TICKET-007 (backend): meals — from-log, unpack, components, recursive nutrition, cycle detection

backend/routers/foods.py

@@ -4,7 +4,7 @@ from fastapi import APIRouter, Depends, HTTPException, Query
 from sqlalchemy.orm import Session
 
 from database import get_db
-from schemas import FoodCreate, FoodRead, FoodUpdate
+from schemas import FoodCreate, FoodRead, FoodUpdate, MealRead
 from services.foods import (
     BarcodeConflictError,
     create_food,
@@ -43,9 +43,11 @@ def _list_foods(
                       include_deleted=include_deleted)
 
 
-@router.get("/{food_id}", response_model=FoodRead)
+@router.get("/{food_id}")
 def _get_food(food_id: int, db: Session = Depends(get_db)):
-    """Get a single food, including soft-deleted ones (for historical logs)."""
+    """Get a single food, including soft-deleted ones (for historical logs).
+    Returns MealRead (with components + computed nutrition) for meals,
+    plain FoodRead for non-meals."""
     food = get_food(db, food_id)
     if food is None:
         raise HTTPException(status_code=404, detail="Food not found")

backend/routers/meals.py

@@ -0,0 +1,91 @@
+"""Meals router (spec §3.2). Thin handlers — business logic in services/meals.py."""
+
+from fastapi import APIRouter, Depends, HTTPException
+from sqlalchemy.orm import Session
+
+from database import get_db
+from schemas import (
+    LogEntryRead,
+    MealComponentsUpdateRequest,
+    MealFromLogRequest,
+    MealFromLogResponse,
+    MealRead,
+    MealUnpackRequest,
+    MealUnpackResponse,
+)
+from services import meals as svc
+
+router = APIRouter(prefix="/api/meals", tags=["meals"])
+
+
+@router.post("/from-log", response_model=MealFromLogResponse, status_code=201)
+def create_meal_from_log(data: MealFromLogRequest, db: Session = Depends(get_db)):
+    """Create a meal food from selected daily log entries (§4.3).
+
+    Runs as one transaction: creates the meal + components, deletes source
+    entries, inserts one replacement entry.  Rolls back entirely on failure.
+    """
+    try:
+        meal, entry = svc.create_meal_from_log(
+            db, data.date, data.entry_ids, data.name,
+        )
+    except svc.EntryNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+    except svc.EntryDateMismatchError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+
+    return MealFromLogResponse(meal=meal, entry=entry)
+
+
+@router.post("/{meal_id}/unpack", response_model=MealUnpackResponse)
+def unpack_meal(
+    meal_id: int,
+    data: MealUnpackRequest,
+    db: Session = Depends(get_db),
+):
+    """Replace a logged meal entry with its leaf component entries (§4.4).
+
+    Components are resolved recursively — nested meals are flattened to
+    leaf foods with their scaling factors multiplied down.
+
+    Runs as one transaction.  If multiple entries match the meal on this
+    date, specify ``entry_id`` to disambiguate.
+    """
+    try:
+        entries = svc.unpack_meal(db, meal_id, data.date, data.entry_id)
+    except svc.EntryNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+    except svc.AmbiguousMealEntryError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+    except ValueError as e:
+        raise HTTPException(status_code=400, detail=str(e))
+
+    return MealUnpackResponse(entries=entries)
+
+
+@router.put("/{meal_id}/components", response_model=MealRead)
+def update_meal_components(
+    meal_id: int,
+    data: MealComponentsUpdateRequest,
+    db: Session = Depends(get_db),
+):
+    """Replace a meal's component list (§3.2 PUT). Cycle-checked.
+
+    Components are validated for cycles (direct or transitive self-reference).
+    A 422 is returned when the update would create a cycle.
+
+    This is a full replacement — all existing components are removed and
+    replaced with the provided list.
+    """
+    comps = [{"food_id": c.food_id, "quantity": c.quantity} for c in data.components]
+
+    try:
+        return svc.update_meal_components(db, meal_id, comps)
+    except svc.MealNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+    except svc.ComponentFoodNotFoundError as e:
+        raise HTTPException(status_code=404, detail=str(e))
+    except svc.MealCycleError as e:
+        raise HTTPException(status_code=422, detail=str(e))