Code review and use isodate library to handle durations for robustly

src/ifcopenshell-python/ifcopenshell/util/date.py

@@ -1,50 +1,28 @@
 import datetime
 from re import findall
 
-# https://gist.github.com/spatialtime/c1924a3b178b4fe721fe406e0bf1a1dc
-import re
-from datetime import timedelta
-
-
-def format_duration(td):
-    s = td.seconds
-    ms = td.microseconds
-    if ms != 0:  # Round microseconds to milliseconds.
-        ms /= 1000000
-        ms = round(ms,3)
-        s += ms
-    return "P{}DT{}S".format(td.days,s)
-
-def parse_duration(iso_duration):
-    m = re.match(r'^P(?:(\d+)Y)?(?:(\d+)M)?(?:(\d+)D)?T(?:(\d+)H)?(?:(\d+)M)?(?:(\d+(?:.\d+)?)S)?$',
-        iso_duration)
-    if m is None:
-        raise ValueError("invalid ISO 8601 duration string")
-    days = 0
-    hours = 0
-    minutes = 0
-    seconds = 0.0
-    if m[3]:
-        days = int(m[3])
-    if m[4]:
-        hours = int(m[4])
-    if m[5]:
-        minutes = int(m[5])
-    if m[6]:
-        seconds = float(m[6])
-    return timedelta(days=days, hours=hours, minutes=minutes, seconds=seconds)
-
-
-def duration2dict(duration):
-    results = {}
-    for number, unit in findall("(?P<number>\d+)(?P<period>S|M|H|D|W|Y)", duration):
-        results[unit] = number
-    return results
+try:
+    import isodate
+except:
+    pass  # Duration parsing not supported
 
 
 def ifc2datetime(element):
     if isinstance(element, str) and element[0] == "P":  # IfcDuration
-        return parse_duration(element)
+        duration = isodate.parse_duration(element)
+        if isinstance(duration, datetime.timedelta):
+            components = {
+                "days": getattr(duration, "days", 0),
+                "hours": 0,
+                "minutes": 0,
+                "seconds": getattr(duration, "seconds", 0),
+            }
+            if components["seconds"]:
+                components["hours"], components["minutes"], components["seconds"] = [
+                    int(i) for i in str(datetime.timedelta(seconds=components["seconds"])).split(":")
+                ]
+            duration = isodate.Duration(**components)
+        return duration
     elif isinstance(element, str) and element[2] == ":":  # IfcTime
         return datetime.time.fromisoformat(element)
     elif isinstance(element, str) and ":" in element:  # IfcDateTime
@@ -72,11 +50,14 @@ def ifc2datetime(element):
 
 
 def datetime2ifc(dt, ifc_type):
-    if isinstance(dt, str) and ifc_type != "IfcDuration":
+    if isinstance(dt, str):
+        if ifc_type == "IfcDuration":
+            return dt
         dt = datetime.datetime.fromisoformat(dt)
+
     if ifc_type == "IfcDuration":
-        return format_duration(dt)
-    if ifc_type == "IfcTimeStamp":
+        return isodate.duration_isoformat(dt)
+    elif ifc_type == "IfcTimeStamp":
         return int(dt.timestamp())
     elif ifc_type == "IfcDateTime":
         if isinstance(dt, datetime.datetime):