import { getLocalParts, localDateKey, normalizeTimezone } from '../schedule-time.mjs';
import { pickDailyLibraryEntry } from './push-content/daily-library-pick.mjs';

export const NIGHT_SUMMARY_REFLECTIONS = Object.freeze([
  '今天认真过就好，不必和完美较劲。',
  '你已经比昨天更前进一步，这就值得晚安。',
  '把未完成留给明天，把休息留给今晚。',
  '今天的小收获，会在未来某天连起来。',
  '允许自己慢下来，明天会继续。',
]);

export const NIGHT_TOMORROW_HINTS = Object.freeze([
  '明天记得留一点空白给意外之喜。',
  '明天优先处理最重要的一件事就好。',
  '明天早起一杯水，会是很不错的开始。',
  '明天如果有难的事，先拆成一小步再行动。',
  '明天也别忘了，给自己留点轻松时间。',
]);

function hashString(input) {
  let hash = 2166136261;
  for (let i = 0; i < input.length; i += 1) {
    hash ^= input.charCodeAt(i);
    hash = Math.imul(hash, 16777619);
  }
  return Math.abs(hash);
}

export function formatNightDateLabel(now = Date.now(), timezone = 'Asia/Shanghai') {
  const parts = getLocalParts(now, normalizeTimezone(timezone));
  return `${parts.year}年${parts.month}月${parts.day}日`;
}

export function pickNightSummaryParts({
  userId = '',
  timezone = 'Asia/Shanghai',
  now = Date.now(),
} = {}) {
  const reflection = pickDailyLibraryEntry({
    userId,
    timezone,
    now,
    library: NIGHT_SUMMARY_REFLECTIONS,
    salt: 'night-reflection',
  });
  const tomorrowHint = pickDailyLibraryEntry({
    userId,
    timezone,
    now,
    library: NIGHT_TOMORROW_HINTS,
    salt: 'night-tomorrow',
  });
  return { reflection, tomorrowHint };
}

export function formatNightSummaryDeliveryText({
  userId,
  timezone = 'Asia/Shanghai',
  now = Date.now(),
} = {}) {
  const dateLabel = formatNightDateLabel(now, timezone);
  const { reflection, tomorrowHint } = pickNightSummaryParts({ userId, timezone, now });
  return [
    `🌙 晚安总结 · ${dateLabel}`,
    '',
    `今日一句：${reflection}`,
    '',
    `明日提醒：${tomorrowHint}`,
    '',
    '晚安，好梦。',
    '',
    '回复「取消9」关闭推送',
  ].join('\n');
}

export function pickSurpriseVariantIndex({ userId, timezone, now }) {
  const tz = normalizeTimezone(timezone);
  const dateKey = localDateKey(now, tz);
  const seed = hashString(`${String(userId)}:${dateKey}:surprise-variant`);
  return seed % 3;
}