import dateUtil from 'element-ui/src/utils/date';

const newArray = function(start, end) {
  let result = [];
  for (let i = start; i <= end; i++) {
    result.push(i);
  }
  return result;
};

export const equalDate = function(dateA, dateB) {
  return dateA === dateB || new Date(dateA).getTime() === new Date(dateB).getTime();
};

export const toDate = function(date) {
  return isDate(date) ? new Date(date) : null;
};

export const isDate = function(date) {
  if (date === null || date === undefined) return false;
  if (isNaN(new Date(date).getTime())) return false;
  return true;
};

export const formatDate = function(date, format) {
  date = toDate(date);
  if (!date) return '';
  return dateUtil.format(date, format || 'yyyy-MM-dd');
};

export const parseDate = function(string, format) {
  return dateUtil.parse(string, format || 'yyyy-MM-dd');
};

export const getDayCountOfMonth = function(year, month) {
  if (month === 3 || month === 5 || month === 8 || month === 10) {
    return 30;
  }

  if (month === 1) {
    if (year % 4 === 0 && year % 100 !== 0 || year % 400 === 0) {
      return 29;
    } else {
      return 28;
    }
  }

  return 31;
};

export const getFirstDayOfMonth = function(date) {
  const temp = new Date(date.getTime());
  temp.setDate(1);
  return temp.getDay();
};

export const DAY_DURATION = 86400000;

export const getStartDateOfMonth = function(year, month) {
  const result = new Date(year, month, 1);
  const day = result.getDay();

  if (day === 0) {
    result.setTime(result.getTime() - DAY_DURATION * 7);
  } else {
    result.setTime(result.getTime() - DAY_DURATION * day);
  }

  return result;
};

export const getWeekNumber = function(src) {
  const date = new Date(src.getTime());
  date.setHours(0, 0, 0, 0);
  // Thursday in current week decides the year.
  date.setDate(date.getDate() + 3 - (date.getDay() + 6) % 7);
  // January 4 is always in week 1.
  const week1 = new Date(date.getFullYear(), 0, 4);
  // Adjust to Thursday in week 1 and count number of weeks from date to week 1.
  return 1 + Math.round(((date.getTime() - week1.getTime()) / 86400000 - 3 + (week1.getDay() + 6) % 7) / 7);
};

export const prevMonth = function(src) {
  const year = src.getFullYear();
  const month = src.getMonth();
  const date = src.getDate();

  const newYear = month === 0 ? year - 1 : year;
  const newMonth = month === 0 ? 11 : month - 1;

  const newMonthDayCount = getDayCountOfMonth(newYear, newMonth);
  if (newMonthDayCount < date) {
    src.setDate(newMonthDayCount);
  }

  src.setMonth(newMonth);
  src.setFullYear(newYear);

  return new Date(src.getTime());
};

export const nextMonth = function(src) {
  const year = src.getFullYear();
  const month = src.getMonth();
  const date = src.getDate();

  const newYear = month === 11 ? year + 1 : year;
  const newMonth = month === 11 ? 0 : month + 1;

  const newMonthDayCount = getDayCountOfMonth(newYear, newMonth);
  if (newMonthDayCount < date) {
    src.setDate(newMonthDayCount);
  }

  src.setMonth(newMonth);
  src.setFullYear(newYear);

  return new Date(src.getTime());
};

export const getRangeHours = function(ranges) {
  const hours = [];
  let disabledHours = [];

  (ranges || []).forEach(range => {
    const value = range.map(date => date.getHours());

    disabledHours = disabledHours.concat(newArray(value[0], value[1]));
  });

  if (disabledHours.length) {
    for (let i = 0; i < 24; i++) {
      hours[i] = disabledHours.indexOf(i) === -1;
    }
  } else {
    for (let i = 0; i < 24; i++) {
      hours[i] = false;
    }
  }

  return hours;
};

export const limitRange = function(date, ranges) {
  if (!ranges || !ranges.length) return date;

  const len = ranges.length;
  const format = 'HH:mm:ss';

  date = dateUtil.parse(dateUtil.format(date, format), format);
  for (let i = 0; i < len; i++) {
    const range = ranges[i];
    if (date >= range[0] && date <= range[1]) {
      return date;
    }
  }

  let maxDate = ranges[0][0];
  let minDate = ranges[0][0];

  ranges.forEach(range => {
    minDate = new Date(Math.min(range[0], minDate));
    maxDate = new Date(Math.max(range[1], maxDate));
  });

  return date < minDate ? minDate : maxDate;
};
