// 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.Generic;
using System.Diagnostics;
using System.Runtime.Serialization;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis
{
    /// <summary>
    /// An identifier that can be used to retrieve the same <see cref="Document"/> across versions of the
    /// workspace.
    /// </summary>
    [DebuggerDisplay("{GetDebuggerDisplay(),nq}")]
    [DataContract]
    public sealed class DocumentId : IEquatable<DocumentId>, IObjectWritable
    {
        [DataMember(Order = 0)]
        public ProjectId ProjectId { get; }
        [DataMember(Order = 1)]
        public Guid Id { get; }
        [DataMember(Order = 2)]
        private readonly string? _debugName;
 
        private DocumentId(ProjectId projectId, Guid guid, string? debugName)
        {
            this.ProjectId = projectId;
            this.Id = guid;
            _debugName = debugName;
        }
 
        /// <summary>
        /// Creates a new <see cref="DocumentId"/> instance.
        /// </summary>
        /// <param name="projectId">The project id this document id is relative to.</param>
        /// <param name="debugName">An optional name to make this id easier to recognize while debugging.</param>
        public static DocumentId CreateNewId(ProjectId projectId, string? debugName = null)
        {
            if (projectId == null)
            {
                throw new ArgumentNullException(nameof(projectId));
            }
 
            return new DocumentId(projectId, Guid.NewGuid(), debugName);
        }
 
        public static DocumentId CreateFromSerialized(ProjectId projectId, Guid id, string? debugName = null)
        {
            if (projectId == null)
            {
                throw new ArgumentNullException(nameof(projectId));
            }
 
            if (id == Guid.Empty)
            {
                throw new ArgumentException(nameof(id));
            }
 
            return new DocumentId(projectId, id, debugName);
        }
 
        internal string? DebugName => _debugName;
 
        internal string GetDebuggerDisplay()
            => string.Format("({0}, #{1} - {2})", this.GetType().Name, this.Id, _debugName);
 
        public override string ToString()
            => GetDebuggerDisplay();
 
        public override bool Equals(object? obj)
            => this.Equals(obj as DocumentId);
 
        public bool Equals(DocumentId? other)
        {
            // Technically, we don't need to check project id.
            return
                other is object &&
                this.Id == other.Id &&
                this.ProjectId == other.ProjectId;
        }
 
        public override int GetHashCode()
            => Hash.Combine(this.ProjectId, this.Id.GetHashCode());
 
        public static bool operator ==(DocumentId? left, DocumentId? right)
            => EqualityComparer<DocumentId?>.Default.Equals(left, right);
 
        public static bool operator !=(DocumentId? left, DocumentId? right)
            => !(left == right);
 
        bool IObjectWritable.ShouldReuseInSerialization => true;
 
        void IObjectWritable.WriteTo(ObjectWriter writer)
        {
            ProjectId.WriteTo(writer);
 
            writer.WriteGuid(Id);
            writer.WriteString(DebugName);
        }
 
        internal static DocumentId ReadFrom(ObjectReader reader)
        {
            var projectId = ProjectId.ReadFrom(reader);
 
            var guid = reader.ReadGuid();
            var debugName = reader.ReadString();
 
            return CreateFromSerialized(projectId, guid, debugName);
        }
    }
}