backend barebone done, big chunk of work done

server/internal/store/migrate.go

@@ -0,0 +1,89 @@
+package store
+
+import (
+	"context"
+	"embed"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+//go:embed migrations/*.sql
+var migrationFiles embed.FS
+
+// Migrate applies any pending SQL migrations in order within a single transaction.
+func (s *Store) Migrate(ctx context.Context) error {
+	conn, err := s.pool.Acquire(ctx)
+	if err != nil {
+		return err
+	}
+	defer conn.Release()
+
+	tx, err := conn.Begin(ctx)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if tx != nil {
+			tx.Rollback(ctx)
+		}
+	}()
+
+	_, err = tx.Exec(ctx, `CREATE TABLE IF NOT EXISTS schema_migrations (
+       version INT PRIMARY KEY
+   )`)
+	if err != nil {
+		return err
+	}
+
+	entries, err := migrationFiles.ReadDir("migrations")
+	if err != nil {
+		return err
+	}
+
+	type mig struct {
+		ver  int
+		name string
+	}
+	var migs []mig
+	for _, e := range entries {
+		name := e.Name()
+		if !strings.HasSuffix(name, ".sql") {
+			continue
+		}
+		parts := strings.SplitN(name, "_", 2)
+		v, err := strconv.Atoi(parts[0])
+		if err != nil {
+			continue
+		}
+		migs = append(migs, mig{ver: v, name: name})
+	}
+	sort.Slice(migs, func(i, j int) bool { return migs[i].ver < migs[j].ver })
+
+	for _, m := range migs {
+		var exists bool
+		err = tx.QueryRow(ctx, "SELECT EXISTS(SELECT 1 FROM schema_migrations WHERE version=$1)", m.ver).Scan(&exists)
+		if err != nil {
+			return err
+		}
+		if exists {
+			continue
+		}
+		data, err := migrationFiles.ReadFile("migrations/" + m.name)
+		if err != nil {
+			return err
+		}
+		if _, err = tx.Exec(ctx, string(data)); err != nil {
+			return err
+		}
+		if _, err = tx.Exec(ctx, "INSERT INTO schema_migrations(version) VALUES($1)", m.ver); err != nil {
+			return err
+		}
+	}
+
+	if err = tx.Commit(ctx); err != nil {
+		return err
+	}
+	tx = nil
+	return nil
+}