From e0d8bc56235f8bf5e1653db0d3da17e5fa3a3043 Mon Sep 17 00:00:00 2001
From: Alex 'AdUser' Z <ad_user@runbox.com>
Date: Mon, 23 Jul 2018 23:15:41 +1000
Subject: [PATCH] + Subtitle::Utils : parse_timeshift()

---
 lib/Subtitle/Utils.pm | 33 +++++++++++++++++++++++++++++----
 t/utils-timing.t      | 15 ++++++++++++++-
 2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/lib/Subtitle/Utils.pm b/lib/Subtitle/Utils.pm
index 991bc64..562addc 100644
--- a/lib/Subtitle/Utils.pm
+++ b/lib/Subtitle/Utils.pm
@@ -7,13 +7,13 @@ use base 'Exporter';
 
 our @EXPORT_OK = qw(
   chomp_all strip_bom trim
-  make_timing parse_timing
+  make_timing parse_timeshift parse_timing
   round
 );
 
 our %EXPORT_TAGS = (
   string => [qw(chomp_all strip_bom trim)],
-  timing => [qw(make_timing parse_timing)],
+  timing => [qw(make_timing parse_timeshift parse_timing)],
 );
 
 ## string functions
@@ -47,11 +47,36 @@ sub make_timing {
   return ($hrs, $min, $sec, $msec);
 }
 
+# recognized format [+-][[hh:]mm:]ss[.ms]
+sub parse_timeshift {
+  my ($str) = @_;
+  my $ts = { sign => '+', hrs => 0, min => 0, sec => 0 };
+
+  return unless defined $str;
+
+  while(1) {
+    if ($str =~ s<^([+-])><>o)                     { $ts->{sign} = $1; }
+    if ($str =~ s<^([0-9](?:\.\d{1,3})?)$><>o)     { $ts->{sec}  = $1; }
+    if ($str =~ s<([0-5][0-9](?:\.\d{1,3})?)$><>o) { $ts->{sec}  = $1; }
+    if ($str =~ s<^([0-9]):$><>o)                  { $ts->{min}  = $1; }
+    if ($str =~ s<([0-5][0-9]):$><>o)              { $ts->{min}  = $1; }
+    if ($str =~ s<^(\d+):$><>o)                    { $ts->{hrs}  = $1; }
+    last;
+  };
+
+  if ($str or $ts->{min} >= 60 or $ts->{sec} >= 60.0) {
+    return; # wrong time format
+  }
+  my $time = $ts->{sec} + $ts->{min} * 60 + $ts->{hrs} * 3600;
+  $time *= -1 if $ts->{sign} eq '-';
+  return $time;
+}
+
 sub parse_timing {
   my ($str) = @_;
   my $time = 0.0;
-  return unless $str =~ m/(\d+):(\d+):(\d+)([.,])(\d+)/oi;
-  my ($hrs, $min, $sec, $delim, $msec) = ($1, $2, $3, $4, $5);
+  return unless $str =~ m/(\d+):(\d+):(\d+)[.,](\d+)/o;
+  my ($hrs, $min, $sec, $msec) = ($1, $2, $3, $4);
   if ($msec < 0 or $msec > 999) {
     return -1; # wrong mseconds part of timing
   }
diff --git a/t/utils-timing.t b/t/utils-timing.t
index 7f8a33b..46a5f6d 100644
--- a/t/utils-timing.t
+++ b/t/utils-timing.t
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 
-use Test::More tests => 11;
+use Test::More tests => 21;
 
 use Subtitle::Utils qw(:timing);
 
@@ -16,6 +16,19 @@ is(parse_timing('123:60:15.45'),   -1);
 is(parse_timing('123:11:65.45'),   -1);
 is(parse_timing('123:11:15.4500'), -1);
 
+## parse_timeshift()
+is(parse_timeshift('1'),              +1.0);
+is(parse_timeshift('-1.2'),           -1.2);
+is(parse_timeshift('+2:15'),        +135.0);
+is(parse_timeshift('+03:07.35'),    +187.35);
+is(parse_timeshift('4:05:17.312'), 14717.312);
+# invalid timecodes
+is(parse_timeshift('o.17'),    undef);
+is(parse_timeshift('-.05'),    undef);
+is(parse_timeshift('1:60'),    undef);
+is(parse_timeshift('57.4321'), undef);
+is(parse_timeshift('1:62:03'), undef);
+
 ## make_timing()
 my @ts = make_timing(8*3600 + 11*60 + 15 + 0.46);
 is($ts[0],   8);