From 6d4dbbb1add8a4181d857cf96abc1065b9478345 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johnny=20Miller=20=28=E9=94=BA=E4=BF=8A=29?=
 <johnnysviva@outlook.com>
Date: Tue, 1 Feb 2022 13:00:59 +0800
Subject: [PATCH] feat($Pagination): create functional pagination response
 composer

---
 .../maf/common/bean/PaginationBase.java       | 12 ++--
 .../FunctionalPaginationResponseComposer.java | 62 +++++++++++++++++++
 2 files changed, 68 insertions(+), 6 deletions(-)
 create mode 100644 spring-cloud-starter/src/main/java/com/jmsoftware/maf/springcloudstarter/function/FunctionalPaginationResponseComposer.java

diff --git a/common/src/main/java/com/jmsoftware/maf/common/bean/PaginationBase.java b/common/src/main/java/com/jmsoftware/maf/common/bean/PaginationBase.java
index 94181eef..30ff793d 100644
--- a/common/src/main/java/com/jmsoftware/maf/common/bean/PaginationBase.java
+++ b/common/src/main/java/com/jmsoftware/maf/common/bean/PaginationBase.java
@@ -1,7 +1,7 @@
 package com.jmsoftware.maf.common.bean;
 
+import cn.hutool.core.text.CharSequenceUtil;
 import cn.hutool.core.util.NumberUtil;
-import cn.hutool.core.util.StrUtil;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import lombok.Data;
 import org.hibernate.validator.constraints.Range;
@@ -54,10 +54,10 @@ public class PaginationBase {
 
     @JsonIgnore
     public String getOrderByStatement() {
-        if (!StrUtil.isBlank(orderBy)) {
-            return String.format("%s `%s` %s", "ORDER BY", orderBy, orderRule);
+        if (!CharSequenceUtil.isBlank(this.orderBy)) {
+            return String.format("%s `%s` %s", "ORDER BY", this.orderBy, this.orderRule);
         }
-        return orderByStatement;
+        return this.orderByStatement;
     }
 
     /**
@@ -68,8 +68,8 @@ public String getOrderByStatement() {
      * @author Johnny Miller (锺俊), email: johnnysviva@outlook.com, date: 6/27/2021 4:37 PM
      */
     public boolean hasNextPage(@NotNull PageResponseBodyBean<?> pageResponseBodyBean) {
-        if (NumberUtil.compare(pageResponseBodyBean.getTotal(), (long) currentPage * pageSize) > 0) {
-            currentPage += 1;
+        if (NumberUtil.compare(pageResponseBodyBean.getTotal(), (long) this.currentPage * this.pageSize) > 0) {
+            this.currentPage += 1;
             return true;
         }
         return false;
diff --git a/spring-cloud-starter/src/main/java/com/jmsoftware/maf/springcloudstarter/function/FunctionalPaginationResponseComposer.java b/spring-cloud-starter/src/main/java/com/jmsoftware/maf/springcloudstarter/function/FunctionalPaginationResponseComposer.java
new file mode 100644
index 00000000..55d626b2
--- /dev/null
+++ b/spring-cloud-starter/src/main/java/com/jmsoftware/maf/springcloudstarter/function/FunctionalPaginationResponseComposer.java
@@ -0,0 +1,62 @@
+package com.jmsoftware.maf.springcloudstarter.function;
+
+import cn.hutool.core.collection.CollUtil;
+import cn.hutool.core.util.PageUtil;
+import com.jmsoftware.maf.common.bean.PageResponseBodyBean;
+import com.jmsoftware.maf.common.bean.PaginationBase;
+import lombok.NonNull;
+import lombok.extern.slf4j.Slf4j;
+import lombok.val;
+
+import java.util.List;
+import java.util.function.Function;
+
+import static java.lang.Math.toIntExact;
+
+/**
+ * <h1>FunctionalPaginationResponseComposer</h1>
+ * <p>
+ * Change description here.
+ *
+ * @author Johnny Miller (鍾俊), email: johnnysviva@outlook.com, 2/1/22 1:13 AM
+ **/
+@Slf4j
+@SuppressWarnings("unused")
+public class FunctionalPaginationResponseComposer {
+    private FunctionalPaginationResponseComposer() {
+    }
+
+    public static <T extends PaginationBase, R> List<R> composePages(
+            @NonNull T paginationBase,
+            @NonNull Function<T, PageResponseBodyBean<R>> callback
+    ) {
+        val result = CollUtil.<R>newArrayList();
+        while (true) {
+            val page = callback.apply(paginationBase);
+            if (CollUtil.isEmpty(page.getList())) {
+                CollUtil.addAll(result, page.getList());
+            }
+            if (!paginationBase.hasNextPage(page)) {
+                val totalPage = PageUtil.totalPage(toIntExact(page.getTotal()), paginationBase.getPageSize());
+                log.warn("Reached the end of the page. totalPage: {}, currentPage: {}, pageSize: {}", totalPage,
+                         paginationBase.getCurrentPage(), paginationBase.getPageSize());
+                break;
+            }
+        }
+        return result;
+    }
+
+    private static <T extends PaginationBase, R> boolean hasNextPage(
+            @NonNull T paginationBase,
+            @NonNull PageResponseBodyBean<R> pageResponse
+    ) {
+        val totalPage = PageUtil.totalPage(toIntExact(pageResponse.getTotal()), paginationBase.getPageSize());
+        if (paginationBase.getCurrentPage() < totalPage) {
+            paginationBase.setCurrentPage(paginationBase.getCurrentPage() + 1);
+            return true;
+        }
+        log.warn("Reached the end of the page. totalPage: {}, currentPage: {}, pageSize: {}", totalPage,
+                 paginationBase.getCurrentPage(), paginationBase.getPageSize());
+        return false;
+    }
+}