Added option to export in CFF (Citation File Format)

CHANGELOG.md

@@ -23,6 +23,7 @@ Note that this project **does not** adhere to [Semantic Versioning](https://semv
 - When pasting HTML into the abstract or a comment field, the hypertext is automatically converted to Markdown. [#10558](https://github.com/JabRef/jabref/issues/10558)
 - We added the possibility to redownload files that had been present but are no longer in the specified location. [#10848](https://github.com/JabRef/jabref/issues/10848)
 - We added the citation key pattern `[camelN]`. Equivalent to the first N words of the `[camel]` pattern.
+- We added ability to export in CFF (Citation File Format) [#10661](https://github.com/JabRef/jabref/issues/10661).
 
 ### Changed
 

src/main/java/org/jabref/logic/exporter/ExporterFactory.java

@@ -55,6 +55,7 @@ public static ExporterFactory create(PreferencesService preferencesService,
         exporters.add(new TemplateExporter("MIS Quarterly", "misq", "misq", "misq", StandardFileType.RTF, layoutPreferences, saveOrder));
         exporters.add(new TemplateExporter("CSL YAML", "yaml", "yaml", null, StandardFileType.YAML, layoutPreferences, saveOrder, BlankLineBehaviour.DELETE_BLANKS));
         exporters.add(new TemplateExporter("Hayagriva YAML", "hayagrivayaml", "hayagrivayaml", null, StandardFileType.YAML, layoutPreferences, saveOrder, BlankLineBehaviour.DELETE_BLANKS));
+        exporters.add(new TemplateExporter("CFF", "cff", "cff", null, StandardFileType.CFF, layoutPreferences, saveOrder, BlankLineBehaviour.DELETE_BLANKS));
         exporters.add(new OpenOfficeDocumentCreator());
         exporters.add(new OpenDocumentSpreadsheetCreator());
         exporters.add(new MSBibExporter());

src/main/java/org/jabref/logic/layout/LayoutEntry.java

@@ -35,6 +35,8 @@
 import org.jabref.logic.layout.format.AuthorOrgSci;
 import org.jabref.logic.layout.format.Authors;
 import org.jabref.logic.layout.format.CSLType;
+import org.jabref.logic.layout.format.CffDate;
+import org.jabref.logic.layout.format.CffType;
 import org.jabref.logic.layout.format.CompositeFormat;
 import org.jabref.logic.layout.format.CreateBibORDFAuthors;
 import org.jabref.logic.layout.format.CreateDocBook4Authors;
@@ -486,6 +488,8 @@ private LayoutFormatter getLayoutFormatterByName(String name) {
             case "ShortMonth" -> new ShortMonthFormatter();
             case "ReplaceWithEscapedDoubleQuotes" -> new ReplaceWithEscapedDoubleQuotes();
             case "HayagrivaType" -> new HayagrivaType();
+            case "CffType" -> new CffType();
+            case "CffDate" -> new CffDate();
             default -> null;
         };
     }

src/main/java/org/jabref/logic/layout/format/CffDate.java

@@ -0,0 +1,70 @@
+package org.jabref.logic.layout.format;
+
+import java.time.LocalDate;
+import java.time.Year;
+import java.time.YearMonth;
+import java.time.format.DateTimeFormatter;
+import java.time.format.DateTimeParseException;
+
+import org.jabref.logic.layout.LayoutFormatter;
+import org.jabref.logic.util.OS;
+
+/**
+ * This class is used to parse dates for CFF exports. Since we do not know if the input String contains
+ *         year, month and day, we must go through all these cases to return the best CFF format possible.
+ *         Different cases are stated below.
+ * <p>
+ *         Year, Month and Day contained   => preferred-citation:
+ *                                              date-released: yyyy-mm-dd
+ * <p>
+ *         Year and Month contained        => preferred-citation
+ *                                              ...
+ *                                              month: mm
+ *                                              year: yyyy
+ * <p>
+ *         Year contained                  => preferred-citation:
+ *                                              ...
+ *                                              year: yyyy
+ * <p>
+ *         Poorly formatted                => preferred-citation:
+ *                                              ...
+ *                                              issue-date: text-as-is
+ */
+public class CffDate implements LayoutFormatter {
+    @Override
+    public String format(String fieldText) {
+        StringBuilder builder = new StringBuilder();
+        String formatString = "yyyy-MM-dd";
+        try {
+            DateTimeFormatter formatter = DateTimeFormatter.ofPattern(formatString);
+            LocalDate date = LocalDate.parse(fieldText, DateTimeFormatter.ISO_LOCAL_DATE);
+            builder.append("date-released: ");
+            builder.append(date.format(formatter));
+        } catch (DateTimeParseException e) {
+            try {
+                formatString = "yyyy-MM";
+                DateTimeFormatter formatter = DateTimeFormatter.ofPattern(formatString);
+                YearMonth yearMonth = YearMonth.parse(fieldText, formatter);
+                int month = yearMonth.getMonth().getValue();
+                int year = yearMonth.getYear();
+                builder.append("month: ");
+                builder.append(month);
+                builder.append(OS.NEWLINE);
+                builder.append("  year: "); // Account for indent since we are in `preferred-citation` indentation block
+                builder.append(year);
+            } catch (DateTimeParseException f) {
+                try {
+                    formatString = "yyyy";
+                    DateTimeFormatter formatter = DateTimeFormatter.ofPattern(formatString);
+                    int year = Year.parse(fieldText, formatter).getValue();
+                    builder.append("year: ");
+                    builder.append(year);
+                } catch (DateTimeParseException g) {
+                    builder.append("issue-date: ");
+                    builder.append(fieldText);
+                }
+            }
+        }
+        return builder.toString();
+    }
+}

src/main/java/org/jabref/logic/layout/format/CffType.java

@@ -0,0 +1,24 @@
+package org.jabref.logic.layout.format;
+
+import org.jabref.logic.layout.LayoutFormatter;
+import org.jabref.model.entry.types.StandardEntryType;
+
+public class CffType implements LayoutFormatter {
+    @Override
+    public String format(String value) {
+        return switch (StandardEntryType.valueOf(value)) {
+            case Article, Conference -> "article";
+            case Book -> "book";
+            case Booklet -> "pamphlet";
+            case InProceedings -> "conference-paper";
+            case Proceedings -> "proceedings";
+            case Misc -> "misc";
+            case Manual -> "manual";
+            case Software -> "software";
+            case Report, TechReport -> "report";
+            case Unpublished -> "unpublished";
+            default -> "generic";
+        };
+    }
+}
+

src/main/resources/resource/layout/cff.layout

@@ -0,0 +1,17 @@
+cff-version: 1.2.0
+message: "If you use this, please cite the work from preferred-citation."
+authors:
+  - name: \format[Default(No author specified.)]{\author}
+title: \format[Default(No title specified.)]{\title}
+preferred-citation:
+  type: \format[CffType, Default(generic)]{\entrytype}
+  authors:
+    - name: \format[Default(No author specified.)]{\author}
+  title: \format[Default(No title specified.)]{\title}
+\begin{date}
+  \format[CffDate]{\date}
+\end{date}
+\begin{abstract}  abstract: \abstract\end{abstract}
+\begin{doi}  doi: \doi\end{doi}
+\begin{volume}  volume: \volume\end{volume}
+\begin{url}  url: "\url"\end{url}

src/test/java/org/jabref/logic/exporter/CffExporterTest.java

@@ -0,0 +1,159 @@
+package org.jabref.logic.exporter;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collections;
+import java.util.List;
+
+import org.jabref.logic.layout.LayoutFormatterPreferences;
+import org.jabref.logic.util.StandardFileType;
+import org.jabref.model.database.BibDatabaseContext;
+import org.jabref.model.entry.BibEntry;
+import org.jabref.model.entry.field.StandardField;
+import org.jabref.model.entry.types.StandardEntryType;
+import org.jabref.model.metadata.SaveOrder;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.mockito.Answers;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
+
+public class CffExporterTest {
+
+    private static Exporter cffExporter;
+    private static BibDatabaseContext databaseContext;
+
+    @BeforeAll
+    static void setUp() {
+        cffExporter = new TemplateExporter(
+                "CFF",
+                "cff",
+                "cff",
+                null,
+                StandardFileType.CFF,
+                mock(LayoutFormatterPreferences.class, Answers.RETURNS_DEEP_STUBS),
+                SaveOrder.getDefaultSaveOrder(),
+                BlankLineBehaviour.DELETE_BLANKS);
+
+        databaseContext = new BibDatabaseContext();
+    }
+
+    @Test
+    public final void exportForNoEntriesWritesNothing(@TempDir Path tempFile) throws Exception {
+        Path file = tempFile.resolve("ThisIsARandomlyNamedFile");
+        Files.createFile(file);
+        cffExporter.export(databaseContext, tempFile, Collections.emptyList());
+        assertEquals(Collections.emptyList(), Files.readAllLines(file));
+    }
+
+    @Test
+    public final void exportsCorrectContent(@TempDir Path tempFile) throws Exception {
+        BibEntry entry = new BibEntry(StandardEntryType.Article)
+                .withCitationKey("test")
+                .withField(StandardField.AUTHOR, "Test Author")
+                .withField(StandardField.TITLE, "Test Title")
+                .withField(StandardField.URL, "http://example.com");
+
+        Path file = tempFile.resolve("RandomFileName");
+        Files.createFile(file);
+        cffExporter.export(databaseContext, file, Collections.singletonList(entry));
+
+        List<String> expected = List.of(
+        "cff-version: 1.2.0",
+        "message: \"If you use this, please cite the work from preferred-citation.\"",
+        "authors:",
+        "  - name: Test Author",
+        "title: Test Title",
+        "preferred-citation:",
+        "  type: article",
+        "  authors:",
+        "    - name: Test Author",
+        "  title: Test Title",
+        "  url: \"http://example.com\"");
+
+        assertEquals(expected, Files.readAllLines(file));
+    }
+
+    @Test
+    public final void usesCorrectType(@TempDir Path tempFile) throws Exception {
+        BibEntry entry = new BibEntry(StandardEntryType.InProceedings)
+                .withCitationKey("test")
+                .withField(StandardField.AUTHOR, "Test Author")
+                .withField(StandardField.TITLE, "Test Title")
+                .withField(StandardField.DOI, "random_doi_value");
+
+        Path file = tempFile.resolve("RandomFileName");
+        Files.createFile(file);
+        cffExporter.export(databaseContext, file, Collections.singletonList(entry));
+
+        List<String> expected = List.of(
+                "cff-version: 1.2.0",
+                "message: \"If you use this, please cite the work from preferred-citation.\"",
+                "authors:",
+                "  - name: Test Author",
+                "title: Test Title",
+                "preferred-citation:",
+                "  type: conference-paper",
+                "  authors:",
+                "    - name: Test Author",
+                "  title: Test Title",
+                "  doi: random_doi_value");
+
+        assertEquals(expected, Files.readAllLines(file));
+    }
+
+    @Test
+    public final void usesCorrectDefaultValues(@TempDir Path tempFile) throws Exception {
+        BibEntry entry = new BibEntry(StandardEntryType.Thesis)
+                .withCitationKey("test");
+
+        Path file = tempFile.resolve("RandomFileName");
+        Files.createFile(file);
+        cffExporter.export(databaseContext, file, Collections.singletonList(entry));
+
+        List<String> expected = List.of(
+                "cff-version: 1.2.0",
+                "message: \"If you use this, please cite the work from preferred-citation.\"",
+                "authors:",
+                "  - name: No author specified.",
+                "title: No title specified.",
+                "preferred-citation:",
+                "  type: generic",
+                "  authors:",
+                "    - name: No author specified.",
+                "  title: No title specified.");
+
+        assertEquals(expected, Files.readAllLines(file));
+    }
+
+    @Test
+    void passesModifiedCharset(@TempDir Path tempFile) throws Exception {
+        BibEntry entry = new BibEntry(StandardEntryType.Article)
+                .withCitationKey("test")
+                .withField(StandardField.AUTHOR, "谷崎 潤一郎")
+                .withField(StandardField.TITLE, "細雪")
+                .withField(StandardField.URL, "http://example.com");
+
+        Path file = tempFile.resolve("RandomFileName");
+        Files.createFile(file);
+        cffExporter.export(databaseContext, file, Collections.singletonList(entry));
+
+        List<String> expected = List.of(
+                "cff-version: 1.2.0",
+                "message: \"If you use this, please cite the work from preferred-citation.\"",
+                "authors:",
+                "  - name: 谷崎 潤一郎",
+                "title: 細雪",
+                "preferred-citation:",
+                "  type: article",
+                "  authors:",
+                "    - name: 谷崎 潤一郎",
+                "  title: 細雪",
+                "  url: \"http://example.com\"");
+
+        assertEquals(expected, Files.readAllLines(file));
+    }
+}

src/test/java/org/jabref/logic/layout/format/CffDateTest.java

@@ -0,0 +1,45 @@
+package org.jabref.logic.layout.format;
+
+import org.jabref.logic.layout.LayoutFormatter;
+import org.jabref.logic.util.OS;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class CffDateTest {
+
+    private LayoutFormatter formatter;
+    private String newLine;
+
+    @BeforeEach
+    public void setUp() {
+        formatter = new CffDate();
+        newLine = OS.NEWLINE;
+    }
+
+    @Test
+    public void dayMonthYear() {
+        String expected = "date-released: 2003-11-06";
+        assertEquals(expected, formatter.format("2003-11-06"));
+    }
+
+    @Test
+    public void monthYear() {
+        String expected = "month: 7" + newLine + "  " + "year: 2016";
+        assertEquals(expected, formatter.format("2016-07"));
+    }
+
+    @Test
+    public void year() {
+        String expected = "year: 2021";
+        assertEquals(expected, formatter.format("2021"));
+    }
+
+    @Test
+    public void poorlyFormatted() {
+        String expected = "issue-date: -2023";
+        assertEquals(expected, formatter.format("-2023"));
+    }
+}