// 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.Generic;
using System.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.FindSymbols;

/// <summary>
/// Represents a single result of the call to the synchronous
/// IFindReferencesService.FindReferences method. Finding the references to a symbol will result
/// in a set of definitions being returned (containing at least the symbol requested) as well as
/// any references to those definitions in the source. Multiple definitions may be found due to
/// how C# and VB allow a symbol to be both a definition and a reference at the same time (for
/// example, a method which implements an interface method).
/// </summary>
[DebuggerDisplay("{GetDebuggerDisplay(),nq}")]
public class ReferencedSymbol
{
    /// <summary>
    /// The symbol definition that these are references to.
    /// </summary>
    public ISymbol Definition { get; }

    /// <summary>
    /// Same as <see cref="Locations"/> but exposed as an <see cref="ImmutableArray{T}"/> for performance.
    /// </summary>
    internal ImmutableArray<ReferenceLocation> LocationsArray { get; }

    /// <summary>
    /// The set of reference locations in the solution.
    /// </summary>
    public IEnumerable<ReferenceLocation> Locations => LocationsArray;

    internal ReferencedSymbol(
        ISymbol definition,
        ImmutableArray<ReferenceLocation> locations)
    {
        this.Definition = definition;
        this.LocationsArray = locations.NullToEmpty();
    }

    private string GetDebuggerDisplay()
    {
        var count = this.Locations.Count();
        return string.Format("{0}, {1} {2}", this.Definition.Name, count, count == 1 ? "ref" : "refs");
    }

    internal TestAccessor GetTestAccessor()
        => new(this);

    internal readonly struct TestAccessor(ReferencedSymbol referencedSymbol)
    {
        internal string GetDebuggerDisplay()
            => referencedSymbol.GetDebuggerDisplay();
    }
}