modify welcome screen support

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

@@ -1241,11 +1241,19 @@ namespace Discord
             RequestOptions options = null);
 
         /// <summary>
-        ///     Gets the welcome screen of the guild.
+        ///     Gets the welcome screen of the guild. Returns <see langword="null"/> is the welcome channel is not set.
         /// </summary>
         /// <returns>
         ///     A task that represents the asynchronous creation operation. The task result contains a <see cref="WelcomeScreen"/>.
         /// </returns>
         Task<WelcomeScreen> GetWelcomeScreenAsync(RequestOptions options = null);
+
+        /// <summary>
+        ///     Modifies the welcome screen of the guild. Returns <see langword="null"/> if welcome screen is removed.
+        /// </summary>
+        /// <returns>
+        ///     A task that represents the asynchronous creation operation. The task result contains a <see cref="WelcomeScreen"/>.
+        /// </returns>
+        Task<WelcomeScreen> ModifyWelcomeScreenAsync(bool enabled, WelcomeScreenChannelProperties[] channels, string description = null, RequestOptions options = null);
     }
 }

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

@@ -40,17 +40,4 @@ public class WelcomeScreenChannel : ISnowflakeEntity
             Emoji = null;
 
     }
-
-    /// <summary>
-    ///     Initializes a new instance of <see cref="WelcomeScreenChannel"/> to be used to modify one.
-    /// </summary>
-    /// <param name="id"></param>
-    /// <param name="description"></param>
-    /// <param name="emoji"></param>
-    public WelcomeScreenChannel(ulong id, string description, IEmote emoji)
-    {
-        Id = id;
-        Description = description;
-        Emoji = emoji;
-    }
 }

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

@@ -0,0 +1,50 @@
+using System;
+using System.Xml.Linq;
+
+namespace Discord;
+
+public class WelcomeScreenChannelProperties : ISnowflakeEntity
+{
+    /// <summary>
+    /// 	Gets or sets the channel's id.
+    /// </summary>
+    public ulong Id { get; set; }
+
+    /// <summary>
+    /// 	Gets or sets the description shown for the channel.
+    /// </summary>
+    public string Description { get; set; }
+
+    /// <summary>
+    ///     Gets or sets the emoji for this channel. <see cref="Emoji"/> if it is unicode emoji, <see cref="Emote"/> if it is a custom one and <see langword="null"/> if none is set.
+    /// </summary>
+    /// <remarks>
+    ///     If the emoji is <see cref="Emote"/> only the <see cref="Emote.Id"/> will be populated.
+    ///     Use <see cref="IGuild.GetEmoteAsync"/> to get the emoji.
+    /// </remarks>
+    public IEmote Emoji { get; set; }
+
+    /// <inheritdoc/>
+    public DateTimeOffset CreatedAt => SnowflakeUtils.FromSnowflake(Id);
+
+    /// <summary>
+    ///     Initializes a new instance of <see cref="WelcomeScreenChannelProperties"/>.
+    /// </summary>
+    /// <param name="id">Id if a channel.</param>
+    /// <param name="description">Description for the channel in the welcome screen.</param>
+    /// <param name="emoji">The emoji for the channel in the welcome screen.</param>
+    public WelcomeScreenChannelProperties(ulong id, string description, IEmote emoji = null)
+    {
+        Id = id;
+        Description = description;
+        Emoji = emoji;
+    }
+
+    /// <summary>
+    ///     Initializes a new instance of <see cref="WelcomeScreenChannelProperties"/>.
+    /// </summary>
+    /// <param name="channel">A welcome screen channel to modify.</param>
+    /// <returns>A new instance of <see cref="WelcomeScreenChannelProperties"/>.</returns>
+    public static WelcomeScreenChannelProperties FromWelcomeScreenChannel(WelcomeScreenChannel channel)
+        => new (channel.Id, channel.Description, channel.Emoji);
+}

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

@@ -10,7 +10,7 @@ internal class ModifyGuildWelcomeScreenParams
     public Optional<bool> Enabled { get; set; }
 
     [JsonProperty("welcome_channels")]
-    public Optional<WelcomeScreenChannel> Channels { get; set; }
+    public Optional<WelcomeScreenChannel[]> WelcomeChannels { get; set; }
 
     [JsonProperty("description")]
     public Optional<string> Description { get; set; }

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

@@ -2,6 +2,7 @@ using Discord.API.Rest;
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Data;
 using System.Linq;
 using System.Threading.Tasks;
 using WidgetModel = Discord.API.GuildWidget;
@@ -19,7 +20,8 @@ namespace Discord.Rest
         public static async Task<Model> ModifyAsync(IGuild guild, BaseDiscordClient client,
             Action<GuildProperties> func, RequestOptions options)
         {
-            if (func == null) throw new ArgumentNullException(nameof(func));
+            if (func == null)
+                throw new ArgumentNullException(nameof(func));
 
             var args = new GuildProperties();
             func(args);
@@ -140,7 +142,7 @@ namespace Discord.Rest
             };
 
             var mebibyte = Math.Pow(2, 20);
-            return (ulong) (tierFactor * mebibyte);
+            return (ulong)(tierFactor * mebibyte);
         }
         #endregion
 
@@ -231,7 +233,8 @@ namespace Discord.Rest
         public static async Task<RestTextChannel> CreateTextChannelAsync(IGuild guild, BaseDiscordClient client,
             string name, RequestOptions options, Action<TextChannelProperties> func = null)
         {
-            if (name == null) throw new ArgumentNullException(paramName: nameof(name));
+            if (name == null)
+                throw new ArgumentNullException(paramName: nameof(name));
 
             var props = new TextChannelProperties();
             func?.Invoke(props);
@@ -260,7 +263,8 @@ namespace Discord.Rest
         public static async Task<RestVoiceChannel> CreateVoiceChannelAsync(IGuild guild, BaseDiscordClient client,
             string name, RequestOptions options, Action<VoiceChannelProperties> func = null)
         {
-            if (name == null) throw new ArgumentNullException(paramName: nameof(name));
+            if (name == null)
+                throw new ArgumentNullException(paramName: nameof(name));
 
             var props = new VoiceChannelProperties();
             func?.Invoke(props);
@@ -316,7 +320,8 @@ namespace Discord.Rest
         public static async Task<RestCategoryChannel> CreateCategoryChannelAsync(IGuild guild, BaseDiscordClient client,
             string name, RequestOptions options, Action<GuildChannelProperties> func = null)
         {
-            if (name == null) throw new ArgumentNullException(paramName: nameof(name));
+            if (name == null)
+                throw new ArgumentNullException(paramName: nameof(name));
 
             var props = new GuildChannelProperties();
             func?.Invoke(props);
@@ -387,7 +392,8 @@ namespace Discord.Rest
             RequestOptions options)
         {
             var vanityModel = await client.ApiClient.GetVanityInviteAsync(guild.Id, options).ConfigureAwait(false);
-            if (vanityModel == null) throw new InvalidOperationException("This guild does not have a vanity URL.");
+            if (vanityModel == null)
+                throw new InvalidOperationException("This guild does not have a vanity URL.");
             var inviteModel = await client.ApiClient.GetInviteAsync(vanityModel.Code, options).ConfigureAwait(false);
             inviteModel.Uses = vanityModel.Uses;
             return RestInviteMetadata.Create(client, guild, null, inviteModel);
@@ -400,7 +406,8 @@ namespace Discord.Rest
         public static async Task<RestRole> CreateRoleAsync(IGuild guild, BaseDiscordClient client,
             string name, GuildPermissions? permissions, Color? color, bool isHoisted, bool isMentionable, RequestOptions options)
         {
-            if (name == null) throw new ArgumentNullException(paramName: nameof(name));
+            if (name == null)
+                throw new ArgumentNullException(paramName: nameof(name));
 
             var createGuildRoleParams = new API.Rest.ModifyGuildRoleParams
             {
@@ -616,7 +623,8 @@ namespace Discord.Rest
         public static async Task<GuildEmote> ModifyEmoteAsync(IGuild guild, BaseDiscordClient client, ulong id, Action<EmoteProperties> func,
             RequestOptions options)
         {
-            if (func == null) throw new ArgumentNullException(paramName: nameof(func));
+            if (func == null)
+                throw new ArgumentNullException(paramName: nameof(func));
 
             var props = new EmoteProperties();
             func(props);
@@ -807,7 +815,7 @@ namespace Discord.Rest
             {
                 switch (args.Status.Value)
                 {
-                    case GuildScheduledEventStatus.Active    when guildEvent.Status != GuildScheduledEventStatus.Scheduled:
+                    case GuildScheduledEventStatus.Active when guildEvent.Status != GuildScheduledEventStatus.Scheduled:
                     case GuildScheduledEventStatus.Completed when guildEvent.Status != GuildScheduledEventStatus.Active:
                     case GuildScheduledEventStatus.Cancelled when guildEvent.Status != GuildScheduledEventStatus.Scheduled:
                         throw new ArgumentException($"Cannot set event to {args.Status.Value} when events status is {guildEvent.Status}");
@@ -849,7 +857,7 @@ namespace Discord.Rest
                     : Optional<ImageModel?>.Unspecified
             };
 
-            if(args.Location.IsSpecified)
+            if (args.Location.IsSpecified)
             {
                 apiArgs.EntityMetadata = new API.GuildScheduledEventEntityMetadata()
                 {
@@ -889,7 +897,7 @@ namespace Discord.Rest
             Image? bannerImage = null,
             RequestOptions options = null)
         {
-            if(location != null)
+            if (location != null)
             {
                 Preconditions.AtMost(location.Length, 100, nameof(location));
             }
@@ -925,7 +933,7 @@ namespace Discord.Rest
                 Image = bannerImage.HasValue ? bannerImage.Value.ToModel() : Optional<ImageModel>.Unspecified
             };
 
-            if(location != null)
+            if (location != null)
             {
                 apiArgs.EntityMetadata = new API.GuildScheduledEventEntityMetadata()
                 {
@@ -951,6 +959,9 @@ namespace Discord.Rest
         {
             var model = await client.ApiClient.GetGuildWelcomeScreenAsync(guild.Id, options);
 
+            if (model.WelcomeChannels.Length == 0)
+                return null;
+
             return new WelcomeScreen(model.Description.GetValueOrDefault(null), model.WelcomeChannels.Select(
                 x => new WelcomeScreenChannel(
                     x.ChannelId, x.Description,
@@ -958,9 +969,28 @@ namespace Discord.Rest
                     x.EmojiId.GetValueOrDefault(0))).ToList());
         }
 
-        public static async Task<WelcomeScreen> ModifyWelcomeScreenAsync(IGuild guild, BaseDiscordClient client, RequestOptions options)
+        public static async Task<WelcomeScreen> ModifyWelcomeScreenAsync(bool enabled, string description, WelcomeScreenChannelProperties[] channels, IGuild guild, BaseDiscordClient client, RequestOptions options)
         {
-            var model = await client.ApiClient.ModifyGuildWelcomeScreenAsync(null, guild.Id, options);
+            if (!guild.Features.HasFeature(GuildFeature.Community))
+                throw new InvalidOperationException("Cannot update welcome screed in a non-community guild.");
+
+            var args = new ModifyGuildWelcomeScreenParams
+            {
+                Enabled = enabled,
+                Description = description,
+                WelcomeChannels = channels?.Select(ch => new API.WelcomeScreenChannel 
+                {
+                    ChannelId = ch.Id,
+                    Description = ch.Description,
+                    EmojiName = ch.Emoji is Emoji emoj ? emoj.Name : Optional<string>.Unspecified,
+                    EmojiId = ch.Emoji is Emote emote ? emote.Id : Optional<ulong?>.Unspecified
+                }).ToArray()
+            };
+
+            var model = await client.ApiClient.ModifyGuildWelcomeScreenAsync(args, guild.Id, options);
+
+            if(model.WelcomeChannels.Length == 0)
+                return null;
 
             return new WelcomeScreen(model.Description.GetValueOrDefault(null), model.WelcomeChannels.Select(
                 x => new WelcomeScreenChannel(

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

@@ -1523,6 +1523,10 @@ namespace Discord.Rest
         public Task<WelcomeScreen> GetWelcomeScreenAsync(RequestOptions options = null)
             => GuildHelper.GetWelcomeScreenAsync(this, Discord, options);
 
+        /// <inheritdoc/>
+        public Task<WelcomeScreen> ModifyWelcomeScreenAsync(bool enabled, WelcomeScreenChannelProperties[] channels, string description = null, RequestOptions options = null)
+            => GuildHelper.ModifyWelcomeScreenAsync(enabled, description, channels, this, Discord, options);
+
         #endregion
     }
 }

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

@@ -2015,6 +2015,10 @@ namespace Discord.WebSocket
         public Task<WelcomeScreen> GetWelcomeScreenAsync(RequestOptions options = null)
             => GuildHelper.GetWelcomeScreenAsync(this, Discord, options);
 
+        /// <inheritdoc/>
+        public Task<WelcomeScreen> ModifyWelcomeScreenAsync(bool enabled, WelcomeScreenChannelProperties[] channels, string description = null, RequestOptions options = null)
+            => GuildHelper.ModifyWelcomeScreenAsync(enabled, description, channels, this, Discord, options);
+
         void IDisposable.Dispose()
         {
             DisconnectAudioAsync().GetAwaiter().GetResult();