refactor(postgres): split fat PostgresRepository into per-port structs

crates/adapters/postgres/src/stats.rs

@@ -0,0 +1,153 @@
+use async_trait::async_trait;
+use domain::{
+    errors::DomainError,
+    models::{DirectorStat, MonthlyRating, UserStats, UserTrends},
+    ports::StatsRepository,
+    value_objects::UserId,
+};
+use sqlx::PgPool;
+
+use crate::format_year_month;
+use crate::models::{DirectorCountRow, MonthlyRatingRow, UserTotalsRow};
+
+pub struct PostgresStatsRepository {
+    pool: PgPool,
+}
+
+impl PostgresStatsRepository {
+    pub fn new(pool: PgPool) -> Self {
+        Self { pool }
+    }
+
+    fn map_err(e: sqlx::Error) -> DomainError {
+        tracing::error!("Database error: {:?}", e);
+        DomainError::InfrastructureError("Database operation failed".into())
+    }
+
+    async fn fetch_user_totals(&self, user_id: &str) -> Result<UserTotalsRow, DomainError> {
+        sqlx::query_as::<_, UserTotalsRow>(
+            r#"SELECT COUNT(DISTINCT movie_id) AS total,
+                      AVG(rating::float) AS avg_rating
+               FROM reviews WHERE user_id = $1"#,
+        )
+        .bind(user_id)
+        .fetch_one(&self.pool)
+        .await
+        .map_err(Self::map_err)
+    }
+
+    async fn fetch_user_favorite_director(
+        &self,
+        user_id: &str,
+    ) -> Result<Option<String>, DomainError> {
+        sqlx::query_scalar::<_, String>(
+            "SELECT m.director
+             FROM reviews r
+             INNER JOIN movies m ON m.id = r.movie_id
+             WHERE r.user_id = $1 AND m.director IS NOT NULL
+             GROUP BY m.director
+             ORDER BY COUNT(*) DESC
+             LIMIT 1",
+        )
+        .bind(user_id)
+        .fetch_optional(&self.pool)
+        .await
+        .map_err(Self::map_err)
+    }
+
+    async fn fetch_user_most_active_month(
+        &self,
+        user_id: &str,
+    ) -> Result<Option<String>, DomainError> {
+        sqlx::query_scalar::<_, String>(
+            "SELECT to_char(watched_at AT TIME ZONE 'UTC', 'YYYY-MM') AS month
+             FROM reviews
+             WHERE user_id = $1
+             GROUP BY to_char(watched_at AT TIME ZONE 'UTC', 'YYYY-MM')
+             ORDER BY COUNT(*) DESC
+             LIMIT 1",
+        )
+        .bind(user_id)
+        .fetch_optional(&self.pool)
+        .await
+        .map_err(Self::map_err)
+    }
+}
+
+#[async_trait]
+impl StatsRepository for PostgresStatsRepository {
+    async fn get_user_stats(&self, user_id: &UserId) -> Result<UserStats, DomainError> {
+        let uid = user_id.value().to_string();
+
+        let (totals, fav_director, most_active) = tokio::try_join!(
+            self.fetch_user_totals(&uid),
+            self.fetch_user_favorite_director(&uid),
+            self.fetch_user_most_active_month(&uid)
+        )?;
+
+        let most_active_month = most_active.map(|ym| format_year_month(&ym));
+
+        Ok(UserStats {
+            total_movies: totals.total,
+            avg_rating: totals.avg_rating,
+            favorite_director: fav_director,
+            most_active_month,
+        })
+    }
+
+    async fn get_user_trends(&self, user_id: &UserId) -> Result<UserTrends, DomainError> {
+        let uid = user_id.value().to_string();
+
+        let (rating_rows, director_rows) = tokio::try_join!(
+            sqlx::query_as::<_, MonthlyRatingRow>(
+                "SELECT to_char(watched_at AT TIME ZONE 'UTC', 'YYYY-MM') AS month,
+                        AVG(rating::float) AS avg_rating,
+                        COUNT(*) AS count
+                 FROM reviews
+                 WHERE user_id = $1 AND watched_at >= NOW() - INTERVAL '12 months'
+                 GROUP BY to_char(watched_at AT TIME ZONE 'UTC', 'YYYY-MM')
+                 ORDER BY to_char(watched_at AT TIME ZONE 'UTC', 'YYYY-MM') ASC"
+            )
+            .bind(&uid)
+            .fetch_all(&self.pool),
+            sqlx::query_as::<_, DirectorCountRow>(
+                "SELECT m.director AS director, COUNT(*) AS count
+                 FROM reviews r
+                 INNER JOIN movies m ON m.id = r.movie_id
+                 WHERE r.user_id = $1 AND m.director IS NOT NULL
+                 GROUP BY m.director
+                 ORDER BY COUNT(*) DESC
+                 LIMIT 5"
+            )
+            .bind(&uid)
+            .fetch_all(&self.pool)
+        )
+        .map_err(Self::map_err)?;
+
+        let max_director_count = director_rows.iter().map(|d| d.count).max().unwrap_or(1);
+
+        let monthly_ratings = rating_rows
+            .into_iter()
+            .map(|r| MonthlyRating {
+                month_label: format_year_month(&r.month),
+                year_month: r.month,
+                avg_rating: r.avg_rating,
+                count: r.count,
+            })
+            .collect();
+
+        let top_directors = director_rows
+            .into_iter()
+            .map(|d| DirectorStat {
+                director: d.director,
+                count: d.count,
+            })
+            .collect();
+
+        Ok(UserTrends {
+            monthly_ratings,
+            top_directors,
+            max_director_count,
+        })
+    }
+}