feat(api): add news to /api/meta response

Catalogger.Backend/Api/ApiCache.cs

@@ -14,11 +14,43 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 using Catalogger.Backend.Database.Redis;
+using Remora.Discord.API;
+using Remora.Discord.API.Abstractions.Objects;
+using Remora.Discord.API.Abstractions.Rest;
 
 namespace Catalogger.Backend.Api;
 
-public class ApiCache(RedisService redisService)
+public class ApiCache(RedisService redisService, IDiscordRestChannelAPI channelApi, Config config)
 {
+    private List<IMessage>? _news;
+    private readonly SemaphoreSlim _newsSemaphore = new(1);
+
+    public async Task<List<IMessage>> GetNewsAsync()
+    {
+        await _newsSemaphore.WaitAsync();
+        try
+        {
+            if (_news != null)
+                return _news;
+
+            if (config.Web.NewsChannel == null)
+                return [];
+
+            var res = await channelApi.GetChannelMessagesAsync(
+                DiscordSnowflake.New(config.Web.NewsChannel.Value),
+                limit: 5
+            );
+            if (res.IsSuccess)
+                return _news = res.Entity.ToList();
+
+            return [];
+        }
+        finally
+        {
+            _newsSemaphore.Release();
+        }
+    }
+
     private static string UserKey(string id) => $"api-user:{id}";
 
     private static string GuildsKey(string userId) => $"api-user-guilds:{userId}";

Catalogger.Backend/Api/GuildsController.cs

@@ -31,7 +31,6 @@ namespace Catalogger.Backend.Api;
 
 [Route("/api/guilds/{id}")]
 public partial class GuildsController(
-    Config config,
     ILogger logger,
     DatabaseContext db,
     ChannelCache channelCache,

Catalogger.Backend/Api/MetaController.cs

@@ -15,7 +15,10 @@
 
 using Catalogger.Backend.Api.Middleware;
 using Catalogger.Backend.Cache.InMemoryCache;
+using Catalogger.Backend.Extensions;
+using Catalogger.Backend.Services;
 using Microsoft.AspNetCore.Mvc;
+using Remora.Discord.API.Abstractions.Objects;
 
 namespace Catalogger.Backend.Api;
 
@@ -23,20 +26,24 @@ namespace Catalogger.Backend.Api;
 public class MetaController(
     Config config,
     GuildCache guildCache,
+    NewsService newsService,
     DiscordRequestService discordRequestService
 ) : ApiControllerBase
 {
     [HttpGet("meta")]
-    public IActionResult GetMeta()
+    public async Task<IActionResult> GetMetaAsync()
     {
         var inviteUrl =
             $"https://discord.com/oauth2/authorize?client_id={config.Discord.ApplicationId}"
             + "&permissions=537250993&scope=bot+applications.commands";
 
+        var news = await newsService.GetNewsAsync();
+
         return Ok(
             new MetaResponse(
                 Guilds: (int)CataloggerMetrics.GuildsCached.Value,
-                InviteUrl: inviteUrl
+                InviteUrl: inviteUrl,
+                News: news
             )
         );
     }
@@ -60,7 +67,11 @@ public class MetaController(
         );
     }
 
-    private record MetaResponse(int Guilds, string InviteUrl);
+    private record MetaResponse(
+        int Guilds,
+        string InviteUrl,
+        IEnumerable<NewsService.NewsMessage> News
+    );
 
     private record CurrentUserResponse(ApiUser User, IEnumerable<ApiGuild> Guilds);
 }

Catalogger.Backend/Config.cs

@@ -62,5 +62,7 @@ public class Config
         public int Port { get; init; } = 5000;
         public string BaseUrl { get; init; } = null!;
         public string Address => $"http://{Host}:{Port}";
+
+        public ulong? NewsChannel { get; init; }
     }
 }

Catalogger.Backend/Extensions/StartupExtensions.cs

@@ -110,6 +110,7 @@ public static class StartupExtensions
             .AddSingleton<AuditLogCache>()
             .AddSingleton<EmojiCache>()
             .AddSingleton<PluralkitApiService>()
+            .AddSingleton<NewsService>()
             .AddScoped<IEncryptionService, EncryptionService>()
             .AddSingleton<MetricsCollectionService>()
             .AddScoped<MessageRepository>()

Catalogger.Backend/Services/NewsService.cs

@@ -0,0 +1,97 @@
+// Copyright (C) 2021-present sam (starshines.gay)
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+using Catalogger.Backend.Extensions;
+using NodaTime;
+using NodaTime.Extensions;
+using Remora.Discord.API;
+using Remora.Discord.API.Abstractions.Objects;
+using Remora.Discord.API.Abstractions.Rest;
+
+namespace Catalogger.Backend.Services;
+
+public class NewsService(
+    Config config,
+    ILogger logger,
+    IDiscordRestChannelAPI channelApi,
+    IClock clock
+)
+{
+    private static readonly Duration MaxNewsAge = Duration.FromDays(90); // 3 months
+    private static readonly Duration ExpiresAfter = Duration.FromHours(1);
+
+    private readonly ILogger _logger = logger.ForContext<NewsService>();
+    private List<IMessage>? _messages;
+    private readonly SemaphoreSlim _lock = new(1);
+    private bool _isExpired => clock.GetCurrentInstant() > clock.GetCurrentInstant() + ExpiresAfter;
+
+    public async Task<IEnumerable<NewsMessage>> GetNewsAsync()
+    {
+        if (_messages != null && !_isExpired)
+            return _messages.Select(FormatIMessage);
+
+        var messages = await GetRawNewsAsync();
+        return messages.Select(FormatIMessage);
+    }
+
+    public void AddMessage(IMessage message) =>
+        _messages = _messages?.Take(4).Prepend(message).ToList();
+
+    private async Task<List<IMessage>> GetRawNewsAsync()
+    {
+        await _lock.WaitAsync();
+        try
+        {
+            if (config.Web.NewsChannel == null)
+                return [];
+
+            _logger.Information("Fetching news from channel {ChannelId}", config.Web.NewsChannel);
+
+            var res = await channelApi.GetChannelMessagesAsync(
+                DiscordSnowflake.New(config.Web.NewsChannel.Value),
+                limit: 5
+            );
+            if (res.IsSuccess)
+                return _messages = res
+                    .Entity.Where(m =>
+                        m.ID.Timestamp.ToInstant() > clock.GetCurrentInstant() - MaxNewsAge
+                    )
+                    .ToList();
+
+            return [];
+        }
+        finally
+        {
+            _lock.Release();
+        }
+    }
+
+    public record NewsMessage(
+        string Author,
+        string Content,
+        IEnumerable<string> AttachmentUrls,
+        DateTimeOffset PostedAt,
+        DateTimeOffset? EditedAt
+    );
+
+    private NewsMessage FormatIMessage(IMessage msg) =>
+        new(
+            msg.Author.Tag(),
+            msg.Content,
+            msg.Attachments.Select(a => a.Url),
+            msg.ID.Timestamp,
+            msg.EditedTimestamp
+        );
+}