source: node_modules/d3-time/src/year.js

import {timeInterval} from "./interval.js";

export const timeYear = timeInterval((date) => {
  date.setMonth(0, 1);
  date.setHours(0, 0, 0, 0);
}, (date, step) => {
  date.setFullYear(date.getFullYear() + step);
}, (start, end) => {
  return end.getFullYear() - start.getFullYear();
}, (date) => {
  return date.getFullYear();
});

// An optimized implementation for this simple case.
timeYear.every = (k) => {
  return !isFinite(k = Math.floor(k)) || !(k > 0) ? null : timeInterval((date) => {
    date.setFullYear(Math.floor(date.getFullYear() / k) * k);
    date.setMonth(0, 1);
    date.setHours(0, 0, 0, 0);
  }, (date, step) => {
    date.setFullYear(date.getFullYear() + step * k);
  });
};

export const timeYears = timeYear.range;

export const utcYear = timeInterval((date) => {
  date.setUTCMonth(0, 1);
  date.setUTCHours(0, 0, 0, 0);
}, (date, step) => {
  date.setUTCFullYear(date.getUTCFullYear() + step);
}, (start, end) => {
  return end.getUTCFullYear() - start.getUTCFullYear();
}, (date) => {
  return date.getUTCFullYear();
});

// An optimized implementation for this simple case.
utcYear.every = (k) => {
  return !isFinite(k = Math.floor(k)) || !(k > 0) ? null : timeInterval((date) => {
    date.setUTCFullYear(Math.floor(date.getUTCFullYear() / k) * k);
    date.setUTCMonth(0, 1);
    date.setUTCHours(0, 0, 0, 0);
  }, (date, step) => {
    date.setUTCFullYear(date.getUTCFullYear() + step * k);
  });
};

export const utcYears = utcYear.range;