feat: user search (#6302)

* feat: user search

* refactor: use sqlx macro

* refactor: better name for escaped query

* style: cleanup unused import

* chore: update sqlx query cache

* fix: tests

---------

Co-authored-by: sychic <47618543+Sychic@users.noreply.github.com>

apps/labrinth/src/database/models/user_item.rs

@@ -57,6 +57,13 @@ pub struct DBUser {
     pub is_subscribed_to_newsletter: bool,
 }
 
+#[derive(Deserialize, Serialize, Clone, Debug)]
+pub struct DBSearchUser {
+    pub id: DBUserId,
+    pub username: String,
+    pub avatar_url: Option<String>,
+}
+
 #[derive(Deserialize, Serialize, Clone, Debug, utoipa::ToSchema)]
 pub struct Pride26CampaignDonation {
     pub last_donated_at: DateTime<Utc>,
@@ -264,6 +271,44 @@ impl DBUser {
         Ok(val)
     }
 
+    pub async fn search<'a, E>(
+        query: &str,
+        exec: E,
+    ) -> Result<Vec<DBSearchUser>, sqlx::Error>
+    where
+        E: crate::database::Executor<'a, Database = sqlx::Postgres>,
+    {
+        if query.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let lowercase_query = query.to_lowercase();
+        let escaped_query = format!("{}%", escape_like(&lowercase_query));
+
+        let users = sqlx::query!(
+            "
+            SELECT id, username, avatar_url
+            FROM users
+            WHERE LOWER(username) LIKE $1 ESCAPE '\'
+            ORDER BY LOWER(username) = $2 DESC, LOWER(username), username
+            LIMIT 25
+            ",
+            escaped_query,
+            lowercase_query
+        )
+        .fetch_all(exec)
+        .await?
+        .into_iter()
+        .map(|row| DBSearchUser {
+            id: DBUserId(row.id),
+            username: row.username,
+            avatar_url: row.avatar_url,
+        })
+        .collect();
+
+        Ok(users)
+    }
+
     pub async fn get_by_email<'a, E>(
         email: &str,
         exec: E,
@@ -1044,3 +1089,14 @@ impl DBUser {
         }
     }
 }
+
+fn escape_like(query: &str) -> String {
+    let mut escaped = String::with_capacity(query.len());
+    for ch in query.chars() {
+        if matches!(ch, '\\' | '%' | '_') {
+            escaped.push('\\');
+        }
+        escaped.push(ch);
+    }
+    escaped
+}