Add SyncPermissionsAsync to Sync Child Channels with its Parent (#1159)

* Initial implementation

* Adjust according to comments

See: 6e76b45713 (diff-58466c35787d448266d026692e467baa)

src/Discord.Net.Core/Entities/Channels/INestedChannel.cs

@@ -25,5 +25,10 @@ namespace Discord
         ///     representing the parent of this channel; <c>null</c> if none is set.
         /// </returns>
         Task<ICategoryChannel> GetCategoryAsync(CacheMode mode = CacheMode.AllowDownload, RequestOptions options = null);
+
+        /// <summary>
+        ///     Syncs the permissions of this nested channel with its parent's.
+        /// </summary>
+        Task SyncPermissionsAsync(RequestOptions options = null);
     }
 }

src/Discord.Net.Rest/API/Common/Overwrite.cs

@@ -1,4 +1,4 @@
-#pragma warning disable CS1591
+#pragma warning disable CS1591
 using Newtonsoft.Json;
 
 namespace Discord.API

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

@@ -1,4 +1,4 @@
-#pragma warning disable CS1591
+#pragma warning disable CS1591
 using Newtonsoft.Json;
 
 namespace Discord.API.Rest
@@ -12,5 +12,7 @@ namespace Discord.API.Rest
         public Optional<int> Position { get; set; }
         [JsonProperty("parent_id")]
         public Optional<ulong?> CategoryId { get; set; }
+        [JsonProperty("permission_overwrites")]
+        public Optional<Overwrite[]> Overwrites { get; set; }
     }
 }

src/Discord.Net.Rest/Entities/Channels/ChannelHelper.cs

@@ -348,6 +348,23 @@ namespace Discord.Rest
             var model = await client.ApiClient.GetChannelAsync(channel.CategoryId.Value, options).ConfigureAwait(false);
             return RestCategoryChannel.Create(client, model) as ICategoryChannel;
         }
+        public static async Task SyncPermissionsAsync(INestedChannel channel, BaseDiscordClient client, RequestOptions options)
+        {
+            var category = await GetCategoryAsync(channel, client, options).ConfigureAwait(false);
+            if (category == null) throw new InvalidOperationException("This channel does not have a parent channel.");
+
+            var apiArgs = new ModifyGuildChannelParams
+            {
+                Overwrites = category.PermissionOverwrites
+                    .Select(overwrite => new API.Overwrite{
+                        TargetId = overwrite.TargetId,
+                        TargetType = overwrite.TargetType,
+                        Allow = overwrite.Permissions.AllowValue,
+                        Deny = overwrite.Permissions.DenyValue
+                    }).ToArray()
+            };
+            await client.ApiClient.ModifyGuildChannelAsync(channel.Id, apiArgs, options).ConfigureAwait(false);
+        }
 
         //Helpers
         private static IUser GetAuthor(BaseDiscordClient client, IGuild guild, UserModel model, ulong? webhookId)

src/Discord.Net.Rest/Entities/Channels/RestTextChannel.cs

@@ -201,6 +201,8 @@ namespace Discord.Rest
         /// </returns>
         public Task<ICategoryChannel> GetCategoryAsync(RequestOptions options = null)
             => ChannelHelper.GetCategoryAsync(this, Discord, options);
+        public Task SyncPermissionsAsync(RequestOptions options = null)
+            => ChannelHelper.SyncPermissionsAsync(this, Discord, options);
 
         private string DebuggerDisplay => $"{Name} ({Id}, Text)";
 

src/Discord.Net.Rest/Entities/Channels/RestVoiceChannel.cs

@@ -57,6 +57,8 @@ namespace Discord.Rest
         /// </returns>
         public Task<ICategoryChannel> GetCategoryAsync(RequestOptions options = null)
             => ChannelHelper.GetCategoryAsync(this, Discord, options);
+        public Task SyncPermissionsAsync(RequestOptions options = null)
+            => ChannelHelper.SyncPermissionsAsync(this, Discord, options);
 
         private string DebuggerDisplay => $"{Name} ({Id}, Voice)";
 

src/Discord.Net.WebSocket/Entities/Channels/SocketTextChannel.cs

@@ -31,6 +31,8 @@ namespace Discord.WebSocket
         /// </returns>
         public ICategoryChannel Category
             => CategoryId.HasValue ? Guild.GetChannel(CategoryId.Value) as ICategoryChannel : null;
+        public Task SyncPermissionsAsync(RequestOptions options = null)
+            => ChannelHelper.SyncPermissionsAsync(this, Discord, options);
 
         private bool _nsfw;
         /// <inheritdoc />

src/Discord.Net.WebSocket/Entities/Channels/SocketVoiceChannel.cs

@@ -30,6 +30,8 @@ namespace Discord.WebSocket
         /// </returns>
         public ICategoryChannel Category
             => CategoryId.HasValue ? Guild.GetChannel(CategoryId.Value) as ICategoryChannel : null;
+        public Task SyncPermissionsAsync(RequestOptions options = null)
+            => ChannelHelper.SyncPermissionsAsync(this, Discord, options);
 
         /// <inheritdoc />
         public override IReadOnlyCollection<SocketGuildUser> Users