feat(store): open encrypted SQLite, schema v1, settings

internal/store/store.go

@@ -0,0 +1,65 @@
+// Package store owns the encrypted SQLite config and read state.
+package store
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strconv"
+
+	_ "modernc.org/sqlite"
+)
+
+// Store wraps the database and the field-encryption key.
+type Store struct {
+	db  *sql.DB
+	key []byte
+}
+
+// Open opens (creating if needed) the DB at path and applies the schema.
+func Open(path string, key []byte) (*Store, error) {
+	if err := os.MkdirAll(filepath.Dir(path), 0o700); err != nil {
+		return nil, fmt.Errorf("create db dir: %w", err)
+	}
+	db, err := sql.Open("sqlite", path)
+	if err != nil {
+		return nil, err
+	}
+	if _, err := db.Exec("PRAGMA foreign_keys = ON;"); err != nil {
+		db.Close()
+		return nil, err
+	}
+	if _, err := db.Exec(schemaSQL); err != nil {
+		db.Close()
+		return nil, fmt.Errorf("apply schema: %w", err)
+	}
+	s := &Store{db: db, key: key}
+	if _, err := s.GetSetting("schema_version"); err != nil {
+		if err := s.SetSetting("schema_version", strconv.Itoa(schemaVersion)); err != nil {
+			db.Close()
+			return nil, err
+		}
+	}
+	return s, nil
+}
+
+func (s *Store) Close() error { return s.db.Close() }
+
+// DefaultDBPath resolves EMCLI_DB or the per-OS default location.
+func DefaultDBPath() (string, error) {
+	if p := os.Getenv("EMCLI_DB"); p != "" {
+		return p, nil
+	}
+	if runtime.GOOS == "windows" {
+		if dir := os.Getenv("AppData"); dir != "" {
+			return filepath.Join(dir, "emcli", "emcli.db"), nil
+		}
+	}
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(home, ".config", "emcli", "emcli.db"), nil
+}