package auth

import (
	"strings"

	"galo/internal/httpx"
)

// Identifier kinds for login and registration.
const (
	IdentifierEmail = "email"
	IdentifierPhone = "phone"
)

// NormalizePhone validates and canonicalises a phone number to E.164: a leading
// plus followed by 8–15 digits. It is the single normalisation point used by
// registration, identifier addition and login, so lookups compare canonical
// values only.
func NormalizePhone(raw string) (string, error) {
	s := strings.TrimSpace(raw)
	if s == "" {
		return "", httpx.BadRequest("invalid_phone", "phone is required")
	}
	if !strings.HasPrefix(s, "+") {
		return "", httpx.BadRequest("invalid_phone", "phone must be in E.164 format with a leading +")
	}
	digits := s[1:]
	if len(digits) < 8 || len(digits) > 15 {
		return "", httpx.BadRequest("invalid_phone", "phone must contain between 8 and 15 digits")
	}
	for _, r := range digits {
		if r < '0' || r > '9' {
			return "", httpx.BadRequest("invalid_phone", "phone may contain digits only after the leading +")
		}
	}
	return s, nil
}

func validEmail(s string) bool {
	i := strings.Index(s, "@")
	return i > 0 && i < len(s)-1 && !strings.ContainsAny(s, " \t\r\n")
}

// NormalizeIdentifier classifies a login identifier as email (contains `@`) or
// phone, returning the canonical value for lookups.
func NormalizeIdentifier(raw string) (kind, value string, err error) {
	s := strings.TrimSpace(raw)
	if s == "" {
		return "", "", httpx.BadRequest("invalid_identifier", "identifier is required")
	}
	if strings.Contains(s, "@") {
		v := strings.ToLower(s)
		if !validEmail(v) {
			return "", "", httpx.BadRequest("invalid_identifier", "valid email is required")
		}
		return IdentifierEmail, v, nil
	}
	v, err := NormalizePhone(s)
	if err != nil {
		return "", "", err
	}
	return IdentifierPhone, v, nil
}