1 files changed, 57 insertions, 0 deletions
diff --git a/mod/src/main/kotlin/moe/nea/ledger/database/Database.kt b/mod/src/main/kotlin/moe/nea/ledger/database/Database.kt
new file mode 100644
index 0000000..025888c
--- /dev/null
+++ b/mod/src/main/kotlin/moe/nea/ledger/database/Database.kt
@@ -0,0 +1,57 @@
+package moe.nea.ledger.database
+
+import moe.nea.ledger.Ledger
+import moe.nea.ledger.database.columns.DBString
+import java.sql.Connection
+import java.sql.DriverManager
+
+class Database {
+	lateinit var connection: Connection
+
+	object MetaTable : Table("LedgerMeta") {
+		val key = column("key", DBString)
+		val value = column("value", DBString)
+
+		init {
+			unique(key)
+		}
+	}
+
+	data class MetaKey(val name: String) {
+		companion object {
+			val DATABASE_VERSION = MetaKey("databaseVersion")
+			val LAST_LAUNCH = MetaKey("lastLaunch")
+		}
+	}
+
+	fun setMetaKey(key: MetaKey, value: String) {
+		MetaTable.insert(connection, Table.OnConflict.REPLACE) {
+			it[MetaTable.key] = key.name
+			it[MetaTable.value] = value
+		}
+	}
+
+	val databaseVersion: Long = 1
+
+	fun loadAndUpgrade() {
+		connection = DriverManager.getConnection("jdbc:sqlite:${Ledger.dataFolder.resolve("database.db")}")
+		MetaTable.createIfNotExists(connection)
+		val meta = MetaTable.selectAll(connection).associate { MetaKey(it[MetaTable.key]) to it[MetaTable.value] }
+		val lastLaunch = meta[MetaKey.LAST_LAUNCH]?.toLong() ?: 0L
+		println("Last launch $lastLaunch")
+		setMetaKey(MetaKey.LAST_LAUNCH, System.currentTimeMillis().toString())
+
+		val oldVersion = meta[MetaKey.DATABASE_VERSION]?.toLong() ?: -1
+		println("Old Database Version: $oldVersion; Current version: $databaseVersion")
+		if (oldVersion > databaseVersion)
+			error("Outdated software. Database is newer than me!")
+		// TODO: create a backup if there is a db version upgrade happening
+		DBUpgrade.performUpgradeChain(
+			connection, oldVersion, databaseVersion,
+			Upgrades().upgrades
+		) { version ->
+			setMetaKey(MetaKey.DATABASE_VERSION, version.toString())
+		}
+	}
+
+}
+\ No newline at end of file