Killed history

NadekoBot.Core/Common/Attributes/Ratelimit.cs

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+using Discord.Commands;
+using NadekoBot.Core.Services;
+using System;
+using System.Threading.Tasks;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace NadekoBot.Core.Common.Attributes
+{
+    [AttributeUsage(AttributeTargets.Method)]
+    public sealed class RatelimitAttribute : PreconditionAttribute
+    {
+        public int Seconds { get; }
+
+        public RatelimitAttribute(int seconds)
+        {
+            if (seconds <= 0)
+                throw new ArgumentOutOfRangeException(nameof(seconds));
+
+            Seconds = seconds;
+        }
+
+        public override Task<PreconditionResult> CheckPermissionsAsync(ICommandContext context, CommandInfo command, IServiceProvider services)
+        {
+            if (Seconds == 0)
+                return Task.FromResult(PreconditionResult.FromSuccess());
+
+            var cache = services.GetService<IDataCache>();
+            var rem = cache.TryAddRatelimit(context.User.Id, command.Name, Seconds);
+
+            if(rem == null)
+                return Task.FromResult(PreconditionResult.FromSuccess());
+
+            var msgContent = $"You can use this command again in {rem.Value.TotalSeconds:F1}s.";
+
+            return Task.FromResult(PreconditionResult.FromError(msgContent));
+        }
+    }
+}