package auth

import "fmt"

// ErrInvalidSession is thrown when an AuthenticatorService is given a missing or invalid session token
var ErrInvalidSession = fmt.Errorf(`invalid session token`)

// User represents a user returned from AuthenticatorService
type User struct {
	Username string `json:"username"`
	Name     string `json:"name"`
	Surname  string `json:"surname"`
	FullName string `json:"fullName"`
	Email    string `json:"email"`
}

// WithDefaultFullName is a utility that returns a copy of the given user with the full name set to the concatenation of the name and surname of the user.
func (u User) WithDefaultFullName() User {
	return User{
		Username: u.Username,
		Name:     u.Name,
		Surname:  u.Surname,
		Email:    u.Email,

		FullName: u.Username + " " + u.Surname,
	}
}

// Session represents a session returned from AuthenticatorService
type Session struct {
	Username string `json:"username"`
	Token    string `json:"token"`
}

// AuthenticatorService can login users using a separate http service or a temporary in memory store. When a user logs in the auth service returns a session token that can be used to read and modify user properties without having to re-send the user password. (TODO: Not yet implemented: this token has to be renewed every so often otherwise it lasts just a couple of days)
type AuthenticatorService interface {
	// GetUser retrieves the user info given the username
	GetUser(username string) (*User, error)

	// GetUsers retrieves the full user list from the authentication service
	GetUsers() ([]*User, error)

	// GetSession retrieves the user session associated to a session token
	GetSession(token string) (*Session, error)

	// Login tries to log in a user given username and password and if successful returns a new user session
	Login(username, password string) (*Session, error)
}

// UserForSession returns the user (object) linked to a session token, this is just a shortcut for calling [AuthenticatorService.GetSession] and then [AuthenticatorService.GetUser]
func UserForSession(as AuthenticatorService, token string) (*User, error) {
	session, err := as.GetSession(token)
	if err != nil {
		return nil, err
	}

	user, err := as.GetUser(session.Username)
	if err != nil {
		return nil, err
	}

	return user, nil
}

// New create an AuthenticatorService given an "host" string, if ":memory:" then this just returns an example AuthenticatorService using the [auth.Memory] implementation, otherwise for now this defaults to [auth.LDAPAuthService]
func New(host string) AuthenticatorService {
	if host == ":memory:" {
		return exampleMemoryUsers
	}

	return &LDAPAuthService{host}
}