package usecase

import (
	"fmt"
	"time"

	"golang.org/x/exp/rand"
)

// GenNewPassword generates new password, writes it to the memory and returns.
func (u *Usecase) GenNewPassword() (string, error) {
	rand.Seed(uint64(time.Now().UnixNano()))
	// gen new password
	pass := genPasswordString()
	// save to the memory
	if err := u.memory.SavePassword(pass); err != nil {
		return "", fmt.Errorf("failed to save password in the memory: %w", err)
	}
	return pass, nil
}

const (
	passwordLen = 8
	letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890"
)

func genPasswordString() string {
	b := make([]byte, passwordLen)
	for i := range b {
		b[i] = letterBytes[rand.Intn(len(letterBytes))]
	}
	return string(b)
}

// PasswordExists checks that password exists in the memory.
func (u *Usecase) PasswordExists(password string) (bool, error) {
	exists, err := u.memory.PasswordExists(password)
	if err != nil {
		return false, fmt.Errorf("failed to check password in the memory: %w", err)
	}
	return exists, nil
}