api: implement /media endpoint

Returns a paged collection of all media entries. Will be used for the
main page in a follow-up commit.

lib/PoorBooru/API/V0.pm

@@ -5,7 +5,6 @@ use Dancer2::Plugin::DBIC;
 our $VERSION = v0;
 
 set serializer => "JSON";
-set database   => "db/booru.db";
 
 use constant {
 	ROUTES => [
@@ -19,8 +18,15 @@ use constant {
 	],
 
 	DEFAULT_CONTENT_TYPE => "application/json",
+	ROWS_PER_PAGE        => 20,
 };
 
+sub surrounding_pages ($)
+{
+	my $pager = $_[0]->pager;
+	return $pager->previous_page, $pager->next_page;
+}
+
 get "/meta" => sub {
 	return ROUTES;
 };
@@ -77,6 +83,24 @@ get "/tag/:tag_id_or_name" => sub {
 	};
 };
 
+get "/media" => sub {
+	my $page = query_parameters->get("page") // 1;
+	send_error("Invalide page number", 400) if $page !~ /^[1-9][0-9]*$/;
+
+	my $paged_media = schema("default")->resultset("Media")
+	    ->search({}, { order_by => "upload_date", rows => ROWS_PER_PAGE })
+	    ->page($page);
+
+	my ($prev, $next) = surrounding_pages($paged_media);
+	my @media = map { "/media/" . $_->media_id } $paged_media->all;
+
+	return {
+		next => ($next and "/media?page=$next"),
+		prev => ($prev and "/media?page=$prev"),
+		media => \@media,
+	};
+};
+
 get "/media/:media_id" => sub {
 	my $media = schema("default")->resultset("Media")
 	    ->single({ media_id => route_parameters->get("media_id") });