Refactor average rating calculation for user clarity and performance (#1406)

* refactor: rename calculate_average_rating to calculate_average_rating_for_user for clarity

* refactor: update calculate_average_rating_for_user to accept user_id as a parameter

* refactor: update calculate_average_rating_for_user to filter reviews by user_id

* refactor: optimize calculate_average_rating_for_user to improve readability and performance

* refactor: optimize calculate_average_rating_for_user to improve performance and readability

Author: IgnisDa

crates/services/miscellaneous/src/user_details.rs

@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use application_utils::calculate_average_rating;
+use application_utils::calculate_average_rating_for_user;
 use async_graphql::Result;
 use database_models::functions::get_user_to_entity_association;
 use database_utils::{entity_in_collections, item_reviews};
@@ -123,7 +123,7 @@ pub async fn user_metadata_details(
     let seen_by: usize = seen_by.try_into().unwrap();
     let user_to_meta =
         get_user_to_entity_association(&ss.db, &user_id, &metadata_id, EntityLot::Metadata).await;
-    let average_rating = calculate_average_rating(&reviews);
+    let average_rating = calculate_average_rating_for_user(&user_id, &reviews);
     let seen_by_user_count = history.len();
     let show_progress = if let Some(show_specifics) = media_details.model.show_specifics {
         let mut seasons = vec![];
@@ -209,7 +209,7 @@ pub async fn user_person_details(
         get_entity_recently_consumed(&user_id, &person_id, EntityLot::Person, ss).await?;
     let person_meta =
         get_user_to_entity_association(&ss.db, &user_id, &person_id, EntityLot::Person).await;
-    let average_rating = calculate_average_rating(&reviews);
+    let average_rating = calculate_average_rating_for_user(&user_id, &reviews);
     Ok(UserPersonDetails {
         reviews,
         collections,
@@ -242,7 +242,7 @@ pub async fn user_metadata_group_details(
     let is_recently_consumed =
         get_entity_recently_consumed(&user_id, &metadata_group_id, EntityLot::MetadataGroup, ss)
             .await?;
-    let average_rating = calculate_average_rating(&reviews);
+    let average_rating = calculate_average_rating_for_user(&user_id, &reviews);
     let metadata_group_meta = get_user_to_entity_association(
         &ss.db,
         &user_id,

crates/utils/application/src/lib.rs

@@ -193,13 +193,19 @@ pub async fn create_oidc_client(
     }
 }
 
-pub fn calculate_average_rating(reviews: &[ReviewItem]) -> Option<Decimal> {
-    let reviews_with_ratings = reviews.iter().filter_map(|r| r.rating).count();
-    match reviews_with_ratings {
+pub fn calculate_average_rating_for_user(
+    user_id: &String,
+    reviews: &[ReviewItem],
+) -> Option<Decimal> {
+    let (sum, count) = reviews
+        .iter()
+        .filter(|r| r.posted_by.id == *user_id && r.rating.is_some())
+        .map(|r| r.rating.unwrap())
+        .fold((Decimal::ZERO, 0), |(sum, count), rating| {
+            (sum + rating, count + 1)
+        });
+    match count {
         0 => None,
-        _ => Some(
-            reviews.iter().filter_map(|r| r.rating).sum::<Decimal>()
-                / Decimal::from(reviews_with_ratings),
-        ),
+        _ => Some(sum / Decimal::from(count)),
     }
 }