# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1425674516 -3600
# Node ID 4a55201d7985addac69c16a49ca84422d6305eac
# Parent  e2771305e3578f653e5287e2779ffa6ea1ce3fd1
Added initial support for duration and period value types.

diff -r e2771305e357 -r 4a55201d7985 imiptools/dates.py
--- a/imiptools/dates.py	Fri Mar 06 00:07:47 2015 +0100
+++ b/imiptools/dates.py	Fri Mar 06 21:41:56 2015 +0100
@@ -33,8 +33,28 @@
     ur'(?P<utc>Z)?' \
     ur')?'
 
+duration_time_icalendar_regexp_str = \
+    ur'T' \
+    ur'(?:' \
+    ur'([0-9]+H)(?:([0-9]+M)([0-9]+S)?)?' \
+    ur'|' \
+    ur'([0-9]+M)([0-9]+S)?' \
+    ur'|' \
+    ur'([0-9]+S)' \
+    ur')'
+
+duration_icalendar_regexp_str = ur'P' \
+    ur'(?:' \
+    ur'([0-9]+W)' \
+    ur'|' \
+    ur'(?:%s)' \
+    ur'|' \
+    ur'([0-9]+D)(?:%s)?' \
+    ur')' % (duration_time_icalendar_regexp_str, duration_time_icalendar_regexp_str)
+
 match_date_icalendar = re.compile(date_icalendar_regexp_str, re.UNICODE).match
 match_datetime_icalendar = re.compile(datetime_icalendar_regexp_str, re.UNICODE).match
+match_duration_icalendar = re.compile(duration_icalendar_regexp_str, re.UNICODE).match
 
 def to_utc_datetime(dt):
 
@@ -169,6 +189,52 @@
 
     return None
 
+def get_period(value, attr=None):
+
+    """
+    Return a tuple of the form (start, end) for the given 'value' in iCalendar
+    format, using the 'attr' mapping (if specified) to control the conversion.
+    """
+
+    if not value or attr and attr.get("VALUE") != "PERIOD":
+        return None
+
+    t = value.split("/")
+    if len(t) != 2:
+        return None
+
+    start = get_datetime(t[0])
+    if t[1].startswith("P"):
+        end = start + get_duration(t[1])
+    else:
+        end = get_datetime(t[1])
+
+    return start, end
+
+def get_duration(value):
+
+    "Return a duration for the given 'value'."
+
+    if not value:
+        return None
+
+    m = match_duration_icalendar(value)
+    if m:
+        weeks, days, hours, minutes, seconds = 0, 0, 0, 0, 0
+        for s in m.groups():
+            if not s: continue
+            if s[-1] == "W": weeks += int(s[:-1])
+            elif s[-1] == "D": days += int(s[:-1])
+            elif s[-1] == "H": hours += int(s[:-1])
+            elif s[-1] == "M": minutes += int(s[:-1])
+            elif s[-1] == "S": seconds += int(s[:-1])
+        return timedelta(
+            int(weeks) * 7 + int(days),
+            (int(hours) * 60 + int(minutes)) * 60 + int(seconds)
+            )
+    else:
+        return None
+
 def get_date(dt):
 
     "Return the date of 'dt'."