import Toybox.Communications;
import Toybox.Lang;

// Reverse-geocodes a lat/lon pair via Photon API. Calls back with
// a formatted address string or null on failure.
class GeocodingService {

    private var _callback as Method(address as String or Null) as Void;
    private var _lat as Float;
    private var _lon as Float;

    function initialize(lat as Float, lon as Float,
                        callback as Method(address as String or Null) as Void) {
        _callback = callback;
        _lat = lat;
        _lon = lon;
    }

    function start() as Void {
        var url = Config.PHOTON_URL;
        var params = { "lon" => _lon, "lat" => _lat, "limit" => 1 };
        var options = {
            :method => Communications.HTTP_REQUEST_METHOD_GET,
            :responseType => Communications.HTTP_RESPONSE_CONTENT_TYPE_JSON,
            :headers => { "Accept" => "application/json" }
        };
        Communications.makeWebRequest(url, params, options, method(:_onResponse));
    }

    function _onResponse(responseCode as Number, data as Dictionary or String or Null) as Void {
        if (responseCode != 200 || data == null || !(data instanceof Dictionary)) {
            _callback.invoke(null);
            return;
        }

        var features = data["features"];
        if (features == null || !(features instanceof Array) || features.size() == 0) {
            _callback.invoke(null);
            return;
        }

        var feature = features[0] as Dictionary;
        var props = feature["properties"] as Dictionary;
        var geometry = feature["geometry"] as Dictionary;

        // Haversine check: only use address if result is within threshold.
        if (geometry != null) {
            var coords = geometry["coordinates"] as Array;
            if (coords != null && coords.size() >= 2) {
                var rLon = (coords[0] as Double).toFloat();
                var rLat = (coords[1] as Double).toFloat();
                var dist = Haversine.distance(_lat, _lon, rLat, rLon);
                if (dist > Config.ADDRESS_MAX_DISTANCE_M) {
                    _callback.invoke(null);
                    return;
                }
            }
        }

        _callback.invoke(_formatAddress(props));
    }

    private function _formatAddress(props as Dictionary) as String {
        var street = props["street"];
        var number = props["housenumber"];
        var city = props["city"];

        var parts = "";
        if (street != null) {
            parts = street as String;
            if (number != null) {
                parts = parts + " " + number;
            }
        }
        if (city != null) {
            if (!parts.equals("")) {
                parts = parts + ", ";
            }
            parts = parts + city;
        }
        return parts.equals("") ? "Unbekannt" : parts;
    }
}