From 002a35427296f3d506261a87f6ef35364a974e84 Mon Sep 17 00:00:00 2001
From: senator <senator@dcc99617-32d9-48b4-a31d-7c20da2025e4>
Date: Wed, 12 Jan 2011 00:24:51 +0000
Subject: [PATCH] Serials: Fix a problem with chronology prediction when
 there's a subfield $y in a caption/pattern with a weekly chronology code

Illustrative 853 tag:
 $2$0$8$1$a$v.$b$no.$u$50$v$r$i$(year)$j$(month)$k$(day)$w$w$x$01$y$ow1198,1204
Holding (863) tag:
 $4$1$8$1$a$1$b$39$i$2011$j$09$k$26$x$AUTOGEN

Before this commit, you get a run of predictions that look like this:
v.1:no.40(2011:Oct.03)
v.1:no.41(2011:Oct.10)
v.1:no.42(2011:Oct.17)
v.1:no.43(2011:Oct.24)
v.1:no.44(2011:Oct.31)
v.1:no.45(2011:Nov.07)
v.1:no.46(2011:Nov.21)
v.1:no.47(2011:Nov.28)
v.1:no.48(2011:Dec.05)
v.1:no.49(2011:Dec.12)
v.1:no.50(2011:Dec.26)
v.2:no.1(2012:Jan.02)

Which I'm pretty sure is wrong.  The next-to-last week in November should have
been skipped, and the fourth week in December should have been skipped.  I think
the week number should be defined in terms of the day of the week on which this
weekly serial is published, so fourth week means fourth Monday in this case (?).

With this commit, you get a run of predictions that look like:
v.1:no.40(2011:Oct.03)
v.1:no.41(2011:Oct.10)
v.1:no.42(2011:Oct.17)
v.1:no.43(2011:Oct.24)
v.1:no.44(2011:Oct.31)
v.1:no.45(2011:Nov.07)
v.1:no.46(2011:Nov.14)
v.1:no.47(2011:Nov.28)
v.1:no.48(2011:Dec.05)
v.1:no.49(2011:Dec.12)
v.1:no.50(2011:Dec.19)
v.2:no.1(2012:Jan.02)

Which seems correct to me. I'm going to consult with others before backporting
this to rel_2_0, however.


git-svn-id: svn://svn.open-ils.org/ILS/trunk@19162 dcc99617-32d9-48b4-a31d-7c20da2025e4
---
 Open-ILS/src/perlmods/OpenILS/Utils/MFHD/Date.pm | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/Open-ILS/src/perlmods/OpenILS/Utils/MFHD/Date.pm b/Open-ILS/src/perlmods/OpenILS/Utils/MFHD/Date.pm
index 34c85d9691..1a1f4cdab1 100644
--- a/Open-ILS/src/perlmods/OpenILS/Utils/MFHD/Date.pm
+++ b/Open-ILS/src/perlmods/OpenILS/Utils/MFHD/Date.pm
@@ -167,7 +167,7 @@ sub nth_week_of_month {
         );
     } else {
         # count backwards
-        $nth_day->subtract(days => ($day - $dow + 7) % 7);
+        $nth_day->subtract(days => ($dow - $day + 7) % 7);
 
         # 99: last week of month, 98: second last, etc.
         for (my $i = 99 - $week; $i > 0; $i--) {
@@ -196,15 +196,10 @@ sub check_date {
     if (!defined $day) {
         # MMWW
         return (
-            ($dt->month == $month)
-              && (
-                ($dt->week_of_month == $weekno)
-                || (
-                    $weekno >= 97
-                    && ($dt->week_of_month ==
-                        nth_week_of_month($dt, $weekno, $day)->week_of_month)
-                )
-              )
+            ($dt->month == $month) && (
+                $dt->week_of_month ==
+                    nth_week_of_month($dt, $weekno, $day)->week_of_month
+            )
         );
     }
 
-- 
2.11.0