fix: better overlap logic for job card (backport #38432) (#38521)

* fix: better overlap logic for job card (#38432)

(cherry picked from commit 74eab91042)

# Conflicts:
#	erpnext/manufacturing/doctype/job_card/job_card.py

* chore: fix conflicts

* chore: fixed existing_time_logs not defined

---------

Co-authored-by: rohitwaghchaure <rohitw1991@gmail.com>

erpnext/manufacturing/doctype/job_card/job_card.py

@@ -213,29 +213,27 @@ class JobCard(Document):
 			production_capacity = 1
 			query = query.where(jctl.employee == args.get("employee"))
 
-		existing = query.run(as_dict=True)
+		existing_time_logs = query.run(as_dict=True)
 
-		overlap_count = self.get_overlap_count(existing)
-		if existing and production_capacity > overlap_count:
-			return
+		if not self.has_overlap(production_capacity, existing_time_logs):
+			return {}
 
 		if self.workstation_type:
-			if workstation := self.get_workstation_based_on_available_slot(existing):
+			if workstation := self.get_workstation_based_on_available_slot(existing_time_logs):
 				self.workstation = workstation
 				return None
 
-		return existing[0] if existing else None
+		return existing_time_logs[0] if existing_time_logs else None
 
-	@staticmethod
-	def get_overlap_count(time_logs):
-		count = 1
+	def has_overlap(self, production_capacity, time_logs):
+		overlap = False
+		if production_capacity == 1 and len(time_logs) > 0:
+			return True
 
 		# Check overlap exists or not between the overlapping time logs with the current Job Card
-		for idx, row in enumerate(time_logs):
-			next_idx = idx
-			if idx + 1 < len(time_logs):
-				next_idx = idx + 1
-				next_row = time_logs[next_idx]
+		for row in time_logs:
+			count = 1
+			for next_row in time_logs:
 				if row.name == next_row.name:
 					continue
 
@@ -255,7 +253,10 @@ class JobCard(Document):
 				):
 					count += 1
 
-		return count
+			if count > production_capacity:
+				return True
+
+		return overlap
 
 	def get_workstation_based_on_available_slot(self, existing) -> Optional[str]:
 		workstations = get_workstations(self.workstation_type)