Added AutoRespond rate limiting

Feature/AutoRespond/RateLimitCache.cs

@@ -0,0 +1,56 @@
+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 = 30; // TODO make configurable
+
+        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)
+        {
+            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;
+        }
+    }
+}

Feature/AutoRespond/ResponseDefinition.cs

@@ -8,7 +8,7 @@ namespace Noikoio.RegexBot.Feature.AutoRespond
     /// <summary>
     /// Represents a single autoresponse definition.
     /// </summary>
-    struct ResponseConfigItem
+    struct ResponseDefinition
     {
         public enum ResponseType { None, Exec, Reply }
 
@@ -16,15 +16,16 @@ namespace Noikoio.RegexBot.Feature.AutoRespond
         Regex _trigger;
         ResponseType _rtype;
         string _rbody; // response body
-        private FilterType _filtermode;
-        private EntityList _filterlist;
+        private FilterList _filter;
+        private RateLimitCache _limit;
 
         public string Label => _label;
         public Regex Trigger => _trigger;
         public (ResponseType, string) Response => (_rtype, _rbody);
-        public (FilterType, EntityList) Filter => (_filtermode, _filterlist);
+        public FilterList Filter => _filter;
+        public RateLimitCache RateLimit => _limit;
 
-        public ResponseConfigItem(JObject definition)
+        public ResponseDefinition(JObject definition)
         {
             // label
             _label = definition["label"]?.Value<string>();
@@ -77,7 +78,25 @@ namespace Noikoio.RegexBot.Feature.AutoRespond
             // ---
 
             // whitelist/blacklist filtering
-            (_filtermode, _filterlist) = EntityList.GetFilterList(definition);
+            _filter = new FilterList(definition);
+
+            // rate limiting
+            string rlstr = definition["ratelimit"].Value<string>();
+            if (string.IsNullOrWhiteSpace(rlstr))
+            {
+                _limit = new RateLimitCache(RateLimitCache.DefaultTimeout);
+            }
+            else
+            {
+                if (ushort.TryParse(rlstr, out var rlval))
+                {
+                    _limit = new RateLimitCache(rlval);
+                }
+                else
+                {
+                    throw new RuleImportException("Rate limit value is invalid" + errorpfx);
+                }
+            }
         }
     }
 }