import { isString } from '@sindresorhus/is';
import { DateTime } from 'luxon';
import { z } from 'zod/v4';

export type Timestamp = string & { __timestamp: never };

const timezoneOffset = new Date().getTimezoneOffset() * 60000;

const millenium = 946684800000; // 2000-01-01T00:00:00.000Z
const tomorrowOffset = 86400000; // 24 * 60 * 60 * 1000;

function isValid(date: DateTime): boolean {
  if (!date.isValid) {
    return false;
  }
  const tomorrow = DateTime.now().toMillis() + tomorrowOffset; // 24 * 60 * 60 * 1000;
  const ts = date.toMillis();
  return ts > millenium && ts < tomorrow;
}

export function asTimestamp(input: unknown): Timestamp | null {
  if (input instanceof Date) {
    const date = DateTime.fromJSDate(input, { zone: 'UTC' });
    if (isValid(date)) {
      return date.toISO() as Timestamp;
    }

    return null;
  }

  if (typeof input === 'number') {
    const millisDate = DateTime.fromMillis(input, { zone: 'UTC' });
    if (isValid(millisDate)) {
      return millisDate.toISO() as Timestamp;
    }

    const secondsDate = DateTime.fromSeconds(input, { zone: 'UTC' });
    if (isValid(secondsDate)) {
      return secondsDate.toISO() as Timestamp;
    }

    return null;
  }

  if (isString(input)) {
    const isoDate = DateTime.fromISO(input, { zone: 'UTC' });
    if (isValid(isoDate)) {
      return isoDate.toISO() as Timestamp;
    }

    const httpDate = DateTime.fromHTTP(input, { zone: 'UTC' });
    if (isValid(httpDate)) {
      return httpDate.toISO() as Timestamp;
    }

    const sqlDate = DateTime.fromSQL(input, { zone: 'UTC' });
    if (isValid(sqlDate)) {
      return sqlDate.toISO() as Timestamp;
    }

    const numberLikeDate = DateTime.fromFormat(input, 'yyyyMMddHHmmss', {
      zone: 'UTC',
    });
    if (isValid(numberLikeDate)) {
      return numberLikeDate.toISO() as Timestamp;
    }

    const numberLikeOffsetDate = DateTime.fromFormat(
      input,
      'yyyyMMddHHmmssZZZ',
      { zone: 'UTC' },
    );
    if (isValid(numberLikeOffsetDate)) {
      return numberLikeOffsetDate.toISO() as Timestamp;
    }

    const fallbackDate = DateTime.fromMillis(
      Date.parse(input) - timezoneOffset,
      { zone: 'UTC' },
    );
    if (isValid(fallbackDate)) {
      return fallbackDate.toISO() as Timestamp;
    }

    return null;
  }

  return null;
}

export const Timestamp = z.unknown().transform((input, ctx) => {
  const timestamp = asTimestamp(input);
  if (!timestamp) {
    ctx.addIssue({
      code: z.ZodIssueCode.custom,
      message: 'Invalid timestamp',
    });
    return z.NEVER;
  }

  return timestamp;
});
export const MaybeTimestamp = Timestamp.nullable().catch(null);