/// <summary>
/// Reads the data from given path and deserializes it taking given expirationTime in consideration.
/// </summary>
/// <typeparam name="T">Data Type to retrieve.</typeparam>
/// <param name="path">Path to the file. Can be just filename.</param>
/// <param name="expiration">Specifies how much time could have passed since last write.</param>
/// <returns>Deserialized data or default if file does not exist or is malformed.</returns>
/// <exception cref="DataExpiredException"> Thrown when data is expired.</exception>
public async Task <T> RetrieveData <T>(string path, TimeSpan?expiration = null)
{
try
{
var json = await _fileStorageProvider.ReadTextAsync(path);
var holder = JsonConvert.DeserializeObject <TimedHolder <T> >(json);
if (expiration != null && DateTime.UtcNow - holder.CreatedAt > expiration)
{
throw new DataExpiredException($"Data stored in {path} is expired as per provided expiration time {expiration}");
}
return(holder.Value);
} // file not exists or malformed
catch (Exception e) when(!(e is DataExpiredException))
{
return(default);
