package main

import (
	"fmt"

	"golang.org/x/crypto/bcrypt"
)

var ErrUserNotFound = fmt.Errorf("user not found")

type User struct {
	Name  string
	Roles []string
}

type storeUser struct {
	name         string
	roles        []string
	passwordHash []byte
}

type Userstore struct {
	users map[string]storeUser
}

func (u *Userstore) Create(name string, roles []string, password string) error {
	if u.users == nil {
		u.users = map[string]storeUser{}
	}
	hashed, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		return err
	}
	u.users[name] = storeUser{
		name:         name,
		roles:        roles,
		passwordHash: hashed,
	}
	return nil
}

func (u *Userstore) UpdatePassword(name string, password string) error {
	if u.users == nil {
		u.users = map[string]storeUser{}
		return ErrUserNotFound
	}
	hashed, err := bcrypt.GenerateFromPassword([]byte(password), bcrypt.DefaultCost)
	if err != nil {
		return err
	}
	user, ok := u.users[name]
	if !ok {
		return ErrUserNotFound
	}
	user.passwordHash = hashed
	u.users[name] = user
	return nil
}

func (u *Userstore) UpdateUser(name string, updatedUser User) error {
	if u.users == nil {
		u.users = map[string]storeUser{}
		return ErrUserNotFound
	}
	user, ok := u.users[name]
	if !ok {
		return ErrUserNotFound
	}
	user.name = updatedUser.Name
	user.roles = updatedUser.Roles
	u.users[name] = user
	return nil
}

func (u *Userstore) Authenticate(name string, password string) (User, error) {
	if u.users == nil {
		u.users = map[string]storeUser{}
		return User{}, ErrUserNotFound
	}
	user, ok := u.users[name]
	if !ok {
		return User{}, ErrUserNotFound
	}
	err := bcrypt.CompareHashAndPassword(user.passwordHash, []byte(password))
	if err != nil {
		return User{}, err
	}
	return User{
		Name:  user.name,
		Roles: user.roles,
	}, nil
}

func (u *Userstore) Delete(name string) error {
	if u.users == nil {
		u.users = map[string]storeUser{}
		return ErrUserNotFound
	}
	_, ok := u.users[name]
	if !ok {
		return ErrUserNotFound
	}
	delete(u.users, name)
	return nil
}