RegexBot/Feature/AutoRespond/RateLimitCache.cs
2017-08-11 23:45:27 -07:00

58 lines
1.7 KiB
C#

using System;
using System.Collections.Generic;
namespace Noikoio.RegexBot.Feature.AutoRespond
{
/// <summary>
/// Stores rate limit settings and caches.
/// </summary>
class RateLimitCache
{
public const ushort DefaultTimeout = 20; // this is Skeeter's fault
private readonly ushort _timeout;
private Dictionary<ulong, DateTime> _cache;
public ushort Timeout => _timeout;
/// <summary>
/// Sets up a new instance of <see cref="RateLimitCache"/>.
/// </summary>
public RateLimitCache(ushort timeout)
{
_timeout = timeout;
_cache = new Dictionary<ulong, DateTime>();
}
/// <summary>
/// Adds a cache item corersponding to the given ID.
/// Items added to cache will be removed after the number of seconds specified in <see cref="Timeout"/>.
/// </summary>
/// <param name="id">The ID to add to the cache.</param>
/// <returns>True on success. False if the given ID already exists.</returns>
public bool AddUsage(ulong id)
{
if (_timeout == 0) return true;
Clean();
if (_cache.ContainsKey(id)) return false;
_cache.Add(id, DateTime.Now);
return true;
}
private void Clean()
{
var now = DateTime.Now;
var clean = new Dictionary<ulong, DateTime>();
foreach (var kp in _cache)
{
if (kp.Value.AddSeconds(Timeout) > now)
{
// Copy items that have not yet timed out to the new dictionary
clean.Add(kp.Key, kp.Value);
}
}
_cache = clean;
}
}
}