import { Solar } from 'lunar-typescript';
import { createChart } from './chart';
import type {
  BaziChart,
  CivilTime,
  DayBoundary,
  FourPillarsInput,
  TraceStep,
} from './types';

export function normalizeCivilTime(civilTime: CivilTime): Required<CivilTime> {
  const normalized = {
    year: civilTime.year,
    month: civilTime.month,
    day: civilTime.day,
    hour: civilTime.hour ?? 0,
    minute: civilTime.minute ?? 0,
    second: civilTime.second ?? 0,
  };
  for (const [key, value] of Object.entries(normalized)) {
    if (!Number.isInteger(value)) {
      throw new TypeError(`civilTime.${key} 必须是整数；收到：${value}`);
    }
  }
  if (normalized.year < 1 || normalized.year > 9999) {
    throw new RangeError('civilTime.year 必须在 1 到 9999 之间');
  }
  if (normalized.hour < 0 || normalized.hour > 23) {
    throw new RangeError('civilTime.hour 必须在 0 到 23 之间');
  }
  if (normalized.minute < 0 || normalized.minute > 59) {
    throw new RangeError('civilTime.minute 必须在 0 到 59 之间');
  }
  if (normalized.second < 0 || normalized.second > 59) {
    throw new RangeError('civilTime.second 必须在 0 到 59 之间');
  }

  // Date.UTC 会把 0..99 年解释为 1900..1999，先创建基准日期再显式设置年份。
  const check = new Date(0);
  check.setUTCFullYear(normalized.year, normalized.month - 1, normalized.day);
  check.setUTCHours(
    normalized.hour,
    normalized.minute,
    normalized.second,
    0,
  );
  if (
    check.getUTCFullYear() !== normalized.year ||
    check.getUTCMonth() !== normalized.month - 1 ||
    check.getUTCDate() !== normalized.day
  ) {
    throw new RangeError('civilTime 中的公历日期无效');
  }
  return normalized;
}

export function chartFromCivilTime(
  civilTime: Required<CivilTime>,
  dayBoundary: DayBoundary,
): { chart: BaziChart; pillars: FourPillarsInput; trace: TraceStep[] } {
  const solar = Solar.fromYmdHms(
    civilTime.year,
    civilTime.month,
    civilTime.day,
    civilTime.hour,
    civilTime.minute,
    civilTime.second,
  );
  const eightChar = solar.getLunar().getEightChar();
  // lunar-typescript: sect 1 为 23:00 换日，sect 2 为 00:00 换日。
  eightChar.setSect(dayBoundary === 'zi-hour' ? 1 : 2);
  const pillars = {
    year: eightChar.getYear(),
    month: eightChar.getMonth(),
    day: eightChar.getDay(),
    hour: eightChar.getTime(),
  };

  return {
    chart: createChart(pillars),
    pillars,
    trace: [
      {
        ruleId: 'calendar.solar-input',
        description: '将中国标准时间的公历民用时间交给历法核心。',
        input: { civilTime },
        output: { solar: solar.toYmdHms() },
      },
      {
        ruleId: 'calendar.four-pillars',
        description: '年柱以立春换年，月柱以节换月，并按配置应用换日规则。',
        input: { dayBoundary },
        output: { pillars },
      },
    ],
  };
}