const SONAR_DURATION = 5;


function computeLatDistanceInKm (dest, orig) {

	// Approximation française
	return ((dest - orig) * 111);
}

function computeLonDistanceInKm (dest, orig) {

	// Approximation française
	return ((dest - orig) * 79);
}

function computeDelay (latDistanceKm, lonDistanceKm, sonarDuration) {

	placeDirection = Math.atan(latDistanceKm / lonDistanceKm);
	placeWay = lonDistanceKm < 0 ? -1 : 1;
	placeAngle = placeDirection * placeWay;

	unsignedAngle = placeAngle + (2 * Math.PI);

	animOrigAngle = 3 * Math.PI / 2;
	animAngle_verbose = animOrigAngle + unsignedAngle;
	animAngle_bounded = fmod(animAngle_verbose, (2 * Math.PI));

	circleRatio = animAngle_bounded / (2 * Math.PI);
	delay = circleRatio * sonarDuration;

	return delay;
}

var places = document.getElementsByClassName('place');
var map = document.getElementById('map');
var origLat = map.getAttribute('data-orig-lat');
var origLon = map.getAttribute('data-orig-lon');

for (place of places) {

	if ( !( (placeLat == origLat) && (placeLon == origLon) ) ) {

		var placeLat = place.getAttribute("data-place-lat");
		var placeLon = place.getAttribute("data-place-lon");

		var latDistanceKm = computeLatDistanceInKm(placeLat, origLat);
		var lonDistanceKm = computeLonDistanceInKm(placeLon, origLon);

		var delay = computeDelay(latDistanceKm, lonDistanceKm, SONAR_DURATION);

		place.style.animationDelay = delay + 's';
		
		console.log('delay JS : ' + delay);
	}
}