import { getTimes } from "/vendor/suncalc/suncalc.js";

// A Locus Pro-style toolbar readout: DMS coordinates (plain decimal degrees
// read less like a "GPS unit" and are harder to scan at a glance) plus
// sunrise/sunset and a countdown to whichever comes next — both computed
// for the map's current center, the same point the coordinates already
// describe, not a GNSS fix (this app's coordinate readout was never tied
// to having one).

function toDMS(value, positiveLabel, negativeLabel) {
  const label = value >= 0 ? positiveLabel : negativeLabel;
  const abs = Math.abs(value);
  const degrees = Math.floor(abs);
  const minutesFull = (abs - degrees) * 60;
  let minutes = Math.floor(minutesFull);
  let seconds = Math.round((minutesFull - minutes) * 60);
  // A seconds value that rounds up to 60 has to carry into minutes (and
  // from there, in the rare case, into degrees) rather than print "60".
  if (seconds === 60) {
    seconds = 0;
    minutes += 1;
  }
  const carriedDegrees = minutes === 60 ? degrees + 1 : degrees;
  const carriedMinutes = minutes === 60 ? 0 : minutes;
  return `${carriedDegrees}°${String(carriedMinutes).padStart(2, "0")}'${String(seconds).padStart(2, "0")}"${label}`;
}

export function formatCoords(lat, lng) {
  return `${toDMS(lat, "N", "S")} ${toDMS(lng, "E", "W")}`;
}

function formatTime(date) {
  return `${String(date.getHours()).padStart(2, "0")}:${String(date.getMinutes()).padStart(2, "0")}`;
}

function formatCountdown(ms) {
  const totalMinutes = Math.max(0, Math.round(ms / 60000));
  const hours = Math.floor(totalMinutes / 60);
  const minutes = totalMinutes % 60;
  return hours > 0 ? `${hours}h ${minutes}m` : `${minutes}m`;
}

const DAY_MS = 24 * 60 * 60 * 1000;

// null when there's no sunrise/sunset to show at all — getTimes returns
// null (not Invalid Date) for both on a polar day/night, per its own
// comment in suncalc.js — the caller just hides the readout in that case
// rather than showing something misleading.
export function formatSunInfo(lat, lng, now = new Date()) {
  const today = getTimes(now, lat, lng);
  if (today.sunrise === null || today.sunset === null) return null;

  let next;
  if (now < today.sunrise) {
    next = { label: "sunrise", at: today.sunrise };
  } else if (now < today.sunset) {
    next = { label: "sunset", at: today.sunset };
  } else {
    // Already past today's sunset — the next event is tomorrow's sunrise.
    const tomorrow = getTimes(new Date(now.getTime() + DAY_MS), lat, lng);
    next = tomorrow.sunrise === null ? null : { label: "sunrise", at: tomorrow.sunrise };
  }

  const countdown = next ? ` · ${formatCountdown(next.at - now)} to ${next.label}` : "";
  return `${formatTime(today.sunrise)}–${formatTime(today.sunset)}${countdown}`;
}