public static async Task <Tuple <List <Category>, Exception> > DownloadIdeasFromGoogleDrive()
{
try
{
var response = await client.GetAsync(AppResources.DbLink);
if (response.IsSuccessStatusCode)
{
var payload = await response.Content.ReadAsStringAsync();
onlineIdeas = JsonConvert.DeserializeObject <List <Category> >(payload);
var newideasdbResponse = await client.GetAsync(AppResources.NewIdeasDbLink);
if (newideasdbResponse.IsSuccessStatusCode)
{
newideastxt = await newideasdbResponse.Content.ReadAsStringAsync();
DBSerializer.SerializeDBAsync(Global.IDEAS_PATH, onlineIdeas);
DBSerializer.SerializeDBAsync(Global.NEWIDEASTXT_PATH, newideastxt);
return(Tuple.Create <List <Category>, Exception>(onlineIdeas, null));
}
}
// To prevent too many requests to server, only invalidate cache once when app is opening fresh from launcher
Global.LockRequests = true;
}
catch (Exception e)
{
return(Tuple.Create <List <Category>, Exception>(null, e));
}
return(null);
}
// During app launch, we check the online data with the cached data. If anything new has been added online we invalidate the cache.
private static async Task InvalidateOldData()
{
Log.Debug(TAG, "Starting full invalidation");
var notesPath = Global.NOTES_PATH;
if (!File.Exists(notesPath))
{
File.Create(notesPath);
}
var notes = await DBSerializer.DeserializeDBAsync <List <Note> >(notesPath);
notes = notes ?? new List <Note>();
// This is the code that does the actual invalidation
for (int i = 0; i < onlineIdeas.Count; i++) // Looping through categories
{
for (int j = 0; j < onlineIdeas[i].Items.Count; j++) // Looping through ideas in each category
{
var newItem = onlineIdeas[i].Items[j];
var oldItem = Global.Categories[i].Items.FirstOrDefault(x => x.Id == newItem.Id);
// We don't want to clear the user's notes for a particular idea during invalidation
Note note = null;
if (oldItem != null)
{
note = notes.FirstOrDefault(x => x.Title == oldItem.Title);
if (note != null)
{
Log.Debug(TAG, $"Note *{note.Title}*, found for old idea *{oldItem.Title}* placed at new idea *{newItem.Title}*");
}
}
newItem.Note = note;
newItem.State = oldItem?.State;
}
}
DBSerializer.SerializeDBAsync(Global.IDEAS_PATH, onlineIdeas);
DBSerializer.SerializeDBAsync(Global.NEWIDEASTXT_PATH, newideastxt);
Global.Categories = onlineIdeas;
Global.LockRequests = true;
Log.Debug(TAG, "Invalidation completed.");
}
