Add missing REST Webhook implemenation (#843)

* Add Webhook API models, REST implementation, and Socket bridges.

* Remove token overrides from REST.

Leaving that as a Webhook package only feature.

* Add Webhook API models, REST implementation, and Socket bridges.

* Remove token overrides from REST.

Leaving that as a Webhook package only feature.

* Webhook core implementation.

* Webhook REST implementation.

* Webhook client implementation.

* Add channel bucket id.

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

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Threading.Tasks;
 
 namespace Discord
@@ -19,5 +20,12 @@ namespace Discord
 
         /// <summary> Modifies this text channel. </summary>
         Task ModifyAsync(Action<TextChannelProperties> func, RequestOptions options = null);
+
+        /// <summary> Creates a webhook in this text channel. </summary>
+        Task<IWebhook> CreateWebhookAsync(string name, Stream avatar = null, RequestOptions options = null);
+        /// <summary> Gets the webhook in this text channel with the provided id, or null if not found. </summary>
+        Task<IWebhook> GetWebhookAsync(ulong id, RequestOptions options = null);
+        /// <summary> Gets the webhooks for this text channel. </summary>
+        Task<IReadOnlyCollection<IWebhook>> GetWebhooksAsync(RequestOptions options = null);
     }
 }

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

@@ -118,6 +118,11 @@ namespace Discord
         /// <summary> Removes all users from this guild if they have not logged on in a provided number of days or, if simulate is true, returns the number of users that would be removed. </summary>
         Task<int> PruneUsersAsync(int days = 30, bool simulate = false, RequestOptions options = null);
 
+        /// <summary> Gets the webhook in this guild with the provided id, or null if not found. </summary>
+        Task<IWebhook> GetWebhookAsync(ulong id, RequestOptions options = null);
+        /// <summary> Gets a collection of all webhooks for this guild. </summary>
+        Task<IReadOnlyCollection<IWebhook>> GetWebhooksAsync(RequestOptions options = null);
+        
         /// <summary> Gets a specific emote from this guild. </summary>
         Task<GuildEmote> GetEmoteAsync(ulong id, RequestOptions options = null);
         /// <summary> Creates a new emote in this guild. </summary>

src/Discord.Net.Core/Entities/Users/IWebhookUser.cs

@@ -1,6 +1,5 @@
 namespace Discord
 {
-    //TODO: Add webhook endpoints
     public interface IWebhookUser : IGuildUser
     {
         ulong WebhookId { get; }

src/Discord.Net.Core/Entities/Webhooks/IWebhook.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    public interface IWebhook : IDeletable, ISnowflakeEntity
+    {
+        /// <summary> Gets the token of this webhook. </summary>
+        string Token { get; }
+
+        /// <summary> Gets the default name of this webhook. </summary>
+        string Name { get; }
+        /// <summary> Gets the id of this webhook's default avatar. </summary>
+        string AvatarId { get; }
+        /// <summary> Gets the url to this webhook's default avatar. </summary>
+        string GetAvatarUrl(ImageFormat format = ImageFormat.Auto, ushort size = 128);
+
+        /// <summary> Gets the channel for this webhook. </summary>
+        ITextChannel Channel { get; }
+        /// <summary> Gets the id of the channel for this webhook. </summary>
+        ulong ChannelId { get; }
+
+        /// <summary> Gets the guild owning this webhook. </summary>
+        IGuild Guild { get; }
+        /// <summary> Gets the id of the guild owning this webhook. </summary>
+        ulong? GuildId { get; }
+
+        /// <summary> Gets the user that created this webhook. </summary>
+        IUser Creator { get; }
+
+        /// <summary> Modifies this webhook. </summary>
+        Task ModifyAsync(Action<WebhookProperties> func, RequestOptions options = null);
+    }
+}

src/Discord.Net.Core/Entities/Webhooks/WebhookProperties.cs

@@ -0,0 +1,41 @@
+namespace Discord
+{
+    /// <summary>
+    /// Modify an <see cref="IWebhook"/> with the specified parameters.
+    /// </summary>
+    /// <example>
+    /// <code language="c#">
+    /// await webhook.ModifyAsync(x =>
+    /// {
+    ///     x.Name = "Bob";
+    ///     x.Avatar = new Image("avatar.jpg");
+    /// });
+    /// </code>
+    /// </example>
+    /// <seealso cref="IWebhook"/>
+    public class WebhookProperties
+    {
+        /// <summary>
+        /// The default name of the webhook.
+        /// </summary>
+        public Optional<string> Name { get; set; }
+        /// <summary>
+        /// The default avatar of the webhook.
+        /// </summary>
+        public Optional<Image?> Image { get; set; }
+        /// <summary>
+        /// The channel for this webhook.
+        /// </summary>
+        /// <remarks>
+        /// This field is not used when authenticated with <see cref="TokenType.Webhook"/>.
+        /// </remarks>
+        public Optional<ITextChannel> Channel { get; set; }
+        /// <summary>
+        /// The channel id for this webhook.
+        /// </summary>
+        /// <remarks>
+        /// This field is not used when authenticated with <see cref="TokenType.Webhook"/>.
+        /// </remarks>
+        public Optional<ulong> ChannelId { get; set; }
+    }
+}

src/Discord.Net.Core/IDiscordClient.cs

@@ -34,5 +34,7 @@ namespace Discord
 
         Task<IReadOnlyCollection<IVoiceRegion>> GetVoiceRegionsAsync(RequestOptions options = null);
         Task<IVoiceRegion> GetVoiceRegionAsync(string id, RequestOptions options = null);
+
+        Task<IWebhook> GetWebhookAsync(ulong id, RequestOptions options = null);
     }
 }