database

func AddGroup(group *model.Group) error

func AddMemberToGroup(groupName string, user *model.User) error

func AddMessage(message *model.Message) error

func AddUser(user *model.User) error

func CheckGroup(groupName string) bool

func GetGroup(groupName string) (*model.Group, error)

func GetGroups(username string) ([]model.Group, error)

func GetMessages(groupName string) ([]model.Message, error)

func GetUser(username, password string) (*model.User, error)

func GetUserByUsername(username string) *model.User

func Publish(message *model.Message) error

func RemoveUserFromGroup(groupName, username string) error