Added Db stuff

src/EllieBot/Db/EllieDbService.cs

@@ -0,0 +1,76 @@
+using LinqToDB.Common;
+using LinqToDB.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore;
+
+namespace EllieBot.Db;
+
+public sealed class EllieDbService : DbService
+{
+    private readonly IBotCredsProvider _creds;
+
+    // these are props because creds can change at runtime
+    private string DbType => _creds.GetCreds().Db.Type.ToLowerInvariant().Trim();
+    private string ConnString => _creds.GetCreds().Db.ConnectionString;
+
+    public EllieDbService(IBotCredsProvider creds)
+    {
+        LinqToDBForEFTools.Initialize();
+        Configuration.Linq.DisableQueryCache = true;
+
+        _creds = creds;
+    }
+
+    public override async Task SetupAsync()
+    {
+        var dbType = DbType;
+        var connString = ConnString;
+
+        await using var context = CreateRawDbContext(dbType, connString);
+
+        // make sure sqlite db is in wal journal mode
+        if (context is SqliteContext)
+        {
+            await context.Database.ExecuteSqlRawAsync("PRAGMA journal_mode=WAL");
+        }
+
+        await context.Database.MigrateAsync();
+    }
+
+    public override EllieContext CreateRawDbContext(string dbType, string connString)
+    {
+        switch (dbType)
+        {
+            case "postgresql":
+            case "postgres":
+            case "pgsql":
+                return new PostgreSqlContext(connString);
+            case "mysql":
+                return new MysqlContext(connString);
+            case "sqlite":
+                return new SqliteContext(connString);
+            default:
+                throw new NotSupportedException($"The database provide type of '{dbType}' is not supported.");
+        }
+    }
+
+    private EllieContext GetDbContextInternal()
+    {
+        var dbType = DbType;
+        var connString = ConnString;
+
+        var context = CreateRawDbContext(dbType, connString);
+        if (context is SqliteContext)
+        {
+            var conn = context.Database.GetDbConnection();
+            conn.Open();
+            using var com = conn.CreateCommand();
+            com.CommandText = "PRAGMA synchronous=OFF";
+            com.ExecuteNonQuery();
+        }
+
+        return context;
+    }
+
+    public override EllieContext GetDbContext()
+        => GetDbContextInternal();
+}