From 91e6bf6c4d595ba6dba65689b6b33897f2828d85 Mon Sep 17 00:00:00 2001
From: Eamon <eamon0989@gmail.com>
Date: Fri, 14 Apr 2023 17:25:32 +0200
Subject: [PATCH] feat: add support for text pagination

---
 src/constants.ts         |  2 ++
 src/data-access/texts.ts | 20 +++++++++++++++-----
 src/routes/texts.ts      | 14 +++++++-------
 src/services/texts.ts    | 22 +++++++++++++++++-----
 4 files changed, 41 insertions(+), 17 deletions(-)
 create mode 100644 src/constants.ts

diff --git a/src/constants.ts b/src/constants.ts
new file mode 100644
index 0000000..93ce330
--- /dev/null
+++ b/src/constants.ts
@@ -0,0 +1,2 @@
+/* eslint-disable import/prefer-default-export */
+export const DEFAULT_OFFSET = 10;
diff --git a/src/data-access/texts.ts b/src/data-access/texts.ts
index 05d2202..0bbd656 100644
--- a/src/data-access/texts.ts
+++ b/src/data-access/texts.ts
@@ -2,6 +2,7 @@
 import { QueryResult } from 'pg';
 import dbQuery from '../model/db-query';
 import { Text } from '../types';
+import { DEFAULT_OFFSET } from '../constants';
 
 const getAll = async function (): Promise<QueryResult> {
   const ALL_TEXTS: string = `
@@ -24,14 +25,23 @@ const getById = async function (textId: number): Promise<QueryResult> {
 
 const getByUserAndLanguage = async function (
   userId: number,
-  languageId: string
+  languageId: string,
+  page: number
 ): Promise<QueryResult> {
   const TEXTS_BY_USER: string = `
-      SELECT * FROM texts
-       WHERE user_id = %L AND language_id = %L
-    ORDER BY upload_time DESC NULLS LAST`;
+    SELECT *, COUNT(*) OVER () as totalTexts 
+    FROM texts
+    WHERE user_id = %L AND language_id = %L
+    ORDER BY upload_time DESC NULLS LAST
+    OFFSET %L FETCH NEXT %L ROWS ONLY`;
 
-  const result = await dbQuery(TEXTS_BY_USER, userId, languageId);
+  const result = await dbQuery(
+    TEXTS_BY_USER,
+    userId,
+    languageId,
+    DEFAULT_OFFSET * page,
+    DEFAULT_OFFSET
+  );
 
   return result;
 };
diff --git a/src/routes/texts.ts b/src/routes/texts.ts
index c9e2553..f49b95a 100644
--- a/src/routes/texts.ts
+++ b/src/routes/texts.ts
@@ -1,19 +1,19 @@
 import express from 'express';
 import texts from '../services/texts';
 import users from '../services/users';
-import { Text } from '../types';
+import { TextPagination, Text } from '../types';
 
 const router: express.Router = express.Router();
 
-router.get('/language/:languageId/', async (req, res): Promise<void> => {
+router.get('/language/:languageId/:page/', async (req, res): Promise<void> => {
   const { user } = res.locals;
-  const { languageId } = req.params;
-
-  const allTexts: Array<Text> = await texts.getByUserAndLanguage(
+  const { languageId, page } = req.params;
+  const textPagination: TextPagination = await texts.getByUserAndLanguage(
     Number(user.id),
-    languageId
+    languageId,
+    page
   );
-  res.json(allTexts);
+  res.json(textPagination);
 });
 
 router.get('/:id', async (req, res): Promise<void> => {
diff --git a/src/services/texts.ts b/src/services/texts.ts
index decd742..16d4202 100644
--- a/src/services/texts.ts
+++ b/src/services/texts.ts
@@ -1,7 +1,8 @@
 import boom from '@hapi/boom';
 import { QueryResult } from 'pg';
 import textData from '../data-access/texts';
-import { convertTextTypes, Text, TextDB } from '../types';
+import { convertTextTypes, TextPagination, Text, TextDB } from '../types';
+import { DEFAULT_OFFSET } from '../constants';
 
 const getAll = async function (): Promise<Array<Text>> {
   const result: QueryResult = await textData.getAll();
@@ -20,14 +21,25 @@ const getById = async function (textId: number): Promise<Text> {
 
 const getByUserAndLanguage = async function (
   userId: number,
-  languageId: string
-): Promise<Array<Text>> {
+  languageId: string,
+  pageNumber: string
+): Promise<TextPagination> {
   const result: QueryResult = await textData.getByUserAndLanguage(
     userId,
-    languageId
+    languageId,
+    Number(pageNumber) - 1
   );
 
-  return result.rows.map((dbItem: TextDB) => convertTextTypes(dbItem));
+  const totalTexts = result.rows[0]?.totaltexts || 0;
+  const paginatedTexts: TextPagination = {
+    currentPage: Number(pageNumber),
+    totalPages: Math.ceil(totalTexts / DEFAULT_OFFSET),
+    totalTexts,
+    nextPage: Number(pageNumber) + 1,
+    prevPage: Number(pageNumber) - 1,
+    data: result.rows.map((dbItem: TextDB) => convertTextTypes(dbItem)),
+  };
+  return paginatedTexts;
 };
 
 const addNew = async function (textObject: Text): Promise<Text> {