Add message caching subservice

Partially implements legacy's ModLogs module on the bot side, with the remainder to be implemented as a proper module.

RegexBot/Data/BotDatabaseContext.cs

@@ -20,6 +20,7 @@ public class BotDatabaseContext : DbContext {
     public DbSet<GuildLogLine> GuildLog { get; set; } = null!;
     public DbSet<CachedUser> UserCache { get; set; } = null!;
     public DbSet<CachedGuildUser> GuildUserCache { get; set; } = null!;
+    public DbSet<CachedGuildMessage> GuildMessageCache { get; set; } = null!;
 
     protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
          => optionsBuilder
@@ -27,9 +28,9 @@ public class BotDatabaseContext : DbContext {
             .UseSnakeCaseNamingConvention();
 
     protected override void OnModelCreating(ModelBuilder modelBuilder) {
-        modelBuilder.Entity<GuildLogLine>(entity =>
-            entity.Property(e => e.Timestamp).HasDefaultValueSql("now()"));
+        modelBuilder.Entity<GuildLogLine>(entity => entity.Property(e => e.Timestamp).HasDefaultValueSql("now()"));
         modelBuilder.Entity<CachedUser>(entity => entity.Property(e => e.Discriminator).HasMaxLength(4).IsFixedLength());
         modelBuilder.Entity<CachedGuildUser>(entity => entity.Navigation(e => e.User).AutoInclude());
+        modelBuilder.Entity<CachedGuildMessage>(entity => entity.Property(e => e.CreatedAt).HasDefaultValueSql("now()"));
     }
 }

RegexBot/Data/CachedGuildMessage.cs

@@ -0,0 +1,36 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace RegexBot.Data;
+[Table("cache_messages")]
+public class CachedGuildMessage {
+    [Key]
+    public long MessageId { get; set; }
+
+    public long AuthorId { get; set; }
+
+    public long GuildId { get; set; }
+
+    public long ChannelId { get; set; }
+
+    public DateTimeOffset CreatedAt { get; set; }
+
+    public DateTimeOffset? EditedAt { get; set; }
+
+    public List<string> AttachmentNames { get; set; } = null!;
+
+    public string Content { get; set; } = null!;
+
+    /// <summary>Gets the timestamp when the message was last updated.</summary>
+    /// <remarks>
+    /// This is equivalent to coalescing the value of <see cref="EditedAt"/> and <see cref="CreatedAt"/>.
+    /// </remarks>
+    [NotMapped]
+    public DateTimeOffset LastUpdatedAt => EditedAt ?? CreatedAt;
+
+    [ForeignKey(nameof(CachedUser.UserId))]
+    [InverseProperty(nameof(CachedUser.GuildMessages))]
+    public CachedUser Author { get; set; } = null!;
+
+    internal new CachedGuildMessage MemberwiseClone() => (CachedGuildMessage)base.MemberwiseClone();
+}

RegexBot/Data/CachedUser.cs

@@ -14,4 +14,7 @@ public class CachedUser {
 
     [InverseProperty(nameof(CachedGuildUser.User))]
     public ICollection<CachedGuildUser> Guilds { get; set; } = null!;
+
+    [InverseProperty(nameof(CachedGuildMessage.Author))]
+    public ICollection<CachedGuildMessage> GuildMessages { get; set; } = null!;
 }

RegexBot/InstanceConfig.cs

@@ -55,20 +55,18 @@ class InstanceConfig {
             throw new Exception(pfx + ex.Message, ex);
         }
 
-#pragma warning disable CS8601 // Possible null reference assignment.
         // Input validation - throw exception on errors. Exception messages printed as-is.
-        BotToken = conf[nameof(BotToken)]?.Value<string>();
+        BotToken = conf[nameof(BotToken)]?.Value<string>()!;
         if (string.IsNullOrEmpty(BotToken))
             throw new Exception($"'{nameof(BotToken)}' is not properly specified in configuration.");
 
-        PostgresConnString = conf[nameof(PostgresConnString)]?.Value<string>();
+        PostgresConnString = conf[nameof(PostgresConnString)]?.Value<string>()!;
         if (string.IsNullOrEmpty(PostgresConnString))
             throw new Exception($"'{nameof(PostgresConnString)}' is not properly specified in configuration.");
 
-        InstanceLogTarget = conf[nameof(InstanceLogTarget)]?.Value<string>();
+        InstanceLogTarget = conf[nameof(InstanceLogTarget)]?.Value<string>()!;
         if (string.IsNullOrEmpty(InstanceLogTarget))
             throw new Exception($"'{nameof(InstanceLogTarget)}' is not properly specified in configuration.");
-#pragma warning restore CS8601
 
         var asmList = conf[nameof(Assemblies)];
         if (asmList == null || asmList.Type != JTokenType.Array) {

RegexBot/Program.cs

@@ -2,7 +2,6 @@
 using Discord.WebSocket;
 
 namespace RegexBot;
-
 class Program {
     /// <summary>
     /// Timestamp specifying the date and time that the program began running.
@@ -51,7 +50,7 @@ class Program {
     private static void Console_CancelKeyPress(object? sender, ConsoleCancelEventArgs e) {
         e.Cancel = true;
 
-        _main.InstanceLogAsync(true, nameof(RegexBot), "Shutting down. Reason: Interrupt signal.");
+        _main._svcLogging.DoInstanceLog(true, nameof(RegexBot), "Shutting down. Reason: Interrupt signal.");
 
         // 5 seconds of leeway - any currently running tasks will need time to finish executing
         var closeWait = Task.Delay(5000);
@@ -62,8 +61,8 @@ class Program {
         closeWait.Wait();
 
         bool success = _main.DiscordClient.StopAsync().Wait(1000);
-        if (!success) _main.InstanceLogAsync(false, nameof(RegexBot),
-            "Failed to disconnect cleanly from Discord. Will force shut down.").Wait();
+        if (!success) _main._svcLogging.DoInstanceLog(false, nameof(RegexBot),
+            "Failed to disconnect cleanly from Discord. Will force shut down.");
         Environment.Exit(0);
     }
 }

RegexBot/RegexBot.csproj

@@ -25,15 +25,15 @@
 
   <ItemGroup>
     <PackageReference Include="CommandLineParser" Version="2.8.0" />
-    <PackageReference Include="Discord.Net" Version="3.4.1" />
+    <PackageReference Include="Discord.Net" Version="3.6.1" />
     <PackageReference Include="EFCore.NamingConventions" Version="6.0.0" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.3">
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="6.0.5">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
     <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
-    <PackageReference Include="Npgsql" Version="6.0.3" />
-    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="6.0.3" />
+    <PackageReference Include="Npgsql" Version="6.0.4" />
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="6.0.4" />
     <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL.Design" Version="1.1.0" />
   </ItemGroup>
 

RegexBot/Services/CommonFunctions/BanKickResult.cs

@@ -4,7 +4,6 @@ using static RegexBot.RegexbotClient;
 // Instances of this class are created by CommonFunctionService and are meant to be sent to modules,
 // therefore we put this in the root RegexBot namespace despite being specific to this service.
 namespace RegexBot;
-
 /// <summary>
 /// Contains information on various success/failure outcomes for a ban or kick operation.
 /// </summary>
@@ -75,7 +74,7 @@ public class BanKickResult {
     /// Returns a message representative of the ban/kick result that may be posted as-is
     /// within the a Discord channel.
     /// </summary>
-    public string GetResultString(RegexbotClient bot, ulong guildId) {
+    public string GetResultString(RegexbotClient bot) {
         string msg;
 
         if (OperationSuccess) msg = ":white_check_mark: ";
@@ -92,10 +91,12 @@ public class BanKickResult {
         }
 
         if (_rptTargetId != 0) {
-            var user = bot.EcQueryUser(guildId, _rptTargetId.ToString()).GetAwaiter().GetResult();
+            var user = bot.EcQueryUser(_rptTargetId.ToString());
             if (user != null) {
                 // TODO sanitize possible formatting characters in display name
                 msg += $" user **{user.Username}#{user.Discriminator}**";
+            } else {
+                msg += $" user with ID **{_rptTargetId}**";
             }
         }
 

RegexBot/Services/CommonFunctions/CommonFunctionsService.cs

@@ -20,6 +20,7 @@ internal class CommonFunctionsService : Service {
     /// Common processing for kicks and bans. Called by DoKickAsync and DoBanAsync.
     /// </summary>
     /// <param name="logReason">The reason to insert into the Audit Log.</param>
+    [System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1822:Mark members as static")]
     internal async Task<BanKickResult> BanOrKickAsync(
         RemovalType t, SocketGuild guild, string source, ulong target, int banPurgeDays,
         string logReason, bool sendDmToTarget) {
@@ -31,7 +32,7 @@ internal class CommonFunctionsService : Service {
         // Can't kick without obtaining user object. Quit here.
         if (t == RemovalType.Kick && utarget == null) return new BanKickResult(null, false, true, RemovalType.Kick, 0);
 
-        // TODO notify services here as soon as we get some who will want to listen to this
+        // TODO notify services here as soon as we get some who will want to listen to this (use source parameter)
 
         // Send DM notification
         if (sendDmToTarget) {

RegexBot/Services/CommonFunctions/Hooks.cs

@@ -2,9 +2,8 @@
 using RegexBot.Services.CommonFunctions;
 
 namespace RegexBot;
-
 partial class RegexbotClient {
-    private CommonFunctionsService _svcCommonFunctions;
+    private readonly CommonFunctionsService _svcCommonFunctions;
 
     public enum RemovalType { None, Ban, Kick }
 
@@ -31,9 +30,9 @@ partial class RegexbotClient {
     /// <param name="targetSearch">The EntityCache search string.</param>
     public async Task<BanKickResult> BanAsync(SocketGuild guild, string source, string targetSearch,
                                               int purgeDays, string reason, bool sendDMToTarget) {
-        var result = await EcQueryUser(guild.Id, targetSearch);
+        var result = EcQueryGuildUser(guild.Id, targetSearch);
         if (result == null) return new BanKickResult(null, false, true, RemovalType.Ban, 0);
-        return await BanAsync(guild, source, result.UserID, purgeDays, reason, sendDMToTarget);
+        return await BanAsync(guild, source, (ulong)result.UserId, purgeDays, reason, sendDMToTarget);
     }
 
     /// <summary>
@@ -44,9 +43,15 @@ partial class RegexbotClient {
     /// <returns>A structure containing results of the ban operation.</returns>
     /// <param name="guild">The guild in which to attempt the kick.</param>
     /// <param name="source">The user, module, or service which is requesting this action to be taken.</param>
-    /// <param name="targetUser">The user which to perform the action to.</param>
-    /// <param name="reason">Reason for the action. Sent to the Audit Log and user (if specified).</param>
-    /// <param name="sendDMToTarget">Specify whether to send a direct message to the target user informing them of the action being taken.</param>
+    /// <param name="targetUser">The user which to perform the action towards.</param>
+    /// <param name="reason">
+    /// Reason for the action. Sent to the guild's audit log and, if
+    /// <paramref name="sendDMToTarget"/> is <see langword="true"/>, the target.
+    /// </param>
+    /// <param name="sendDMToTarget">
+    /// Specify whether to send a direct message to the target user informing them of the action
+    /// (that is, a ban/kick message).
+    /// </param>
     public Task<BanKickResult> KickAsync(SocketGuild guild, string source, ulong targetUser, string reason, bool sendDMToTarget)
         => _svcCommonFunctions.BanOrKickAsync(RemovalType.Ban, guild, source, targetUser, 0, reason, sendDMToTarget);
 
@@ -56,8 +61,8 @@ partial class RegexbotClient {
     /// </summary>
     /// <param name="targetSearch">The EntityCache search string.</param>
     public async Task<BanKickResult> KickAsync(SocketGuild guild, string source, string targetSearch, string reason, bool sendDMToTarget) {
-        var result = await EcQueryUser(guild.Id, targetSearch);
+        var result = EcQueryGuildUser(guild.Id, targetSearch);
         if (result == null) return new BanKickResult(null, false, true, RemovalType.Kick, 0);
-        return await KickAsync(guild, source, result.UserID, reason, sendDMToTarget);
+        return await KickAsync(guild, source, (ulong)result.UserId, reason, sendDMToTarget);
     }
 }

RegexBot/Services/EntityCache/EntityCacheService.cs

@@ -1,7 +1,6 @@
 using RegexBot.Data;
 
 namespace RegexBot.Services.EntityCache;
-
 /// <summary>
 /// Provides and maintains a database-backed cache of entities. Portions of information collected by this
 /// service may be used by modules, while other portions are useful only for external applications which may
@@ -9,17 +8,25 @@ namespace RegexBot.Services.EntityCache;
 /// </summary>
 class EntityCacheService : Service {
     private readonly UserCachingSubservice _uc;
+    private readonly MessageCachingSubservice _mc;
 
     internal EntityCacheService(RegexbotClient bot) : base(bot) {
         // Currently we only have UserCache. May add Channel and Server caches later.
         _uc = new UserCachingSubservice(bot);
+        _mc = new MessageCachingSubservice(bot, Log);
     }
 
     // Hooked
-    internal static CachedUser? QueryUserCache(string search)
-        => UserCachingSubservice.DoUserQuery(search);
+    internal CachedUser? QueryUserCache(string search)
+        => _uc.DoUserQuery(search);
 
     // Hooked
-    internal static CachedGuildUser? QueryGuildUserCache(ulong guildId, string search)
-        => UserCachingSubservice.DoGuildUserQuery(guildId, search);
+    internal CachedGuildUser? QueryGuildUserCache(ulong guildId, string search)
+        => _uc.DoGuildUserQuery(guildId, search);
+
+    // Hooked
+    internal event RegexbotClient.CachePreUpdateHandler? OnCachePreUpdate {
+        add { lock (_mc) _mc.OnCachePreUpdate += value; }
+        remove { lock (_mc) _mc.OnCachePreUpdate -= value; }
+    }
 }

RegexBot/Services/EntityCache/Hooks.cs

@@ -1,11 +1,9 @@
-#pragma warning disable CA1822
-using RegexBot.Data;
+using RegexBot.Data;
 using RegexBot.Services.EntityCache;
 
 namespace RegexBot;
-
 partial class RegexbotClient {
-    private EntityCacheService _svcEntityCache;
+    private readonly EntityCacheService _svcEntityCache;
 
     /// <summary>
     /// Queries the entity cache for user information. The given search string may contain a user ID
@@ -14,7 +12,7 @@ partial class RegexbotClient {
     /// </summary>
     /// <param name="search">Search string. May be a name with discriminator, a name, or an ID.</param>
     /// <returns>A <see cref="CachedUser"/> instance containing cached information, or null if no result.</returns>
-    public CachedUser? EcQueryUser(string search) => EntityCacheService.QueryUserCache(search);
+    public CachedUser? EcQueryUser(string search) => _svcEntityCache.QueryUserCache(search);
 
     /// <summary>
     /// Queries the entity cache for guild-specific user information. The given search string may contain a user ID,
@@ -24,5 +22,20 @@ partial class RegexbotClient {
     /// <param name="guildId">ID of the corresponding guild in which to search.</param>
     /// <param name="search">Search string. May be a name with discriminator, a name, or an ID.</param>
     /// <returns>A <see cref="CachedGuildUser"/> instance containing cached information, or null if no result.</returns>
-    public CachedGuildUser? EcQueryGuildUser(ulong guildId, string search) => EntityCacheService.QueryGuildUserCache(guildId, search);
+    public CachedGuildUser? EcQueryGuildUser(ulong guildId, string search) => _svcEntityCache.QueryGuildUserCache(guildId, search);
+
+    /// <summary>
+    /// Fired after a message edit, when the message cache is about to be updated with the edited message.
+    /// </summary>
+    /// <remarks>
+    /// An alternative to <seealso cref="Discord.WebSocket.BaseSocketClient.MessageUpdated"/>.<br />
+    /// This event is fired in response to a guild message being edited and provides handlers with existing
+    /// cached contents before it is updated and the previous contents permanently lost.
+    /// </remarks>
+    public event CachePreUpdateHandler? OnCachePreUpdate {
+        add { _svcEntityCache.OnCachePreUpdate += value; }
+        remove { _svcEntityCache.OnCachePreUpdate -= value; }
+    }
+
+    public delegate Task CachePreUpdateHandler(CachedGuildMessage cachedMsg);
 }

RegexBot/Services/EntityCache/MessageCachingSubservice.cs

@@ -0,0 +1,69 @@
+using Discord;
+using Discord.WebSocket;
+using RegexBot.Data;
+using static RegexBot.RegexbotClient;
+
+namespace RegexBot.Services.EntityCache;
+class MessageCachingSubservice {
+    // Hooked
+    public event CachePreUpdateHandler? OnCachePreUpdate;
+
+    private readonly Action<string, bool> _log;
+
+    internal MessageCachingSubservice(RegexbotClient bot, Action<string, bool> logMethod) {
+        _log = logMethod;
+        bot.DiscordClient.MessageReceived += DiscordClient_MessageReceived;
+        bot.DiscordClient.MessageUpdated += DiscordClient_MessageUpdated;
+    }
+
+    private Task DiscordClient_MessageReceived(SocketMessage arg) {
+        if (arg.Channel is IDMChannel || arg is not SocketSystemMessage) return Task.CompletedTask;
+        return AddOrUpdateCacheItemAsync(arg);
+    }
+    private Task DiscordClient_MessageUpdated(Cacheable<IMessage, ulong> arg1, SocketMessage arg2, ISocketMessageChannel arg3) {
+        if (arg2.Channel is IDMChannel || arg2 is not SocketSystemMessage) return Task.CompletedTask;
+        return AddOrUpdateCacheItemAsync(arg2);
+    }
+
+    private async Task AddOrUpdateCacheItemAsync(SocketMessage arg) {
+        using var db = new BotDatabaseContext();
+
+        CachedGuildMessage? msg = db.GuildMessageCache.Where(m => m.MessageId == (long)arg.Id).SingleOrDefault();
+        if (msg == null) {
+            msg = new() {
+                MessageId = (long)arg.Id,
+                AuthorId = (long)arg.Author.Id,
+                GuildId = (long)((SocketGuildUser)arg.Author).Guild.Id,
+                ChannelId = (long)arg.Channel.Id,
+                AttachmentNames = arg.Attachments.Select(a => a.Filename).ToList(),
+                Content = arg.Content
+            };
+            db.GuildMessageCache.Add(msg);
+        } else {
+            // Notify any listeners of cache update before it happens
+            var oldMsg = msg.MemberwiseClone();
+            await Task.Factory.StartNew(async () => await RunPreUpdateHandlersAsync(oldMsg));
+
+            msg.EditedAt = DateTimeOffset.UtcNow;
+            msg.Content = arg.Content;
+            msg.AttachmentNames = arg.Attachments.Select(a => a.Filename).ToList();
+            db.GuildMessageCache.Update(msg);
+        }
+        await db.SaveChangesAsync();
+    }
+
+    private async Task RunPreUpdateHandlersAsync(CachedGuildMessage msg) {
+        CachePreUpdateHandler? eventList;
+        lock (this) eventList = OnCachePreUpdate;
+        if (eventList == null) return;
+
+        foreach (var handler in eventList.GetInvocationList()) {
+            try {
+                await (Task)handler.DynamicInvoke(msg)!;
+            } catch (Exception ex) {
+                _log($"Unhandled exception in {nameof(RegexbotClient.OnCachePreUpdate)} handler '{handler.Method.Name}':", false);
+                _log(ex.ToString(), false);
+            }
+        }
+    }
+}

RegexBot/Services/EntityCache/UserCachingSubservice.cs

@@ -3,12 +3,12 @@ using RegexBot.Data;
 using System.Text.RegularExpressions;
 
 namespace RegexBot.Services.EntityCache;
-
 /// <summary>
 /// Provides and maintains a database-backed cache of users.
 /// It is meant to work as a supplement to Discord.Net's own user caching capabilities. Its purpose is to 
 /// provide information on users which the library may not be aware about, such as users no longer in a guild.
 /// </summary>
+[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1822:Mark members as static")]
 class UserCachingSubservice {
     private static Regex DiscriminatorSearch { get; } = new(@"(.+)#(\d{4}(?!\d))", RegexOptions.Compiled);
 
@@ -58,7 +58,7 @@ class UserCachingSubservice {
     }
 
     // Hooked
-    internal static CachedUser? DoUserQuery(string search) {
+    internal CachedUser? DoUserQuery(string search) {
         static CachedUser? innerQuery(ulong? sID, (string name, string? disc)? nameSearch) {
             var db = new BotDatabaseContext();
 
@@ -87,7 +87,7 @@ class UserCachingSubservice {
     }
 
     // Hooked
-    internal static CachedGuildUser? DoGuildUserQuery(ulong guildId, string search) {
+    internal CachedGuildUser? DoGuildUserQuery(ulong guildId, string search) {
         static CachedGuildUser? innerQuery(ulong guildId, ulong? sID, (string name, string? disc)? nameSearch) {
             var db = new BotDatabaseContext();