From d49d82305fb8441062cf66667a477fb04055a996 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Sun, 13 May 2012 17:24:34 +0530
Subject: [PATCH] utility function to generate datetime from date strings such
 that the year and month are always correct

---
 src/calibre/ebooks/metadata/sources/amazon.py |  4 ++--
 src/calibre/utils/date.py                     | 20 +++++++++++++++++++
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/calibre/ebooks/metadata/sources/amazon.py b/src/calibre/ebooks/metadata/sources/amazon.py
index 4ff4726139..6764e2f6f7 100644
--- a/src/calibre/ebooks/metadata/sources/amazon.py
+++ b/src/calibre/ebooks/metadata/sources/amazon.py
@@ -18,7 +18,7 @@ from calibre.ebooks.metadata import check_isbn
 from calibre.ebooks.metadata.sources.base import (Source, Option, fixcase,
         fixauthors)
 from calibre.ebooks.metadata.book.base import Metadata
-from calibre.utils.date import parse_date
+from calibre.utils.date import parse_only_date
 from calibre.utils.localization import canonicalize_lang
 
 class Worker(Thread): # Get details {{{
@@ -471,7 +471,7 @@ class Worker(Thread): # Get details {{{
                 ans = x.tail
                 date = ans.rpartition('(')[-1].replace(')', '').strip()
                 date = self.delocalize_datestr(date)
-                return parse_date(date, assume_utc=True)
+                return parse_only_date(date, assume_utc=True)
 
     def parse_language(self, pd):
         for x in reversed(pd.xpath(self.language_xpath)):
diff --git a/src/calibre/utils/date.py b/src/calibre/utils/date.py
index 8741cb6a9e..e269683ee3 100644
--- a/src/calibre/utils/date.py
+++ b/src/calibre/utils/date.py
@@ -82,6 +82,26 @@ def parse_date(date_string, assume_utc=False, as_utc=True, default=None):
         dt = dt.replace(tzinfo=_utc_tz if assume_utc else _local_tz)
     return dt.astimezone(_utc_tz if as_utc else _local_tz)
 
+def parse_only_date(raw, assume_utc=True):
+    '''
+    Parse a date string that contains no time information in a manner that
+    guarantees that the month and year are always correct in all timezones, and
+    the day is at most one day wrong.
+    '''
+    from calibre.utils.date import utcnow, now, parse_date
+    from datetime import timedelta
+    f = utcnow if assume_utc else now
+    default = f().replace(hour=0, minute=0, second=0, microsecond=0,
+            day=15)
+    ans = parse_date(raw, default=default, assume_utc=assume_utc)
+    n = ans + timedelta(days=1)
+    if n.month > ans.month:
+        ans = ans.replace(day=ans.day-1)
+    if ans.day == 1:
+        ans = ans.replace(day=2)
+    return ans
+
+
 def strptime(val, fmt, assume_utc=False, as_utc=True):
     dt = datetime.strptime(val, fmt)
     if dt.tzinfo is None: