/** Notifies the backend service of a potential Covid-19 infection. */
public static async Task <HttpResponseMessage> Notify(
DateTime symptomsOnset, bool isTested, string comment)
{
// Generates the daily tracer keys that have been or will be used
// during the infectious period, based on the symptoms onset.
//
// Use median incubation and virus positive periods according to
// <https://www.atsjournals.org/doi/pdf/10.1164/rccm.202003-0524LE>
var keys = new List <Tuple <Date, DailyTracerKey> >();
{
const int INCUBATION_PERIOD = 5;
const int SYMPTOMS_TO_VIRUS_NEGATIVE = 11;
var begin = symptomsOnset.AddDays(-INCUBATION_PERIOD);
var end = symptomsOnset.AddDays(SYMPTOMS_TO_VIRUS_NEGATIVE);
var masterKey = TracerKey.CurrentAppInstance();
for (var dt = begin; dt < end; dt = dt.AddDays(1))
{
var date = new Date(dt);
var key = masterKey.DerivateDailyKey(date);
keys.Add(Tuple.Create(date, key));
}
}
// Constructs and submit the POST request.
//
// Keys are encoded as a repeated HTTP field.
var queryParams = new List <KeyValuePair <String, String> > {
new KeyValuePair <string, string>(
"is_tested", isTested ? "true" : "false"
),
new KeyValuePair <string, string>("comment", comment),
};
for (int i = 0; i < keys.Count; ++i)
{
queryParams.Add(new KeyValuePair <string, string>(
$"keys-{i}-date", keys[i].Item1.ToString()
));
queryParams.Add(new KeyValuePair <string, string>(
$"keys-{i}-value", keys[i].Item2.ToString()
));
}
var content = new FormUrlEncodedContent(queryParams.ToArray());
return(await Client.PostAsync($"{ROOT}/notify", content));
}
public TracerService(IBLEServer server_)
{
Key = TracerKey.CurrentAppInstance();
Contacts = new ContactDatabase();
server = server_;
Logger.Info(
$"TracerService instanced with key " +
$"'{Key.ToHumanReadableString()}'");
}