package auth

import (
	"context"
	"errors"
	"fmt"
	"strings"

	"codeberg.org/maxwelljensen/weimar/internal/db"
	"golang.org/x/crypto/bcrypt"
)

var (
	ErrUsernameTaken     = errors.New("username already taken")
	ErrPasswordTooShort  = errors.New("password must be at least 8 characters")
	ErrUsernameTooShort  = errors.New("username must be at least 3 characters")
	ErrRegistrationClosed = errors.New("registration is closed")
)

const (
	MinPasswordLength = 8
	MinUsernameLength = 3
	bcryptCost        = 12
)

// Register creates a new user account. If allowRegistration is false it
// returns ErrRegistrationClosed.
func Register(ctx context.Context, database *db.DB, username, password string, isAdmin bool) (*db.User, error) {
	if len(username) < MinUsernameLength {
		return nil, ErrUsernameTooShort
	}
	if len(password) < MinPasswordLength {
		return nil, ErrPasswordTooShort
	}

	hash, err := bcrypt.GenerateFromPassword([]byte(password), bcryptCost)
	if err != nil {
		return nil, fmt.Errorf("hash password: %w", err)
	}

	user, err := database.CreateUser(ctx, username, string(hash), isAdmin)
	if err != nil {
		if isUniqueViolation(err) {
			return nil, ErrUsernameTaken
		}
		return nil, fmt.Errorf("create user: %w", err)
	}
	return user, nil
}

func isUniqueViolation(err error) bool {
	return err != nil && strings.Contains(err.Error(), "UNIQUE constraint failed")
}