/// <summary>
/// Returns a Json serialized list of Person (user) that only specifies username.
/// </summary>
/// <returns>Json list of Person</returns>
public ActionResult GetPersons()
{
using (DataContext context = new DataContext())
{
return Content ( JsonConvert.SerializeObject(context.Persons.ToList().Select(x=> new Person() { Username = x.Username })));
}
}
/// <summary>
/// Renews a LoginSession and replaces an already existing session.
/// </summary>
/// <param name="context">DataContext</param>
/// <param name="session">LoginSession</param>
/// <param name="person">Person (user)</param>
/// <returns>LoginSession</returns>
public static LoginSession RenewSession(DataContext context,LoginSession session,Person person)
{
session = new LoginSession (Guid.NewGuid ().ToString (), DateTime.Now);
if (person.LoginSession != null)
context.LoginSessions.Remove (person.LoginSession);
person.LoginSession = session;
context.SaveChanges();
return session;
}
/// <summary>
/// Validates a string token representing a LoginSession. Will keep the LoginSession up to date if it's valid.
/// </summary>
/// <param name="context">DateContext</param>
/// <param name="token">String token</param>
/// <returns>bool valid</returns>
public static bool ValidateLoginSession(DataContext context,string token)
{
Person person = context.Persons.FirstOrDefault (x => x.LoginSessionToken != null && x.LoginSessionToken == token);
int loginLifetimeMs = Convert.ToInt32(WebConfigurationManager.AppSettings["LoginLifetimeMs"]);
if (person == null)
return false;
if (DateTime.Now - person.LoginSession.LastUpdatedDateTime > new TimeSpan (0, 0, 0, 0, loginLifetimeMs)) {
context.LoginSessions.Remove (person.LoginSession);
person.LoginSession = null;
context.SaveChanges ();
return false;
}
return true;
}
public ActionResult CreateNewStatement(TrustLessModelLib.Statement statement)
{
using (DataContext context = new DataContext())
{
if (!PersonController.ValidateLoginSession(context,statement.Person.LoginSession.Token))
return new HttpStatusCodeResult((int)HttpStatusCode.Forbidden);
var match =
context.Statements.FirstOrDefault(x => x.MedicinOne == statement.MedicinOne && x.MedicinTwo == statement.MedicinTwo);
//Does a statement already exists with the same two medicins.
if (match != null) // && IsStatementValid(context,match)
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
//Security: Don't allow user to specify the person who created the statement. Set it to the current user logged in.
statement.Person =
context.Persons.FirstOrDefault(x => x.Username == statement.Person.Username);
//If the person does not exist, abort.
if (statement.Person == null)
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
//Rule: refuse a user with zero trust from creating statements.
if (CalculateBayesianModelTrust(statement.Person) == 0)
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
context.Statements.Add(statement);
//Add recommendation from user
var recommendation = new TrustLessModelLib.Recommendation(){ Person = statement.Person, Statement = statement, IsRecommended = true, Transaction = null, Description = statement.Description, CreationDate = DateTime.Now};
//This will fail if a racecondition was to add two recommendations (given that our key assignment of the table ensures only one of the same recommendation exist).
context.Recommendations.Add (recommendation);
context.SaveChanges ();
BlockChain.MakeRecommendation (context, recommendation);
return new HttpStatusCodeResult((int)HttpStatusCode.Created);
}
}
public ActionResult Login(Person person)
{
using (DataContext context = new DataContext())
{
var match =
context.Persons.FirstOrDefault(x => x.PublicKey == person.PublicKey &&x.Username == person.Username && x.Password == person.Password);
if (match == null) {
if (!CreateNewPerson (person))
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
match =
context.Persons.FirstOrDefault(x => x.PublicKey == person.PublicKey &&x.Username == person.Username && x.Password == person.Password);
}
if (match.LoginSession != null)
return Content ( JsonConvert.SerializeObject(RenewSession(context,match.LoginSession,match)));
match.LoginSession = RenewSession(context,null,match);
context.SaveChanges();
return Content ( JsonConvert.SerializeObject(match.LoginSession));
}
}
/// <summary>
/// Refreshes a LoginSession such that the login token won't expire.
/// </summary>
/// <param name="context">DataContext</param>
/// <param name="session">LoginSession</param>
public static void UpdateLoginSession(DataContext context,LoginSession session)
{
session.LastUpdatedDateTime = DateTime.Now;
context.SaveChanges();
}
/// <summary>
/// Creates a new user and returns a boolean (success).
/// </summary>
/// <param name="person">Person</param>
/// <returns>Success boolean</returns>
private bool CreateNewPerson(Person person)
{
using (DataContext context = new DataContext())
{
var match =
context.Persons.FirstOrDefault(x => x.PublicKey == person.PublicKey);
if (match != null)
return false;
if (String.IsNullOrEmpty(person.PublicKey) || String.IsNullOrEmpty(person.Username) || String.IsNullOrEmpty(person.Password))
return false;
person.LoginSession = null;
context.Persons.Add(person);
context.SaveChanges();
BlockChain.ImportPublicKeyToWallet (person);
return true;
}
}
/// <summary>
/// Reserves/locks away one S and F asset and sets the recommendation to reference these assets.
/// </summary>
/// <param name="db">DataContext</param>
/// <param name="recommendation">Recommendation</param>
public static void MakeRecommendation(DataContext db, TrustLessModelLib.Recommendation recommendation)
{
string chainName = WebConfigurationManager.AppSettings["ChainName"];
string nodeIp = WebConfigurationManager.AppSettings["NodeIp"];
MultiChainClient client = new MultiChainClient(chainName,nodeIp);
Dictionary<string,int> dictionary = new Dictionary<string, int>();
AddressBalance[] addressBalances = client.GetTotalBalances ().Balances;
var lastFasset = addressBalances.OrderBy (x => x.name).LastOrDefault (x => x.name.StartsWith ("F_"));
var lastSasset = addressBalances.OrderBy (x => x.name).LastOrDefault (x => x.name.StartsWith ("S_"));
if (lastFasset == null || lastSasset == null) {
GenerateFunds (client);
MakeRecommendation (db, recommendation);
return;
}
string lastF = lastFasset.name;
string lastS = lastSasset.name;
dictionary.Add(lastF,1);
dictionary.Add(lastS,1);
try
{
var resp = client.PrepareLockUnspent(dictionary);
recommendation.Transaction = new ReservedTransaction()
{
Tx = resp.txid,
Vout = resp.vout
};
}
catch {
//Insurficient funds
GenerateFunds(client);
MakeRecommendation (db, recommendation);
return;
}
db.SaveChanges ();
}
/// <summary>
/// Gets the recommendations for a given statement.
/// </summary>
/// <param name="statement">int id of statement</param>
/// <returns>Json list of recommendations</returns>
public ActionResult GetRecommendations(int statement)
{
using (DataContext context = new DataContext())
{
var recommendations = context.Recommendations.Include("Person").Where (x => x.StatementId == statement).ToList ();
recommendations.ForEach(x => x.Person.Reputation = CalculateBayesianModelTrust(x.Person));
return Content ( JsonConvert.SerializeObject(recommendations));
}
}
/// <summary>
/// Rewards users that have made a correct recommendation with an S asset and punishes users
/// who were wrong in their recommendation.
/// </summary>
/// <param name="context">DataContext</param>
/// <param name="statement">Statement</param>
private void IssueTrustForStatement(DataContext context,TrustLessModelLib.Statement statement)
{
var recommendations =
context.Recommendations.Include("Person").Include("Transaction").Where(x => x.StatementId== statement.Id && x.Transaction != null).ToList();
int sAmount = recommendations.Count (x => x.IsRecommended) +1;
int fAmount = recommendations.Count (x => !x.IsRecommended);
foreach (Recommendation recommendation in recommendations) {
if (sAmount >= fAmount) {
if (recommendation.IsRecommended) {
BlockChain.Issue (recommendation,true);
} else {
BlockChain.Issue (recommendation,false);
}
} else {
if (recommendation.IsRecommended) {
BlockChain.Issue (recommendation,false);
} else {
BlockChain.Issue (recommendation,true);
}
}
}
}
/// <summary>
/// Returns a boolean clarifying that a statement is complete.
/// </summary>
/// <param name="context"></param>
/// <param name="statement"></param>
/// <returns></returns>
private bool IsStatementRecommendationsComplete(DataContext context,TrustLessModelLib.Statement statement)
{
var recommendationAmount =
context.Recommendations.Count(x => x.StatementId== statement.Id && x.Transaction != null);
int maxVotings = Convert.ToInt32(WebConfigurationManager.AppSettings["MaxVotings"]);
return recommendationAmount >= maxVotings;
}
/// <summary>
/// Searches for a completed statement (recommendations complete) that fits medicineOne taken with medicineTwo parameter.
/// </summary>
/// <param name="medicinOne">String name</param>
/// <param name="medicinTwo">String name</param>
/// <returns>Statement</returns>
public ActionResult SearchStatement(string medicinOne, string medicinTwo)
{
using (DataContext context = new DataContext())
{
int maxVotings = Convert.ToInt32(WebConfigurationManager.AppSettings["MaxVotings"]);
return Content ( JsonConvert.SerializeObject(
context.Statements.Include("Person").Where (x => x.MedicinOne == medicinOne && x.MedicinTwo == medicinTwo &&
context.Recommendations.Count (y => y.StatementId == x.Id) >= maxVotings &&
context.Recommendations.Count (y => y.StatementId == x.Id && y.IsRecommended) >= maxVotings / 2).ToList()));
}
}
public ActionResult Recommend(int statement, string token, bool trust)
{
var possibleStatements = GetStatements (token);
if(possibleStatements.GetType() != typeof(ContentResult))
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
if (!JsonConvert.DeserializeObject<List<Statement>>(((ContentResult)possibleStatements).Content, new JsonSerializerSettings{
MissingMemberHandling = MissingMemberHandling.Ignore
}).Any(x => x.Id == statement))
return new HttpStatusCodeResult((int)HttpStatusCode.Forbidden);
Stream req = Request.InputStream;
req.Seek (0, System.IO.SeekOrigin.Begin);
string description = new StreamReader(req).ReadToEnd();
using (DataContext context = new DataContext())
{
if (!PersonController.ValidateLoginSession(context,token))
return new HttpStatusCodeResult((int)HttpStatusCode.Forbidden);
Person person = context.Persons.FirstOrDefault (x => x.LoginSessionToken != null && x.LoginSessionToken == token);
var statementObject =
context.Statements.FirstOrDefault(x => x.Id == statement);
if (statementObject == null)
return new HttpStatusCodeResult((int)HttpStatusCode.NotFound);
var recommendation =
context.Recommendations.FirstOrDefault(x => x.StatementId== statement && x.PersonUsername == person.Username);
if (recommendation != null)
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
if (IsStatementRecommendationsComplete (context, statementObject))
return new HttpStatusCodeResult((int)HttpStatusCode.Forbidden);
recommendation = new TrustLessModelLib.Recommendation(){ Person = person, Statement = statementObject, IsRecommended = trust, Transaction = null, Description = description, CreationDate = DateTime.Now};
lock (recommendationLock)
{
if (IsStatementRecommendationsComplete(context, statementObject))
return new HttpStatusCodeResult((int)HttpStatusCode.BadRequest);
//This will fail if a racecondition was to add two recommendations (given that our key assignment of the table ensures only one of the same recommendation exist).
context.Recommendations.Add(recommendation);
//Race condition is not possible after the next line of code, only one will succeed in adding the row below from the same user.
context.SaveChanges();
}
BlockChain.MakeRecommendation(context, recommendation);
if (IsStatementRecommendationsComplete (context, statementObject))
IssueTrustForStatement (context, statementObject);
return new HttpStatusCodeResult((int)HttpStatusCode.Created);
}
}
/// <summary>
/// Gets a Json list of statements that the current user can recommend.
/// </summary>
/// <param name="token">String token</param>
/// <returns>Json list of Statement</returns>
public ActionResult GetStatements(string token)
{
using (DataContext context = new DataContext())
{
if (!PersonController.ValidateLoginSession (context, token)) {
return new HttpStatusCodeResult((int)HttpStatusCode.Forbidden);
}
Person person = context.Persons.FirstOrDefault (x => x.LoginSessionToken != null && x.LoginSessionToken == token);
int maxVotings = Convert.ToInt32(WebConfigurationManager.AppSettings["MaxVotings"]);
double initialTrust = Convert.ToDouble(WebConfigurationManager.AppSettings["InitialTrust"]);
int maxStatementsForVoting = Convert.ToInt32(WebConfigurationManager.AppSettings["MaxStatementsForVoting"]);
var statements = context.Statements.Include ("Person").Where (x => x.Person.Username != person.Username && context.Recommendations.Count (y => y.StatementId == x.Id) < maxVotings &&
!context.Recommendations.Any (y => y.PersonUsername == person.Username && y.StatementId == x.Id));
if (CalculateBayesianModelTrust (person) <= initialTrust) {
// List<Statement> finalStatement = new List<Statement> ();
// foreach (Statement statement in statements) {
// var people =
// context.Persons.Where(x =>
// //Haven't voted on the statement
// x.Username != person.Username && !context.Recommendations.Any (y => y.PersonUsername == person.Username && y.StatementId == statement.Id)
// //Has made a statement that is correct.
// && context.Statements.Any (y=> context.Recommendations.Count(z => z.StatementId == y.Id) == maxVotings && ((y.Person.Username == x.Username && context.Recommendations.Count(z => z.StatementId == y.Id && z.IsRecommended) >= maxVotings / 2) ||
// //Contains a recommendation that is correct with the outcome
// (context.Recommendations.Any (z => z.PersonUsername == person.Username && z.StatementId == y.Id
// && context.Recommendations.Count(a => a.StatementId == z.StatementId && z.IsRecommended == a.IsRecommended) >= maxVotings / 2))))).ToList();
//
// people.RemoveAll (x => CalculateBayesianModelTrust (x) <= initialTrust);
// if (!people.Any ())
// finalStatement.Add (statement);
// }
// return Content ( JsonConvert.SerializeObject(finalStatement));
var dt = DateTime.Now ;
dt.AddDays (-8);
if (context.Recommendations.Any(x => x.CreationDate > dt && x.PersonUsername == person.Username))
return Content ("[]");
string newId = Guid.NewGuid ().ToString();
return Content ( JsonConvert.SerializeObject( statements.OrderBy(r => newId).Take(maxStatementsForVoting).ToList ()));
}
return Content ( JsonConvert.SerializeObject( statements.ToList ()));
}
}
