Merge branch 'dev/modlogs'

BotModule.cs

@@ -25,6 +25,7 @@ namespace Noikoio.RegexBot
 
         /// <summary>
         /// Processes module-specific configuration.
+        /// This method is not called if the user did not provide configuration for the module.
         /// </summary>
         /// <remarks>
         /// Module code <i>should not</i> hold on to this data, but instead use <see cref="GetConfig(ulong)"/> to retrieve
@@ -36,8 +37,8 @@ namespace Noikoio.RegexBot
         /// Processed configuration data prepared for later use.
         /// </returns>
         /// <exception cref="ConfigItem.RuleImportException">
-        /// This method should throw RuleImportException in the event of any error.
-        /// The exception message will be properly logged.
+        /// This method should throw <see cref="ConfigItem.RuleImportException"/>
+        /// in the event of configuration errors. The exception message will be properly displayed.
         /// </exception>
         public abstract Task<object> ProcessConfiguration(JToken configSection);
 

ConfigItem/EntityName.cs

@@ -3,9 +3,7 @@
     enum EntityType { Channel, Role, User }
     
     /// <summary>
-    /// Used to join together an entity ID and its name, particularly when read from configuration.
-    /// In the event of an unknown ID, the ID is found and cached. The ID should preferably be used
-    /// over the entity's string-based name, as it can change at any time.
+    /// Used to join together an entity ID and its name when read from configuration.
     /// In configuration, entities are fully specified with a prefix (if necessary), an ID, two colons, and a name.
     /// </summary>
     struct EntityName

EntityCache/Module.cs

@@ -19,9 +19,7 @@ namespace Noikoio.RegexBot.EntityCache
 
         public Module(DiscordSocketClient client) : base(client)
         {
-            _db = RegexBot.Config.Database;
-
-            if (_db.Available)
+            if (RegexBot.Config.DatabaseAvailable)
             {
                 SqlHelper.CreateCacheTablesAsync().Wait();
 

EntityCache/SqlHelper.cs

@@ -19,7 +19,7 @@ namespace Noikoio.RegexBot.EntityCache
         // Reminder: Check Cache query methods if making changes to tables
         internal static async Task CreateCacheTablesAsync()
         {
-            var db = await RegexBot.Config.Database.GetOpenConnectionAsync();
+            var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync();
             if (db == null) return;
             using (db)
             {
@@ -83,7 +83,7 @@ namespace Noikoio.RegexBot.EntityCache
         #region Insertions and updates
         internal static async Task UpdateGuildAsync(SocketGuild g)
         {
-            var db = await RegexBot.Config.Database.GetOpenConnectionAsync();
+            var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync();
             if (db == null) return;
             using (db)
             {
@@ -109,7 +109,7 @@ namespace Noikoio.RegexBot.EntityCache
         }
         internal static async Task UpdateGuildMemberAsync(IEnumerable<SocketGuildUser> users)
         {
-            var db = await RegexBot.Config.Database.GetOpenConnectionAsync();
+            var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync();
             if (db == null) return;
             using (db)
             {

Module/ModLogs/Entry.cs

@@ -0,0 +1,168 @@
+using Npgsql;
+using System;
+using System.Collections.Generic;
+using System.Data.Common;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    /// <summary>
+    /// Represents a log entry in the database.
+    /// </summary>
+    class Entry
+    {
+        readonly int _logId;
+        readonly DateTime _ts;
+        readonly ulong _guildId;
+        readonly ulong? _invokeId;
+        readonly ulong _targetId;
+        readonly ulong? _channelId;
+        readonly string _type;
+        readonly string _message;
+
+        /// <summary>
+        /// Gets the ID value of this log entry.
+        /// </summary>
+        public int Id => _logId;
+        /// <summary>
+        /// Gets the timestamp (a <see cref="DateTime"/> with <see cref="DateTimeKind.Utc"/>) of the entry.
+        /// </summary>
+        public DateTime Timestamp => _ts;
+        /// <summary>
+        /// Gets the ID of the guild to which this log entry corresponds.
+        /// </summary>
+        public ulong Guild => _guildId;
+        /// <summary>
+        /// Gets the ID of the user to which this log entry corresponds.
+        /// </summary>
+        public ulong Target => _targetId;
+        /// <summary>
+        /// Gets the ID of the invoking user.
+        /// This value exists only if this entry was created through action of another user that is not the target.
+        /// </summary>
+        public ulong? Invoker => _invokeId;
+        /// <summary>
+        /// Gets the guild channel ID to which this log entry corresponds, if any.
+        /// </summary>
+        public ulong? TargetChannel => _channelId;
+        /// <summary>
+        /// Gets this log entry's category.
+        /// </summary>
+        public string Category => _type;
+        /// <summary>
+        /// Gets the content of this log entry.
+        /// </summary>
+        public string Message => _message;
+
+        public Entry(DbDataReader r)
+        {
+            // Double-check ordinals if making changes to QueryColumns
+
+            _logId = r.GetInt32(0);
+            _ts = r.GetDateTime(1).ToUniversalTime();
+            unchecked
+            {
+                _guildId = (ulong)r.GetInt64(2);
+                _targetId = (ulong)r.GetInt64(3);
+                if (r.IsDBNull(4)) _invokeId = null;
+                else _invokeId = (ulong)r.GetInt64(4);
+                if (r.IsDBNull(5)) _channelId = null;
+                else _channelId = (ulong)r.GetInt64(5);
+            }
+            _type = r.GetString(6);
+            _message = r.GetString(7);
+        }
+
+        // TODO lazy loading of channel, user, etc from caches
+        // TODO methods for updating this log entry(?)
+
+        // TODO figure out some helper methods to retrieve data of other entities by ID, if it becomes necessary
+
+        #region Queries
+        // Double-check constructor if making changes to this constant
+        const string QueryColumns = "id, entry_ts, guild_id, target_id, invoke_id, target_channel_id, category, message";
+        
+        /// <summary>
+        /// Attempts to look up a log entry with the given ID.
+        /// </summary>
+        /// <returns>Null if no result.</returns>
+        public static async Task<Entry> QueryIdAsync(ulong guild, int id)
+        {
+            using (var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"SELECT {QueryColumns} FROM {Sql.TableLog} "
+                        + "WHERE guild_id = @Guild and id = @Id";
+                    c.Parameters.Add("@Guild", NpgsqlTypes.NpgsqlDbType.Bigint).Value = guild;
+                    c.Parameters.Add("@Id", NpgsqlTypes.NpgsqlDbType.Numeric).Value = id;
+                    c.Prepare();
+                    using (var r = await c.ExecuteReaderAsync())
+                    {
+                        if (r.Read()) return new Entry(r);
+                        else return null;
+                    }
+                }
+            }
+        }
+
+        public static async Task<IEnumerable<Entry>> QueryLogAsync
+            (ulong guild,
+            ulong? target = null,
+            ulong? invoker = null,
+            ulong? channel = null,
+            IEnumerable<string> category = null)
+        {
+            // Enforce some limits - can't search too broadly here. Requires this at a minimum:
+            if (target.HasValue == false && invoker.HasValue == false)
+            {
+                throw new ArgumentNullException("Query requires at minimum searching of a target or invoker.");
+            }
+
+            var result = new List<Entry>();
+            using (var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"SELECT {QueryColumns} FROM {Sql.TableLog} WHERE";
+
+                    bool and = false;
+                    if (target.HasValue)
+                    {
+                        if (and) c.CommandText += " AND";
+                        else and = true;
+                        c.CommandText += " target_id = @TargetId";
+                        c.Parameters.Add("@TargetId", NpgsqlTypes.NpgsqlDbType.Bigint).Value = target.Value;
+                    }
+                    if (invoker.HasValue)
+                    {
+                        if (and) c.CommandText += " AND";
+                        else and = true;
+                        c.CommandText += " invoke_id = @InvokeId";
+                        c.Parameters.Add("@InvokeId", NpgsqlTypes.NpgsqlDbType.Bigint).Value = invoker.Value;
+                    }
+                    if (channel.HasValue)
+                    {
+                        if (and) c.CommandText += " AND";
+                        else and = true;
+                        c.CommandText += " target_channel_id = @ChannelId";
+                        c.Parameters.Add("@ChannelId", NpgsqlTypes.NpgsqlDbType.Bigint).Value = channel.Value;
+                    }
+                    c.Prepare();
+
+                    using (var r = await c.ExecuteReaderAsync())
+                    {
+                        while (r.Read())
+                        {
+                            result.Add(new Entry(r));
+                        }
+                    }
+                }
+            }
+
+            return result;
+        }
+        #endregion
+    }
+}

Module/ModLogs/EventListener.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Threading.Tasks;
+using Discord.WebSocket;
+using Newtonsoft.Json.Linq;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    /// <summary>
+    /// Listens for Discord-based events and writes them to the log (database).
+    /// Additionally writes certain messages to a designated logging channel if configured.
+    /// </summary>
+    class EventListener : BotModule
+    {
+        public override string Name => "ModLogs";
+        public EventListener(DiscordSocketClient client) : base(client)
+        {
+
+        }
+
+        [ConfigSection("modlogs")]
+        public override Task<object> ProcessConfiguration(JToken configSection)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}

Module/ModLogs/EventType.cs

@@ -0,0 +1,22 @@
+using System;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    // Types of non-custom events that can be referenced by ModLogs in configuration.
+    // Enum value names will show themselves to the user in the form of strings valid in configuration,
+    // so try not to change those without good reason.
+    [Flags]
+    enum EventType
+    {
+        None        = 0x0,
+        Note        = 0x1,
+        Warn        = 0x2,
+        Kick        = 0x4,
+        Ban         = 0x8,
+        JoinGuild   = 0x10,
+        LeaveGuild  = 0x20,
+        NameChange  = 0x40,
+        MsgEdit     = 0x80,
+        MsgDelete   = 0x100
+    }
+}

Module/ModLogs/GuildConfig.cs

@@ -0,0 +1,127 @@
+using Newtonsoft.Json.Linq;
+using Noikoio.RegexBot.ConfigItem;
+using System;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    /// <summary>
+    /// ModLogs guild-specific configuration values.
+    /// </summary>
+    class GuildConfig
+    {
+        // Event reporting
+        private readonly EntityName _rptTarget;
+        private EventType _rptTypes;
+        /// <summary>
+        /// Target reporting channel.
+        /// </summary>
+        public EntityName? RptTarget => _rptTarget;
+        /// <summary>
+        /// Event types to send to the reporting channel.
+        /// </summary>
+        public EventType RptTypes => _rptTypes;
+
+        // Query command
+        private readonly string _qCmd; // command name
+        private readonly EntityList _qAccess; // list of those able to issue the command
+        private readonly EventType _qDefaultAnswer; // default entry types to display
+        /// <summary>
+        /// Query command. The first word in an incoming message, including prefix, that triggers a query.
+        /// </summary>
+        public string QrCommand => _qCmd;
+        /// <summary>
+        /// List of users permitted to invoke the query command.
+        /// If null, refer to the guild's Moderators list.
+        /// </summary>
+        public EntityList QrPermittedUsers => _qAccess;
+        /// <summary>
+        /// Event types to display in a query.
+        /// </summary>
+        public EventType QrTypes => _qDefaultAnswer;
+
+        public GuildConfig(JObject cfgRoot)
+        {
+            // AutoReporting settings
+            var arcfg = cfgRoot["AutoReporting"];
+            if (arcfg == null)
+            {
+                _rptTarget = default(EntityName); // NOTE: Change this if EntityName becomes a class later
+                _rptTypes = EventType.None;
+            }
+            else if (arcfg.Type == JTokenType.Object)
+            {
+                string chval = arcfg["Channel"]?.Value<string>();
+                if (chval == null) throw new RuleImportException("Reporting channel is not defined.");
+                if (!string.IsNullOrWhiteSpace(chval) && chval[0] == '#')
+                    _rptTarget = new EntityName(chval.Substring(1, chval.Length-1), EntityType.Channel);
+                else
+                    throw new RuleImportException("Reporting channel is not properly defined.");
+                // Require the channel's ID for now.
+                if (!_rptTarget.Id.HasValue) throw new RuleImportException("Reporting channel's ID must be specified.");
+
+                // TODO make optional
+                string rpval = arcfg["Events"]?.Value<string>();
+                _rptTypes = GetTypesFromString(rpval);
+            }
+            else
+            {
+                throw new RuleImportException("Section for AutoReporting is not correctly defined.");
+            }
+            
+            // QueryCommand settings
+            var qccfg = cfgRoot["QueryCommand"];
+            if (qccfg == null)
+            {
+                _qCmd = null;
+                _qAccess = null;
+                _qDefaultAnswer = EventType.None;
+            }
+            else if (arcfg.Type == JTokenType.Object)
+            {
+                _qCmd = arcfg["Command"]?.Value<string>();
+                if (string.IsNullOrWhiteSpace(_qCmd))
+                    throw new RuleImportException("Query command option must have a value.");
+                if (_qCmd.Contains(" "))
+                    throw new RuleImportException("Query command must not contain spaces.");
+
+                var acl = arcfg["AllowedUsers"];
+                if (acl == null) _qAccess = null;
+                else _qAccess = new EntityList(acl);
+
+                // TODO make optional
+                string ansval = arcfg["DefaultEvents"]?.Value<string>();
+                _qDefaultAnswer = GetTypesFromString(ansval);
+            }
+            else
+            {
+                throw new RuleImportException("Section for QueryCommand is not correctly defined.");
+            }
+        }
+
+        public static EventType GetTypesFromString(string input)
+        {
+            if (string.IsNullOrWhiteSpace(input))
+                throw new RuleImportException("Types are not properly defined.");
+
+            var strTypes = input.Split(
+                new char[] { ' ', ',', '/', '+' }, // and more?
+                StringSplitOptions.RemoveEmptyEntries);
+
+            EventType endResult = EventType.None;
+            foreach (var item in strTypes)
+            {
+                try
+                {
+                    var result = Enum.Parse<EventType>(item, true);
+                    endResult |= result;
+                }
+                catch (ArgumentException)
+                {
+                    throw new RuleImportException($"Unable to determine the given event type \"{item}\"");
+                }
+            }
+
+            return endResult;
+        }
+    }
+}

Module/ModLogs/MessageCache.cs

@@ -0,0 +1,307 @@
+using Discord;
+using Discord.WebSocket;
+using Npgsql;
+using NpgsqlTypes;
+using System;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    /// <summary>
+    /// Helper class for <see cref="ModLogs"/>. Keeps a database-backed cache of recent messages for use
+    /// in reporting message changes and deletions, if configured to do so.
+    /// Despite its place, it does not manipulate moderation logs. It simply pulls from the same configuration.
+    /// </summary>
+    class MessageCache
+    {
+        private readonly DiscordSocketClient _dClient;
+        private readonly AsyncLogger _outLog;
+        private readonly Func<ulong, object> _outGetConfig;
+
+        // TODO: How to clear the cache after a time? Can't hold on to this forever.
+
+        public MessageCache(DiscordSocketClient client, AsyncLogger logger, Func<ulong, object> getConfFunc)
+        {
+            _dClient = client;
+            _outLog = logger;
+            _outGetConfig = getConfFunc;
+
+            CreateCacheTables();
+
+            client.MessageReceived += Client_MessageReceived;
+            client.MessageUpdated += Client_MessageUpdated;
+            client.MessageDeleted += Client_MessageDeleted;
+        }
+
+        #region Event handling
+        private async Task Client_MessageReceived(SocketMessage arg)
+        {
+            if (arg.Author.IsBot) return;
+
+            await AddOrUpdateCacheItemAsync(arg);
+        }
+
+        private async Task Client_MessageUpdated(
+            Cacheable<IMessage, ulong> before, SocketMessage after, ISocketMessageChannel channel)
+        {
+            if (after.Author.IsBot) return;
+
+            // We only want channel messages
+            if (after is SocketUserMessage afterMsg && !(afterMsg is IDMChannel))
+            {
+                if (after.Author.IsBot) return;
+
+                // We're not interested in all message updates, only those that leave a timestamp.
+                if (!afterMsg.EditedTimestamp.HasValue) return;
+            }
+            else return; // probably unnecessary?
+
+            // Once an edited message is cached, the original message contents are lost.
+            // This is the only time available to report it.
+            await ProcessReportMessage(false, before.Id, channel, after.Content);
+            
+            await AddOrUpdateCacheItemAsync(after);
+        }
+
+        private async Task Client_MessageDeleted(Cacheable<Discord.IMessage, ulong> msg, ISocketMessageChannel channel)
+        {
+            if (channel is IDMChannel) return; // No DMs
+            await ProcessReportMessage(true, msg.Id, channel, null);
+        }
+        #endregion
+
+        #region Reporting
+        // Reports an edited or deleted message as if it were a log entry (even though it's not).
+        private async Task ProcessReportMessage(
+            bool isDelete, ulong messageId, ISocketMessageChannel ch, string editMsg)
+        {
+            ulong guildId;
+            if (ch is SocketTextChannel sch)
+            {
+                if (sch is IDMChannel) return;
+                guildId = sch.Guild.Id;
+            }
+            else return;
+
+            // Check if this feature is enabled before doing anything else.
+            var cfg = _outGetConfig(guildId) as GuildConfig;
+            if (cfg == null) return;
+            if (isDelete && (cfg.RptTypes & EventType.MsgDelete) == 0) return;
+            if (!isDelete && (cfg.RptTypes & EventType.MsgEdit) == 0) return;
+
+            // Ignore if it's a message being deleted withing the reporting channel.
+            if (isDelete && cfg.RptTarget.Value.Id.Value == ch.Id) return;
+
+            // Regardless of delete or edit, it is necessary to get the equivalent database information.
+            EntityCache.CacheUser ucd = null;
+            ulong userId;
+            string cacheMsg;
+            try
+            {
+                using (var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync())
+                {
+                    using (var c = db.CreateCommand())
+                    {
+                        c.CommandText = "SELECT author_id, message FROM " + TableMessage
+                            + " WHERE message_id = @MessageId";
+                        c.Parameters.Add("@MessageId", NpgsqlDbType.Bigint).Value = messageId;
+                        c.Prepare();
+                        using (var r = await c.ExecuteReaderAsync())
+                        {
+                            if (await r.ReadAsync())
+                            {
+                                userId = unchecked((ulong)r.GetInt64(0));
+                                cacheMsg = r.GetString(1);
+                            }
+                            else
+                            {
+                                userId = 0;
+                                cacheMsg = "*(Message not in cache.)*";
+                            }
+                        }
+                    }
+                }
+                if (userId != 0) ucd = await EntityCache.EntityCache.QueryAsync(guildId, userId);
+            }
+            catch (NpgsqlException ex)
+            {
+                await _outLog($"SQL error in {nameof(ProcessReportMessage)}: " + ex.Message);
+                cacheMsg = "**Database error. See log.**";
+            }
+
+            // Find target channel, prepare and send out message
+            var g = _dClient.GetGuild(guildId);
+            var rptTargetChannel = g?.GetTextChannel(cfg.RptTarget.Value.Id.Value);
+            if (rptTargetChannel == null)
+            {
+                await _outLog($"WARNING: Reporting channel {cfg.RptTarget.Value.ToString()} could not be determined.");
+                return;
+            }
+            var em = CreateReportEmbed(isDelete, ucd, messageId, ch, (cacheMsg, editMsg));
+            await rptTargetChannel.SendMessageAsync("", embed: em);
+        }
+
+        const int ReportCutoffLength = 500;
+        const string ReportCutoffNotify = "**Message length too long; showing first {0} characters.**\n\n";
+        private EmbedBuilder CreateReportEmbed(
+            bool isDelete,
+            EntityCache.CacheUser ucd, ulong messageId, ISocketMessageChannel chInfo,
+            (string, string) content) // Item1 = cached content. Item2 = after-edit message (null if isDelete)
+        {
+            string msgCached = content.Item1;
+            string msgPostEdit = content.Item2;
+            if (content.Item1.Length > ReportCutoffLength)
+            {
+                msgCached = string.Format(ReportCutoffNotify, ReportCutoffLength)
+                    + content.Item1.Substring(0, ReportCutoffLength);
+            }
+            if (!isDelete && content.Item2.Length > ReportCutoffLength)
+            {
+                msgPostEdit = string.Format(ReportCutoffNotify, ReportCutoffLength)
+                    + content.Item2.Substring(0, ReportCutoffLength);
+            }
+
+            // Note: Value for ucb can be null if cached user could not be determined.
+            var eb = new EmbedBuilder
+            {
+                Author = new EmbedAuthorBuilder()
+                {
+                    IconUrl = ucd?.AvatarUrl
+                },
+                Fields = new System.Collections.Generic.List<EmbedFieldBuilder>(),
+                Footer = new EmbedFooterBuilder()
+                {
+                    Text = "User ID: " + ucd?.UserId.ToString() ?? "Unknown",
+                    IconUrl = _dClient.CurrentUser.GetAvatarUrl()
+                },
+                Timestamp = DateTimeOffset.UtcNow
+            };
+
+            if (isDelete)
+            {
+                eb.Author.Name = "Deleted message by ";
+                eb.Color = new Color(0xff7373);
+                eb.Description = msgCached;
+            }
+            else
+            {
+                eb.Author.Name = "Edited message by ";
+                eb.Color = new Color(0xffcc40);
+                eb.Fields.Add(new EmbedFieldBuilder()
+                {
+                    Name = "Before",
+                    Value = msgCached
+                });
+                eb.Fields.Add(new EmbedFieldBuilder()
+                {
+                    Name = "After",
+                    Value = msgPostEdit
+                });
+            }
+
+            eb.Author.Name += ucd == null ? "unknown user" : $"{ucd.Username}#{ucd.Discriminator}";
+
+            var context = new StringBuilder();
+            if (ucd != null) context.AppendLine($"Username: <@!{ucd.UserId}>");
+            context.AppendLine($"Channel: <#{chInfo.Id}> #{chInfo.Name}");
+            context.Append($"Message ID: {messageId}");
+            eb.Fields.Add(new EmbedFieldBuilder()
+            {
+                Name = "Context",
+                Value = context.ToString()
+            });
+
+            return eb;
+        }
+        #endregion
+
+        #region Database storage/retrieval
+        const string TableMessage = "cache_messages";
+
+        private void CreateCacheTables()
+        {
+            using (var db = RegexBot.Config.GetOpenDatabaseConnectionAsync().GetAwaiter().GetResult())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = "CREATE TABLE IF NOT EXISTS " + TableMessage + " ("
+                        + "message_id bigint primary key, "
+                        + "author_id bigint not null, "
+                        + "guild_id bigint not null, "
+                        + "channel_id bigint not null, " // TODO channel cache fk when that gets implemented
+                        + "created_ts timestamptz not null, "
+                        + "edited_ts timestamptz null, "
+                        + "message text not null, "
+                        + $"FOREIGN KEY (author_id, guild_id) references {EntityCache.SqlHelper.TableUser} (user_id, guild_id)"
+                        + ")";
+                    c.ExecuteNonQuery();
+                }
+            }
+        }
+
+        private async Task AddOrUpdateCacheItemAsync(SocketMessage msg)
+        {
+            try
+            {
+                using (var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync())
+                {
+                    using (var c = db.CreateCommand())
+                    {
+                        c.CommandText = "INSERT INTO " + TableMessage
+                            + " (message_id, author_id, guild_id, channel_id, created_ts, edited_ts, message) VALUES"
+                            + " (@MessageId, @UserId, @GuildId, @ChannelId, @Date, @Edit, @Message)"
+                            + " ON CONFLICT (message_id) DO UPDATE"
+                            + " SET message = EXCLUDED.message, edited_ts = EXCLUDED.edited_ts";
+                        c.Parameters.Add("@MessageId", NpgsqlDbType.Bigint).Value = msg.Id;
+                        c.Parameters.Add("@UserId", NpgsqlDbType.Bigint).Value = msg.Author.Id;
+                        c.Parameters.Add("@GuildId", NpgsqlDbType.Bigint).Value = ((SocketGuildUser)msg.Author).Guild.Id;
+                        c.Parameters.Add("@ChannelId", NpgsqlDbType.Bigint).Value = msg.Channel.Id;
+                        c.Parameters.Add("@Date", NpgsqlDbType.TimestampTZ).Value = msg.Timestamp;
+                        if (msg.EditedTimestamp.HasValue)
+                            c.Parameters.Add("@Edit", NpgsqlDbType.TimestampTZ).Value = msg.EditedTimestamp.Value;
+                        else
+                            c.Parameters.Add("@Edit", NpgsqlDbType.TimestampTZ).Value = DBNull.Value;
+                        c.Parameters.Add("@Message", NpgsqlDbType.Text).Value = msg.Content;
+                        c.Prepare();
+                        await c.ExecuteNonQueryAsync();
+                    }
+                }
+            }
+            catch (NpgsqlException ex)
+            {
+                await _outLog($"SQL error in {nameof(AddOrUpdateCacheItemAsync)}: " + ex.Message);
+            }
+        }
+        
+        private async Task<string> GetCachedMessageAsync(ulong messageId)
+        {
+            try
+            {
+                using (var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync())
+                {
+                    using (var c = db.CreateCommand())
+                    {
+                        c.CommandText = "SELECT message FROM " + TableMessage
+                            + " WHERE message_id = @MessageId";
+                        c.Parameters.Add("@MessageId", NpgsqlDbType.Bigint).Value = messageId;
+                        c.Prepare();
+                        using (var r = await c.ExecuteReaderAsync())
+                        {
+                            if (await r.ReadAsync())
+                                return r.GetString(0);
+                            else
+                                return null;
+                        }
+                    }
+                }
+            }
+            catch (NpgsqlException ex)
+            {
+                await _outLog($"SQL error in {nameof(GetCachedMessageAsync)}: " + ex.Message);
+                return null;
+            }
+        }
+        #endregion
+    }
+}

Module/ModLogs/ModLogs.cs

@@ -0,0 +1,49 @@
+using Discord.WebSocket;
+using Newtonsoft.Json.Linq;
+using Noikoio.RegexBot.ConfigItem;
+using System.Threading.Tasks;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    /// <summary>
+    /// Logs certain events of note to a database for moderators to keep track of user behavior.
+    /// Makes use of a helper class, <see cref="MessageCache"/>.
+    /// </summary>
+    class ModLogs : BotModule
+    {
+        public override string Name => "ModLogs";
+
+        private readonly MessageCache _msgCacheInstance;
+
+        public ModLogs(DiscordSocketClient client) : base(client)
+        {
+            // Do nothing if database unavailable. The user will be informed by ProcessConfiguration.
+            if (!RegexBot.Config.DatabaseAvailable) return;
+            
+            // MessageCache (reporting of MessageEdit, MessageDelete) handled by helper class
+            _msgCacheInstance = new MessageCache(client, Log, GetConfig);
+
+            // TODO add handlers for detecting joins, leaves, bans, kicks, user edits (nick/username/discr)
+            // TODO add handler for processing the log query command
+        }
+
+        [ConfigSection("ModLogs")]
+        public override async Task<object> ProcessConfiguration(JToken configSection)
+        {
+            if (configSection.Type != JTokenType.Object)
+                throw new RuleImportException("Configuration for this section is invalid.");
+            
+            if (!RegexBot.Config.DatabaseAvailable)
+            {
+                await Log("Database access is not available. This module be unavailable.");
+                return null;
+            }
+
+            var conf = new GuildConfig((JObject)configSection);
+            if (conf.RptTypes != EventType.None)
+                await Log("Enabled event autoreporting to " + conf.RptTarget);
+
+            return conf;
+        }
+    }
+}

Module/ModLogs/Sql.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Noikoio.RegexBot.Module.ModLogs
+{
+    /// <summary>
+    /// Contains common constants and static methods used for accessing the log database.
+    /// </summary>
+    class Sql
+    {
+        public const string TableLog = "modlogs_entries";
+        public const string TableLogIncr = TableLog + "_id";
+        public const string TableMsgCache = "modlogs_msgcache";
+
+        static void CreateTables()
+        {
+            using (var db = RegexBot.Config.GetOpenDatabaseConnectionAsync().GetAwaiter().GetResult())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = "CREATE TABLE IF NOT EXISTS " + TableLog + " ("
+                        + "id int primary key, "
+                        + "entry_ts timestamptz not null, "
+                        + "guild_id bigint not null, "
+                        + "target_id bigint not null, "
+                        + $"invoke_id bigint null references {EntityCache.SqlHelper.TableUser}.user_id, "
+                        + "target_channel_id bigint null, " // TODO channel cache reference?
+                        + "category text not null, "
+                        + "message text not null, "
+                        + $"FOREIGN KEY (target_id, guild_id) REFERENCES {EntityCache.SqlHelper.TableUser} (user_id, guild_id)";
+                    c.ExecuteNonQuery();
+                }
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"CREATE SEQUENCE IF NOT EXISTS {TableLogIncr} "
+                        + $"START 100 MAXVALUE {int.MaxValue}";
+                    c.ExecuteNonQuery();
+                }
+            }
+        }
+
+        #region Log entry manipulation
+        // what was I doing again
+        #endregion
+    }
+}

RegexBot.cs

@@ -58,7 +58,10 @@ namespace Noikoio.RegexBot
                 new Module.AutoMod.AutoMod(_client),
                 new Module.ModTools.ModTools(_client),
                 new Module.AutoRespond.AutoRespond(_client),
-                new EntityCache.Module(_client) // EntityCache goes before anything else that uses its data
+
+                // EntityCache loads before anything using it
+                new EntityCache.Module(_client),
+                new Module.ModLogs.ModLogs(_client)
             };
 
             // Set up logging

docs/modlogs.md

@@ -0,0 +1,38 @@
+## ModLogs
+
+ModLogs is a work in progress and not all features are yet available.
+When completed, it will be the component that records certain information and notifies moderators of actions on the server deemed important enough to show as they happen.
+
+Sample within a [server definition](serverdef.html):
+```
+"ModLogs": {
+	"AutoReporting": {
+		"Channel": "#99999999:mod-events",
+		"Events": "msgedit,msgdelete"
+	}
+}
+```
+
+### Definition structure
+Behavior of the ModLogs component is defined within a JSON object named `ModLogs`. Omitting this section from a server definition will disable the component for the given server.
+
+The following values can be defined within the `ModLogs` object:
+* AutoReporting (*object*) - See below for details
+* QueryCommand (*object*) - Unavailable; Work in progress
+
+#### AutoReporting
+As its name implies, the `AutoReporting` section allows the bot operator to configure automatic reporting of one or more events as they occur to a designated reporting channel. Omitting this section in configuration disables this function.
+
+The following values are accepted within this object:
+* Channel (*string*) - **Required.** The channel name in which to report events.
+  * The channel ID is currently required to be specified (see [EntityList](entitylist.html)). This limitation will be removed in a future update.
+* Events (*string*) - **Required** for now. A comma-separated list of event types to be sent to the reporting channel.
+
+#### Event types
+All events fall into one of a number of categories.
+* Custom - The catch-all term for all event types that are not built in, created either by an AutoMod response or an external module.
+* (name) - (description)
+
+Additionally, the following event types are also valid only for `AutoReporting` and are otherwise not logged:
+* MsgEdit - Message was edited by the message author.
+* MsgDelete - Message was deleted either by the message author or another user.