import {
  DatepickerFormatOptions, YearsCalendarViewModel, CalendarCellViewModel
} from '../models/index';
import { shiftDate } from '../../bs-moment/utils/date-setters';
import { formatDate } from '../../bs-moment/format';
import { TimeUnit } from '../../bs-moment/types';
import { createMatrix } from '../utils/matrix-utils';

const height = 4;
const width = 4;
export const yearsPerCalendar = height * width;
const initialShift = (Math.floor(yearsPerCalendar / 2) - 1) * -1;
const shift = {year: 1};

export function formatYearsCalendar(viewDate: Date, formatOptions: DatepickerFormatOptions): YearsCalendarViewModel {

  const initialDate = shiftDate(viewDate, {year: initialShift});
  const matrixOptions = {width, height, initialDate, shift};
  const yearsMatrix = createMatrix<CalendarCellViewModel>(matrixOptions,
    date => ({
      date,
      label: formatDate(date, formatOptions.yearLabel, formatOptions.locale)
    }));
  const yearTitle = formatYearRangeTitle(yearsMatrix, formatOptions);

  return {
    years: yearsMatrix,
    monthTitle: '',
    yearTitle
  };
}

function formatYearRangeTitle(yearsMatrix: CalendarCellViewModel[][], formatOptions: DatepickerFormatOptions): string {
  const from = formatDate(yearsMatrix[0][0].date, formatOptions.yearTitle, formatOptions.locale);
  const to = formatDate(yearsMatrix[height - 1][width - 1].date, formatOptions.yearTitle, formatOptions.locale);

  return `${from} - ${to}`;
}