Added EntityCache - UserCache component

Kerobot/Kerobot.cs

@@ -47,6 +47,8 @@ namespace Kerobot
             var ver = System.Reflection.Assembly.GetExecutingAssembly().GetName().Version;
             InstanceLogAsync(false, "Kerobot",
                 $"This is Kerobot v{ver.ToString(3)}. https://github.com/Noikoio/Kerobot").Wait();
+
+            // We return to Program.cs at this point.
         }
 
         private IReadOnlyCollection<Service> InitializeServices()
@@ -59,6 +61,9 @@ namespace Kerobot
             _svcGuildState = new Services.GuildState.GuildStateService(this);
             svcList.Add(_svcGuildState);
             _svcCommonFunctions = new Services.CommonFunctions.CommonFunctionsService(this);
+            svcList.Add(_svcCommonFunctions);
+            _svcEntityCache = new Services.EntityCache.EntityCacheService(this);
+            svcList.Add(_svcEntityCache);
 
             return svcList.AsReadOnly();
         }

Kerobot/Services/EntityCache/CachedUser.cs

@@ -0,0 +1,67 @@
+using System;
+using System.Data.Common;
+
+namespace Kerobot // Publicly accessible class; placing in main namespace
+{
+    /// <summary>
+    /// Representation of user information retrieved from Kerobot's UserCache.
+    /// </summary>
+    public class CachedUser
+    {
+        /// <summary>
+        /// The user's snowflake ID.
+        /// </summary>
+        public ulong UserID { get; }
+
+        /// <summary>
+        /// The corresponding guild's snowflake ID.
+        /// </summary>
+        public ulong GuildID { get; }
+
+        /// <summary>
+        /// The date in which this user was first recorded onto the database.
+        /// </summary>
+        public DateTimeOffset FirstSeenDate { get; }
+
+        /// <summary>
+        /// The date in which cache information for this user was last updated.
+        /// </summary>
+        public DateTimeOffset CacheDate { get; }
+
+        /// <summary>
+        /// The user's corresponding username, without discriminator.
+        /// </summary>
+        public string Username { get; }
+
+        /// <summary>
+        /// The user's corresponding discriminator value.
+        /// </summary>
+        public string Discriminator { get; }
+
+        /// <summary>
+        /// The user's nickname in the corresponding guild. May be null.
+        /// </summary>
+        public string Nickname { get; }
+
+        /// <summary>
+        /// A link to a high resolution version of the user's current avatar. May be null.
+        /// </summary>
+        public string AvatarUrl { get; }
+
+        internal CachedUser(DbDataReader row)
+        {
+            // Highly dependent on column order in the cache view defined in UserCacheService.
+            unchecked
+            {
+                UserID = (ulong)row.GetInt64(0);
+                GuildID = (ulong)row.GetInt64(1);
+            }
+            FirstSeenDate = row.GetDateTime(2).ToUniversalTime();
+            CacheDate = row.GetDateTime(3).ToUniversalTime();
+            Username = row.GetString(4);
+            Discriminator = row.GetString(5);
+            Nickname = row.IsDBNull(6) ? null : row.GetString(6);
+            AvatarUrl = row.IsDBNull(7) ? null : row.GetString(7);
+        }
+    }
+}

Kerobot/Services/EntityCache/EntityCacheService.cs

@@ -1,10 +1,25 @@
-using System;
+using System.Threading.Tasks;
+
 namespace Kerobot.Services.EntityCache
 {
-    public class EntityCacheService
+    /// <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
+    /// require this information, such as an external web interface.
+    /// </summary>
+    class EntityCacheService : Service
     {
-        public EntityCacheService()
+        private readonly UserCache _uc;
+
+        internal EntityCacheService(Kerobot kb) : base(kb)
         {
-        }
+            // Currently we only have UserCache. May add Channel and Server caches later.
+            _uc = new UserCache(kb);
+        }
+
+        /// <summary>
+        /// See documentation in Kerobot_hooks.
+        /// </summary>
+        internal Task<CachedUser> QueryUserCache(ulong guildId, string search) => _uc.Query(guildId, search);
     }
 }

Kerobot/Services/EntityCache/Kerobot_hooks.cs

@@ -0,0 +1,20 @@
+using Kerobot.Services.EntityCache;
+using System.Threading.Tasks;
+
+namespace Kerobot
+{
+    partial class Kerobot
+    {
+        private EntityCacheService _svcEntityCache;
+
+        /// <summary>
+        /// Queries the Entity Cache for user information. The given search string may contain a user ID
+        /// or a username with optional discriminator. In case there are multiple results, the most recently
+        /// cached user will be returned.
+        /// </summary>
+        /// <param name="guildId">ID of the corresponding guild in which to search.</param>
+        /// <param name="search">Search string. Either </param>
+        /// <returns>A <see cref="CachedUser"/> instance containing cached information.</returns>
+        public Task<CachedUser> EcQueryUser(ulong guildId, string search) => _svcEntityCache.QueryUserCache(guildId, search);
+    }
+}

Kerobot/Services/EntityCache/UserCacheService.cs

@@ -0,0 +1,205 @@
+using Discord.WebSocket;
+using NpgsqlTypes;
+using System;
+using System.Collections.Generic;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+
+namespace Kerobot.Services.EntityCache
+{
+    /// <summary>
+    /// Provides and maintains a database-backed cache of users.
+    /// It is meant to work as an addition 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>
+    class UserCache
+    {
+        private Kerobot _kb;
+
+        internal UserCache(Kerobot kb)
+        {
+            _kb = kb;
+            CreateDatabaseTablesAsync().Wait();
+
+            kb.DiscordClient.GuildMemberUpdated += DiscordClient_GuildMemberUpdated;
+            kb.DiscordClient.UserUpdated += DiscordClient_UserUpdated;
+        }
+
+        #region Database setup
+        public const string GlobalUserTable = "cache_userdata";
+        public const string GuildUserTable = "cache_guildmemberdata";
+        public const string UserView = "cache_guildusers"; // <- intended way to access data
+
+        private async Task CreateDatabaseTablesAsync()
+        {
+            using (var db = await _kb.GetOpenNpgsqlConnectionAsync())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"create table if not exists {GlobalUserTable} (" +
+                        "user_id bigint primary key, " +
+                        "cache_update_time timestamptz not null, " + // TODO auto update w/ trigger?
+                        "username text not null, " +
+                        "discriminator text not null, " +
+                        "avatar_url text null" +
+                        ")";
+                    await c.ExecuteNonQueryAsync();
+                }
+
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"create table if not exists {GuildUserTable} (" +
+                        $"user_id bigint references {GlobalUserTable}, " +
+                        "guild_id bigint, " + // TODO foreign key reference?
+                        "first_seen timestamptz not null default NOW(), " + // TODO also make immutable w/ trigger?
+                        "cache_update_time timestamptz not null, " + // TODO auto update w/ trigger?
+                        "nickname text null, " +
+                        "primary key (user_id, guild_id)" +
+                        ")";
+                    await c.ExecuteNonQueryAsync();
+                }
+                // note to self: https://stackoverflow.com/questions/9556474/how-do-i-automatically-update-a-timestamp-in-postgresql
+                
+                using (var c = db.CreateCommand())
+                {
+                    // NOTE: CachedUser constructor is highly dependent of the row order specified here.
+                    // Any changes here must be reflected there.
+                    c.CommandText = $"create or replace view {UserView} as " +
+                        $"select {GlobalUserTable}.user_id, {GuildUserTable}.guild_id, {GuildUserTable}.first_seen, " +
+                        $"{GuildUserTable}.cache_update_time, " +
+                        $"{GlobalUserTable}.username, {GlobalUserTable}.discriminator, {GlobalUserTable}.nickname, " +
+                        $"{GlobalUserTable}.avatar_url " +
+                        $"from {GlobalUserTable} join {GuildUserTable} on {GlobalUserTable}.user_id = {GuildUserTable}.user_id";
+                    await c.ExecuteNonQueryAsync();
+                    // TODO consolidate both tables' cache_update_time, show the greater value.
+                    // Right now we will have just the guild table's data visible.
+                }
+            }
+        }
+        #endregion
+
+        #region Database updates
+        private async Task DiscordClient_UserUpdated(SocketUser old, SocketUser current)
+        {
+            using (var db = await _kb.GetOpenNpgsqlConnectionAsync())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"insert into {GlobalUserTable} " +
+                        "(user_id, cache_update_time, username, discriminator, avatar_url) values " +
+                        "(@Uid, now(), @Uname, @Disc, @Aurl) " +
+                        "on conflict (user_id) do update " +
+                        "set cache_update_time = EXCLUDED.cache_update_time, username = EXCLUDED.username, " +
+                        "discriminator = EXCLUDED.discriminator, avatar_url = EXCLUDED.avatar_url";
+                    c.Parameters.Add("@Uid", NpgsqlDbType.Bigint).Value = current.Id;
+                    c.Parameters.Add("@Uname", NpgsqlDbType.Text).Value = current.Username;
+                    c.Parameters.Add("@Disc", NpgsqlDbType.Text).Value = current.Discriminator;
+                    var aurl = c.Parameters.Add("@Aurl", NpgsqlDbType.Text);
+                    var aurlval = current.GetAvatarUrl(Discord.ImageFormat.Png, 1024);
+                    if (aurlval != null) aurl.Value = aurlval;
+                    else aurl.Value = DBNull.Value;
+
+                    c.Prepare();
+                    await c.ExecuteNonQueryAsync();
+                }
+            }
+        }
+
+        private async Task DiscordClient_GuildMemberUpdated(SocketGuildUser old, SocketGuildUser current)
+        {
+            using (var db = await _kb.GetOpenNpgsqlConnectionAsync())
+            {
+                using (var c = db.CreateCommand())
+                {
+                    c.CommandText = $"insert into {GuildUserTable} " +
+                        "(user_id, guild_id, cache_update_time, nickname) values " +
+                        "(@Uid, @Gid, now(), @Nname) " +
+                        "on conflict (user_id) do update " +
+                        "set cache_update_time = EXCLUDED.cache_update_time, username = EXCLUDED.username, " +
+                        "discriminator = EXCLUDED.discriminator, avatar_url = EXCLUDED.avatar_url";
+                    c.Parameters.Add("@Uid", NpgsqlDbType.Bigint).Value = current.Id;
+                    c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = current.Guild.Id;
+                    var nname = c.Parameters.Add("@Nname", NpgsqlDbType.Text);
+                    if (current.Nickname != null) nname.Value = current.Nickname;
+                    else nname.Value = DBNull.Value;
+
+                    c.Prepare();
+                    await c.ExecuteNonQueryAsync();
+                }
+            }
+        }
+        #endregion
+
+        #region Querying
+        private static Regex DiscriminatorSearch = new Regex(@"(.+)#(\d{4}(?!\d))", RegexOptions.Compiled);
+
+        internal async Task<CachedUser> Query(ulong guildID, string search)
+        {
+            // Is search just a number? Assume ID, pass it on to the correct place.
+            // If it fails, assume the number may be a username.
+            if (ulong.TryParse(search, out var searchid))
+            {
+                var idres = await InternalDoQuery(guildID, searchid, null, null);
+                if (idres != null) return idres;
+            }
+
+            // Split name/discriminator
+            string name, disc;
+            var split = DiscriminatorSearch.Match(search);
+            if (split.Success)
+            {
+                name = split.Groups[1].Value;
+                disc = split.Groups[2].Value;
+            }
+            else
+            {
+                name = search;
+                disc = null;
+            }
+
+            // Strip leading @ from username, if any
+            if (name.Length > 0 && name[0] == '@') name = name.Substring(1);
+
+            // Ready to query
+            return await InternalDoQuery(guildID, null, name, disc);
+            // TODO exception handling
+        }
+
+        private async Task<CachedUser> InternalDoQuery(ulong guildId, ulong? sID, string sName, string sDisc)
+        {
+            using (var db = await _kb.GetOpenNpgsqlConnectionAsync())
+            {
+                var c = db.CreateCommand();
+                c.CommandText = $"select * from {UserView} " +
+                    "where guild_id = @Gid";
+                c.Parameters.Add("@Gid", NpgsqlDbType.Bigint).Value = guildId;
+
+                if (sID.HasValue)
+                {
+                    c.CommandText += " and user_id = @Uid";
+                    c.Parameters.Add("@Uid", NpgsqlDbType.Bigint).Value = sID.Value;
+                }
+
+                if (sName != null)
+                {
+                    c.CommandText += " and username = @Uname";
+                    c.Parameters.Add("@Uname", NpgsqlDbType.Text).Value = sName;
+                    if (sDisc != null) // only search discriminator if name has been provided
+                    {
+                        c.CommandText += " and discriminator = @Udisc";
+                        c.Parameters.Add("@Udisc", NpgsqlDbType.Text).Value = sDisc;
+                    }
+                }
+
+                c.CommandText += " order by cache_update_time desc limit 1";
+                c.Prepare();
+                using (var r = await c.ExecuteReaderAsync())
+                {
+                    if (await r.ReadAsync()) return new CachedUser(r);
+                    return null;
+                }
+            }
+        }
+        #endregion
+    }
+}

Kerobot/Services/UserCache/UserCacheService.cs

@@ -1,16 +0,0 @@
-using System;
-
-namespace Kerobot.Services.EntityCache
-{
-    /// <summary>
-    /// Provides and maintains a database-backed cache of users.
-    /// It is meant to work as an addition to Discord.Net's own user caching capabilities, and its main purpose
-    /// is to be able to provide basic information on users which the bot may not currently be aware about.
-    /// </summary>
-    class EntityCacheService : Service
-    {
-        public EntityCacheService(Kerobot kb) : base(kb)
-        {
-        }
-    }
-}