public void NewContact(HourlyTracerKey key, DateHour time)
{
Case matchingCase = null;
// Adds the new case to the database.
db.RunInTransaction(() => {
var exists = db.Find <Contact>(c =>
c.Key == key.Value &&
c.Year == time.Year &&
c.Month == time.Month &&
c.Day == time.Day &&
c.Hour == time.Hour
) != null;
if (!exists)
{
Logger.Info(
$"New contact: {key.ToHumanReadableString()} at {time}."
);
db.Insert(new Contact {
Key = key.Value,
Year = time.Year,
Month = time.Month,
Day = time.Day,
Hour = time.Hour
});
// Gets any matching know case
matchingCase = db.Find <Case>(ca =>
ca.Key == key.Value &&
ca.Year == time.Year &&
ca.Month == time.Month &&
ca.Day == time.Day
);
}
});
// Classifies the newly added case
if (matchingCase != null)
{
lock (Matches) {
if (matchingCase.Type == "positive")
{
Matches.Positives.Add(time);
}
else
{
Matches.Symptomatics.Add(time);
}
}
MatchesChange?.Invoke(this, Matches);
CurrentInfectionStatusChange?.Invoke(
this, CurrentInfectionStatus);
}
}
/** Returns the current tracer key that should be sent over BLE. */
protected byte[] HandleReadCharacteristic()
{
var now = DateHour.Now;
// TODO key generation could be cached instead of being recomputed
// at every characteristic read.
HourlyTracerKey currentKey = Key
.DerivateDailyKey(now.AsDate())
.DerivateHourlyKey(now);
Logger.Info($"BLE characteristic read request.");
return(currentKey.Value);
}
/** Record a new device contact that happens at the moment. */
public void NewContact(HourlyTracerKey key)
{
NewContact(key, DateHour.Now);
}
/** Processes a discovery response of a Bluetooth device.
*
* Adds the device to the persistent data-store when required.
*
* Returns `false` if the discovery failed with a Bluetooth exception.
*/
protected async Task <bool> DiscoverDevice(
IAdapter adapter, IDevice device)
{
var deviceIdStr = FormatDeviceId(device.Id);
Logger.Info(
$"Discovering BLE device: " +
$"{deviceIdStr}/{device.Name} ({device.Rssi} dBm)"
);
// Cancellation token that will abort the discovery process after
// DEVICE_CONNECT_TIMEOUT.
var tokenSource = new CancellationTokenSource();
tokenSource.CancelAfter(DEVICE_CONNECT_TIMEOUT);
var token = tokenSource.Token;
try {
// Retrives the CovidTracerID from the BLE characteristic.
if (device.State != DeviceState.Connected)
{
var connectParams = new ConnectParameters(
/* autoConnect = */ false,
/* forceBleTransport = */ true);
await adapter.ConnectToDeviceAsync(
device, connectParams, token);
}
if (device.State != DeviceState.Connected)
{
Logger.Error($"Failed to connect to {deviceIdStr}");
return(false);
}
var service = await device.GetServiceAsync(SERVICE_NAME, token);
if (service == null)
{
Logger.Info(
$"Device {deviceIdStr} does not have CovidTracer " +
"service");
return(true);
}
var characteristic =
await service.GetCharacteristicAsync(CHARACTERISTIC_NAME);
if (characteristic == null)
{
Logger.Error(
$"Device {deviceIdStr} does not support CovidTracer " +
"characteristic.");
return(false);
}
var keyBytes = await characteristic.ReadAsync(token);
if (keyBytes == null)
{
Logger.Error(
$"Device {deviceIdStr} characteristic can not be read."
);
return(false);
}
var key = new HourlyTracerKey(keyBytes);
// Logs the successful encounter
Contacts.NewContact(key);
return(true);
} catch (Exception e) {
Logger.Error($"Bluetooth exception: '{e.Message}'.");
return(false);
} finally {
tokenSource.Dispose();
device.Dispose();
};
}
