Refactor Article search functionality to support pagination and enhance output formatting

hibernate-project/src/main/java/com/humanbooster/dao/ArticleDao.java

@@ -3,9 +3,12 @@ package com.humanbooster.dao;
 import com.humanbooster.model.Article;
 import jakarta.persistence.criteria.CriteriaBuilder;
 import jakarta.persistence.criteria.CriteriaQuery;
+import jakarta.persistence.criteria.Predicate;
+import jakarta.persistence.criteria.Root;
 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 
@@ -37,37 +40,36 @@ public class ArticleDao extends GenericDaoImpl<Article, Long> {
         }
     }
 
-    public List<Article> findByCriteria(String keyword, Long authorId) {
-
-        Optional<String> optKeyword = Optional.ofNullable(keyword);
-        Optional<Long> optAuthorId = Optional.ofNullable(authorId);
-
-        List<Article> articles;
-
+    public List<Article> findByCriteria(String keyword, Long authorId, int page, int size) {
         try (Session session = sessionFactory.openSession()) {
-            session.beginTransaction();
 
             CriteriaBuilder cb = session.getCriteriaBuilder();
             CriteriaQuery<Article> query = cb.createQuery(Article.class);
 
-            var root = query.from(Article.class);
-
+            Root<Article> root = query.from(Article.class);
             query.select(root);
 
-            optKeyword.ifPresent(s -> query.where(
-                    cb.like(
-                            cb.lower(
-                                    root.get("title")), "%" + s.toLowerCase() + "%")
-            ));
+            List<Predicate> predicates = new ArrayList<>();
 
-            optAuthorId.ifPresent(l -> query.where(
-                    cb.equal(
-                            root.get("author"), l)
+            if (keyword != null && !keyword.isEmpty()) {
+                predicates.add(
+                        cb.like(root.get("title"), "%" + keyword + "%")
+                );
+            }
 
-            ));
+            if (authorId != null) {
+                predicates.add(
+                        cb.equal(root.get("author").get("id"), authorId)
+                );
+            }
 
-            articles = session.createQuery(query).getResultList();
+            query.where(predicates.toArray(Predicate[]::new));
+            query.orderBy(cb.asc(root.get("title")));
+
+            return session.createQuery(query)
+                    .setFirstResult(page * size)
+                    .setMaxResults(size)
+                    .getResultList();
         }
-        return articles;
     }
 }