Add GetRoleUserCounts REST method (#3195)

src/Discord.Net.Core/Entities/Guilds/IGuild.cs

@@ -1,6 +1,7 @@
 using Discord.Audio;
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.Globalization;
 using System.IO;
 using System.Threading.Tasks;
@@ -1469,5 +1470,10 @@ namespace Discord
         ///     A task that represents the asynchronous creation operation. The task result contains a <see cref="BulkBanResult"/>.
         /// </returns>
         Task<BulkBanResult> BulkBanAsync(IEnumerable<ulong> userIds, int? deleteMessageSeconds = null, RequestOptions options = null);
+
+        /// <summary>
+        ///     Gets a mapping of role IDs to the number of users that have each role.
+        /// </summary>
+        Task<ImmutableDictionary<ulong, int>> GetRoleUserCountsAsync(RequestOptions options = null);
     }
 }

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -1711,6 +1711,15 @@ namespace Discord.API
             return await SendJsonAsync<GuildIncidentsData>("PUT", () => $"guilds/{guildId}/incident-actions", args, ids, options: options).ConfigureAwait(false);
         }
 
+        public async Task<Dictionary<ulong, int>> GetRoleUserCountsAsync(ulong guildId, RequestOptions options = null)
+        {
+            Preconditions.NotEqual(guildId, 0, nameof(guildId));
+
+            var ids = new BucketIds(guildId: guildId);
+
+            return await SendAsync<Dictionary<ulong, int>>("GET", () => $"guilds/{guildId}/roles/member-counts", ids, options: options);
+        }
+
         #endregion
 
         #region Guild Bans

src/Discord.Net.Rest/Entities/Guilds/GuildHelper.cs

@@ -651,6 +651,13 @@ namespace Discord.Rest
             return model is null ? null : RestRole.Create(client, guild, model);
         }
 
+        public static async Task<ImmutableDictionary<ulong, int>> GetRoleUserCountsAsync(IGuild guild, BaseDiscordClient client, RequestOptions options = null)
+        {
+            var model = await client.ApiClient.GetRoleUserCountsAsync(guild.Id, options);
+            return model.ToImmutableDictionary();
+        }
+
+
         #endregion
 
         #region Users

src/Discord.Net.Rest/Entities/Guilds/RestGuild.cs

@@ -412,6 +412,10 @@ namespace Discord.Rest
         /// <inheritdoc />
         public Task<BulkBanResult> BulkBanAsync(IEnumerable<ulong> userIds, int? deleteMessageSeconds = null, RequestOptions options = null)
             => GuildHelper.BulkBanAsync(this, Discord, userIds.ToArray(), deleteMessageSeconds, options);
+
+        /// <inheritdoc />
+        public Task<ImmutableDictionary<ulong, int>> GetRoleUserCountsAsync(RequestOptions options = null)
+            => GuildHelper.GetRoleUserCountsAsync(this, Discord, options);
         #endregion
 
         #region Channels

src/Discord.Net.WebSocket/Entities/Guilds/SocketGuild.cs

@@ -1187,6 +1187,9 @@ namespace Discord.WebSocket
                 return sticker;
             return null;
         }
+        /// <inheritdoc />
+        public Task<ImmutableDictionary<ulong, int>> GetRoleUserCountsAsync(RequestOptions options = null)
+            => GuildHelper.GetRoleUserCountsAsync(this, Discord, options);
         #endregion
 
         #region Users