Add local-first refactor foundation

internal/store/db.go

@@ -0,0 +1,92 @@
+package store
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	_ "modernc.org/sqlite"
+)
+
+// Store owns the local domain SQLite database.
+type Store struct {
+	db *sql.DB
+}
+
+// Open opens or creates a domain database at path and applies pending migrations.
+func Open(path string) (*Store, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return nil, fmt.Errorf("create database directory: %w", err)
+	}
+
+	dsn := path + "?_journal_mode=WAL&_busy_timeout=5000&_foreign_keys=ON"
+	db, err := sql.Open("sqlite", dsn)
+	if err != nil {
+		return nil, fmt.Errorf("open database: %w", err)
+	}
+
+	db.SetMaxOpenConns(1)
+
+	s := &Store{db: db}
+	if err := s.applyMigrations(); err != nil {
+		_ = db.Close()
+		return nil, err
+	}
+
+	return s, nil
+}
+
+// OpenDefault opens the default user domain database path.
+func OpenDefault() (*Store, error) {
+	return Open(DefaultDBPath())
+}
+
+// DefaultDBPath returns the default domain database file path.
+func DefaultDBPath() string {
+	home, err := os.UserHomeDir()
+	if err == nil {
+		return filepath.Join(home, ".local", "share", "box-box", "boxbox.db")
+	}
+	return filepath.Join(".local", "share", "box-box", "boxbox.db")
+}
+
+// DB exposes the underlying connection for advanced callers and tests.
+func (s *Store) DB() *sql.DB {
+	return s.db
+}
+
+// Close closes the database connection.
+func (s *Store) Close() error {
+	if s.db == nil {
+		return nil
+	}
+	return s.db.Close()
+}
+
+// WithTx runs fn inside a transaction, rolling back on error.
+func (s *Store) WithTx(fn func(tx *sql.Tx) error) error {
+	tx, err := s.db.Begin()
+	if err != nil {
+		return err
+	}
+
+	if err := fn(tx); err != nil {
+		_ = tx.Rollback()
+		return err
+	}
+	return tx.Commit()
+}
+
+// SchemaVersion returns the highest applied migration version.
+func (s *Store) SchemaVersion() (int, error) {
+	var version sql.NullInt64
+	err := s.db.QueryRow(`SELECT MAX(version) FROM schema_migrations`).Scan(&version)
+	if err != nil {
+		return 0, err
+	}
+	if !version.Valid {
+		return 0, nil
+	}
+	return int(version.Int64), nil
+}