From 744e9fde84a28da157d896344224a85ab3c234f1 Mon Sep 17 00:00:00 2001
From: pipinet <zourongchuan@handaotech.com>
Date: Fri, 1 Nov 2024 22:32:16 +0800
Subject: [PATCH] feature: add PageRequests

---
 .../com/qwlabs/jakarta/data/PageRequests.java |  8 ++++++++
 .../src/test/java/com/qwlabs/jakarta/.gitkeep |  0
 .../qwlabs/jakarta/data/PageRequestsTest.java | 20 +++++++++++++++++++
 3 files changed, 28 insertions(+)
 delete mode 100644 jakarta-data/src/test/java/com/qwlabs/jakarta/.gitkeep

diff --git a/jakarta-data/src/main/java/com/qwlabs/jakarta/data/PageRequests.java b/jakarta-data/src/main/java/com/qwlabs/jakarta/data/PageRequests.java
index 097b83c..f36bda1 100644
--- a/jakarta-data/src/main/java/com/qwlabs/jakarta/data/PageRequests.java
+++ b/jakarta-data/src/main/java/com/qwlabs/jakarta/data/PageRequests.java
@@ -20,4 +20,12 @@ static PageRequest of(@Nullable String after, int first) {
         var pageNumber = (startAt + first) / first;
         return PageRequest.ofPage(pageNumber, first, true);
     }
+
+    static int firstResult(PageRequest request){
+        return Long.valueOf((request.page() - 1) * request.size()).intValue();
+    }
+
+    static int maxResults(PageRequest request){
+        return request.size();
+    }
 }
diff --git a/jakarta-data/src/test/java/com/qwlabs/jakarta/.gitkeep b/jakarta-data/src/test/java/com/qwlabs/jakarta/.gitkeep
deleted file mode 100644
index e69de29..0000000
diff --git a/jakarta-data/src/test/java/com/qwlabs/jakarta/data/PageRequestsTest.java b/jakarta-data/src/test/java/com/qwlabs/jakarta/data/PageRequestsTest.java
index 071c3e5..ad24969 100644
--- a/jakarta-data/src/test/java/com/qwlabs/jakarta/data/PageRequestsTest.java
+++ b/jakarta-data/src/test/java/com/qwlabs/jakarta/data/PageRequestsTest.java
@@ -20,6 +20,26 @@ void should_of() {
         checkRequest("2", 4, 1L);
     }
 
+    @Test
+    void should_firstResult() {
+        assertThat(PageRequests.firstResult(PageRequests.of("0", 3)), is(0));
+        assertThat(PageRequests.firstResult(PageRequests.of("0", 1)), is(0));
+        assertThat(PageRequests.firstResult(PageRequests.of("1", 2)), is(0));
+        assertThat(PageRequests.firstResult(PageRequests.of("2", 2)), is(2));
+        assertThat(PageRequests.firstResult(PageRequests.of("3", 2)), is(2));
+        assertThat(PageRequests.firstResult(PageRequests.of("4", 2)), is(4));
+    }
+
+    @Test
+    void should_maxResults() {
+        assertThat(PageRequests.maxResults(PageRequests.of("0", 3)), is(3));
+        assertThat(PageRequests.maxResults(PageRequests.of("0", 1)), is(1));
+        assertThat(PageRequests.maxResults(PageRequests.of("1", 2)), is(2));
+        assertThat(PageRequests.maxResults(PageRequests.of("2", 2)), is(2));
+        assertThat(PageRequests.maxResults(PageRequests.of("3", 2)), is(2));
+        assertThat(PageRequests.maxResults(PageRequests.of("4", 2)), is(2));
+    }
+
     void checkRequest(String after, Integer first, long page) {
         var pageRequest = PageRequests.of(after, first);
         assertThat(pageRequest.page(), is(page));