add createForumChannelAsync to guild

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

@@ -761,6 +761,18 @@ namespace Discord
         /// </returns>
         Task<ICategoryChannel> CreateCategoryAsync(string name, Action<GuildChannelProperties> func = null, RequestOptions options = null);
 
+        /// <summary>
+        ///     Creates a new channel forum in this guild.
+        /// </summary>
+        /// <param name="name">The new name for the forum.</param>
+        /// <param name="func">The delegate containing the properties to be applied to the channel upon its creation.</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <returns>
+        ///     A task that represents the asynchronous creation operation. The task result contains the newly created
+        ///     forum channel.
+        /// </returns>
+        Task<IForumChannel> CreateForumChannelAsync(string name, Action<ForumChannelProperties> func = null, RequestOptions options = null);
+
         /// <summary>
         ///     Gets a collection of all the voice regions this guild can access.
         /// </summary>

src/Discord.Net.Rest/API/Rest/CreateGuildChannelParams.cs

@@ -23,6 +23,8 @@ namespace Discord.API.Rest
         public Optional<bool> IsNsfw { get; set; }
         [JsonProperty("rate_limit_per_user")]
         public Optional<int> SlowModeInterval { get; set; }
+        [JsonProperty("default_auto_archive_duration")]
+        public Optional<ThreadArchiveDuration> DefaultAutoArchiveDuration { get; set; }
 
         //Voice channels
         [JsonProperty("bitrate")]
@@ -30,6 +32,14 @@ namespace Discord.API.Rest
         [JsonProperty("user_limit")]
         public Optional<int?> UserLimit { get; set; }
 
+        //Forum channels
+        [JsonProperty("default_reaction_emoji")]
+        public Optional<ModifyForumReactionEmojiParams> DefaultReactionEmoji { get; set; }
+        [JsonProperty("default_thread_rate_limit_per_user")]
+        public Optional<int> ThreadRateLimitPerUser { get; set; }
+        [JsonProperty("available_tags")]
+        public Optional<ModifyForumTagParams[]> AvailableTags { get; set; }
+
         public CreateGuildChannelParams(string name, ChannelType type)
         {
             Name = name;

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

@@ -1,3 +1,4 @@
+using Discord.API;
 using Discord.API.Rest;
 using System;
 using System.Collections.Generic;
@@ -252,6 +253,7 @@ namespace Discord.Rest
                         Deny = overwrite.Permissions.DenyValue.ToString()
                     }).ToArray()
                     : Optional.Create<API.Overwrite[]>(),
+                DefaultAutoArchiveDuration = props.AutoArchiveDuration
             };
             var model = await client.ApiClient.CreateGuildChannelAsync(guild.Id, args, options).ConfigureAwait(false);
             return RestTextChannel.Create(client, guild, model);
@@ -338,6 +340,62 @@ namespace Discord.Rest
             var model = await client.ApiClient.CreateGuildChannelAsync(guild.Id, args, options).ConfigureAwait(false);
             return RestCategoryChannel.Create(client, guild, model);
         }
+
+        /// <exception cref="ArgumentNullException"><paramref name="name"/> is <c>null</c>.</exception>
+        public static async Task<RestForumChannel> CreateForumChannelAsync(IGuild guild, BaseDiscordClient client,
+            string name, RequestOptions options, Action<ForumChannelProperties> func = null)
+        {
+            if (name == null)
+                throw new ArgumentNullException(paramName: nameof(name));
+
+            var props = new ForumChannelProperties();
+            func?.Invoke(props);
+
+            var args = new CreateGuildChannelParams(name, ChannelType.Forum)
+            {
+                Position = props.Position,
+                Overwrites = props.PermissionOverwrites.IsSpecified
+                    ? props.PermissionOverwrites.Value.Select(overwrite => new API.Overwrite
+                    {
+                        TargetId = overwrite.TargetId,
+                        TargetType = overwrite.TargetType,
+                        Allow = overwrite.Permissions.AllowValue.ToString(),
+                        Deny = overwrite.Permissions.DenyValue.ToString()
+                    }).ToArray()
+                    : Optional.Create<API.Overwrite[]>(),
+                SlowModeInterval = props.ThreadCreationInterval,
+                AvailableTags = props.Tags.GetValueOrDefault().Select(
+                    x => new ModifyForumTagParams
+                    {
+                        Id = x.Id,
+                        Name = x.Name,
+                        EmojiId = x.Emoji is Emote emote
+                            ? emote.Id
+                            : Optional<ulong?>.Unspecified,
+                        EmojiName = x.Emoji is Emoji emoji
+                            ? emoji.Name
+                            : Optional<string>.Unspecified,
+                        Moderated = x.IsModerated
+                    }).ToArray(),
+                DefaultReactionEmoji = props.DefaultReactionEmoji.IsSpecified
+                    ? new API.ModifyForumReactionEmojiParams
+                    {
+                        EmojiId = props.DefaultReactionEmoji.Value is Emote emote ?
+                            emote.Id : Optional<ulong?>.Unspecified,
+                        EmojiName = props.DefaultReactionEmoji.Value is Emoji emoji ?
+                            emoji.Name : Optional<string>.Unspecified
+                    }
+                    : Optional<ModifyForumReactionEmojiParams>.Unspecified,
+                ThreadRateLimitPerUser = props.DefaultSlowModeInterval,
+                CategoryId = props.CategoryId,
+                IsNsfw = props.IsNsfw,
+                Topic = props.Topic,
+                DefaultAutoArchiveDuration = props.AutoArchiveDuration
+            };
+
+            var model = await client.ApiClient.CreateGuildChannelAsync(guild.Id, args, options).ConfigureAwait(false);
+            return RestForumChannel.Create(client, guild, model);
+        }
         #endregion
 
         #region Voice Regions

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

@@ -710,6 +710,19 @@ namespace Discord.Rest
         public Task<RestCategoryChannel> CreateCategoryChannelAsync(string name, Action<GuildChannelProperties> func = null, RequestOptions options = null)
             => GuildHelper.CreateCategoryChannelAsync(this, Discord, name, options, func);
 
+        /// <summary>
+        ///     Creates a category channel with the provided name.
+        /// </summary>
+        /// <param name="name">The name of the new channel.</param>
+        /// <param name="func">The delegate containing the properties to be applied to the channel upon its creation.</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="name" /> is <see langword="null"/>.</exception>
+        /// <returns>
+        ///     The created category channel.
+        /// </returns>
+        public Task<RestForumChannel> CreateForumChannelAsync(string name, Action<ForumChannelProperties> func = null, RequestOptions options = null)
+            => GuildHelper.CreateForumChannelAsync(this, Discord, name, options, func);
+
         /// <summary>
         ///     Gets a collection of all the voice regions this guild can access.
         /// </summary>
@@ -1370,6 +1383,9 @@ namespace Discord.Rest
         /// <inheritdoc />
         async Task<ICategoryChannel> IGuild.CreateCategoryAsync(string name, Action<GuildChannelProperties> func, RequestOptions options)
             => await CreateCategoryChannelAsync(name, func, options).ConfigureAwait(false);
+        /// <inheritdoc />
+        async Task<IForumChannel> IGuild.CreateForumChannelAsync(string name, Action<ForumChannelProperties> func, RequestOptions options)
+            => await CreateForumChannelAsync(name, func, options).ConfigureAwait(false);
 
         /// <inheritdoc />
         async Task<IReadOnlyCollection<IVoiceRegion>> IGuild.GetVoiceRegionsAsync(RequestOptions options)

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

@@ -790,6 +790,7 @@ namespace Discord.WebSocket
         /// </returns>
         public Task<RestStageChannel> CreateStageChannelAsync(string name, Action<VoiceChannelProperties> func = null, RequestOptions options = null)
             => GuildHelper.CreateStageChannelAsync(this, Discord, name, options, func);
+
         /// <summary>
         ///     Creates a new channel category in this guild.
         /// </summary>
@@ -801,9 +802,24 @@ namespace Discord.WebSocket
         ///     A task that represents the asynchronous creation operation. The task result contains the newly created
         ///     category channel.
         /// </returns>
-        public Task<RestCategoryChannel> CreateCategoryChannelAsync(string name, Action<GuildChannelProperties> func = null, RequestOptions options = null)
+        public Task<RestCategoryChannel> CreateCategoryChannelAsync(string name,
+            Action<GuildChannelProperties> func = null, RequestOptions options = null)
             => GuildHelper.CreateCategoryChannelAsync(this, Discord, name, options, func);
 
+        /// <summary>
+        ///     Creates a new channel forum in this guild.
+        /// </summary>
+        /// <param name="name">The new name for the forum.</param>
+        /// <param name="func">The delegate containing the properties to be applied to the channel upon its creation.</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <exception cref="ArgumentNullException"><paramref name="name"/> is <see langword="null"/>.</exception>
+        /// <returns>
+        ///     A task that represents the asynchronous creation operation. The task result contains the newly created
+        ///     forum channel.
+        /// </returns>
+        public Task<RestForumChannel> CreateForumChannelAsync(string name, Action<ForumChannelProperties> func = null, RequestOptions options = null)
+            => GuildHelper.CreateForumChannelAsync(this, Discord, name, options, func);
+
         internal SocketGuildChannel AddChannel(ClientState state, ChannelModel model)
         {
             var channel = SocketGuildChannel.Create(this, state, model);
@@ -1897,6 +1913,9 @@ namespace Discord.WebSocket
         /// <inheritdoc />
         async Task<ICategoryChannel> IGuild.CreateCategoryAsync(string name, Action<GuildChannelProperties> func, RequestOptions options)
             => await CreateCategoryChannelAsync(name, func, options).ConfigureAwait(false);
+        /// <inheritdoc />
+        async Task<IForumChannel> IGuild.CreateForumChannelAsync(string name, Action<ForumChannelProperties> func, RequestOptions options)
+            => await CreateForumChannelAsync(name, func, options).ConfigureAwait(false);
 
         /// <inheritdoc />
         async Task<IReadOnlyCollection<IVoiceRegion>> IGuild.GetVoiceRegionsAsync(RequestOptions options)