refactor: consolidate db package and flatten structure

internal/db/sqlite.go

@@ -0,0 +1,47 @@
+package db
+
+import (
+	"database/sql"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func Open(dbFile string) (*sql.DB, error) {
+	db, err := sql.Open("sqlite3", fmt.Sprintf("file:%s?_foreign_keys=on", dbFile))
+	if err != nil {
+		return nil, fmt.Errorf("failed to open db: %w", err)
+	}
+	return db, nil
+}
+
+func GetDBFile() string {
+	if f := os.Getenv("DATABASE_FILE"); f != "" {
+		return f
+	}
+	return "mal.db"
+}
+
+func GetMigrationsDir() (string, error) {
+	if dir := os.Getenv("MIGRATIONS_DIR"); dir != "" {
+		return dir, nil
+	}
+	wd, err := os.Getwd()
+	if err != nil {
+		return "", fmt.Errorf("failed to get working directory: %w", err)
+	}
+	return filepath.Join(wd, "migrations"), nil
+}
+
+func Init(db *sql.DB) (*Queries, error) {
+	migrationsDir, err := GetMigrationsDir()
+	if err != nil {
+		return nil, err
+	}
+	if err := RunMigrations(db, migrationsDir); err != nil {
+		return nil, fmt.Errorf("failed to run migrations: %w", err)
+	}
+	return New(db), nil
+}