From be8d1ea0395de818b8f3f6b8610ccdedd19fe71a Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Mon, 3 Oct 2022 18:55:41 +0200
Subject: add optional cache support

---
 lib/Travel/Status/DE/HAFAS.pm | 67 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 57 insertions(+), 10 deletions(-)

diff --git a/lib/Travel/Status/DE/HAFAS.pm b/lib/Travel/Status/DE/HAFAS.pm
index 105bf0f..2f1834c 100644
--- a/lib/Travel/Status/DE/HAFAS.pm
+++ b/lib/Travel/Status/DE/HAFAS.pm
@@ -200,6 +200,7 @@ sub new {
 	my $self = {
 		active_service => $service,
 		arrivals       => $conf{arrivals},
+		cache          => $conf{cache},
 		developer_mode => $conf{developer_mode},
 		exclusive_mots => $conf{exclusive_mots},
 		excluded_mots  => $conf{excluded_mots},
@@ -212,7 +213,6 @@ sub new {
 
 	bless( $self, $obj );
 
-	my $json = JSON->new->utf8;
 	my $date = ( $conf{datetime} // $now )->strftime('%Y%m%d');
 	my $time = ( $conf{datetime} // $now )->strftime('%H%M%S');
 
@@ -264,6 +264,14 @@ sub new {
 		%{ $hafas_instance{$service}{request} }
 	};
 
+	my $json = JSON->new->utf8;
+
+	# The JSON request is the cache key, so if we have a cache we must ensure
+	# that JSON serialization is deterministic.
+	if ( $self->{cache} ) {
+		$json->canonical;
+	}
+
 	$req = $json->encode($req);
 	$self->{post} = $req;
 
@@ -288,21 +296,18 @@ sub new {
 			say "requesting $req from $url";
 		}
 
-		my $reply = $self->{ua}->post(
-			$url,
-			'Content-Type' => 'application/json',
-			Content        => $self->{post}
-		);
-		if ( $reply->is_error ) {
-			$self->{errstr} = $reply->status_line;
+		my ( $content, $error ) = $self->post_with_cache($url);
+
+		if ($error) {
+			$self->{errstr} = $error;
 			return $self;
 		}
 
 		if ( $self->{developer_mode} ) {
-			say decode( 'utf-8', $reply->content );
+			say decode( 'utf-8', $content );
 		}
 
-		$self->{raw_json} = $json->decode( $reply->content );
+		$self->{raw_json} = $json->decode($content);
 	}
 
 	$self->check_mgate;
@@ -311,6 +316,48 @@ sub new {
 	return $self;
 }
 
+sub post_with_cache {
+	my ( $self, $url ) = @_;
+	my $cache = $self->{cache};
+
+	if ( $self->{developer_mode} ) {
+		say "GET $url";
+	}
+
+	if ($cache) {
+		my $content = $cache->thaw( $self->{post} );
+		if ($content) {
+			if ( $self->{developer_mode} ) {
+				say '  cache hit';
+			}
+			return ( ${$content}, undef );
+		}
+	}
+
+	if ( $self->{developer_mode} ) {
+		say '  cache miss';
+	}
+
+	my $ua    = $self->{user_agent};
+	my $reply = $self->{ua}->post(
+		$url,
+		'Content-Type' => 'application/json',
+		Content        => $self->{post}
+	);
+
+	if ( $reply->is_error ) {
+		return ( undef, $reply->status_line );
+	}
+	my $content = $reply->content;
+
+	if ($cache) {
+		say "freeeez";
+		$cache->freeze( $self->{post}, \$content );
+	}
+
+	return ( $content, undef );
+}
+
 sub check_mgate {
 	my ($self) = @_;
 
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