fix: Different ratelimits for the same route (implement discord buckets) (#1546)

* Don't disable when there's no resetTick

Sometimes Discord won't send any ratelimit headers, disabling the semaphore for endpoints that should have them.

* Undo changes and change comment

* Add HttpMethod to BucketIds

* Add X-RateLimit-Bucket

* BucketId changes

- BucketId is it's own class now
- Add WebhookId as a major parameter
- Add shared buckets using the hash and major parameters

* Add webhookId to BucketIds

* Update BucketId and redirect requests

* General bugfixes

* Assign semaphore and follow the same standard as Reset for ResetAfter

src/Discord.Net.Core/Net/BucketId.cs

@@ -0,0 +1,118 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+
+namespace Discord.Net
+{
+    /// <summary>
+    ///     Represents a ratelimit bucket.
+    /// </summary>
+    public class BucketId : IEquatable<BucketId>
+    {
+        /// <summary>
+        ///     Gets the http method used to make the request if available.
+        /// </summary>
+        public string HttpMethod { get; }
+        /// <summary>
+        ///     Gets the endpoint that is going to be requested if available.
+        /// </summary>
+        public string Endpoint { get; }
+        /// <summary>
+        ///     Gets the major parameters of the route.
+        /// </summary>
+        public IOrderedEnumerable<KeyValuePair<string, string>> MajorParameters { get; }
+        /// <summary>
+        ///     Gets the hash of this bucket.
+        /// </summary>
+        /// <remarks>
+        ///     The hash is provided by Discord to group ratelimits.
+        /// </remarks>
+        public string BucketHash { get; }
+        /// <summary>
+        ///     Gets if this bucket is a hash type.
+        /// </summary>
+        public bool IsHashBucket { get => BucketHash != null; }
+
+        private BucketId(string httpMethod, string endpoint, IEnumerable<KeyValuePair<string, string>> majorParameters, string bucketHash)
+        {
+            HttpMethod = httpMethod;
+            Endpoint = endpoint;
+            MajorParameters = majorParameters.OrderBy(x => x.Key);
+            BucketHash = bucketHash;
+        }
+
+        /// <summary>
+        ///     Creates a new <see cref="BucketId"/> based on the
+        ///     <see cref="HttpMethod"/> and <see cref="Endpoint"/>.
+        /// </summary>
+        /// <param name="httpMethod">Http method used to make the request.</param>
+        /// <param name="endpoint">Endpoint that is going to receive requests.</param>
+        /// <param name="majorParams">Major parameters of the route of this endpoint.</param>
+        /// <returns>
+        ///     A <see cref="BucketId"/> based on the <see cref="HttpMethod"/>
+        ///     and the <see cref="Endpoint"/> with the provided data.
+        /// </returns>
+        public static BucketId Create(string httpMethod, string endpoint, Dictionary<string, string> majorParams)
+        {
+            Preconditions.NotNullOrWhitespace(endpoint, nameof(endpoint));
+            majorParams ??= new Dictionary<string, string>();
+            return new BucketId(httpMethod, endpoint, majorParams, null);
+        }
+
+        /// <summary>
+        ///     Creates a new <see cref="BucketId"/> based on a
+        ///     <see cref="BucketHash"/> and a previous <see cref="BucketId"/>.
+        /// </summary>
+        /// <param name="hash">Bucket hash provided by Discord.</param>
+        /// <param name="oldBucket"><see cref="BucketId"/> that is going to be upgraded to a hash type.</param>
+        /// <returns>
+        ///     A <see cref="BucketId"/> based on the <see cref="BucketHash"/>
+        ///     and <see cref="MajorParameters"/>.
+        /// </returns>
+        public static BucketId Create(string hash, BucketId oldBucket)
+        {
+            Preconditions.NotNullOrWhitespace(hash, nameof(hash));
+            Preconditions.NotNull(oldBucket, nameof(oldBucket));
+            return new BucketId(null, null, oldBucket.MajorParameters, hash);
+        }
+
+        /// <summary>
+        ///     Gets the string that will define this bucket as a hash based one.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="string"/> that defines this bucket as a hash based one.
+        /// </returns>
+        public string GetBucketHash()
+            => IsHashBucket ? $"{BucketHash}:{string.Join("/", MajorParameters.Select(x => x.Value))}" : null;
+
+        /// <summary>
+        ///     Gets the string that will define this bucket as an endpoint based one.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="string"/> that defines this bucket as an endpoint based one.
+        /// </returns>
+        public string GetUniqueEndpoint()
+            => HttpMethod != null ? $"{HttpMethod} {Endpoint}" : Endpoint;
+
+        public override bool Equals(object obj)
+            => Equals(obj as BucketId);
+
+        public override int GetHashCode()
+            =>  IsHashBucket ? (BucketHash, string.Join("/", MajorParameters.Select(x => x.Value))).GetHashCode() : (HttpMethod, Endpoint).GetHashCode();
+
+        public override string ToString()
+            => GetBucketHash() ?? GetUniqueEndpoint();
+
+        public bool Equals(BucketId other)
+        {
+            if (other is null)
+                return false;
+            if (ReferenceEquals(this, other))
+                return true;
+            if (GetType() != other.GetType())
+                return false;
+            return ToString() == other.ToString();
+        }        
+    }
+}

src/Discord.Net.Core/RequestOptions.cs

@@ -1,3 +1,4 @@
+using Discord.Net;
 using System.Threading;
 
 namespace Discord
@@ -57,7 +58,7 @@ namespace Discord
 		public bool? UseSystemClock { get; set; }
 
         internal bool IgnoreState { get; set; }
-        internal string BucketId { get; set; }
+        internal BucketId BucketId { get; set; }
         internal bool IsClientBucket { get; set; }
         internal bool IsReactionBucket { get; set; }