Add entry based on ISSN number #10124

src/main/java/org/jabref/logic/importer/fetcher/IssnFetcher.java

@@ -0,0 +1,80 @@
+package org.jabref.logic.importer.fetcher;
+
+import java.util.List;
+import java.util.Optional;
+
+import org.jabref.logic.importer.FetcherException;
+import org.jabref.logic.importer.IdBasedFetcher;
+import org.jabref.logic.importer.IdFetcher;
+import org.jabref.logic.importer.ImportFormatPreferences;
+import org.jabref.logic.integrity.ISSNChecker;
+import org.jabref.model.entry.BibEntry;
+import org.jabref.model.entry.identifier.ISSN;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Fetcher to generate the BibTex entry from an ISSN.
+ * The idea is to use the {@link DOAJFetcher} to do a request for a given ISSN number.
+ */
+
+public class IssnFetcher implements IdBasedFetcher, IdFetcher<ISSN> {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(IssnFetcher.class);
+    private final DOAJFetcher doajFetcher;
+    private final String SEARCH_URL = "https://doaj.org/api/search/journals/";
+    private final ISSNChecker issnChecker;
+    private final ImportFormatPreferences importFormatPreferences;
+
+    public IssnFetcher(ImportFormatPreferences importFormatPreferences) {
+        this.importFormatPreferences = importFormatPreferences;
+        this.doajFetcher = new DOAJFetcher(importFormatPreferences);
+        this.issnChecker = new ISSNChecker();
+    }
+
+    @Override
+    public Optional<BibEntry> performSearchById(String identifier) throws FetcherException {
+
+        Optional<String> checkedId = issnChecker.checkValue(identifier);
+        if (checkedId.isEmpty()) {
+            LOGGER.warn("Not a valid ISSN");
+            return Optional.empty();
+        }
+
+        Optional<BibEntry> bibEntry = Optional.empty();
+
+        String queryString = concatenateIssnWithId(identifier);
+        List<BibEntry> bibEntries = doajFetcher.performSearch(queryString);
+
+        if (!bibEntries.isEmpty()) {
+            for (int i = 0; i < bibEntries.size(); i++) {
+                bibEntry = Optional.ofNullable(bibEntries.get(0));
+            }
+        } else {
+            LOGGER.warn("ISSN search failed, no results found");
+        }
+
+        return bibEntry;
+    }
+
+    @Override
+    public Optional<ISSN> findIdentifier(BibEntry entry) throws FetcherException {
+        // Need to create a getIssn() method in BibEntry that returns a Optional
+        return Optional.empty();
+    }
+
+    @Override
+    public String getIdentifierName() {
+        return getName();
+    }
+
+    @Override
+    public String getName() {
+        return "ISSN";
+    }
+
+    public String concatenateIssnWithId(String identifier) {
+        return "issn:" + identifier;
+    }
+}

src/main/java/org/jabref/model/entry/identifier/ISSN.java

@@ -1,10 +1,15 @@
 package org.jabref.model.entry.identifier;
 
+import java.net.URI;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
-public class ISSN {
+import org.jabref.model.entry.field.Field;
+import org.jabref.model.entry.field.StandardField;
+
+public class ISSN implements Identifier {
 
     private static final Pattern ISSN_PATTERN = Pattern.compile("^\\d{4}-\\d{3}[\\dxX]$");
     private static final Pattern ISSN_PATTERN_NODASH = Pattern.compile("^(\\d{4})(\\d{3}[\\dxX])$");
@@ -48,4 +53,19 @@ public boolean isValidChecksum() {
         }
         return ((((sum % 11) + control) - '0') == 11) || ((sum % 11) == 0);
     }
+
+    @Override
+    public String getNormalized() {
+        return issnString;
+    }
+
+    @Override
+    public Field getDefaultField() {
+        return StandardField.ISSN;
+    }
+
+    @Override
+    public Optional<URI> getExternalURI() {
+        return Optional.empty();
+    }
 }