// 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.Collections.Immutable;
using System.Diagnostics;
using System.Linq;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis
{
    [DebuggerDisplay("{GetDebuggerDisplay(),nq}")]
    public sealed class ProjectReference : IEquatable<ProjectReference>
    {
        private readonly ProjectId _projectId;
        private readonly ImmutableArray<string> _aliases;
        private readonly bool _embedInteropTypes;
 
        public ProjectReference(ProjectId projectId, ImmutableArray<string> aliases = default, bool embedInteropTypes = false)
        {
            Contract.ThrowIfNull(projectId);
 
            _projectId = projectId;
            _aliases = aliases.NullToEmpty();
            _embedInteropTypes = embedInteropTypes;
        }
 
        public ProjectId ProjectId => _projectId;
 
        /// <summary>
        /// Aliases for the reference. Empty if the reference has no aliases.
        /// </summary>
        public ImmutableArray<string> Aliases => _aliases;
 
        /// <summary>
        /// True if interop types defined in the referenced project should be embedded into the referencing project.
        /// </summary>
        public bool EmbedInteropTypes => _embedInteropTypes;
 
        public override bool Equals(object obj)
            => this.Equals(obj as ProjectReference);
 
        public bool Equals(ProjectReference reference)
        {
            if (ReferenceEquals(this, reference))
            {
                return true;
            }
 
            return reference is object &&
                   _projectId == reference._projectId &&
                   _aliases.SequenceEqual(reference._aliases) &&
                   _embedInteropTypes == reference._embedInteropTypes;
        }
 
        public static bool operator ==(ProjectReference left, ProjectReference right)
            => EqualityComparer<ProjectReference>.Default.Equals(left, right);
 
        public static bool operator !=(ProjectReference left, ProjectReference right)
            => !(left == right);
 
        public override int GetHashCode()
            => Hash.CombineValues(_aliases, Hash.Combine(_projectId, _embedInteropTypes.GetHashCode()));
 
        private string GetDebuggerDisplay()
            => _projectId.ToString();
    }
}