Audit Logs implementation (#1055)

* Copy audit logs impl from old branch and clean up

I suck at using git, so I'm gonna use brute force.

* Remove unnecessary TODOs

Category channels do not provide any new information, and the other
I forgot to remove beforehand

* Add invite update data, clean up after feedback

* Remove TODOs, add WebhookType enum for future use

WebhookType is a future-use type, as currently audit logs are the only
thing which may return it.

src/Discord.Net.Core/DiscordConfig.cs

@@ -4,10 +4,10 @@ namespace Discord
 {
     public class DiscordConfig
     {
-        public const int APIVersion = 6;        
+        public const int APIVersion = 6;
         public static string Version { get; } =
             typeof(DiscordConfig).GetTypeInfo().Assembly.GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion ??
-            typeof(DiscordConfig).GetTypeInfo().Assembly.GetName().Version.ToString(3) ?? 
+            typeof(DiscordConfig).GetTypeInfo().Assembly.GetName().Version.ToString(3) ??
             "Unknown";
 
         public static string UserAgent { get; } = $"DiscordBot (https://github.com/RogueException/Discord.Net, v{Version})";
@@ -20,10 +20,11 @@ public class DiscordConfig
         public const int MaxMessagesPerBatch = 100;
         public const int MaxUsersPerBatch = 1000;
         public const int MaxGuildsPerBatch = 100;
+        public const int MaxAuditLogEntriesPerBatch = 100;
 
         /// <summary> Gets or sets how a request should act in the case of an error, by default. </summary>
         public RetryMode DefaultRetryMode { get; set; } = RetryMode.AlwaysRetry;
-        
+
         /// <summary> Gets or sets the minimum log level severity that will be sent to the Log event. </summary>
         public LogSeverity LogLevel { get; set; } = LogSeverity.Info;
 

src/Discord.Net.Core/Entities/AuditLogs/ActionType.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    /// <summary>
+    /// The action type within a <see cref="IAuditLogEntry"/>
+    /// </summary>
+    public enum ActionType
+    {
+        GuildUpdated = 1,
+
+        ChannelCreated = 10,
+        ChannelUpdated = 11,
+        ChannelDeleted = 12,
+
+        OverwriteCreated = 13,
+        OverwriteUpdated = 14,
+        OverwriteDeleted = 15,
+
+        Kick = 20,
+        Prune = 21,
+        Ban = 22,
+        Unban = 23,
+
+        MemberUpdated = 24,
+        MemberRoleUpdated = 25,
+
+        RoleCreated = 30,
+        RoleUpdated = 31,
+        RoleDeleted = 32,
+
+        InviteCreated = 40,
+        InviteUpdated = 41,
+        InviteDeleted = 42,
+
+        WebhookCreated = 50,
+        WebhookUpdated = 51,
+        WebhookDeleted = 52,
+
+        EmojiCreated = 60,
+        EmojiUpdated = 61,
+        EmojiDeleted = 62,
+
+        MessageDeleted = 72
+    }
+}

src/Discord.Net.Core/Entities/AuditLogs/IAuditLogData.cs

@@ -0,0 +1,14 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    /// <summary>
+    /// Represents data applied to an <see cref="IAuditLogEntry"/>
+    /// </summary>
+    public interface IAuditLogData
+    { }
+}

src/Discord.Net.Core/Entities/AuditLogs/IAuditLogEntry.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Discord
+{
+    /// <summary>
+    /// Represents an entry in an audit log
+    /// </summary>
+    public interface IAuditLogEntry : IEntity<ulong>
+    {
+        /// <summary>
+        /// The action which occured to create this entry
+        /// </summary>
+        ActionType Action { get; }
+
+        /// <summary>
+        /// The data for this entry. May be <see cref="null"/> if no data was available.
+        /// </summary>
+        IAuditLogData Data { get; }
+
+        /// <summary>
+        /// The user responsible for causing the changes
+        /// </summary>
+        IUser User { get; }
+
+        /// <summary>
+        /// The reason behind the change. May be <see cref="null"/> if no reason was provided.
+        /// </summary>
+        string Reason { get; }
+    }
+}

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

@@ -139,6 +139,10 @@ public interface IGuild : IDeletable, ISnowflakeEntity
         /// <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 specified number of audit log entries for this guild. </summary>
+        Task<IReadOnlyCollection<IAuditLogEntry>> GetAuditLogAsync(int limit = DiscordConfig.MaxAuditLogEntriesPerBatch,
+            CacheMode mode = CacheMode.AllowDownload, 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>

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

@@ -0,0 +1,14 @@
+namespace Discord
+{
+    /// <summary>
+    /// Represents the type of a webhook.
+    /// </summary>
+    /// <remarks>
+    /// This type is currently unused, and is only returned in audit log responses.
+    /// </remarks>
+    public enum WebhookType
+    {
+        /// <summary> An incoming webhook </summary>
+        Incoming = 1
+    }
+}

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

@@ -0,0 +1,16 @@
+using Newtonsoft.Json;
+
+namespace Discord.API
+{
+    internal class AuditLog
+    {
+        [JsonProperty("webhooks")]
+        public Webhook[] Webhooks { get; set; }
+
+        [JsonProperty("users")]
+        public User[] Users { get; set; }
+
+        [JsonProperty("audit_log_entries")]
+        public AuditLogEntry[] Entries { get; set; }
+    }
+}

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

@@ -0,0 +1,17 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+
+namespace Discord.API
+{
+    internal class AuditLogChange
+    {
+        [JsonProperty("key")]
+        public string ChangedProperty { get; set; }
+
+        [JsonProperty("new_value")]
+        public JToken NewValue { get; set; }
+
+        [JsonProperty("old_value")]
+        public JToken OldValue { get; set; }
+    }
+}

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

@@ -0,0 +1,26 @@
+using Newtonsoft.Json;
+
+namespace Discord.API
+{
+    internal class AuditLogEntry
+    {
+        [JsonProperty("target_id")]
+        public ulong? TargetId { get; set; }
+        [JsonProperty("user_id")]
+        public ulong UserId { get; set; }
+
+        [JsonProperty("changes")]
+        public AuditLogChange[] Changes { get; set; }
+        [JsonProperty("options")]
+        public AuditLogOptions Options { get; set; }
+
+        [JsonProperty("id")]
+        public ulong Id { get; set; }
+
+        [JsonProperty("action_type")]
+        public ActionType Action { get; set; }
+
+        [JsonProperty("reason")]
+        public string Reason { get; set; }
+    }
+}

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

@@ -0,0 +1,27 @@
+using Newtonsoft.Json;
+
+namespace Discord.API
+{
+    internal class AuditLogOptions
+    {
+        //Message delete
+        [JsonProperty("count")]
+        public int? MessageDeleteCount { get; set; }
+        [JsonProperty("channel_id")]
+        public ulong? MessageDeleteChannelId { get; set; }
+
+        //Prune
+        [JsonProperty("delete_member_days")]
+        public int? PruneDeleteMemberDays { get; set; }
+        [JsonProperty("members_removed")]
+        public int? PruneMembersRemoved { get; set; }
+
+        //Overwrite Update
+        [JsonProperty("role_name")]
+        public string OverwriteRoleName { get; set; }
+        [JsonProperty("type")]
+        public string OverwriteType { get; set; }
+        [JsonProperty("id")]
+        public ulong? OverwriteTargetId { get; set; }
+    }
+}

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

@@ -0,0 +1,8 @@
+namespace Discord.API.Rest
+{
+    class GetAuditLogsParams
+    {
+        public Optional<int> Limit { get; set; }
+        public Optional<ulong> BeforeEntryId { get; set; }
+    }
+}

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -1206,6 +1206,26 @@ public async Task<IReadOnlyCollection<VoiceRegion>> GetGuildVoiceRegionsAsync(ul
             return await SendAsync<IReadOnlyCollection<VoiceRegion>>("GET", () => $"guilds/{guildId}/regions", ids, options: options).ConfigureAwait(false);
         }
 
+        //Audit logs
+        public async Task<AuditLog> GetAuditLogsAsync(ulong guildId, GetAuditLogsParams args, RequestOptions options = null)
+        {
+            Preconditions.NotEqual(guildId, 0, nameof(guildId));
+            Preconditions.NotNull(args, nameof(args));
+            options = RequestOptions.CreateOrClone(options);
+
+            int limit = args.Limit.GetValueOrDefault(int.MaxValue);
+
+            var ids = new BucketIds(guildId: guildId);
+            Expression<Func<string>> endpoint;
+
+            if (args.BeforeEntryId.IsSpecified)
+                endpoint = () => $"guilds/{guildId}/audit-logs?limit={limit}&before={args.BeforeEntryId.Value}";
+            else
+                endpoint = () => $"guilds/{guildId}/audit-logs?limit={limit}";
+
+            return await SendAsync<AuditLog>("GET", endpoint, ids, options: options).ConfigureAwait(false);
+        }
+
         //Webhooks
         public async Task<Webhook> CreateWebhookAsync(ulong channelId, CreateWebhookParams args, RequestOptions options = null)
         {

src/Discord.Net.Rest/Entities/AuditLogs/AuditLogHelper.cs

@@ -0,0 +1,58 @@
+using System;
+using System.Collections.Generic;
+
+using Model = Discord.API.AuditLog;
+using EntryModel = Discord.API.AuditLogEntry;
+
+namespace Discord.Rest
+{
+    internal static class AuditLogHelper
+    {
+        private static readonly Dictionary<ActionType, Func<BaseDiscordClient, Model, EntryModel, IAuditLogData>> CreateMapping
+            = new Dictionary<ActionType, Func<BaseDiscordClient, Model, EntryModel, IAuditLogData>>()
+        {
+            [ActionType.GuildUpdated] = GuildUpdateAuditLogData.Create,
+
+            [ActionType.ChannelCreated] = ChannelCreateAuditLogData.Create,
+            [ActionType.ChannelUpdated] = ChannelUpdateAuditLogData.Create,
+            [ActionType.ChannelDeleted] = ChannelDeleteAuditLogData.Create,
+
+            [ActionType.OverwriteCreated] = OverwriteCreateAuditLogData.Create,
+            [ActionType.OverwriteUpdated] = OverwriteUpdateAuditLogData.Create,
+            [ActionType.OverwriteDeleted] = OverwriteDeleteAuditLogData.Create,
+
+            [ActionType.Kick] = KickAuditLogData.Create,
+            [ActionType.Prune] = PruneAuditLogData.Create,
+            [ActionType.Ban] = BanAuditLogData.Create,
+            [ActionType.Unban] = UnbanAuditLogData.Create,
+            [ActionType.MemberUpdated] = MemberUpdateAuditLogData.Create,
+            [ActionType.MemberRoleUpdated] = MemberRoleAuditLogData.Create,
+
+            [ActionType.RoleCreated] = RoleCreateAuditLogData.Create,
+            [ActionType.RoleUpdated] = RoleUpdateAuditLogData.Create,
+            [ActionType.RoleDeleted] = RoleDeleteAuditLogData.Create,
+
+            [ActionType.InviteCreated] = InviteCreateAuditLogData.Create,
+            [ActionType.InviteUpdated] = InviteUpdateAuditLogData.Create,
+            [ActionType.InviteDeleted] = InviteDeleteAuditLogData.Create,
+
+            [ActionType.WebhookCreated] = WebhookCreateAuditLogData.Create,
+            [ActionType.WebhookUpdated] = WebhookUpdateAuditLogData.Create,
+            [ActionType.WebhookDeleted] = WebhookDeleteAuditLogData.Create,
+
+            [ActionType.EmojiCreated] = EmoteCreateAuditLogData.Create,
+            [ActionType.EmojiUpdated] = EmoteUpdateAuditLogData.Create,
+            [ActionType.EmojiDeleted] = EmoteDeleteAuditLogData.Create,
+
+            [ActionType.MessageDeleted] = MessageDeleteAuditLogData.Create,
+        };
+
+        public static IAuditLogData CreateData(BaseDiscordClient discord, Model log, EntryModel entry)
+        {
+            if (CreateMapping.TryGetValue(entry.Action, out var func))
+                return func(discord, log, entry);
+
+            return null;
+        }
+    }
+}

src/Discord.Net.Rest/Entities/AuditLogs/DataTypes/BanAuditLogData.cs

@@ -0,0 +1,23 @@
+using System.Linq;
+
+using Model = Discord.API.AuditLog;
+using EntryModel = Discord.API.AuditLogEntry;
+
+namespace Discord.Rest
+{
+    public class BanAuditLogData : IAuditLogData
+    {
+        private BanAuditLogData(IUser user)
+        {
+            Target = user;
+        }
+
+        internal static BanAuditLogData Create(BaseDiscordClient discord, Model log, EntryModel entry)
+        {
+            var userInfo = log.Users.FirstOrDefault(x => x.Id == entry.TargetId);
+            return new BanAuditLogData(RestUser.Create(discord, userInfo));
+        }
+
+        public IUser Target { get; }
+    }
+}