import Toybox.Lang;
import Toybox.Sensor;
import Toybox.UserProfile;

// Wraps the heart-rate sensor and maps the current bpm to a zone (1..5).
// Returns null bpm when no reading is available (e.g. simulator without data
// simulation), so the view can show a placeholder.
class HeartRateProvider {
    private var _hr as Number?;
    private var _zones as Array<Number>?;

    public function initialize() {
        _hr = null;
        _zones = null;
    }

    public function onStart() as Void {
        Sensor.setEnabledSensors([Sensor.SENSOR_HEARTRATE]);
        Sensor.enableSensorEvents(method(:onSensor));
        _zones = UserProfile.getHeartRateZones(UserProfile.HR_ZONE_SPORT_GENERIC);
    }

    public function onStop() as Void {
        Sensor.enableSensorEvents(null);
    }

    public function onSensor(info as Sensor.Info) as Void {
        _hr = info.heartRate;
    }

    public function getHeartRate() as Number? {
        return _hr;
    }

    // Returns 1..5, or 0 if HR/zones unavailable.
    public function getZone() as Number {
        if (_hr == null || _zones == null) { return 0; }
        var z = _zones as Array<Number>;
        var hr = _hr as Number;
        // _zones holds 6 boundaries: [z1lo, z2lo, z3lo, z4lo, z5lo, max]
        for (var i = z.size() - 2; i >= 0; i -= 1) {
            if (hr >= z[i]) { return i + 1 > 5 ? 5 : i + 1; }
        }
        return 1;
    }
}