>
    /// Display parts for this parameter.  This should normally be presented to the user as part
    /// of the entire signature display.
    /// </summary>
    public IList<TaggedText> DisplayParts { get; }
 
    /// <summary>
    /// True if this parameter is optional or not.  Optional parameters may be presented in a
    /// different manner to users.
    /// </summary>
    public bool IsOptional { get; }
 
    /// <summary>
    /// Display parts for this parameter that should be presented to the user when this
    /// parameter is selected.
    /// </summary>
    public IList<TaggedText> SelectedDisplayParts { get; }
 
    private static readonly Func<CancellationToken, IEnumerable<TaggedText>> s_emptyDocumentationFactory = _ => [];
 
    public FSharpSignatureHelpParameter(
        string name,
        bool isOptional,
        Func<CancellationToken, IEnumerable<TaggedText>> documentationFactory,
        IEnumerable<TaggedText> displayParts,
        IEnumerable<TaggedText> prefixDisplayParts = null,
        IEnumerable<TaggedText> suffixDisplayParts = null,
        IEnumerable<TaggedText> selectedDisplayParts = null)
    {
        this.Name = name ?? string.Empty;
        this.IsOptional = isOptional;
        this.DocumentationFactory = documentationFactory ?? s_emptyDocumentationFactory;
        this.DisplayParts = displayParts.ToImmutableArrayOrEmpty();
        this.PrefixDisplayParts = prefixDisplayParts.ToImmutableArrayOrEmpty();
        this.SuffixDisplayParts = suffixDisplayParts.ToImmutableArrayOrEmpty();
        this.SelectedDisplayParts = selectedDisplayParts.ToImmutableArrayOrEmpty();
    }
 
    internal IEnumerable<TaggedText> GetAllParts()
    {
        return this.PrefixDisplayParts.Concat(this.DisplayParts)
                                      .Concat(this.SuffixDisplayParts)
                                      .Concat(this.SelectedDisplayParts);
    }
 
    public override string ToString()
    {
        var prefix = string.Concat(PrefixDisplayParts);
        var display = string.Concat(DisplayParts);
        var suffix = string.Concat(SuffixDisplayParts);
        return string.Concat(prefix, display, suffix);
    }
}