import React, { PureComponent } 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 class Days extends PureComponent {
  get offset() {
    if (this.props.showNeighboringMonth) {
      return 0;
    }

    const { activeStartDate, calendarType } = this.props;
    return getDayOfWeek(activeStartDate, calendarType);
  }

  /**
   * 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.
   */
  get start() {
    if (this.props.showNeighboringMonth) {
      const { activeStartDate, calendarType } = this.props;
      return -getDayOfWeek(activeStartDate, calendarType) + 1;
    }
    return 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.
   */
  get end() {
    const { activeStartDate } = this.props;
    const daysInMonth = getDaysInMonth(activeStartDate);
    if (this.props.showNeighboringMonth) {
      const { year, monthIndex } = this;
      const { calendarType } = this.props;
      const activeEndDate = new Date(year, monthIndex, daysInMonth);
      return daysInMonth + (7 - getDayOfWeek(activeEndDate, calendarType) - 1);
    }
    return daysInMonth;
  }

  get year() {
    const { activeStartDate } = this.props;
    return getYear(activeStartDate);
  }

  get monthIndex() {
    const { activeStartDate } = this.props;
    return getMonthIndex(activeStartDate);
  }

  render() {
    const { monthIndex } = this;

    const {
      activeStartDate,
      calendarType,
      showNeighboringMonth,
      ...otherProps
    } = this.props;

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

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