SPT-Server-Build/Libraries/SPTarkov.Server.Core/Context/ApplicationContext.cs

using SPTarkov.DI.Annotations;
using SPTarkov.Server.Core.Models.Utils;

namespace SPTarkov.Server.Core.Context;

[Injectable(InjectionType.Singleton)]
public class ApplicationContext
{
    private const short MaxSavedValues = 10;

    private static ApplicationContext? _applicationContext;
    private readonly ISptLogger<ApplicationContext> _logger;
    private readonly Dictionary<ContextVariableType, LinkedList<ContextVariable>> _variables = new();
    private readonly Lock _lockObject = new();

    /// <summary>
    ///     When ApplicationContext gets created by the DI container we store the singleton reference so we can provide it
    ///     statically for harmony patches!
    /// </summary>
    public ApplicationContext(ISptLogger<ApplicationContext> logger)
    {
        _logger = logger;
        _applicationContext = this;
    }

    public static ApplicationContext? GetInstance()
    {
        return _applicationContext;
    }

    public ContextVariable? GetLatestValue(ContextVariableType type)
    {
        lock (_lockObject)
        {
            if (_variables.TryGetValue(type, out var savedValues))
            {
                return savedValues.Last!.Value;
            }

            return null;
        }
    }

    public ICollection<ContextVariable> GetValues(ContextVariableType type)
    {
        lock (_lockObject)
        {
            var values = new List<ContextVariable>();
            if (_variables.TryGetValue(type, out var savedValues))
            {
                values.AddRange(savedValues);
            }

            return values;
        }
    }

    public void AddValue(ContextVariableType type, object value)
    {
        lock (_lockObject)
        {
            if (!_variables.TryGetValue(type, out var savedValues))
            {
                savedValues = [];
                if (!_variables.TryAdd(type, savedValues))
                {
                    _logger.Error($"Unable to add context variable type: {type}");
                }
            }

            if (savedValues.Count >= MaxSavedValues)
            {
                savedValues.RemoveFirst();
            }

            savedValues.AddLast(new ContextVariable(value, type));
        }
    }

    public void ClearValues(ContextVariableType type)
    {
        lock (_lockObject)
        {
            if (!_variables.Remove(type, out _))
            {
                _logger.Error($"Unable to clear context variable type: {type}");
            }
        }
    }
}