Refactor domain_utils.py overlap helpers, add ONE_DAY constant, remove inflated comments, and standardize _add_row() calls

src/domain_utils.py

@@ -6,6 +6,9 @@ from sqlalchemy.orm import Session
 from src.models.category import Category, CategoryBudget, CategoryBudgetDb, CategoryDb
 
 
+ONE_DAY = timedelta(days=1)
+
+
 def find_category_db(session: Session, category: Category | None) -> CategoryDb | None:
     """Find a CategoryDb in the database given a Pydantic Category object.
     
@@ -57,6 +60,7 @@ def set_category_budget(session: Session, category_budget: CategoryBudget):
 
     new_start = category_budget.valid_from
     new_end = category_budget.valid_to
+    new_amount = category_budget.amount_eur
 
     # Helper to add a budget row
     def _add_row(amount_eur: Decimal, valid_from: date | None, valid_to: date | None):
@@ -70,13 +74,7 @@ def set_category_budget(session: Session, category_budget: CategoryBudget):
     # Helper to check if two date ranges overlap
     def _ranges_overlap(start1: date | None, end1: date | None,
                         start2: date | None, end2: date | None) -> bool:
-        """Check if two date ranges overlap.
-        
-        Two bounded ranges overlap if start2 < end1 and start1 < end2.
-        An unbounded range (None, None) only overlaps with another fully unbounded range.
-        Partially unbounded ranges (e.g., valid_from=None but valid_to=date) 
-        only overlap if the bounded ranges themselves would overlap.
-        """
+        """Check if two date ranges overlap."""
         # Both completely unbounded - always overlap
         if start1 is None and end1 is None and start2 is None and end2 is None:
             return True
@@ -94,47 +92,19 @@ def set_category_budget(session: Session, category_budget: CategoryBudget):
                        start2: date | None, end2: date | None) -> tuple[date | None, date | None]:
         """Return the overlapping sub-range of two ranges."""
         
-        # Handle completely unbounded cases
+        # Handle completely unbounded cases first
         if start1 is None and end1 is None:
-            # First range is completely unbounded - overlap is second range
-            return (start2, end2) if (start2 is not None or end2 is not None) else (None, None)
-        
+            return (start2, end2) if any(x is not None for x in (start2, end2)) else (None, None)
         if start2 is None and end2 is None:
-            # Second range is completely unbounded - overlap is first range  
-            return (start1, end1) if (start1 is not None or end1 is not None) else (None, None)
+            return (start1, end1) if any(x is not None for x in (start1, end1)) else (None, None)
         
-        # Initialize with defaults
-        o_start = None
-        o_end = None
-        
-        # Handle one-sided unbounded cases
-        if start1 is not None and end1 is not None:
-            # Range 1 is bounded, range 2 may be unbounded
-            if start2 is None:  # New starts at beginning, so overlap starts at existing_start
-                o_start = start1
-            else:
-                o_start = max(start1, start2)
-            
-            if end2 is None:  # New ends at end of time, so overlap ends at existing_end
-                o_end = end1
-            elif o_start is not None:
-                o_end = min(end1, end2)
-        
-        if start2 is not None and end2 is not None:
-            # Range 2 is bounded, range 1 may be unbounded  
-            if start1 is None:  # Existing starts at beginning
-                o_start = start2
-            elif o_start is None:
-                o_start = max(start1, start2)
-            
-            if end1 is None:  # Existing ends at end of time
-                o_end = end2
-            elif o_start is not None:
-                o_end = min(end1, end2)
+        # Both ranges are bounded or partially unbounded
+        o_start = max((s for s in (start1, start2) if s is not None), default=None)
+        o_end = min((e for e in (end1, end2) if e is not None), default=None)
         
         # Check for actual overlap
         if o_start is None or o_start > o_end:
-            return (None, None)  # No overlap
+            return (None, None)
         
         return (o_start, o_end)
 
@@ -163,7 +133,7 @@ def set_category_budget(session: Session, category_budget: CategoryBudget):
 
         if overlap_start is None or overlap_end is None:
             # Full unbounded overlap - replace entirely with new budget
-            row = _add_row(category_budget.amount_eur, category_budget.valid_from, category_budget.valid_to)
+            row = _add_row(new_amount, new_start, new_end)
             session.add(row)
             return [row]
         
@@ -172,28 +142,16 @@ def set_category_budget(session: Session, category_budget: CategoryBudget):
         
         # Part 1: Before the overlap (if any)
         if budget.valid_from is not None and budget.valid_from < overlap_start:
-            row = _add_row(
-                amount_eur=budget.amount_eur,
-                valid_from=budget.valid_from,
-                valid_to=overlap_start - timedelta(days=1),
-            )
+            row = _add_row(budget.amount_eur, budget.valid_from, overlap_start - ONE_DAY)
             parts.append(row)
         
         # Part 2: After the overlap (if any)  
         if budget.valid_to is not None and overlap_end < budget.valid_to:
-            row = _add_row(
-                amount_eur=budget.amount_eur,
-                valid_from=overlap_end + timedelta(days=1),
-                valid_to=budget.valid_to,
-            )
+            row = _add_row(budget.amount_eur, overlap_end + ONE_DAY, budget.valid_to)
             parts.append(row)
         
         # Add the new budget
-        row = _add_row(
-            amount_eur=category_budget.amount_eur,
-            valid_from=category_budget.valid_from,
-            valid_to=category_budget.valid_to,
-        )
+        row = _add_row(new_amount, new_start, new_end)
         parts.append(row)
 
         # Add all parts to session
@@ -220,9 +178,5 @@ def set_category_budget(session: Session, category_budget: CategoryBudget):
 
     # Always add the new budget unless it was already added during overlap handling
     if not new_budget_added:
-        row = _add_row(
-            amount_eur=category_budget.amount_eur,
-            valid_from=category_budget.valid_from,
-            valid_to=category_budget.valid_to,
-        )
+        row = _add_row(new_amount, new_start, new_end)
         session.add(row)