refactor: reorganize packages into a domain-based layered structure

internal/account/entity.go

@@ -0,0 +1,7 @@
+package account
+
+type User struct {
+	ID       uint   `gorm:"primaryKey" json:"id"`
+	Username string `gorm:"unique" json:"username"`
+	Password string `json:"-"`
+}

internal/account/repo.go

@@ -0,0 +1,50 @@
+package account
+
+import (
+	"gorm.io/gorm"
+)
+
+type UserRepository struct {
+	db *gorm.DB
+}
+
+func NewUserRepository(db *gorm.DB) *UserRepository {
+	return &UserRepository{db: db}
+}
+
+func (ur *UserRepository) CreateUser(user *User) error {
+	if err := ur.db.Create(user).Error; err != nil {
+		return err
+	}
+	return nil
+}
+
+func (ur *UserRepository) RenameByID(id uint, newUsername string) error {
+	if err := ur.db.Model(&User{}).Where("id = ?", id).Update("username", newUsername).Error; err != nil {
+		return err
+	}
+	return nil
+}
+
+func (ur *UserRepository) ChangePassword(id uint, newPassword string) error {
+	if err := ur.db.Model(&User{}).Where("id = ?", id).Update("password", newPassword).Error; err != nil {
+		return err
+	}
+	return nil
+}
+
+func (ur *UserRepository) FindByID(id uint) (*User, error) {
+	var user User
+	if err := ur.db.First(&user, id).Error; err != nil {
+		return nil, err
+	}
+	return &user, nil
+}
+
+func (ur *UserRepository) FindByUsername(username string) (*User, error) {
+	var user User
+	if err := ur.db.Where("username = ?", username).First(&user).Error; err != nil {
+		return nil, err
+	}
+	return &user, nil
+}

internal/account/service.go

@@ -0,0 +1,46 @@
+package account
+
+type UserService struct {
+	userRepository *UserRepository
+}
+
+func NewUserService(userRepository *UserRepository) *UserService {
+	return &UserService{userRepository: userRepository}
+}
+
+func (us *UserService) CreateUser(user *User) error {
+	if err := us.userRepository.CreateUser(user); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (us *UserService) RenameByID(id uint, newUsername string) error {
+	if err := us.userRepository.RenameByID(id, newUsername); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (us *UserService) ChangePassword(id uint, newPassword string) error {
+	if err := us.userRepository.ChangePassword(id, newPassword); err != nil {
+		return err
+	}
+	return nil
+}
+
+func (us *UserService) FindByID(id uint) (*User, error) {
+	if user, err := us.userRepository.FindByID(id); err != nil {
+		return nil, err
+	} else {
+		return user, nil
+	}
+}
+
+func (us *UserService) FindByUsername(username string) (*User, error) {
+	if user, err := us.userRepository.FindByUsername(username); err != nil {
+		return nil, err
+	} else {
+		return user, nil
+	}
+}