refactor: sonarcloud quality gate (#111)

* refactor(S1118): utility classes should not have public constructors

* refactor: fail-fast approach while splitting

* refactor: adopt java 17 features

* refactor: drop unreachable statement

* refactor: generic data factory provider

* fix: invalid mockito-inline version

* refactor: rename test data factory

* feat: switch to mixed memory buffer

* refactor: command handler + test coverage

* test: make path tests os-agnostic

* fix: list files sorted by name

* test: cover command factory

* test: fix new line test output

* test: cover no-arg command execution

opdf-api/pom.xml

@@ -12,4 +12,12 @@
 
   <artifactId>opdf-api</artifactId>
   <name>Open PDF Tool :: API</name>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
 </project>

opdf-api/src/main/java/dev/noid/toolbox/opdf/spi/DataFactoryProvider.java

@@ -5,19 +5,15 @@
 
 public final class DataFactoryProvider {
 
-  public static DataMergerFactory getMergerFactory() {
-    return getDataFactory(DataMergerFactory.class);
-  }
-
-  public static DataSplitterFactory getSplitterFactory() {
-    return getDataFactory(DataSplitterFactory.class);
-  }
-
-  private static <T> T getDataFactory(Class<T> type) {
+  public static <T> T getInstance(Class<T> type) {
     Iterator<T> iterator = ServiceLoader.load(type).iterator();
     if (!iterator.hasNext()) {
       throw new NoClassDefFoundError("Cannot find any implementations of factory class: " + type);
     }
     return iterator.next();
   }
+
+  private DataFactoryProvider() {
+    throw new UnsupportedOperationException();
+  }
 }

opdf-api/src/test/java/dev/noid/toolbox/opdf/spi/DataFactoryProviderTest.java

@@ -0,0 +1,38 @@
+package dev.noid.toolbox.opdf.spi;
+
+import static dev.noid.toolbox.opdf.spi.DataFactoryProvider.getInstance;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import java.lang.reflect.Constructor;
+import org.junit.jupiter.api.Test;
+
+class DataFactoryProviderTest {
+
+  @Test
+  void lookup_default_merger_factory() {
+    assertEquals(NoopDataFactory.class, getInstance(DataMergerFactory.class).getClass());
+  }
+
+  @Test
+  void lookup_default_splitter_factory() {
+    assertEquals(NoopDataFactory.class, getInstance(DataSplitterFactory.class).getClass());
+  }
+
+  @Test
+  void lookup_unknown_data_factory() {
+    var error = assertThrows(NoClassDefFoundError.class, () -> getInstance(UnknownDataFactory.class));
+    assertEquals("Cannot find any implementations of factory class: " + UnknownDataFactory.class, error.getMessage());
+  }
+
+  @Test
+  void prohibit_instance_creation() {
+    try {
+      Constructor<DataFactoryProvider> constructor = DataFactoryProvider.class.getDeclaredConstructor();
+      constructor.setAccessible(true);
+      constructor.newInstance();
+    } catch (Exception cause) {
+      assertEquals(UnsupportedOperationException.class, cause.getCause().getClass());
+    }
+  }
+}

opdf-api/src/test/java/dev/noid/toolbox/opdf/spi/NoopDataFactory.java

@@ -0,0 +1,17 @@
+package dev.noid.toolbox.opdf.spi;
+
+import dev.noid.toolbox.opdf.api.DataMerger;
+import dev.noid.toolbox.opdf.api.DataSplitter;
+
+public class NoopDataFactory implements DataMergerFactory, DataSplitterFactory {
+
+  @Override
+  public DataMerger getMerger() {
+    return (sources, sink) -> {};
+  }
+
+  @Override
+  public DataSplitter getSplitter() {
+    return (source, sink) -> {};
+  }
+}

opdf-api/src/test/java/dev/noid/toolbox/opdf/spi/UnknownDataFactory.java

@@ -0,0 +1,5 @@
+package dev.noid.toolbox.opdf.spi;
+
+public interface UnknownDataFactory {
+
+}

opdf-api/src/test/resources/META-INF/services/dev.noid.toolbox.opdf.spi.DataMergerFactory

@@ -0,0 +1 @@
+dev.noid.toolbox.opdf.spi.NoopDataFactory

opdf-api/src/test/resources/META-INF/services/dev.noid.toolbox.opdf.spi.DataSplitterFactory

@@ -0,0 +1 @@
+dev.noid.toolbox.opdf.spi.NoopDataFactory

opdf-cli/src/main/java/dev/noid/toolbox/opdf/cli/CommandFactory.java

@@ -0,0 +1,33 @@
+package dev.noid.toolbox.opdf.cli;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Map;
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+class CommandFactory {
+
+  private final Map<String, Function<String[], Runnable>> registry;
+
+  CommandFactory(Consumer<String> stdout) {
+    this.registry = Map.of(
+            "help", args -> new HelpCommand(stdout),
+            "version", args -> new VersionCommand(stdout),
+            "split", args -> new SplitCommand(getSource(args)),
+            "merge", args -> new MergeCommand(getSource(args))
+    );
+  }
+
+  public Runnable getCommand(String... args) {
+    String key = args.length > 0 ? args[0] : "help";
+    return registry.getOrDefault(key, registry.get("help")).apply(args);
+  }
+
+  private Path getSource(String[] args) {
+    if (args.length < 2) {
+      throw new IllegalArgumentException("Source path is missing");
+    }
+    return Paths.get(args[1]);
+  }
+}

opdf-cli/src/main/java/dev/noid/toolbox/opdf/cli/HelpCommand.java

@@ -0,0 +1,28 @@
+package dev.noid.toolbox.opdf.cli;
+
+import java.util.function.Consumer;
+
+class HelpCommand implements Runnable {
+
+  private static final String HELP = """
+          Open PDF Tool
+                    
+          Usage: opdf [COMMAND]
+          Commands:
+            help     Displays help information about the specified command
+            version  Displays version information
+            merge    Merge several PDF files into one
+            split    Split one PDF file into pages
+          """;
+
+  private final Consumer<String> stdout;
+
+  HelpCommand(Consumer<String> stdout) {
+    this.stdout = stdout;
+  }
+
+  @Override
+  public void run() {
+    stdout.accept(HELP);
+  }
+}

opdf-cli/src/main/java/dev/noid/toolbox/opdf/cli/MergeCommand.java

@@ -0,0 +1,36 @@
+package dev.noid.toolbox.opdf.cli;
+
+import dev.noid.toolbox.opdf.api.DataMerger;
+import dev.noid.toolbox.opdf.api.DataSink;
+import dev.noid.toolbox.opdf.io.FileSink;
+import dev.noid.toolbox.opdf.io.FileSource;
+import dev.noid.toolbox.opdf.spi.DataFactoryProvider;
+import dev.noid.toolbox.opdf.spi.DataMergerFactory;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.stream.Stream;
+
+class MergeCommand implements Runnable {
+
+  private final Path sourceDir;
+
+  MergeCommand(Path sourceDir) {
+    this.sourceDir = sourceDir;
+  }
+
+  @Override
+  public void run() {
+    Path outputFile = sourceDir.resolve("merged.pdf");
+    try (Stream<Path> fileStream = Files.list(sourceDir).sorted()) {
+      List<FileSource> sources = fileStream.map(FileSource::of).toList();
+      DataSink sink = FileSink.of(outputFile);
+
+      DataMerger merger = DataFactoryProvider.getInstance(DataMergerFactory.class).getMerger();
+      merger.merge(sources, sink);
+    } catch (Exception cause) {
+      throw new IllegalArgumentException(cause);
+    }
+  }
+}

opdf-cli/src/main/java/dev/noid/toolbox/opdf/cli/Opdf.java

@@ -1,85 +1,8 @@
 package dev.noid.toolbox.opdf.cli;
 
-import dev.noid.toolbox.opdf.api.DataMerger;
-import dev.noid.toolbox.opdf.api.DataSink;
-import dev.noid.toolbox.opdf.api.DataSource;
-import dev.noid.toolbox.opdf.api.DataSplitter;
-import dev.noid.toolbox.opdf.io.FileSink;
-import dev.noid.toolbox.opdf.io.FileSource;
-import dev.noid.toolbox.opdf.io.FileUtil;
-import dev.noid.toolbox.opdf.io.NamingStrategy;
-import dev.noid.toolbox.opdf.spi.DataFactoryProvider;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.Paths;
-import java.util.List;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
 public class Opdf {
 
   public static void main(String[] args) {
-    if (args.length == 0) {
-      printHelp();
-    } else if ("version".equals(args[0])) {
-      printVersion();
-    } else if ("split".equals(args[0])) {
-      splitDocument(Paths.get(args[1]));
-    } else if ("merge".equals(args[0])) {
-      mergeDocuments(Paths.get(args[1]));
-    } else {
-      printHelp();
-    }
-  }
-
-  private static void printHelp() {
-    String help = "Open PDF Tool\n"
-        + "\n"
-        + "Usage: opdf [COMMAND]\n"
-        + "Commands:\n"
-        + "  help     Displays help information about the specified command\n"
-        + "  version  Displays version information\n"
-        + "  merge    Merge several PDF files into one\n"
-        + "  split    Split one PDF file into pages";
-    System.out.println(help);
-  }
-
-  private static void printVersion() {
-    String version = Opdf.class.getPackage().getImplementationVersion();
-    System.out.println(version);
-  }
-
-  private static void splitDocument(Path sourceFile) {
-    Path outputDirectory = sourceFile.getParent();
-    DataSource source = new FileSource(sourceFile);
-    DataSink sink = getStreamSink(outputDirectory, sourceFile);
-    DataSplitter splitter = DataFactoryProvider.getSplitterFactory().getSplitter();
-    splitter.split(source, sink);
-  }
-
-  private static void mergeDocuments(Path sourceDir) {
-    if (!Files.isDirectory(sourceDir)) {
-      return;
-    }
-
-    Path outputFile = sourceDir.resolve("merged.pdf");
-    try (Stream<Path> fileStream = Files.list(sourceDir)) {
-      List<DataSource> sources = fileStream.map(FileSource::new).collect(Collectors.toList());
-      DataSink sink = new FileSink(outputFile);
-
-      DataMerger merger = DataFactoryProvider.getMergerFactory().getMerger();
-      merger.merge(sources, sink);
-    } catch (Exception cause) {
-      throw new IllegalArgumentException(cause);
-    }
-  }
-
-  private static DataSink getStreamSink(Path targetDir, Path sourceFile) {
-    String nameOnly = FileUtil.getNameWithoutExtension(sourceFile);
-    String filePath = targetDir.resolve(nameOnly).toString();
-    String extension = FileUtil.getExtension(sourceFile);
-
-    NamingStrategy naming = NamingStrategy.ordinary(filePath, extension);
-    return () -> new FileSink(Paths.get(naming.getName())).getWriting();
+    new CommandFactory(System.out::println).getCommand(args).run();
   }
 }

opdf-cli/src/main/java/dev/noid/toolbox/opdf/cli/SplitCommand.java

@@ -0,0 +1,41 @@
+package dev.noid.toolbox.opdf.cli;
+
+import dev.noid.toolbox.opdf.api.DataSink;
+import dev.noid.toolbox.opdf.api.DataSource;
+import dev.noid.toolbox.opdf.api.DataSplitter;
+import dev.noid.toolbox.opdf.io.FileSink;
+import dev.noid.toolbox.opdf.io.FileSource;
+import dev.noid.toolbox.opdf.io.FileUtil;
+import dev.noid.toolbox.opdf.io.NamingStrategy;
+import dev.noid.toolbox.opdf.spi.DataFactoryProvider;
+import dev.noid.toolbox.opdf.spi.DataSplitterFactory;
+
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+class SplitCommand implements Runnable {
+
+  private final Path sourceFile;
+
+  SplitCommand(Path sourceFile) {
+    this.sourceFile = sourceFile;
+  }
+
+  @Override
+  public void run() {
+    Path outputDirectory = sourceFile.getParent();
+    DataSource source = FileSource.of(sourceFile);
+    DataSink sink = getStreamSink(outputDirectory, sourceFile);
+    DataSplitter splitter = DataFactoryProvider.getInstance(DataSplitterFactory.class).getSplitter();
+    splitter.split(source, sink);
+  }
+
+  private DataSink getStreamSink(Path targetDir, Path sourceFile) {
+    String nameOnly = FileUtil.getNameWithoutExtension(sourceFile);
+    String filePath = targetDir.resolve(nameOnly).toString();
+    String extension = FileUtil.getExtension(sourceFile);
+
+    NamingStrategy naming = NamingStrategy.ordinary(filePath, extension);
+    return () -> FileSink.of(Paths.get(naming.getName())).getWriting();
+  }
+}

opdf-cli/src/main/java/dev/noid/toolbox/opdf/cli/VersionCommand.java

@@ -0,0 +1,22 @@
+package dev.noid.toolbox.opdf.cli;
+
+import java.util.Objects;
+import java.util.function.Consumer;
+
+class VersionCommand implements Runnable {
+
+  private final Consumer<String> stdout;
+  private final String version;
+
+  VersionCommand(Consumer<String> stdout) {
+    this.stdout = stdout;
+
+    String implVersion = VersionCommand.class.getPackage().getImplementationVersion();
+    this.version = Objects.requireNonNullElse(implVersion, "unknown");
+  }
+
+  @Override
+  public void run() {
+    stdout.accept(version);
+  }
+}

opdf-cli/src/main/java/dev/noid/toolbox/opdf/io/FileSink.java

@@ -9,9 +9,13 @@
 
 public class FileSink implements DataSink {
 
+  public static FileSink of(Path filePath) {
+    return new FileSink(filePath);
+  }
+
   private final Path filePath;
 
-  public FileSink(Path filePath) {
+  private FileSink(Path filePath) {
     this.filePath = filePath;
   }
 

opdf-cli/src/main/java/dev/noid/toolbox/opdf/io/FileSource.java

@@ -9,9 +9,13 @@
 
 public class FileSource implements DataSource {
 
+  public static FileSource of(Path filePath) {
+    return new FileSource(filePath);
+  }
+
   private final Path filePath;
 
-  public FileSource(Path filePath) {
+  private FileSource(Path filePath) {
     this.filePath = filePath;
   }