/// <summary>
/// Initializes a new instance of the <see cref="DataObservable" /> class.
/// </summary>
/// <param name="filename">The filename to be scanned.</param>
/// <param name="settings">The application user settings.</param>
/// <param name="traceSource">The trace source.</param>
/// <exception cref="System.ArgumentNullException">
/// settings
/// or
/// traceSource
/// </exception>
internal DataObservable(string filename, ITextReaderProtocolParameters settings, ITraceSource traceSource)
{
m_Settings = settings ?? throw new ArgumentNullException(nameof(settings));
TraceSource = traceSource ?? throw new ArgumentNullException(nameof(traceSource));
m_FileFullPath = Path.GetFullPath(filename);
string _path = Path.GetDirectoryName(m_FileFullPath);
string _fileName = Path.GetFileName(m_FileFullPath);
m_FileSystemWatcher = new FileSystemWatcher(_path, _fileName)
{
IncludeSubdirectories = false, EnableRaisingEvents = true, NotifyFilter = NotifyFilters.LastWrite
};
m_DataEntityObservable = Observable
.FromEventPattern <FileSystemEventHandler, FileSystemEventArgs>(x => m_FileSystemWatcher.Changed += x, y => m_FileSystemWatcher.Changed -= y)
.Buffer <EventPattern <FileSystemEventArgs> >(TimeSpan.FromMilliseconds(settings.DelayFileScan))
.Where <IList <EventPattern <FileSystemEventArgs> > >(_list => _list.Count > 0)
.Select <IList <EventPattern <FileSystemEventArgs> >, FileSystemEventPattern>(x => new FileSystemEventPattern(x[x.Count - 1]))
.Delay <FileSystemEventPattern>(TimeSpan.FromMilliseconds(settings.DelayFileScan))
.Select <FileSystemEventPattern, IDataEntity>(x => DataEntity.ReadFile(x.EventPattern.EventArgs.FullPath, x.TimeStamp, m_Settings.ColumnSeparator))
.Do <IDataEntity>(data => { }, exception => LogException(exception));
TraceSource.TraceMessage(TraceEventType.Verbose, 107, $"Successfully created data observer for the file {filename} with parameters {settings}");
}
