import absFloor from '../utils/abs-floor';
import { cloneWithOffset } from '../units/offset';
import { normalizeUnits } from '../units/aliases';
export function diff (input, units, asFloat) {
var that,
zoneDelta,
delta, output;
if (!this.isValid()) {
return NaN;
}
that = cloneWithOffset(input, this);
if (!that.isValid()) {
return NaN;
}
zoneDelta = (that.utcOffset() - this.utcOffset()) * 6e4;
units = normalizeUnits(units);
if (units === 'year' || units === 'month' || units === 'quarter') {
output = monthDiff(this, that);
if (units === 'quarter') {
output = output / 3;
} else if (units === 'year') {
output = output / 12;
}
} else {
delta = this - that;
output = units === 'second' ? delta / 1e3 : // 1000
units === 'minute' ? delta / 6e4 : // 1000 * 60
units === 'hour' ? delta / 36e5 : // 1000 * 60 * 60
units === 'day' ? (delta - zoneDelta) / 864e5 : // 1000 * 60 * 60 * 24, negate dst
units === 'week' ? (delta - zoneDelta) / 6048e5 : // 1000 * 60 * 60 * 24 * 7, negate dst
delta;
}
return asFloat ? output : absFloor(output);
}
function monthDiff (a, b) {
// difference in months
var wholeMonthDiff = ((b.year() - a.year()) * 12) + (b.month() - a.month()),
// b is in (anchor - 1 month, anchor + 1 month)
anchor = a.clone().add(wholeMonthDiff, 'months'),
anchor2, adjust;
if (b - anchor < 0) {
anchor2 = a.clone().add(wholeMonthDiff - 1, 'months');
// linear across the month
adjust = (b - anchor) / (anchor - anchor2);
} else {
anchor2 = a.clone().add(wholeMonthDiff + 1, 'months');
// linear across the month
adjust = (b - anchor) / (anchor2 - anchor);
}
//check for negative zero, return zero if negative zero
return -(wholeMonthDiff + adjust) || 0;
}
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