Tweaks to the file manager make archive page.

If the chose archvie file exists, then don't blindly overwrite it.  Add
a checkbox to that allows the user to select to overwrite the file.
Only replace the existing archive file if that checkbox is checked.
Otherwise show a message that the file exists, and don't overwrite.

If a single file is selected (or single directory initially selected)
then use that filename (without extension) for a default for the archive
name.

lib/WeBWorK/ContentGenerator/Instructor/FileManager.pm

@@ -371,10 +371,18 @@ sub MakeArchive ($c) {
 			return $c->include('ContentGenerator/Instructor/FileManager/archive', dir => $dir, files => \@files);
 		}
 
-		my $archive = $c->param('archive_filename');
+		my $archive = $c->param('archive_filename') . '.' . $c->param('archive_type');
+
+		if (-e "$dir/$archive" && !$c->param('overwrite')) {
+			$c->addbadmessage($c->maketext(
+				'The file [_1] exists. Check "Overwrite existing archive" to force this file to be replaced.',
+				$archive
+			));
+			return $c->include('ContentGenerator/Instructor/FileManager/archive', dir => $dir, files => \@files);
+		}
+
 		my ($error, $ok);
 		if ($c->param('archive_type') eq 'zip') {
-			$archive .= '.zip';
 			if (my $zip = Archive::Zip::SimpleZip->new("$dir/$archive")) {
 				for (@files) {
 					$zip->add("$dir/$_", Name => $_, storelinks => 1);
@@ -383,7 +391,6 @@ sub MakeArchive ($c) {
 			}
 			$error = $SimpleZipError unless $ok;
 		} else {
-			$archive .= '.tgz';
 			my $tar = Archive::Tar->new;
 			$tar->add_files(map {"$dir/$_"} @files);
 			# Make file names in the archive relative to the current working directory.

templates/ContentGenerator/Instructor/FileManager/archive.html.ep

@@ -1,6 +1,6 @@
 % use Mojo::File qw(path);
 %
-<div class="card mx-auto" style="max-width:700px">
+<div class="card mx-auto mb-2" style="max-width:700px">
 	<div class="card-body">
 		<div class="mb-3">
 			<b><%= maketext('The following files have been selected for archiving.  Select the type '
@@ -10,7 +10,7 @@
 			<div class="col-12">
 				<div class="input-group input-group-sm mb-2">
 					<span class="input-group-text"><%= maketext('Archive Filename') %>:</span>
-					<%= text_field archive_filename => '',
+					<%= text_field archive_filename => @$files == 1 ? $files->[0] =~ s/\..*$//r : '',
 						'aria-labelledby' => 'archive_filename', placeholder => maketext('Archive Filename'),
 						class => 'form-control', size => 30 =%>
 					<span class="input-group-text" id="filename_suffix">.zip</span>
@@ -32,6 +32,18 @@
 				</div>
 			</div>
 		</div>
+		<div class="row">
+			<div class="col-md-12">
+				<div class="input-group input-group-sm mb-2">
+					<div class="input-group-text flex-grow-1">
+						<label class="form-check-label">
+							<%= check_box overwrite => 1, class => 'form-check-input me-2' =%>
+							<%= maketext('Overwrite existing archive') =%>
+						</label>
+					</div>
+				</div>
+			</div>
+		</div>
 		<div class="row mb-2">
 			<div class="col-12">
 				<button type="button" class="btn btn-sm btn-secondary" id="select-all-files-button">
@@ -49,7 +61,7 @@
 		% }
 		%
 		% # Select all files initially. Even those that are in previously selected directories or subdirectories.
-		% param('files', \@files_to_compress);
+		% param('files', \@files_to_compress) unless param('confirmed');
 		<%= select_field files => \@files_to_compress, id => 'archive-files', class => 'form-select mb-2',
 			size => 20, multiple => undef =%>
 		%