fix: incorrect night shift assignment timings in shift calendar

(cherry picked from commit 70f6c48)

hrms/hr/doctype/shift_assignment/shift_assignment.py

@@ -159,19 +159,18 @@ def get_events(start, end, filters=None):
 		employee = ""
 		company = frappe.db.get_value("Global Defaults", None, "default_company")
 
-	events = add_assignments(start, end, filters)
-	return events
+	assignments = get_shift_assignments(start, end, filters)
+	return get_shift_events(assignments)
 
 
-def add_assignments(start, end, filters):
+def get_shift_assignments(start: str, end: str, filters: list) -> list[dict]:
 	import json
 
-	events = []
 	if isinstance(filters, str):
 		filters = json.loads(filters)
 	filters.extend([["start_date", ">=", start], ["end_date", "<=", end], ["docstatus", "=", 1]])
 
-	records = frappe.get_list(
+	return frappe.get_list(
 		"Shift Assignment",
 		filters=filters,
 		fields=[
@@ -185,21 +184,28 @@ def add_assignments(start, end, filters):
 		],
 	)
 
-	shift_timing_map = get_shift_type_timing([d.shift_type for d in records])
 
-	for d in records:
+def get_shift_events(assignments: list[dict]) -> list[dict]:
+	events = []
+	shift_timing_map = get_shift_type_timing([d.shift_type for d in assignments])
+
+	for d in assignments:
 		daily_event_start = d.start_date
-		daily_event_end = d.end_date if d.end_date else getdate()
+		daily_event_end = d.end_date or getdate()
+		shift_start = shift_timing_map[d.shift_type]["start_time"]
+		shift_end = shift_timing_map[d.shift_type]["end_time"]
+
 		delta = timedelta(days=1)
 		while daily_event_start <= daily_event_end:
-			start_timing = (
-				frappe.utils.get_datetime(daily_event_start) + shift_timing_map[d.shift_type]["start_time"]
-			)
-			end_timing = (
-				frappe.utils.get_datetime(daily_event_start) + shift_timing_map[d.shift_type]["end_time"]
-			)
-			daily_event_start += delta
-			e = {
+			start_timing = frappe.utils.get_datetime(daily_event_start) + shift_start
+
+			if shift_start > shift_end:
+				# shift spans across 2 days
+				end_timing = frappe.utils.get_datetime(daily_event_start) + shift_end + delta
+			else:
+				end_timing = frappe.utils.get_datetime(daily_event_start) + shift_end
+
+			event = {
 				"name": d.name,
 				"doctype": "Shift Assignment",
 				"start_date": start_timing,
@@ -209,8 +215,10 @@ def add_assignments(start, end, filters):
 				"allDay": 0,
 				"convertToUserTz": 0,
 			}
-			if e not in events:
-				events.append(e)
+			if event not in events:
+				events.append(event)
+
+			daily_event_start += delta
 
 	return events