finished: check update

service/service.go

@@ -3,7 +3,8 @@ package service
 import (
 	"database/sql"
 	"fmt"
-	"log"
+	"os"
+	"path/filepath"
 
 	_ "github.com/mattn/go-sqlite3"
 )
@@ -18,21 +19,50 @@ type MacAddress struct {
 }
 
 type SQLiteHelper struct {
-	connectionString string
-	db               *sql.DB
+	db *sql.DB
 }
 
-func NewSQLiteHelper(dbFilePath string) *SQLiteHelper {
-	connectionString := fmt.Sprintf("file:%s?cache=shared&mode=rwc", dbFilePath)
-	db, err := sql.Open("sqlite3", connectionString)
-	if err != nil {
-		log.Fatal(err)
+// create the instance of SQLiteHelper but not initialize the database connection
+func NewSQLiteHelper() *SQLiteHelper {
+	return &SQLiteHelper{
+		db: nil,
+	}
+}
+
+// check if the directory and file for the database exist
+func (helper *SQLiteHelper) CheckBeforeInit() bool {
+	userHomeDir, _ := os.UserHomeDir()
+	dbFileDir := filepath.Join(userHomeDir, ".macfastlookup")
+	dbFileName := "mac_vendors.sqlite3"
+	dbFilePath := filepath.Join(dbFileDir, dbFileName)
+
+	if _, err := os.Stat(dbFileDir); os.IsNotExist(err) {
+		os.Mkdir(dbFileDir, 0755)
 	}
 
-	return &SQLiteHelper{
-		connectionString: connectionString,
-		db:               db,
+	if _, err := os.Stat(dbFilePath); os.IsNotExist(err) {
+		return false
 	}
+
+	return true
+}
+
+// initialize the database connection
+func (helper *SQLiteHelper) InitSQLiteHelper() bool {
+	dbFileDir := ".macfastlookup"
+	userHomeDir, _ := os.UserHomeDir()
+	dbFileName := "mac_vendors.sqlite3"
+	dbFilePath := filepath.Join(userHomeDir, dbFileDir, dbFileName)
+
+	connectionString := fmt.Sprintf("file:%s?cache=shared&mode=rwc", dbFilePath)
+	db, err := sql.Open("sqlite3", connectionString)
+
+	if err != nil {
+		return false
+	}
+
+	helper.db = db
+	return true
 }
 
 func (helper *SQLiteHelper) Close() {
@@ -40,14 +70,7 @@ func (helper *SQLiteHelper) Close() {
 }
 
 func (helper *SQLiteHelper) ReloadDatabase() bool {
-	helper.db.Close()
-	db, err := sql.Open("sqlite3", helper.connectionString)
-	if err != nil {
-		log.Fatal(err)
-		return false
-	}
-	helper.db = db
-	return true
+	return helper.InitSQLiteHelper()
 }
 
 func (helper *SQLiteHelper) QueryMacAddressByPrefix(prefix string) (*MacAddress, error) {