// 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;
using System.Collections.Immutable;
using Roslyn.Utilities;

namespace Microsoft.CodeAnalysis.FindUsages;

/// <summary>
/// A collection of <see cref="DefinitionItem"/>s and <see cref="SourceReferenceItem"/>s
/// that can be presented in an editor and used to navigate to the defintions and
/// references found for a symbol.
/// </summary>
internal readonly struct DefinitionsAndReferences
{
    public static readonly DefinitionsAndReferences Empty =
        new([], []);

    /// <summary>
    /// All the definitions to show.  Note: not all definitions may have references.
    /// </summary>
    public ImmutableArray<DefinitionItem> Definitions { get; }

    /// <summary>
    /// All the references to show.  Note: every <see cref="SourceReferenceItem.Definition"/> 
    /// should be in <see cref="Definitions"/> 
    /// </summary>
    public ImmutableArray<SourceReferenceItem> References { get; }

    public DefinitionsAndReferences(
        ImmutableArray<DefinitionItem> definitions,
        ImmutableArray<SourceReferenceItem> references)
    {
        var definitionSet = definitions.ToSet();
        for (int i = 0, n = references.Length; i < n; i++)
        {
            var reference = references[i];

            if (!definitionSet.Contains(reference.Definition))
            {
                throw new ArgumentException(
                    $"{nameof(references)}[{i}].{nameof(reference.Definition)} not found in '{nameof(definitions)}'");
            }
        }

        Definitions = definitions;
        References = references;
    }
}