'use strict';

const SunCalc = require('suncalc');

/**

* sunEvents(lat, lon, date)

*

* Returns key solar times for a given location and calendar date.

* All returned values are native JS Date objects (UTC).

*

* @param {number} lat – Latitude (decimal degrees, + = North)

* @param {number} lon – Longitude (decimal degrees, + = East)

* @param {Date} date – Any moment on the desired local date (midnight is fine)

* @returns {{

* sunrise: Date, // upper limb of sun crosses horizon (morning)

* sunriseEnd: Date, // upper limb fully above horizon

* goldenHourEnd: Date, // morning golden hour ends

* goldenHour: Date, // evening golden hour starts

* sunsetStart: Date, // upper limb starts touching horizon

* sunset: Date, // upper limb disappears (evening)

* solarNoon: Date, // sun at highest point

* }}

*/

function sunEvents(lat, lon, date) {

const times = SunCalc.getTimes(date, lat, lon);

return {

// ── Morning ──────────────────────────────────────────────────────────

sunrise: times.sunrise, // classic "sunrise" moment

sunriseEnd: times.sunriseEnd, // disc fully clear of horizon

goldenHourEnd: times.goldenHourEnd, // end of morning golden hour

// ── Midday ───────────────────────────────────────────────────────────

solarNoon: times.solarNoon,

// ── Evening ──────────────────────────────────────────────────────────

goldenHour: times.goldenHour, // start of evening golden hour

sunsetStart: times.sunsetStart, // disc starts touching horizon

sunset: times.sunset, // classic "sunset" moment

};

}

/**

* fireAt(eventDate, leadMinutes)

*

* Returns the UTC time at which a push notification should be sent,

* i.e. `leadMinutes` before the solar event.

*

* @param {Date} eventDate – The sunrise or sunset Date

* @param {number} leadMinutes – Minutes before the event (default 20)

* @returns {Date}

*/

function fireAt(eventDate, leadMinutes = 20) {

return new Date(eventDate.getTime() - leadMinutes * 60 * 1000);

}

module.exports = { sunEvents, fireAt };