add option waitForConnection in database config

bot/src/main/kotlin/dev/inmo/plagubot/config/DatabaseConfig.kt

@@ -6,6 +6,7 @@ import org.jetbrains.exposed.sql.Database
 import org.jetbrains.exposed.sql.transactions.transactionManager
 import org.koin.core.scope.Scope
 import org.sqlite.JDBC
+import java.lang.Exception
 import java.sql.Connection
 
 inline val Scope.database: Database?
@@ -16,15 +17,30 @@ data class DatabaseConfig(
     val url: String = "jdbc:sqlite:file:test?mode=memory&cache=shared",
     val driver: String = JDBC::class.qualifiedName!!,
     val username: String = "",
-    val password: String = ""
+    val password: String = "",
+    val waitForConnection: Boolean = true
 ) {
     @Transient
-    val database: Database = Database.connect(
-        url,
-        driver,
-        username,
-        password
-    ).also {
-        it.transactionManager.defaultIsolationLevel = Connection.TRANSACTION_SERIALIZABLE // Or Connection.TRANSACTION_READ_UNCOMMITTED
+    val database: Database by lazy(LazyThreadSafetyMode.SYNCHRONIZED) {
+        while (true) {
+            return@lazy try {
+                Database.connect(
+                    url,
+                    driver,
+                    username,
+                    password
+                ).also {
+                    it.transactionManager.defaultIsolationLevel = Connection.TRANSACTION_SERIALIZABLE // Or Connection.TRANSACTION_READ_UNCOMMITTED
+                }
+            } catch (e: Throwable) {
+                if (waitForConnection) {
+                    Thread.sleep(1000L)
+                    continue
+                } else {
+                    throw e
+                }
+            }
+        }
+        error("Unable to get database by some reason")
     }
 }