Removed public access to database config

Database connection is now acquired directly via Configuration
instead of an object within it.

ConfigItem/DatabaseConfig.cs

@@ -1,56 +1,43 @@
 using Newtonsoft.Json.Linq;
 using Npgsql;
+using System;
 using System.Threading.Tasks;
 
 namespace Noikoio.RegexBot.ConfigItem
 {
     class DatabaseConfig
     {
-        private readonly bool _enabled;
         private readonly string _host;
         private readonly string _user;
         private readonly string _pass;
         private readonly string _dbname;
-        private readonly string _parsemsg;
-
-        /// <summary>
-        /// Gets whether database storage is available.
-        /// </summary>
-        public bool Available => _enabled;
-        /// <summary>
-        /// Constructor error message (only if not enabled)
-        /// </summary>
-        public string ParseMsg => _parsemsg;
 
         public DatabaseConfig(JToken ctok)
         {
             if (ctok == null || ctok.Type != JTokenType.Object)
             {
-                _enabled = false;
-                _parsemsg = "Database configuration not defined.";
-                return;
+                throw new DatabaseConfigLoadException("");
             }
             var conf = (JObject)ctok;
 
             _host = conf["hostname"]?.Value<string>() ?? "localhost"; // default to localhost
+
             _user = conf["username"]?.Value<string>();
+            if (string.IsNullOrWhiteSpace(_user))
+                throw new DatabaseConfigLoadException("Value for username is not defined.");
+
             _pass = conf["password"]?.Value<string>();
+            if (string.IsNullOrWhiteSpace(_pass))
+                throw new DatabaseConfigLoadException(
+                    $"Value for password is not defined. {nameof(RegexBot)} only supports password authentication.");
+
             _dbname = conf["database"]?.Value<string>();
-
-            if (string.IsNullOrWhiteSpace(_user) || string.IsNullOrWhiteSpace(_pass) || string.IsNullOrWhiteSpace(_dbname))
-            {
-                _parsemsg = "One or more required values are invalid or not defined.";
-                _enabled = false;
-            }
-
-            _parsemsg = null;
-            _enabled = true;
+            if (string.IsNullOrWhiteSpace(_dbname))
+                throw new DatabaseConfigLoadException("Value for database name is not defined.");
         }
 
-        public async Task<NpgsqlConnection> GetOpenConnectionAsync()
+        internal async Task<NpgsqlConnection> GetOpenConnectionAsync()
         {
-            if (!Available) return null;
-
             var cs = new NpgsqlConnectionStringBuilder()
             {
                 Host = _host,
@@ -63,5 +50,10 @@ namespace Noikoio.RegexBot.ConfigItem
             await db.OpenAsync();
             return db;
         }
+
+        internal class DatabaseConfigLoadException : Exception
+        {
+            public DatabaseConfigLoadException(string message) : base(message) { }
+        }
     }
 }

Configuration.cs

@@ -29,7 +29,6 @@ namespace Noikoio.RegexBot
 
         public string BotUserToken => _botToken;
         public string CurrentGame => _currentGame;
-        public DatabaseConfig Database => _dbConfig;
 
         public ServerConfig[] Servers => _servers;
 
@@ -72,22 +71,44 @@ namespace Noikoio.RegexBot
         /// <summary>
         /// Loads essential, unchanging values needed for bot startup. Returns false on failure.
         /// </summary>
-        public bool LoadInitialConfig()
+        internal bool LoadInitialConfig()
         {
             var lt = LoadFile();
             lt.Wait();
             JObject conf = lt.Result;
             if (conf == null) return false;
 
+            var log = Logger.GetLogger(LogPrefix);
+
             _botToken = conf["bot-token"]?.Value<string>();
             if (String.IsNullOrWhiteSpace(_botToken))
             {
-                Logger.GetLogger(LogPrefix)("Error: Bot token not defined. Cannot continue.").Wait();
+                log("Error: Bot token not defined. Cannot continue.").Wait();
                 return false;
             }
             _currentGame = conf["playing"]?.Value<string>();
 
-            _dbConfig = new DatabaseConfig(conf["database"]);
+            // Database configuration:
+            // Either it exists or it doesn't. Read config, but also attempt to make a database connection
+            // right here, or else make it known that database support is disabled for this instance.
+            try
+            {
+                _dbConfig = new DatabaseConfig(conf["database"]);
+                var conn = _dbConfig.GetOpenConnectionAsync().GetAwaiter().GetResult();
+                conn.Dispose();
+            }
+            catch (DatabaseConfig.DatabaseConfigLoadException ex)
+            {
+                if (ex.Message == "") log("Database configuration not found.").Wait();
+                else log("Error within database config: " + ex.Message).Wait();
+                _dbConfig = null;
+            }
+            catch (Npgsql.NpgsqlException ex)
+            {
+                log("An error occurred while establishing initial database connection: " + ex.Message).Wait();
+                _dbConfig = null;
+            }
+            // Modules that will not enable due to lack of database access should say so in their constructors.
 
             return true;
         }
@@ -179,7 +200,23 @@ namespace Noikoio.RegexBot
             _servers = newservers.ToArray();
             return true;
         }
-    }
 
-    
+        /// <summary>
+        /// Gets a value stating if database access is available.
+        /// Specifically, indicates if <see cref="GetOpenDatabaseConnectionAsync"/> will return a non-null value.
+        /// </summary>
+        /// <remarks>
+        /// Ideally, this value remains constant on runtime. It does not take into account
+        /// the possibility of the database connection failing during the program's run time.
+        /// </remarks>
+        public bool DatabaseAvailable => _dbConfig != null;
+        /// <summary>
+        /// Gets an opened connection to the SQL database, if available.
+        /// </summary>
+        /// <returns>
+        /// An <see cref="Npgsql.NpgsqlConnection"/> in the opened state,
+        /// or null if an SQL database is not available.
+        /// </returns>
+        public Task<Npgsql.NpgsqlConnection> GetOpenDatabaseConnectionAsync() => _dbConfig?.GetOpenConnectionAsync();
+    }
 }

EntityCache/CacheUser.cs

@@ -100,7 +100,7 @@ namespace Noikoio.RegexBot.EntityCache
             if (lresult != null) return lresult;
 
             // Database cache search
-            var db = await RegexBot.Config.Database.GetOpenConnectionAsync();
+            var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync();
             if (db == null) return null; // Database not available for query.
             using (db) return await DbQueryAsync(db, guild, user);
         }
@@ -171,7 +171,7 @@ namespace Noikoio.RegexBot.EntityCache
             if (lresult.Count() != 0) return lresult;
 
             // Database cache search
-            var db = await RegexBot.Config.Database.GetOpenConnectionAsync();
+            var db = await RegexBot.Config.GetOpenDatabaseConnectionAsync();
             if (db == null) return null; // Database not available for query.
             using (db) return await DbQueryAsync(db, guild, name, disc);
         }
@@ -207,7 +207,7 @@ namespace Noikoio.RegexBot.EntityCache
         {
             var result = new List<CacheUser>();
 
-            using (db = await RegexBot.Config.Database.GetOpenConnectionAsync())
+            using (db = await RegexBot.Config.GetOpenDatabaseConnectionAsync())
             {
                 using (var c = db.CreateCommand())
                 {