package handlers

import (
	"regexp"
	"strings"

	"github.com/gin-gonic/gin/binding"
	"github.com/go-playground/validator/v10"
)

func init() {
	// Register custom validators
	if v, ok := binding.Validator.Engine().(*validator.Validate); ok {
		v.RegisterValidation("alphanumdash", alphanumdashValidator)
	}
}

// alphanumdashValidator validates that a string contains only alphanumeric characters and hyphens
var alphanumdashValidator validator.Func = func(fl validator.FieldLevel) bool {
	value := fl.Field().String()
	// Allow alphanumeric and hyphens only
	match := regexp.MustCompile(`^[a-zA-Z0-9-]+$`).MatchString(value)
	return match
}

// IsValidSubdomainFormat checks if a subdomain string is valid (exported for use in validation)
func IsValidSubdomainFormat(subdomain string) bool {
	// Must be at least 3 characters
	if len(subdomain) < 3 {
		return false
	}

	// Must not exceed 63 characters
	if len(subdomain) > 63 {
		return false
	}

	// Must not start or end with hyphen
	if strings.HasPrefix(subdomain, "-") || strings.HasSuffix(subdomain, "-") {
		return false
	}

	// Must contain only alphanumeric and hyphens
	return regexp.MustCompile(`^[a-zA-Z0-9-]+$`).MatchString(subdomain)
}