From 54a9c2a82c060ec54874964db90a05a5deaac3ae Mon Sep 17 00:00:00 2001
From: Jiaqi Liu <jack20220723@gmail.com>
Date: Thu, 3 Oct 2024 13:06:05 +0800
Subject: [PATCH] Replace all-in-one with paginated endpoint (#3)

---
 .gitignore                                    |  1 +
 .../wilhelm/web/endpoints/DataServlet.java    | 29 ++++++++++++-------
 .../web/endpoints/DataServletITSpec.groovy    |  3 +-
 3 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/.gitignore b/.gitignore
index c6edaa3..a4498b0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 *.iml
 .idea/
 target/
+logback/
 .DS_Store
 application.properties
diff --git a/src/main/java/org/qubitpi/wilhelm/web/endpoints/DataServlet.java b/src/main/java/org/qubitpi/wilhelm/web/endpoints/DataServlet.java
index f962819..000b668 100644
--- a/src/main/java/org/qubitpi/wilhelm/web/endpoints/DataServlet.java
+++ b/src/main/java/org/qubitpi/wilhelm/web/endpoints/DataServlet.java
@@ -15,8 +15,6 @@
  */
 package org.qubitpi.wilhelm.web.endpoints;
 
-import org.qubitpi.wilhelm.config.ApplicationConfig;
-
 import org.aeonbits.owner.ConfigFactory;
 import org.neo4j.driver.AuthTokens;
 import org.neo4j.driver.Driver;
@@ -25,6 +23,7 @@
 import org.neo4j.driver.QueryConfig;
 import org.neo4j.driver.Value;
 import org.neo4j.driver.internal.types.InternalTypeSystem;
+import org.qubitpi.wilhelm.config.ApplicationConfig;
 
 import jakarta.inject.Inject;
 import jakarta.inject.Singleton;
@@ -33,6 +32,7 @@
 import jakarta.ws.rs.Path;
 import jakarta.ws.rs.PathParam;
 import jakarta.ws.rs.Produces;
+import jakarta.ws.rs.QueryParam;
 import jakarta.ws.rs.core.MediaType;
 import jakarta.ws.rs.core.Response;
 import net.jcip.annotations.Immutable;
@@ -62,10 +62,10 @@ public class DataServlet {
     private static final String NEO4J_DATABASE = APPLICATION_CONFIG.neo4jDatabase();
 
     private static final Map<String, String> LANGUAGES = Stream.of(
-            new AbstractMap.SimpleImmutableEntry<>("german", "German"),
-            new AbstractMap.SimpleImmutableEntry<>("ancientGreek", "Ancient Greek"),
-            new AbstractMap.SimpleImmutableEntry<>("latin", "Latin")
-    )
+                    new AbstractMap.SimpleImmutableEntry<>("german", "German"),
+                    new AbstractMap.SimpleImmutableEntry<>("ancientGreek", "Ancient Greek"),
+                    new AbstractMap.SimpleImmutableEntry<>("latin", "Latin")
+            )
             .collect(Collectors.toUnmodifiableMap(Map.Entry::getKey, Map.Entry::getValue));
 
 
@@ -91,17 +91,23 @@ public Response healthcheck() {
     }
 
     /**
-     * Get all vocabularies of a language.
+     * Get paginated vocabularies of a language.
      *
      * @param language  The language. Must be one of "german", "ancientGreek", or "latin". Otherwise a 404 response is
      * returned
+     * @param perPage  Requested number of words to be displayed on each page of results
+     * @param page  Requested page of results desired
      *
-     * @return the Neo4J query results in JSON format
+     * @return the paginated Neo4J query results in JSON format
      */
     @GET
     @Path("/languages/{language}")
     @Produces(MediaType.APPLICATION_JSON)
-    public Response getVocabularyByLanguage(@NotNull @PathParam("language") final String language) {
+    public Response getVocabularyByLanguagePaged(
+            @NotNull @PathParam("language") final String language,
+            @NotNull @QueryParam("perPage") final String perPage,
+            @NotNull @QueryParam("page") final String page
+    ) {
         if (!LANGUAGES.containsKey(Objects.requireNonNull(language, "language"))) {
             return Response
                     .status(Response.Status.BAD_REQUEST)
@@ -116,8 +122,9 @@ public Response getVocabularyByLanguage(@NotNull @PathParam("language") final St
 
         final String query = String.format(
                 "MATCH (t:Term WHERE t.language = '%s')-[r]->(d:Definition) " +
-                        "RETURN t.name AS term, d.name AS definition",
-                LANGUAGES.get(language)
+                "RETURN t.name AS term, d.name AS definition " +
+                "SKIP %s LIMIT %s",
+                LANGUAGES.get(language), (Integer.parseInt(page) - 1) * Integer.parseInt(perPage), perPage
         );
 
         try (Driver driver = GraphDatabase.driver(NEO4J_URL, AuthTokens.basic(NEO4J_USERNAME, NEO4J_PASSWORD))) {
diff --git a/src/test/groovy/org/qubitpi/wilhelm/web/endpoints/DataServletITSpec.groovy b/src/test/groovy/org/qubitpi/wilhelm/web/endpoints/DataServletITSpec.groovy
index 503ee08..65e2a6e 100644
--- a/src/test/groovy/org/qubitpi/wilhelm/web/endpoints/DataServletITSpec.groovy
+++ b/src/test/groovy/org/qubitpi/wilhelm/web/endpoints/DataServletITSpec.groovy
@@ -88,12 +88,13 @@ class DataServletITSpec extends Specification {
                 .statusCode(200)
     }
 
-    def "Get vocabulary by language"() {
+    def "Get vocabulary by language and retrieve the very first word"() {
         expect:
         RestAssured
                 .given()
                 .contentType(MediaType.APPLICATION_JSON)
                 .accept(MediaType.APPLICATION_JSON)
+                .queryParams([perPage: "10", page: "1"])
                 .when()
                 .get("/data/languages/german")
                 .then()