feature: Update bans to support pagination (#2223)

* Cacheless impl

* Ignore cache impl

* Update src/Discord.Net.Core/Entities/Channels/Direction.cs

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Channels/Direction.cs

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

* Update src/Discord.Net.Core/Entities/Channels/Direction.cs

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

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

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

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

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

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

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

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

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

* Implement xmldoc consistency

Co-authored-by: Quin Lynch <49576606+quinchs@users.noreply.github.com>

src/Discord.Net.Core/DiscordConfig.cs

@@ -97,6 +97,13 @@ namespace Discord
         /// </returns>
         public const int MaxUsersPerBatch = 1000;
         /// <summary>
+        ///     Returns the max bans allowed to be in a request.
+        /// </summary>
+        /// <returns>
+        ///     The maximum number of bans that can be gotten per-batch.
+        /// </returns>
+        public const int MaxBansPerBatch = 1000;
+        /// <summary>
         ///     Returns the max users allowed to be in a request for guild event users.
         /// </summary>
         /// <returns>

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

@@ -1,10 +1,10 @@
 namespace Discord
 {
     /// <summary>
-    ///     Specifies the direction of where message(s) should be retrieved from.
+    ///     Specifies the direction of where entities (e.g. bans/messages) should be retrieved from.
     /// </summary>
     /// <remarks>
-    ///     This enum is used to specify the direction for retrieving messages.
+    ///     This enum is used to specify the direction for retrieving entities.
     ///     <note type="important">
     ///         At the time of writing, <see cref="Around"/> is not yet implemented into 
     ///         <see cref="IMessageChannel.GetMessagesAsync(int, CacheMode, RequestOptions)"/>.
@@ -15,15 +15,15 @@ namespace Discord
     public enum Direction
     {
         /// <summary>
-        ///     The message(s) should be retrieved before a message.
+        ///     The entity(s) should be retrieved before an entity.
         /// </summary>
         Before,
         /// <summary>
-        ///     The message(s) should be retrieved after a message.
+        ///     The entity(s) should be retrieved after an entity.
         /// </summary>
         After,
         /// <summary>
-        ///     The message(s) should be retrieved around a message.
+        ///     The entity(s) should be retrieved around an entity.
         /// </summary>
         Around
     }

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

@@ -409,17 +409,70 @@ namespace Discord
         ///     A task that represents the asynchronous leave operation.
         /// </returns>
         Task LeaveAsync(RequestOptions options = null);
-
         /// <summary>
-        ///     Gets a collection of all users banned in this guild.
+        ///     Gets <paramref name="limit"/> amount of bans from the guild ordered by user ID.
         /// </summary>
+        /// <remarks>
+        ///     <note type="important">
+        ///         The returned collection is an asynchronous enumerable object; one must call 
+        ///         <see cref="AsyncEnumerableExtensions.FlattenAsync{T}"/> to access the individual messages as a
+        ///         collection.
+        ///     </note>
+        ///     <note type="warning">
+        ///         Do not fetch too many bans at once! This may cause unwanted preemptive rate limit or even actual
+        ///         rate limit, causing your bot to freeze!
+        ///     </note>
+        /// </remarks>
+        /// <param name="limit">The amount of bans to get from the guild.</param>
         /// <param name="options">The options to be used when sending the request.</param>
         /// <returns>
-        ///     A task that represents the asynchronous get operation. The task result contains a read-only collection of
-        ///     ban objects that this guild currently possesses, with each object containing the user banned and reason
-        ///     behind the ban.
+        ///     A paged collection of bans.
+        /// </returns>
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> GetBansAsync(int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null);
+        /// <summary>
+        ///     Gets <paramref name="limit"/> amount of bans from the guild starting at the provided <paramref name="fromUserId"/> ordered by user ID.
+        /// </summary>
+        /// <remarks>
+        ///     <note type="important">
+        ///         The returned collection is an asynchronous enumerable object; one must call 
+        ///         <see cref="AsyncEnumerableExtensions.FlattenAsync{T}"/> to access the individual messages as a
+        ///         collection.
+        ///     </note>
+        ///     <note type="warning">
+        ///         Do not fetch too many bans at once! This may cause unwanted preemptive rate limit or even actual
+        ///         rate limit, causing your bot to freeze!
+        ///     </note>
+        /// </remarks>
+        /// <param name="fromUserId">The ID of the user to start to get bans from.</param>
+        /// <param name="dir">The direction of the bans to be gotten.</param>
+        /// <param name="limit">The number of bans to get.</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <returns>
+        ///     A paged collection of bans.
+        /// </returns>
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> GetBansAsync(ulong fromUserId, Direction dir, int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null);
+        /// <summary>
+        ///     Gets <paramref name="limit"/> amount of bans from the guild starting at the provided <paramref name="fromUser"/> ordered by user ID.
+        /// </summary>
+        /// <remarks>
+        ///     <note type="important">
+        ///         The returned collection is an asynchronous enumerable object; one must call 
+        ///         <see cref="AsyncEnumerableExtensions.FlattenAsync{T}"/> to access the individual messages as a
+        ///         collection.
+        ///     </note>
+        ///     <note type="warning">
+        ///         Do not fetch too many bans at once! This may cause unwanted preemptive rate limit or even actual
+        ///         rate limit, causing your bot to freeze!
+        ///     </note>
+        /// </remarks>
+        /// <param name="fromUser">The user to start to get bans from.</param>
+        /// <param name="dir">The direction of the bans to be gotten.</param>
+        /// <param name="limit">The number of bans to get.</param>
+        /// <param name="options">The options to be used when sending the request.</param>
+        /// <returns>
+        ///     A paged collection of bans.
         /// </returns>
-        Task<IReadOnlyCollection<IBan>> GetBansAsync(RequestOptions options = null);
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> GetBansAsync(IUser fromUser, Direction dir, int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null);
         /// <summary>
         ///     Gets a ban object for a banned user.
         /// </summary>

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

@@ -0,0 +1,9 @@
+namespace Discord.API.Rest
+{
+    internal class GetGuildBansParams
+    {
+        public Optional<int> Limit { get; set; }
+        public Optional<Direction> RelativeDirection { get; set; }
+        public Optional<ulong> RelativeUserId { get; set; }
+    }
+}

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -1545,13 +1545,29 @@ namespace Discord.API
         #endregion
 
         #region Guild Bans
-        public async Task<IReadOnlyCollection<Ban>> GetGuildBansAsync(ulong guildId, RequestOptions options = null)
+        public async Task<IReadOnlyCollection<Ban>> GetGuildBansAsync(ulong guildId, GetGuildBansParams args, RequestOptions options = null)
         {
             Preconditions.NotEqual(guildId, 0, nameof(guildId));
+            Preconditions.NotNull(args, nameof(args));
+            Preconditions.AtLeast(args.Limit, 0, nameof(args.Limit));
+            Preconditions.AtMost(args.Limit, DiscordConfig.MaxBansPerBatch, nameof(args.Limit));
             options = RequestOptions.CreateOrClone(options);
 
+            int limit = args.Limit.GetValueOrDefault(DiscordConfig.MaxBansPerBatch);
+            ulong? relativeId = args.RelativeUserId.IsSpecified ? args.RelativeUserId.Value : (ulong?)null;
+            var relativeDir = args.RelativeDirection.GetValueOrDefault(Direction.Before) switch
+            {
+                Direction.After => "after",
+                Direction.Around => "around",
+                _ => "before",
+            };
             var ids = new BucketIds(guildId: guildId);
-            return await SendAsync<IReadOnlyCollection<Ban>>("GET", () => $"guilds/{guildId}/bans", ids, options: options).ConfigureAwait(false);
+            Expression<Func<string>> endpoint;
+            if (relativeId != null)
+                endpoint = () => $"guilds/{guildId}/bans?limit={limit}&{relativeDir}={relativeId}";
+            else
+                endpoint = () => $"guilds/{guildId}/bans?limit={limit}";
+            return await SendAsync<IReadOnlyCollection<Ban>>("GET", endpoint, ids, options: options).ConfigureAwait(false);
         }
         public async Task<Ban> GetGuildBanAsync(ulong guildId, ulong userId, RequestOptions options)
         {

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

@@ -142,12 +142,54 @@ namespace Discord.Rest
         #endregion
 
         #region Bans
-        public static async Task<IReadOnlyCollection<RestBan>> GetBansAsync(IGuild guild, BaseDiscordClient client,
-            RequestOptions options)
+        public static IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(IGuild guild, BaseDiscordClient client,
+            ulong? fromUserId, Direction dir, int limit, RequestOptions options)
         {
-            var models = await client.ApiClient.GetGuildBansAsync(guild.Id, options).ConfigureAwait(false);
-            return models.Select(x => RestBan.Create(client, x)).ToImmutableArray();
+            if (dir == Direction.Around && limit > DiscordConfig.MaxBansPerBatch)
+            {
+                int around = limit / 2;
+                if (fromUserId.HasValue)
+                    return GetBansAsync(guild, client, fromUserId.Value + 1, Direction.Before, around + 1, options)
+                        .Concat(GetBansAsync(guild, client, fromUserId.Value, Direction.After, around, options));
+                else 
+                    return GetBansAsync(guild, client, null, Direction.Before, around + 1, options);
+            }
+
+            return new PagedAsyncEnumerable<RestBan>(
+                DiscordConfig.MaxBansPerBatch,
+                async (info, ct) =>
+                {
+                    var args = new GetGuildBansParams
+                    {
+                        RelativeDirection = dir,
+                        Limit = info.PageSize
+                    };
+                    if (info.Position != null)
+                        args.RelativeUserId = info.Position.Value;
+
+                    var models = await client.ApiClient.GetGuildBansAsync(guild.Id, args, options).ConfigureAwait(false);
+                    var builder = ImmutableArray.CreateBuilder<RestBan>();
+
+                    foreach (var model in models)
+                        builder.Add(RestBan.Create(client, model));
+
+                    return builder.ToImmutable();
+                },
+                nextPage: (info, lastPage) =>
+                {
+                    if (lastPage.Count != DiscordConfig.MaxMessagesPerBatch)
+                        return false;
+                    if (dir == Direction.Before)
+                        info.Position = lastPage.Min(x => x.User.Id);
+                    else
+                        info.Position = lastPage.Max(x => x.User.Id);
+                    return true;
+                },
+                start: fromUserId,
+                count: limit
+                );
         }
+
         public static async Task<RestBan> GetBanAsync(IGuild guild, BaseDiscordClient client, ulong userId, RequestOptions options)
         {
             var model = await client.ApiClient.GetGuildBanAsync(guild.Id, userId, options).ConfigureAwait(false);

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

@@ -333,17 +333,18 @@ namespace Discord.Rest
         #endregion
 
         #region Bans
-        /// <summary>
-        ///     Gets a collection of all users banned in this guild.
-        /// </summary>
-        /// <param name="options">The options to be used when sending the request.</param>
-        /// <returns>
-        ///     A task that represents the asynchronous get operation. The task result contains a read-only collection of
-        ///     ban objects that this guild currently possesses, with each object containing the user banned and reason
-        ///     behind the ban.
-        /// </returns>
-        public Task<IReadOnlyCollection<RestBan>> GetBansAsync(RequestOptions options = null)
-            => GuildHelper.GetBansAsync(this, Discord, options);
+
+        /// <inheritdoc cref="IGuild.GetBansAsync(int, RequestOptions)" />
+        public IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null)
+            => GuildHelper.GetBansAsync(this, Discord, null, Direction.Before, limit, options);
+
+        /// <inheritdoc cref="IGuild.GetBansAsync(ulong, Direction, int, RequestOptions)" />
+        public IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(ulong fromUserId, Direction dir, int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null)
+            => GuildHelper.GetBansAsync(this, Discord, fromUserId, dir, limit, options);
+
+        /// <inheritdoc cref="IGuild.GetBansAsync(IUser, Direction, int, RequestOptions)" />
+        public IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(IUser fromUser, Direction dir, int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null)
+            => GuildHelper.GetBansAsync(this, Discord, fromUser.Id, dir, limit, options);
         /// <summary>
         ///     Gets a ban object for a banned user.
         /// </summary>
@@ -1193,22 +1194,24 @@ namespace Discord.Rest
         IReadOnlyCollection<IRole> IGuild.Roles => Roles;
 
         IReadOnlyCollection<ICustomSticker> IGuild.Stickers => Stickers;
-
         /// <inheritdoc />
         async Task<IGuildScheduledEvent> IGuild.CreateEventAsync(string name, DateTimeOffset startTime, GuildScheduledEventType type, GuildScheduledEventPrivacyLevel privacyLevel, string description, DateTimeOffset? endTime, ulong? channelId, string location, Image? coverImage, RequestOptions options)
             => await CreateEventAsync(name, startTime, type, privacyLevel, description, endTime, channelId, location, coverImage, options).ConfigureAwait(false);
-
         /// <inheritdoc />
         async Task<IGuildScheduledEvent> IGuild.GetEventAsync(ulong id, RequestOptions options)
             => await GetEventAsync(id, options).ConfigureAwait(false);
-
         /// <inheritdoc />
         async Task<IReadOnlyCollection<IGuildScheduledEvent>> IGuild.GetEventsAsync(RequestOptions options)
             => await GetEventsAsync(options).ConfigureAwait(false);
-
         /// <inheritdoc />
-        async Task<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(RequestOptions options)
-            => await GetBansAsync(options).ConfigureAwait(false);
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(int limit, RequestOptions options)
+            => GetBansAsync(limit, options);
+        /// <inheritdoc />
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(ulong fromUserId, Direction dir, int limit, RequestOptions options)
+            => GetBansAsync(fromUserId, dir, limit, options);
+        /// <inheritdoc />
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(IUser fromUser, Direction dir, int limit, RequestOptions options)
+            => GetBansAsync(fromUser, dir, limit, options);
         /// <inheritdoc/>
         async Task<IBan> IGuild.GetBanAsync(IUser user, RequestOptions options)
             => await GetBanAsync(user, options).ConfigureAwait(false);

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

@@ -621,17 +621,19 @@ namespace Discord.WebSocket
         #endregion
 
         #region Bans
-        /// <summary>
-        ///     Gets a collection of all users banned in this guild.
-        /// </summary>
-        /// <param name="options">The options to be used when sending the request.</param>
-        /// <returns>
-        ///     A task that represents the asynchronous get operation. The task result contains a read-only collection of
-        ///     ban objects that this guild currently possesses, with each object containing the user banned and reason
-        ///     behind the ban.
-        /// </returns>
-        public Task<IReadOnlyCollection<RestBan>> GetBansAsync(RequestOptions options = null)
-            => GuildHelper.GetBansAsync(this, Discord, options);
+
+        /// <inheritdoc cref="IGuild.GetBansAsync(int, RequestOptions)" />
+        public IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null)
+            => GuildHelper.GetBansAsync(this, Discord, null, Direction.Before, limit, options);
+
+        /// <inheritdoc cref="IGuild.GetBansAsync(ulong, Direction, int, RequestOptions)" />
+        public IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(ulong fromUserId, Direction dir, int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null)
+            => GuildHelper.GetBansAsync(this, Discord, fromUserId, dir, limit, options);
+
+        /// <inheritdoc cref="IGuild.GetBansAsync(IUser, Direction, int, RequestOptions)" />
+        public IAsyncEnumerable<IReadOnlyCollection<RestBan>> GetBansAsync(IUser fromUser, Direction dir, int limit = DiscordConfig.MaxBansPerBatch, RequestOptions options = null)
+            => GuildHelper.GetBansAsync(this, Discord, fromUser.Id, dir, limit, options);
+
         /// <summary>
         ///     Gets a ban object for a banned user.
         /// </summary>
@@ -1810,8 +1812,14 @@ namespace Discord.WebSocket
         async Task<IReadOnlyCollection<IGuildScheduledEvent>> IGuild.GetEventsAsync(RequestOptions options)
             => await GetEventsAsync(options).ConfigureAwait(false);
         /// <inheritdoc />
-        async Task<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(RequestOptions options)
-            => await GetBansAsync(options).ConfigureAwait(false);
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(int limit, RequestOptions options)
+            => GetBansAsync(limit, options);
+        /// <inheritdoc />
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(ulong fromUserId, Direction dir, int limit, RequestOptions options)
+            => GetBansAsync(fromUserId, dir, limit, options);
+        /// <inheritdoc />
+        IAsyncEnumerable<IReadOnlyCollection<IBan>> IGuild.GetBansAsync(IUser fromUser, Direction dir, int limit, RequestOptions options)
+            => GetBansAsync(fromUser, dir, limit, options);
         /// <inheritdoc/>
         async Task<IBan> IGuild.GetBanAsync(IUser user, RequestOptions options)
             => await GetBanAsync(user, options).ConfigureAwait(false);