add meal carry over feature

src/http.rs

@@ -133,6 +133,11 @@ pub fn build_router(state: AppState) -> Router {
             "/lists/{list_id}/meals/{list_meal_id}/remove",
             post(remove_meal_from_list),
         )
+        .route(
+            "/lists/{list_id}/carry",
+            get(carry_over_modal).post(carry_meals),
+        )
+        .route("/lists/{list_id}/carry/meals", get(carry_source_meals))
         .route("/rewards", get(rewards_page).post(create_rewards_card))
         .route("/rewards/{card_id}", get(rewards_scan_page))
         .route("/rewards/{card_id}/delete", post(delete_rewards_card))
@@ -338,6 +343,21 @@ struct AddMealForm {
     csrf: String,
 }
 
+#[derive(Debug, Deserialize)]
+struct CarrySourceQuery {
+    source: i64,
+}
+
+#[derive(Debug, Deserialize)]
+struct CarryMealsForm {
+    source_list_id: i64,
+    /// Selected list_meal ids as a comma-separated string, since the form
+    /// extractor does not coalesce repeated keys into a Vec.
+    #[serde(default)]
+    list_meal_ids: String,
+    csrf: String,
+}
+
 #[derive(Debug, Deserialize)]
 struct MealPickerQuery {
     picker: Option<i64>,
@@ -1157,6 +1177,87 @@ async fn remove_meal_from_list(
     list_fragment_response(&state, &user, list_id).await
 }
 
+/// Renders the carry-over modal: a picker of active source lists (newest first,
+/// excluding the current list) that the user can import meals from.
+async fn carry_over_modal(
+    State(state): State<AppState>,
+    _user: CurrentUser,
+    Path(dest_list_id): Path<i64>,
+) -> Result<Response, AppError> {
+    require_mutable_list(&state, dest_list_id).await?;
+    let lists = state.lists.list_summaries().await?;
+    let sources: Vec<_> = lists
+        .into_iter()
+        .filter(|list| list.id != dest_list_id)
+        .collect();
+    Ok(html_response(views::carry_over_modal(
+        &sources,
+        dest_list_id,
+    )))
+}
+
+/// Renders the selectable meal rows for a chosen source list inside the carry
+/// modal.
+async fn carry_source_meals(
+    State(state): State<AppState>,
+    user: CurrentUser,
+    Path(dest_list_id): Path<i64>,
+    Query(query): Query<CarrySourceQuery>,
+) -> Result<Response, AppError> {
+    require_mutable_list(&state, dest_list_id).await?;
+    let source = require_list(&state, query.source).await?;
+    if source.id == dest_list_id {
+        return Err(AppError::BadRequest(
+            "Cannot carry meals from a list into itself.".into(),
+        ));
+    }
+    let list_meals = state.meals.list_meals_on_list(source.id).await?;
+    Ok(html_response(views::carry_source_meals(
+        &list_meals,
+        source.id,
+        dest_list_id,
+        &user.session.csrf_token,
+    )))
+}
+
+/// Copies the selected meals from a source list into the current list without
+/// re-adding their ingredients.
+async fn carry_meals(
+    State(state): State<AppState>,
+    user: CurrentUser,
+    Path(dest_list_id): Path<i64>,
+    LoggedForm(form): LoggedForm<CarryMealsForm>,
+) -> Result<Response, AppError> {
+    verify_csrf(&user, &form.csrf)?;
+    require_mutable_list(&state, dest_list_id).await?;
+    let source = require_list(&state, form.source_list_id).await?;
+    if source.id == dest_list_id {
+        return Err(AppError::BadRequest(
+            "Cannot carry meals from a list into itself.".into(),
+        ));
+    }
+    if form.list_meal_ids.is_empty() {
+        return Err(AppError::BadRequest(
+            "Select at least one meal to carry over.".into(),
+        ));
+    }
+    let list_meal_ids: Vec<i64> = form
+        .list_meal_ids
+        .split(',')
+        .filter_map(|id| id.trim().parse().ok())
+        .collect();
+    if list_meal_ids.is_empty() {
+        return Err(AppError::BadRequest(
+            "Select at least one meal to carry over.".into(),
+        ));
+    }
+    state
+        .meals
+        .carry_meals_to_list(source.id, dest_list_id, &list_meal_ids)
+        .await?;
+    list_fragment_response(&state, &user, dest_list_id).await
+}
+
 async fn create_invitation(
     State(state): State<AppState>,
     user: CurrentUser,