From ad37e97ef75cbe8f48a98d71874d4632dc157d59 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Adri=C3=A1n=20Oliva?= <adrian.oliva@cimat.mx>
Date: Thu, 25 May 2023 21:35:01 -0600
Subject: New GET for sorted to dos.

GET request with path "/todos/{field}/{order}", where {field} can be
"Id", "Priority" or "DueDate" for sorting the corresponding fields, and
{order} can be "ASC" or "DESC" for ascending or descending order,
respectively.
---
 src/main/java/com/encora/ToDosRepository.java | 59 +++++++++++++++++++++++----
 1 file changed, 50 insertions(+), 9 deletions(-)

(limited to 'src/main/java/com/encora/ToDosRepository.java')

diff --git a/src/main/java/com/encora/ToDosRepository.java b/src/main/java/com/encora/ToDosRepository.java
index f19d1ce..65c1b39 100644
--- a/src/main/java/com/encora/ToDosRepository.java
+++ b/src/main/java/com/encora/ToDosRepository.java
@@ -11,10 +11,7 @@ import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.repository.query.FluentQuery;
 
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Objects;
-import java.util.Optional;
+import java.util.*;
 import java.util.function.Function;
 
 public class ToDosRepository implements JpaRepository<ToDos, Integer> {
@@ -39,6 +36,21 @@ public class ToDosRepository implements JpaRepository<ToDos, Integer> {
         return this.todos;
     }
 
+    // Return all to dos and sorted.
+    @Override
+    public List<ToDos> findAll(Sort sort) {
+        List<ToDos> sortedList = new ArrayList<>(this.todos);
+
+        try {
+            Comparator<ToDos> comparator = this.getToDoComparator(sort);
+            Collections.sort(sortedList, comparator);
+        } catch (Exception e) {
+            throw new RuntimeException(e);
+        }
+
+        return sortedList;
+    }
+
     // Save new element.
     @Override
     public <S extends ToDos> S save(S entity) {
@@ -81,6 +93,40 @@ public class ToDosRepository implements JpaRepository<ToDos, Integer> {
         return null;
     }
 
+    private Comparator<ToDos> getToDoComparator(Sort sort) throws Exception {
+        // Personal function. Creates a `Comparator` based on the `sort`
+        // parameter. This is for us to successfully sort our List without the
+        // need of a database.
+        String sortString = sort.toString();    // <- '{field}: {order}'
+        String[] sortCriteria = sortString.split(": ");
+
+        String field = sortCriteria[0];
+        String order = sortCriteria[1];
+
+        Comparator<ToDos> comparator = null;
+        switch (field) {
+            case "Id":
+                comparator = Comparator.comparing(ToDos::getId);
+                break;
+
+            case "Priority":
+                comparator = Comparator.comparing(ToDos::getPriority);
+                break;
+
+            case "DueDate":
+                comparator = Comparator.comparing(ToDos::getDueDate);
+                break;
+
+            default:
+                throw new Exception("Field sorting not implemented.");
+        }
+
+        if (order.equalsIgnoreCase("desc")) {
+            comparator = comparator.reversed();
+        }
+        return comparator;
+    }
+
     /*
     *         N O T   Y E T   D E F I N E D .
     */
@@ -209,11 +255,6 @@ public class ToDosRepository implements JpaRepository<ToDos, Integer> {
 
     }
 
-    @Override
-    public List<ToDos> findAll(Sort sort) {
-        return null;
-    }
-
     @Override
     public Page<ToDos> findAll(Pageable pageable) {
         return null;
-- 
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