/// <summary>
/// Updates the local database by syncing with the server
/// </summary>
/// <returns>an awaitable task for the completion of syncing</returns>
public static async Task UpdateLocalDatabaseAsync()
{
if (App.Path != null && App.UserPath.Length > 2)
{
RealmConfiguration threadConfig = App.realmConfiguration(RosterPath);
Realm threadInstance = Realm.GetInstance(threadConfig);
List <QuizInfo> QuizInfos = new List <QuizInfo>(threadInstance.All <QuizInfo>());
if (CrossConnectivity.Current.IsConnected)
{
for (int i = 0; i < QuizInfos.Count(); i++)
{
if (CredentialManager.IsLoggedIn)
{
if (QuizInfos[i].IsDeletedLocally)
{
if (await ServerOperations.DeleteQuiz(QuizInfos[i].DBId) == OperationReturnMessage.True)
{
string toDeleteDBId = QuizInfos[i].DBId;
QuizInfos.Remove(QuizInfos[i]);
DeleteQuizInfo(toDeleteDBId);
}
}
else if (QuizInfos[i].SyncStatus != (int)SyncStatusEnum.NotDownloadedAndNeedDownload)
{
string lastModifiedDate = ServerOperations.GetLastModifiedDate(QuizInfos[i].DBId);
if (lastModifiedDate == "") // returns empty string could not reach server
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.Offline // 3 represents offline
};
EditQuizInfo(copy, threadInstance);
}
else
{
// Server returns "false" if quiz is not already on the server
if (lastModifiedDate == "false" || lastModifiedDate == null)
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.NeedUpload // 1 represents need upload
};
EditQuizInfo(copy, threadInstance);
}
else
{
DateTime localModifiedDateTime = Convert.ToDateTime(QuizInfos[i].LastModifiedDate);
DateTime serverModifiedDateTime = Convert.ToDateTime(lastModifiedDate);
if (localModifiedDateTime > serverModifiedDateTime)
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.NeedUpload // 1 represents need upload
};
EditQuizInfo(copy, threadInstance);
}
else if (localModifiedDateTime < serverModifiedDateTime)
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.NeedDownload // 0 represents needs download
};
EditQuizInfo(copy, threadInstance);
}
else if (localModifiedDateTime == serverModifiedDateTime)
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.Synced // 2 represents in sync
};
EditQuizInfo(copy, threadInstance);
}
}
}
}
}
else
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.Synced // 2 represents in sync
};
EditQuizInfo(copy, threadInstance);
}
}
string[] dbIds = new string[QuizInfos.Count];
for (int i = 0; i < dbIds.Length; i++)
{
dbIds[i] = QuizInfos[i].DBId;
}
List <string[]> missingQuizs = ServerOperations.GetMissingQuizzesByAuthorName(CredentialManager.Username, dbIds);
foreach (string[] missingQuiz in missingQuizs)
{
QuizInfo info = new QuizInfo
{
DBId = missingQuiz[0],
AuthorName = missingQuiz[1],
QuizName = missingQuiz[2],
Category = missingQuiz[3],
LastModifiedDate = missingQuiz[4],
SubscriberCount = int.Parse(missingQuiz[5]),
SyncStatus = (int)SyncStatusEnum.NotDownloadedAndNeedDownload
};
threadInstance.Write(() =>
{
threadInstance.Add(info);
});
}
}
else
{
for (int i = 0; i < QuizInfos.Count; i++)
{
QuizInfo copy = new QuizInfo(QuizInfos[i])
{
SyncStatus = (int)SyncStatusEnum.Offline // 3 represents offline
};
EditQuizInfo(copy, threadInstance);
}
}
}
}
