Initial

backend/internal/migration/errors.go

@@ -0,0 +1,10 @@
+package migration
+
+import "errors"
+
+var (
+	ErrEnableForeignKeys      = errors.New("enable foreign keys")
+	ErrCreateSchemaMigrations = errors.New("create schema_migrations")
+	ErrCheckMigration         = errors.New("check migration")
+	ErrMigrationFailed        = errors.New("migration failed")
+)

backend/internal/migration/migrator.go

@@ -0,0 +1,127 @@
+package migration
+
+import (
+	"context"
+	"database/sql"
+	"log/slog"
+	"sort"
+	"time"
+)
+
+type Migration struct {
+	Version int64
+	SQL     string
+}
+
+type packageMigration struct {
+	pkg       string
+	migration Migration
+}
+
+type Migrator struct {
+	db   *sql.DB
+	list []packageMigration
+}
+
+func NewMigrator(db *sql.DB) *Migrator {
+	return &Migrator{db: db}
+}
+
+func (m *Migrator) Register(pkg string, migrations ...Migration) {
+	for _, migration := range migrations {
+		m.list = append(m.list, packageMigration{pkg: pkg, migration: migration})
+	}
+}
+
+func (m *Migrator) Run(ctx context.Context) error {
+	if _, err := m.db.ExecContext(ctx, "PRAGMA foreign_keys = ON"); err != nil {
+		slog.Info("enable foreign keys failed", "error", err)
+		return ErrEnableForeignKeys
+	}
+
+	const createTracking = `CREATE TABLE IF NOT EXISTS schema_migrations (
+    package    TEXT    NOT NULL,
+    version    INTEGER NOT NULL,
+    applied_at TEXT    NOT NULL,
+    PRIMARY KEY (package, version)
+);`
+	if _, err := m.db.ExecContext(ctx, createTracking); err != nil {
+		slog.Info("create schema_migrations failed", "error", err)
+		return ErrCreateSchemaMigrations
+	}
+
+	m.sort()
+
+	for _, entry := range m.list {
+		ok, err := m.isApplied(ctx, entry)
+		if err != nil {
+			slog.Info("check migration failed", "package", entry.pkg, "version", entry.migration.Version, "error", err)
+			return ErrCheckMigration
+		}
+		if ok {
+			continue
+		}
+		if err := m.apply(ctx, entry); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (m *Migrator) sort() {
+	order := make(map[string]int)
+	for _, entry := range m.list {
+		if _, ok := order[entry.pkg]; !ok {
+			order[entry.pkg] = len(order)
+		}
+	}
+	sort.SliceStable(m.list, func(i, j int) bool {
+		if m.list[i].pkg != m.list[j].pkg {
+			return order[m.list[i].pkg] < order[m.list[j].pkg]
+		}
+		return m.list[i].migration.Version < m.list[j].migration.Version
+	})
+}
+
+func (m *Migrator) isApplied(ctx context.Context, entry packageMigration) (bool, error) {
+	const query = "SELECT 1 FROM schema_migrations WHERE package = ? AND version = ?"
+	var one int
+	err := m.db.QueryRowContext(ctx, query, entry.pkg, entry.migration.Version).Scan(&one)
+	if err == sql.ErrNoRows {
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	return true, nil
+}
+
+func (m *Migrator) apply(ctx context.Context, entry packageMigration) error {
+	fail := func(err error) error {
+		slog.Info("apply migration failed", "package", entry.pkg, "version", entry.migration.Version, "error", err)
+		return ErrMigrationFailed
+	}
+
+	tx, err := m.db.BeginTx(ctx, nil)
+	if err != nil {
+		return fail(err)
+	}
+
+	if _, err := tx.ExecContext(ctx, entry.migration.SQL); err != nil {
+		_ = tx.Rollback()
+		return fail(err)
+	}
+
+	const insertTracking = "INSERT INTO schema_migrations(package, version, applied_at) VALUES(?, ?, ?)"
+	if _, err := tx.ExecContext(ctx, insertTracking, entry.pkg, entry.migration.Version, time.Now().UTC()); err != nil {
+		_ = tx.Rollback()
+		return fail(err)
+	}
+
+	if err := tx.Commit(); err != nil {
+		return fail(err)
+	}
+
+	return nil
+}