package validators

import (
	"fmt"
	"github.com/go-playground/validator/v10"
	"reflect"
	"regexp"
	"strings"
	"time"
)

var Validate *validator.Validate

func init() {
	Validate = validator.New()
	Validate.RegisterTagNameFunc(func(fld reflect.StructField) string {
		name := strings.SplitN(fld.Tag.Get("json"), ",", 2)[0]
		if name == "-" {
			return ""
		}
		return name
	})
}

// ID format: 12-character hexadecimal string (from gen_random_bytes(6) encoded as hex)
var validIDRegex = regexp.MustCompile(`^[0-9a-f]{12}$`)

// IsValidID checks if an ID is valid based on the database constraint (CHAR(12) hex string)
// Valid IDs are exactly 12 hexadecimal characters (0-9, a-f)
func IsValidID(id string) bool {
	if id == "" {
		return false
	}
	return validIDRegex.MatchString(id)
}

// ParseCursor splits a "createdAt|id" cursor string into its components.
func ParseCursor(cursor string) (time.Time, string, error) {
	parts := strings.SplitN(cursor, "|", 2)
	if len(parts) != 2 {
		return time.Time{}, "", fmt.Errorf("invalid cursor format")
	}
	t, err := time.Parse(time.RFC3339, parts[0])
	if err != nil {
		return time.Time{}, "", fmt.Errorf("invalid cursor created_at: %w", err)
	}
	return t, parts[1], nil
}