Added Message pinning

src/Discord.Net/API/Common/Message.cs

@@ -20,12 +20,14 @@ namespace Discord.API
         [JsonProperty("tts")]
         public Optional<bool> IsTextToSpeech { get; set; }
         [JsonProperty("mention_everyone")]
-        public Optional<bool> IsMentioningEveryone { get; set; }
+        public Optional<bool> MentionEveryone { get; set; }
         [JsonProperty("mentions")]
         public Optional<User[]> Mentions { get; set; }
         [JsonProperty("attachments")]
         public Optional<Attachment[]> Attachments { get; set; }
         [JsonProperty("embeds")]
         public Optional<Embed[]> Embeds { get; set; }
+        [JsonProperty("pinned")]
+        public Optional<bool> Pinned { get; set; }
     }
 }

src/Discord.Net/API/DiscordAPIClient.cs

@@ -494,15 +494,37 @@ namespace Discord.API
         //Channel Permissions
         public async Task ModifyChannelPermissionsAsync(ulong channelId, ulong targetId, ModifyChannelPermissionsParams args, RequestOptions options = null)
         {
+            Preconditions.NotEqual(channelId, 0, nameof(channelId));
+            Preconditions.NotEqual(targetId, 0, nameof(targetId));
             Preconditions.NotNull(args, nameof(args));
 
             await SendAsync("PUT", $"channels/{channelId}/permissions/{targetId}", args, options: options).ConfigureAwait(false);
         }
         public async Task DeleteChannelPermissionAsync(ulong channelId, ulong targetId, RequestOptions options = null)
         {
+            Preconditions.NotEqual(channelId, 0, nameof(channelId));
+            Preconditions.NotEqual(targetId, 0, nameof(targetId));
+
             await SendAsync("DELETE", $"channels/{channelId}/permissions/{targetId}", options: options).ConfigureAwait(false);
         }
 
+        //Channel Pins
+        public async Task AddPinAsync(ulong channelId, ulong messageId, RequestOptions options = null)
+        {
+            Preconditions.GreaterThan(channelId, 0, nameof(channelId));
+            Preconditions.GreaterThan(messageId, 0, nameof(messageId));
+
+            await SendAsync("PUT", $"channels/{channelId}/pins/{messageId}", options: options).ConfigureAwait(false);
+
+        }
+        public async Task RemovePinAsync(ulong channelId, ulong messageId, RequestOptions options = null)
+        {
+            Preconditions.NotEqual(channelId, 0, nameof(channelId));
+            Preconditions.NotEqual(messageId, 0, nameof(messageId));
+
+            await SendAsync("DELETE", $"channels/{channelId}/pins/{messageId}", options: options).ConfigureAwait(false);
+        }
+
         //Guilds
         public async Task<Guild> GetGuildAsync(ulong guildId, RequestOptions options = null)
         {

src/Discord.Net/Entities/Messages/IMessage.cs

@@ -11,6 +11,8 @@ namespace Discord
         DateTimeOffset? EditedTimestamp { get; }
         /// <summary> Returns true if this message was sent as a text-to-speech message. </summary>
         bool IsTTS { get; }
+        /// <summary> Returns true if this message was added to its channel's pinned messages. </summary>
+        bool IsPinned { get; }
         /// <summary> Returns the original, unprocessed text for this message. </summary>
         string RawText { get; }
         /// <summary> Returns the text for this message after mention processing. </summary>
@@ -35,5 +37,9 @@ namespace Discord
 
         /// <summary> Modifies this message. </summary>
         Task ModifyAsync(Action<ModifyMessageParams> func);
+        /// <summary> Adds this message to its channel's pinned messages. </summary>
+        Task PinAsync();
+        /// <summary> Removes this message from its channel's pinned messages. </summary>
+        Task UnpinAsync();
     }
 }

src/Discord.Net/Entities/Messages/Message.cs

@@ -18,6 +18,7 @@ namespace Discord
         public bool IsTTS { get; private set; }
         public string RawText { get; private set; }
         public string Text { get; private set; }
+        public bool IsPinned { get; private set; }
         
         public IMessageChannel Channel { get; }
         public IUser Author { get; }
@@ -57,13 +58,15 @@ namespace Discord
 
             if (model.IsTextToSpeech.IsSpecified)
                 IsTTS = model.IsTextToSpeech.Value;
+            if (model.Pinned.IsSpecified)
+                IsPinned = model.Pinned.Value;
             if (model.Timestamp.IsSpecified)
                 _timestampTicks = model.Timestamp.Value.UtcTicks;
             if (model.EditedTimestamp.IsSpecified)
                 _editedTimestampTicks = model.EditedTimestamp.Value?.UtcTicks;
-            if (model.IsMentioningEveryone.IsSpecified)
-                _isMentioningEveryone = model.IsMentioningEveryone.Value;
-            
+            if (model.MentionEveryone.IsSpecified)
+                _isMentioningEveryone = model.MentionEveryone.Value;
+
             if (model.Attachments.IsSpecified)
             {
                 var value = model.Attachments.Value;
@@ -144,6 +147,9 @@ namespace Discord
                 model = await Discord.ApiClient.ModifyMessageAsync(guildChannel.Guild.Id, Channel.Id, Id, args).ConfigureAwait(false);
             else
                 model = await Discord.ApiClient.ModifyDMMessageAsync(Channel.Id, Id, args).ConfigureAwait(false);
+        {
+            await Discord.ApiClient.AddPinAsync(Channel.Id, Id).ConfigureAwait(false);
+        }
             Update(model, UpdateSource.Rest);
         }        
         public async Task DeleteAsync()
@@ -154,6 +160,16 @@ namespace Discord
             else
                 await Discord.ApiClient.DeleteDMMessageAsync(Channel.Id, Id).ConfigureAwait(false);
         }
+        /// <summary> Adds this message to its channel's pinned messages. </summary>
+        public async Task PinAsync()
+        {
+            await Discord.ApiClient.AddPinAsync(Channel.Id, Id).ConfigureAwait(false);
+        }
+        /// <summary> Removes this message from its channel's pinned messages. </summary>
+        public async Task UnpinAsync()
+        {
+            await Discord.ApiClient.RemovePinAsync(Channel.Id, Id).ConfigureAwait(false);
+        }
 
         public override string ToString() => Text;
         private string DebuggerDisplay => $"{Author}: {Text}{(Attachments.Length > 0 ? $" [{Attachments.Length} Attachments]" : "")}";