import { t } from '@/shared/i18n'

export const emailError = (email: string) =>
  /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email) && new TextEncoder().encode(email).length <= 254
    ? ''
    : t('validation.email.invalid')

// 与后端 PasswordPolicy 默认档（src/config/auth.rs）对齐：
// ≥8 位且含大写、小写、数字，避免用户提交后才收到服务端报错。
export const passwordError = (value: string) => {
  if (value.length < 8) return t('validation.password.short')
  if (!/[A-Z]/.test(value) || !/[a-z]/.test(value) || !/[0-9]/.test(value)) {
    return t('validation.password.weak')
  }
  return ''
}
export const usernameError = (value: string) =>
  /^[a-zA-Z0-9_.-]{1,64}$/.test(value) ? '' : t('validation.username.invalid')
export const normalizeEmail = (value: string) => value.trim().toLowerCase()

export function birthError(year: string, month: string, day: string) {
  if (!year || !month || !day) return t('validation.birth.incomplete')
  const date = new Date(Date.UTC(Number(year), Number(month) - 1, Number(day)))
  const today = new Date()
  if (
    Number(year) < 1900 ||
    date.getUTCFullYear() !== Number(year) ||
    date.getUTCMonth() !== Number(month) - 1 ||
    date.getUTCDate() !== Number(day) ||
    date > today
  )
    return t('validation.birth.invalid')
  const age =
    today.getUTCFullYear() -
    Number(year) -
    (today.getUTCMonth() + 1 < Number(month) ||
    (today.getUTCMonth() + 1 === Number(month) && today.getUTCDate() < Number(day))
      ? 1
      : 0)
  return age >= 13 ? '' : t('validation.birth.underage')
}