From 086629d67ae49520bd4dc4ef5938ab03f0637ca7 Mon Sep 17 00:00:00 2001
From: Stefan Kolb <stefan-kolb@web.de>
Date: Sun, 15 Mar 2020 12:55:20 +0100
Subject: [PATCH] Improve OpenAccessDoi fetcher

---
 .../logic/importer/fetcher/OpenAccessDoi.java | 38 ++++++++++---------
 .../logic/importer/FulltextFetchersTest.java  |  2 +-
 .../importer/fetcher/OpenAccessDoiTest.java   | 10 +++++
 3 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/src/main/java/org/jabref/logic/importer/fetcher/OpenAccessDoi.java b/src/main/java/org/jabref/logic/importer/fetcher/OpenAccessDoi.java
index e06c1157308..b5290ca8cea 100644
--- a/src/main/java/org/jabref/logic/importer/fetcher/OpenAccessDoi.java
+++ b/src/main/java/org/jabref/logic/importer/fetcher/OpenAccessDoi.java
@@ -11,6 +11,8 @@
 import org.jabref.model.entry.field.StandardField;
 import org.jabref.model.entry.identifier.DOI;
 
+import kong.unirest.HttpResponse;
+import kong.unirest.JsonNode;
 import kong.unirest.Unirest;
 import kong.unirest.UnirestException;
 import org.slf4j.Logger;
@@ -22,10 +24,9 @@
  * @implSpec API is documented at http://unpaywall.org/api/v2
  */
 public class OpenAccessDoi implements FulltextFetcher {
-
     private static final Logger LOGGER = LoggerFactory.getLogger(FulltextFetcher.class);
 
-    private static String API_URL = "https://api.oadoi.org/v2/";
+    private static final String API_URL = "https://api.oadoi.org/v2/";
 
     @Override
     public Optional<URL> findFullText(BibEntry entry) throws IOException {
@@ -33,15 +34,16 @@ public Optional<URL> findFullText(BibEntry entry) throws IOException {
 
         Optional<DOI> doi = entry.getField(StandardField.DOI)
                                  .flatMap(DOI::parse);
-        if (doi.isPresent()) {
-            try {
-                return findFullText(doi.get());
-            } catch (UnirestException e) {
-                throw new IOException(e);
-            }
-        } else {
+
+        if (!doi.isPresent()) {
             return Optional.empty();
         }
+
+        try {
+            return findFullText(doi.get());
+        } catch (UnirestException e) {
+            throw new IOException(e);
+        }
     }
 
     @Override
@@ -50,15 +52,17 @@ public TrustLevel getTrustLevel() {
     }
 
     public Optional<URL> findFullText(DOI doi) throws UnirestException {
-        return Optional.of(Unirest.get(API_URL + doi.getDOI() + "?email=developers@jabref.org")
-                                  .header("accept", "application/json")
-                                  .asJson())
-                       .map(response -> response.getBody())
-                       .filter(body -> body != null)
-                       .map(body -> body.getObject())
-                       .filter(root -> root != null)
+        HttpResponse<JsonNode> request = Unirest.get(API_URL + doi.getDOI() + "?email=developers@jabref.org")
+                                                .header("accept", "application/json")
+                                                .asJson();
+
+        return Optional.of(request)
+                       .map(HttpResponse::getBody)
+                       .filter(Objects::nonNull)
+                       .map(JsonNode::getObject)
+                       .filter(Objects::nonNull)
                        .map(root -> root.optJSONObject("best_oa_location"))
-                       .filter(object -> object != null)
+                       .filter(Objects::nonNull)
                        .map(location -> location.optString("url"))
                        .flatMap(url -> {
                            try {
diff --git a/src/test/java/org/jabref/logic/importer/FulltextFetchersTest.java b/src/test/java/org/jabref/logic/importer/FulltextFetchersTest.java
index 3db92d048c1..724c0b52c80 100644
--- a/src/test/java/org/jabref/logic/importer/FulltextFetchersTest.java
+++ b/src/test/java/org/jabref/logic/importer/FulltextFetchersTest.java
@@ -59,7 +59,7 @@ public void noTrustLevel() throws MalformedURLException {
     }
 
     @Test
-    public void higherTrustLevelWins() throws MalformedURLException, IOException, FetcherException {
+    public void higherTrustLevelWins() throws IOException, FetcherException {
         final URL lowUrl = new URL("http://docs.oasis-open.org/opencsa/sca-bpel/sca-bpel-1.1-spec-cd-01.pdf");
         final URL highUrl = new URL("http://docs.oasis-open.org/wsbpel/2.0/OS/wsbpel-v2.0-OS.pdf");
 
diff --git a/src/test/java/org/jabref/logic/importer/fetcher/OpenAccessDoiTest.java b/src/test/java/org/jabref/logic/importer/fetcher/OpenAccessDoiTest.java
index 936d685712c..9fa8d7f361e 100644
--- a/src/test/java/org/jabref/logic/importer/fetcher/OpenAccessDoiTest.java
+++ b/src/test/java/org/jabref/logic/importer/fetcher/OpenAccessDoiTest.java
@@ -36,4 +36,14 @@ void notFoundByDOI() throws IOException {
         entry.setField(StandardField.DOI, "10.1186/unknown-doi");
         assertEquals(Optional.empty(), finder.findFullText(entry));
     }
+
+    @Test
+    void entryWithoutDoi() throws IOException {
+        assertEquals(Optional.empty(), finder.findFullText(entry));
+    }
+
+    @Test
+    void trustLevel() {
+        assertEquals(TrustLevel.META_SEARCH, finder.getTrustLevel());
+    }
 }