// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable enable
 
using System.Collections.Generic;
 
namespace System.Windows
{
    /// <summary>
    ///  Helper to create and track records for <see cref="BinaryObjectString"/> and <see cref="MemberReference"/>
    ///  when duplicates are found.
    /// </summary>
    internal class StringRecordsCollection
    {
        private readonly Dictionary<string, int> _strings = new();
        private readonly Dictionary<int, MemberReference> _memberReferences = new();
 
        public int CurrentId { get; set; }
 
        public StringRecordsCollection(int currentId) => CurrentId = currentId;
 
        /// <summary>
        ///  Returns the appropriate record for the given string.
        /// </summary>
        public IRecord GetStringRecord(string? value)
        {
            if (value is null)
            {
                return ObjectNull.Instance;
            }
 
            if (_strings.TryGetValue(value, out int id))
            {
                // The record with the data has already been retrieved, only a reference is needed now
                if (_memberReferences.TryGetValue(id, out MemberReference? memberReference))
                {
                    return memberReference;
                }
 
                MemberReference reference = new(id);
                _memberReferences.Add(id, reference);
                return reference;
            }
 
            _strings[value] = CurrentId;
            IRecord record = new BinaryObjectString(CurrentId, value);
            CurrentId++;
            return record;
        }
    }
}