Preserve date offset in meal logging flow

Adds session storage of the 'offset' parameter to ensure the correct date is used when adding meals and redirecting to the daily log. Updates the add_meal and user routes to handle and validate the offset, improving navigation and data consistency for users logging meals on different days.

application/add_meal/routes.py

@@ -6,12 +6,14 @@ from flask import (
     session,
     request,
     jsonify,
+    abort,
 )
 from flask_login import current_user
 from forms import FoodItemForm, FoodLogForm
 from application import db
 from models import FoodItem, FoodLog
 from sqlalchemy import and_
+from datetime import datetime, timedelta, timezone
 
 bp = Blueprint(
     "add_meal",
@@ -116,7 +118,13 @@ def step4():
     form = FoodLogForm()
     item = db.session.get(FoodItem, session["item_id"])
 
-    assert item
+    offset = session["offset"]
+    if offset is None or item is None:
+        abort(404)
+
+    today = datetime.now(timezone.utc).date()
+    day = today + timedelta(days=offset)
+
     if form.validate_on_submit():
         assert form.amount.data
         db.session.add(
@@ -125,12 +133,13 @@ def step4():
                 user_id=current_user.id,
                 amount=form.amount.data,
                 part_of_day=session["meal_type"],
+                date_=day,
             )
         )
         db.session.commit()
         session.pop("meal_type")
         session.pop("item_id")
-        return redirect("/")
+        return redirect(url_for("user.daily_log", offset=offset))
 
     match session["meal_type"]:
         case 0: