/// <summary>
/// Loads the list of flashcards from the user's app data directory
/// </summary>
private void LoadCards()
{
try
{
//attempts to load every file in the card directory
foreach (string name in Directory.EnumerateFiles(CARD_DIR))
{
//if a flashcard can be loaded
if (Flashcard.TryLoad(Path.GetFileName(name), out Flashcard card))
{
//add it to the list
Cards.Add(Path.GetFileName(name), card);
}
else
{
//otherwise, delete the file
if (File.Exists(name))
{
File.Delete(name);
}
}
}
}
catch (DirectoryNotFoundException)
{
//if the directory doesn't exist, create it
Directory.CreateDirectory(CARD_DIR);
}
}
/// <summary>
/// Attempts to load a flashcard from the given path
/// </summary>
/// <param name="filepath">The path from which to load a flashcard</param>
/// <param name="card">The loaded flashcard</param>
/// <returns>Whether the operation was successful</returns>
public static bool TryLoad(string filename, out Flashcard card)
{
//sets the output in case of early exit
card = null;
//navigates to the card directory
string filepath = Path.Combine(FLERForm.CARD_DIR, filename);
if (!File.Exists(filepath))
{
return(false); //if the file doesn't exist, the load fails
}
using FileStream stream = File.OpenRead(filepath); //the file to be read
if (!VerifyChecksum(stream))
{
return(false); //if it doesn't have a valid checksum, the load fails
}
using MemoryStream copy = new MemoryStream(); //a copy of the data without the 96-checksum
//cuts off the last 96 bits
stream.Position = 0;
stream.CopyTo(copy, (int)stream.Length - 12);
copy.Position = 0;
using GZipStream deflate = new GZipStream(copy, CompressionMode.Decompress); //a gzip decompression stream
using StreamReader sr = new StreamReader(deflate, Encoding.UTF8); //a string reader to get the json data
try
{
//parse the json data and set the output
card = JsonConvert.DeserializeObject <Flashcard>(sr.ReadToEnd());
//if either face doesn't exist, the load fails
if (card.Visible == null || card.Hidden == null)
{
card = null;
}
//sets the filename from which the flashcard was loaded
card.Filename = filename;
return(card != null); //returns whether the load was successful
}
catch (Exception)
{
return(false); //if any errors occurred, the load fails
}
}