import React from 'react';
import PropTypes from 'prop-types';

import TileGroup from '../TileGroup';
import Day from './Day';

import {
  getDayOfWeek,
  getDaysInMonth,
  getMonthIndex,
  getYear,
} from '../shared/dates';
import { isCalendarType, tileGroupProps } from '../shared/propTypes';

export default function Days(props) {
  const {
    activeStartDate,
    calendarType,
  } = props;
  const {
    showFixedNumberOfWeeks,
    showNeighboringMonth,
    ...otherProps
  } = props;

  const year = getYear(activeStartDate);
  const monthIndex = getMonthIndex(activeStartDate);

  const hasFixedNumberOfWeeks = showFixedNumberOfWeeks || showNeighboringMonth;
  const dayOfWeek = getDayOfWeek(activeStartDate, calendarType);

  const offset = hasFixedNumberOfWeeks ? 0 : dayOfWeek;

  /**
   * Defines on which day of the month the grid shall start. If we simply show current
   * month, we obviously start on day one, but if showNeighboringMonth is set to
   * true, we need to find the beginning of the week the first day of the month is in.
   */
  const start = (hasFixedNumberOfWeeks ? -dayOfWeek : 0) + 1;

  /**
   * Defines on which day of the month the grid shall end. If we simply show current
   * month, we need to stop on the last day of the month, but if showNeighboringMonth
   * is set to true, we need to find the end of the week the last day of the month is in.
   */
  const end = (() => {
    if (showFixedNumberOfWeeks) {
      // Always show 6 weeks
      return start + (6 * 7) - 1;
    }

    const daysInMonth = getDaysInMonth(activeStartDate);

    if (showNeighboringMonth) {
      const activeEndDate = new Date(year, monthIndex, daysInMonth);
      return daysInMonth + (7 - getDayOfWeek(activeEndDate, calendarType) - 1);
    }

    return daysInMonth;
  })();

  return (
    <TileGroup
      {...otherProps}
      className="react-calendar__month-view__days"
      count={7}
      currentMonthIndex={monthIndex}
      dateTransform={day => new Date(year, monthIndex, day)}
      dateType="day"
      end={end}
      offset={offset}
      start={start}
      tile={Day}
    />
  );
}

Days.propTypes = {
  calendarType: isCalendarType.isRequired,
  showFixedNumberOfWeeks: PropTypes.bool,
  showNeighboringMonth: PropTypes.bool,
  ...tileGroupProps,
};