Add database migrations and handle leaving private chat portals. Fixes #7

database/upgrades/upgrades.go

@@ -0,0 +1,87 @@
+package upgrades
+
+import (
+	"database/sql"
+	"fmt"
+	"strings"
+
+	log "maunium.net/go/maulogger/v2"
+)
+
+type Dialect int
+
+const (
+	Postgres Dialect = iota
+	SQLite
+)
+
+type upgradeFunc func(Dialect, *sql.Tx) error
+
+type upgrade struct {
+	message string
+	fn upgradeFunc
+}
+
+var upgrades [2]upgrade
+
+func getVersion(dialect Dialect, db *sql.DB) (int, error) {
+	_, err := db.Exec("CREATE TABLE IF NOT EXISTS version (version INTEGER)")
+	if err != nil {
+		return -1, err
+	}
+
+	version := 0
+	row := db.QueryRow("SELECT version FROM version LIMIT 1")
+	if row != nil {
+		_ = row.Scan(&version)
+	}
+	return version, nil
+}
+
+func setVersion(dialect Dialect, tx *sql.Tx, version int) error {
+	_, err := tx.Exec("DELETE FROM version")
+	if err != nil {
+		return err
+	}
+	_, err = tx.Exec("INSERT INTO version (version) VALUES ($1)", version)
+	return err
+}
+
+func Run(log log.Logger, dialectName string, db *sql.DB) error {
+	var dialect Dialect
+	switch strings.ToLower(dialectName) {
+	case "postgres":
+		dialect = Postgres
+	case "sqlite3":
+		dialect = SQLite
+	default:
+		return fmt.Errorf("unknown dialect %s", dialectName)
+	}
+
+	version, err := getVersion(dialect, db)
+	if err != nil {
+		return err
+	}
+
+	log.Infofln("Database currently on v%d, latest: v%d", version, len(upgrades))
+	for i, upgrade := range upgrades[version:] {
+		log.Infofln("Upgrading database to v%d: %s", i+1, upgrade.message)
+		tx, err := db.Begin()
+		if err != nil {
+			return err
+		}
+		err = upgrade.fn(dialect, tx)
+		if err != nil {
+			return err
+		}
+		err = setVersion(dialect, tx, i+1)
+		if err != nil {
+			return err
+		}
+		err = tx.Commit()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}