public async Task <IActionResult> OnPostAsync(Guid id, CancellationToken cancellationToken)
{
EnsureArg.IsNotEmpty(id, nameof(id));
var f = await this.fileService.GetPostFile(id, cancellationToken);
return(await f.Match(async some =>
{
var hash = ImageHasher.Hash(some.Data);
await fileService.BanImage(hash, Reason, cancellationToken);
return this.RedirectToPage <IndexModel>().ToIAR();
}, () => this.NotFound().ToIART()));
}