export function connectionAction({ connected, selectedTag, configExists }) {
  if (connected) return { type: 'stop' };
  if (selectedTag) return { type: 'apply', selectedTag };
  if (configExists) return { type: 'restart' };
  return null;
}

export function formatConnectionDuration(startedAt, now = Date.now()) {
  const { totalHours, minutes, seconds } = connectionDurationParts(startedAt, now);

  return [totalHours, minutes.value, seconds.value]
    .map((part) => String(part).padStart(2, '0'))
    .join(':');
}

function durationLabel(value, forms) {
  const mod10 = value % 10;
  const mod100 = value % 100;
  return mod10 === 1 && mod100 !== 11
    ? forms[0]
    : mod10 >= 2 && mod10 <= 4 && (mod100 < 12 || mod100 > 14) ? forms[1] : forms[2];
}

export function connectionDurationParts(startedAt, now = Date.now()) {
  const started = Date.parse(startedAt);
  const totalSeconds = Number.isFinite(started)
    ? Math.max(0, Math.floor((now - started) / 1000))
    : 0;
  const days = Math.floor(totalSeconds / 86_400);
  const totalHours = Math.floor(totalSeconds / 3600);
  const hours = Math.floor((totalSeconds % 86_400) / 3600);
  const minutes = Math.floor((totalSeconds % 3600) / 60);
  const seconds = totalSeconds % 60;

  return {
    totalHours,
    days: { value: days, label: durationLabel(days, ['день', 'дня', 'дней']) },
    hours: { value: hours, label: durationLabel(hours, ['час', 'часа', 'часов']) },
    minutes: { value: minutes, label: durationLabel(minutes, ['минута', 'минуты', 'минут']) },
    seconds: { value: seconds, label: durationLabel(seconds, ['секунда', 'секунды', 'секунд']) },
  };
}

export function formatConnectionDurationWords(startedAt, now = Date.now()) {
  const { days, hours, minutes, seconds } = connectionDurationParts(startedAt, now);

  return [
    days.value && `${days.value} ${days.label}`,
    hours.value && `${hours.value} ${hours.label}`,
    minutes.value && `${minutes.value} ${minutes.label}`,
    `${seconds.value} ${seconds.label}`,
  ].filter(Boolean).join(' ');
}

export function subscriptionDomain(subscriptionHost) {
  const value = String(subscriptionHost || '');
  try {
    return new URL(value).host;
  } catch {
    return value.split('/')[0];
  }
}

export function localProxyUrls(port = 8082, host = '127.0.0.1') {
  const urlHost = host.includes(':') && !host.startsWith('[') ? `[${host}]` : host;
  return {
    socks5: `socks5://${urlHost}:${port}`,
    http: `http://${urlHost}:${port}`,
  };
}

export async function copyText(text, options = {}) {
  const clipboard = options.clipboard ?? globalThis.navigator?.clipboard;
  const documentRef = options.documentRef ?? globalThis.document;

  if (documentRef?.execCommand) {
    const textarea = documentRef.createElement('textarea');
    textarea.value = text;
    textarea.setAttribute('readonly', '');
    textarea.style.position = 'fixed';
    textarea.style.opacity = '0';
    documentRef.body.append(textarea);
    textarea.select();
    const copied = documentRef.execCommand('copy');
    textarea.remove();
    if (copied) return;
  }

  if (!clipboard?.writeText) throw new Error('Copy failed');
  await clipboard.writeText(text);
}

export function subscriptionUsage(userInfo = {}) {
  const upload = Math.max(0, Number(userInfo.upload) || 0);
  const download = Math.max(0, Number(userInfo.download) || 0);
  const total = Math.max(0, Number(userInfo.total) || 0);
  const used = upload + download;

  return {
    upload,
    download,
    total,
    used,
    percent: total ? Math.min(100, (used / total) * 100) : null,
    expiresAt: userInfo.expire ? new Date(Number(userInfo.expire) * 1000) : null,
  };
}

export function subscriptionDaysLeft(expiresAt, now = Date.now()) {
  const days = Math.ceil((expiresAt?.getTime() - now) / 86_400_000);
  if (!Number.isFinite(days)) return '';
  if (days <= 0) return 'срок истёк';
  const mod10 = days % 10;
  const mod100 = days % 100;
  const unit = mod10 === 1 && mod100 !== 11
    ? 'день'
    : mod10 >= 2 && mod10 <= 4 && (mod100 < 12 || mod100 > 14) ? 'дня' : 'дней';
  return `${days === 1 ? 'остался' : 'осталось'} ${days} ${unit}`;
}