/// <summary>
/// Initializes a new instance of <see cref="AutoSaveTextFile{TUpdate}"/>.
/// </summary>
/// <param name="remoteState">
/// Object responsible for converting updates to text.
/// </param>
/// <param name="autoSaveFiles">
/// The <see cref="FileStreamPair"/> containing <see cref="FileStream"/>s to write to.
/// Any existing contents in the files will be overwritten.
/// <see cref="AutoSaveTextFile{TUpdate}"/> assumes ownership of the <see cref="FileStream"/>s
/// so it takes care of disposing it after use.
/// To be used as an auto-save <see cref="FileStream"/>,
/// it must support seeking, reading and writing, and not be able to time out.
/// </param>
/// <exception cref="ArgumentNullException">
/// <paramref name="remoteState"/> and/or <paramref name="autoSaveFiles"/> are null.
/// </exception>
/// <exception cref="ArgumentException">
/// One or both <see cref="FileStream"/>s in <paramref name="autoSaveFiles"/>
/// do not have the right capabilities to be used as an auto-save file stream.
/// See also: <seealso cref="CanAutoSaveTo"/>.
/// </exception>
public AutoSaveTextFile(RemoteState remoteState, FileStreamPair autoSaveFiles)
{
if (remoteState == null)
{
throw new ArgumentNullException(nameof(remoteState));
}
AutoSaveFiles = autoSaveFiles ?? throw new ArgumentNullException(nameof(autoSaveFiles));
// Assert capabilities of the file streams.
VerifyFileStream(autoSaveFiles.FileStream1, nameof(autoSaveFiles));
VerifyFileStream(autoSaveFiles.FileStream2, nameof(autoSaveFiles));
// Immediately attempt to load the saved contents from either FileStream.
// Choose first auto-save file to load from.
FileStream latestAutoSaveFile = autoSaveFiles.FileStream1.Length == 0 ? autoSaveFiles.FileStream2 : autoSaveFiles.FileStream1;
string loadedText = null;
try
{
loadedText = Load(latestAutoSaveFile);
}
catch (Exception firstLoadException)
{
// Trace and try the other auto-save file as a backup.
firstLoadException.Trace();
}
// If null is returned from the first Load(), the integrity check failed.
if (loadedText == null)
{
latestAutoSaveFile = autoSaveFiles.Different(latestAutoSaveFile);
try
{
loadedText = Load(latestAutoSaveFile);
}
catch (Exception secondLoadException)
{
secondLoadException.Trace();
}
}
// Initialize remote state with the loaded text.
// If both reads failed, loadedText == null.
remoteState.Initialize(loadedText);
// Initialize encoder and buffers.
// Always use UTF8 for auto-saved text files.
Encoding encoding = Encoding.UTF8;
encoder = encoding.GetEncoder();
buffer = new char[CharBufferSize];
encodedBuffer = new byte[encoding.GetMaxByteCount(CharBufferSize)];
// Set up long running task to keep auto-saving updates.
updateQueue = new ConcurrentQueue <TUpdate>();
cts = new CancellationTokenSource();
autoSaveBackgroundTask = Task.Run(() => AutoSaveLoop(latestAutoSaveFile, remoteState, cts.Token));
}
/// <summary>
/// Initializes a new <see cref="WorkingCopyTextFile"/> from an open <see cref="LiveTextFile"/>
/// and a <see cref="FileStreamPair"/> from which to load an <see cref="AutoSaveTextFile{TUpdate}"/> with auto-saved local changes.
/// Use this constructor for <see cref="LiveTextFile"/> instances which must remain live after this
/// <see cref="WorkingCopyTextFile"/> is disposed.
/// It is not possible to use <see cref="Replace(string)"/> on <see cref="WorkingCopyTextFile"/> instances
/// created with this method.
/// </summary>
/// <param name="openTextFile">
/// The open text file.
/// </param>
/// <param name="autoSaveFiles">
/// The <see cref="FileStreamPair"/> from which to load the auto-save file that contains local changes,
/// or null to not load from an auto-save file.
/// </param>
/// <returns>
/// The new <see cref="WorkingCopyTextFile"/>.
/// </returns>
/// <exception cref="ArgumentNullException">
/// <paramref name="openTextFile"/> is null.
/// </exception>
public static WorkingCopyTextFile FromLiveTextFile(LiveTextFile openTextFile, FileStreamPair autoSaveFiles)
=> new WorkingCopyTextFile(
/// <summary>
/// Initializes a new <see cref="WorkingCopyTextFile"/> from a file path and a <see cref="FileStreamPair"/>
/// from which to load an <see cref="AutoSaveTextFile{TUpdate}"/> with auto-saved local changes.
/// </summary>
/// <param name="path">
/// The path of the file to load and watch, or null to create a new file.
/// </param>
/// <param name="autoSaveFiles">
/// The <see cref="FileStreamPair"/> from which to load the auto-save file that contains local changes,
/// or null to not load from an auto-save file.
/// </param>
/// <exception cref="ArgumentException">
/// <paramref name="path"/> is empty, contains only whitespace, or contains invalid characters
/// (see also <seealso cref="Path.GetInvalidPathChars"/>), or is in an invalid format,
/// or is a relative path and its absolute path could not be resolved.
/// </exception>
/// <exception cref="IOException">
/// <paramref name="path"/> is longer than its maximum length (this is OS specific).
/// </exception>
/// <exception cref="System.Security.SecurityException">
/// The caller does not have sufficient permissions to read the file.
/// </exception>
/// <exception cref="NotSupportedException">
/// <paramref name="path"/> is in an invalid format.
/// </exception>
/// <returns>
/// The new <see cref="WorkingCopyTextFile"/>.
/// </returns>
public static WorkingCopyTextFile Open(string path, FileStreamPair autoSaveFiles)
=> new WorkingCopyTextFile(
path == null ? null : new LiveTextFile(path),
autoSaveFiles,
isTextFileOwner: true);
