From c67a99fb5d3ed3b771f769f5c40e947453e66dda Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Fri, 22 Jan 2021 16:21:17 +1100
Subject: [PATCH] New IfcOpenShell date utility module, because we shouldn't
 need to think too hard about dates

---
 .../ifcopenshell/util/date.py                 | 45 +++++++++++++++++++
 1 file changed, 45 insertions(+)
 create mode 100644 src/ifcopenshell-python/ifcopenshell/util/date.py

diff --git a/src/ifcopenshell-python/ifcopenshell/util/date.py b/src/ifcopenshell-python/ifcopenshell/util/date.py
new file mode 100644
index 0000000000..e1bca4089b
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/util/date.py
@@ -0,0 +1,45 @@
+from re import findall
+from datetime import datetime
+
+
+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
+
+
+def ifc2datetime(element):
+    if isinstance(element, str) and element[0] == "P":  # IfcDuration
+        return duration2dict(element)
+    elif isinstance(element, str):  # IfcDateTime, IfcDate
+        return datetime.fromisoformat(element)
+    elif isinstance(element, int):  # IfcTimeStamp
+        return datetime.fromtimestamp(element)
+    elif element.is_a("IfcDateAndTime"):
+        return datetime(
+            element.DateComponent.YearComponent,
+            element.DateComponent.MonthComponent,
+            element.DateComponent.DayComponent,
+            element.TimeComponent.HourComponent,
+            element.TimeComponent.MinuteComponent,
+            element.TimeComponent.SecondComponent,
+            # TODO: implement TimeComponent timezone
+        )
+    elif element.is_a("IfcCalendarDate"):
+        return datetime(
+            element.YearComponent,
+            element.MonthComponent,
+            element.DayComponent,
+        )
+
+
+def datetime2ifc(dt, ifc_type):
+    if ifc_type == "IfcTimeStamp":
+        return int(dt.timestamp())
+    elif ifc_type == "IfcDateTime":
+        return dt.isoformat()
+    elif ifc_type == "IfcDate":
+        return dt.date().isoformat()
+    elif ifc_type == "IfcTime":
+        return dt.time().isoformat()