public static async Task DownloadFileAsync(string url, string destination)
{
var downloadFile = new DownloadFile();
// frustratingly copy pasta from wireUpEvents(IDownloadable downloadable) due to Completed being EventHandler<LibraryBook>
var downloadDialog = new DownloadForm();
downloadFile.DownloadBegin += (_, str) =>
{
downloadDialog.UpdateFilename(str);
downloadDialog.Show();
};
downloadFile.DownloadProgressChanged += (_, progress) => downloadDialog.DownloadProgressChanged(progress.BytesReceived, progress.TotalBytesToReceive);
downloadFile.DownloadCompleted += (_, __) => downloadDialog.Close();
await downloadFile.PerformDownloadFileAsync(url, destination);
}
// subscribed to Begin event because a new form should be created+processed+closed on each iteration
private static void wireUpEvents(IDownloadableProcessable downloadable)
{
#region create form
var downloadDialog = new DownloadForm();
#endregion
// extra complexity for wiring up download form:
// case 1: download is needed
// dialog created. subscribe to events
// downloadable.DownloadBegin fires. shows dialog
// downloadable.DownloadCompleted fires. closes dialog. which fires FormClosing, FormClosed, Disposed
// Disposed unsubscribe from events
// case 2: download is not needed
// dialog created. subscribe to events
// dialog is never shown nor closed
// downloadable.Completed fires. disposes dialog and unsubscribes from events
#region define how model actions will affect form behavior
void downloadBegin(object _, string str)
{
downloadDialog.UpdateFilename(str);
downloadDialog.Show();
}
// close form on DOWNLOAD completed, not final Completed. Else for BackupBook this form won't close until DECRYPT is also complete
void fileDownloadCompleted(object _, string __) => downloadDialog.Close();
void downloadProgressChanged(object _, Dinah.Core.Net.Http.DownloadProgress progress)
=> downloadDialog.DownloadProgressChanged(progress.BytesReceived, progress.TotalBytesToReceive);
void unsubscribe(object _ = null, EventArgs __ = null)
{
downloadable.DownloadBegin -= downloadBegin;
downloadable.DownloadCompleted -= fileDownloadCompleted;
downloadable.DownloadProgressChanged -= downloadProgressChanged;
downloadable.Completed -= dialogDispose;
}
// unless we dispose, if the form is created but un-used/never-shown then weird UI stuff can happen
// also, since event unsubscribe occurs on FormClosing and an unused form is never closed, then the events will never be unsubscribed
void dialogDispose(object _, object __)
{
if (!downloadDialog.IsDisposed)
{
downloadDialog.Dispose();
}
}
#endregion
#region subscribe new form to model's events
downloadable.DownloadBegin += downloadBegin;
downloadable.DownloadCompleted += fileDownloadCompleted;
downloadable.DownloadProgressChanged += downloadProgressChanged;
downloadable.Completed += dialogDispose;
#endregion
#region when form closes, unsubscribe from model's events
// unsubscribe so disposed forms aren't still trying to receive notifications
// FormClosing is more UI safe but won't fire unless the form is shown and closed
// if form was shown, Disposed will fire for FormClosing, FormClosed, and Disposed
// if not shown, it will still fire for Disposed
downloadDialog.Disposed += unsubscribe;
#endregion
}
