Add an ability to open files, move IO methods to separate package

app/src/main/java/com/annimon/hotarufx/Main.java

@@ -25,6 +25,7 @@ public class Main extends Application {
                     getClass().getResource("/styles/color-picker-box.css").toExternalForm()
                     );
             controller = loader.getController();
+            controller.setPrimaryStage(primaryStage);
             primaryStage.setScene(scene);
         } catch (IOException e) {
             // TODO: notice me!!

app/src/main/java/com/annimon/hotarufx/io/DocumentListener.java

@@ -0,0 +1,6 @@
+package com.annimon.hotarufx.io;
+
+public interface DocumentListener {
+
+    void logError(String message);
+}

app/src/main/java/com/annimon/hotarufx/io/DocumentManager.java

@@ -0,0 +1,14 @@
+package com.annimon.hotarufx.io;
+
+import java.util.function.Consumer;
+import javafx.stage.Stage;
+
+public interface DocumentManager {
+
+    void newDocument();
+
+    boolean open(Stage stage, Consumer<String> contentConsumer);
+
+
+    void addDocumentListener(DocumentListener listener);
+}

app/src/main/java/com/annimon/hotarufx/io/FileManager.java

@@ -0,0 +1,68 @@
+package com.annimon.hotarufx.io;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.function.Consumer;
+import javafx.stage.FileChooser;
+import javafx.stage.Stage;
+import lombok.val;
+
+public class FileManager implements DocumentManager {
+
+    private static final String FILE_OPEN_TITLE = "Select file to open";
+    private final FileChooser fileChooser;
+    private File currentFile;
+    private DocumentListener listener;
+
+    public FileManager() {
+        fileChooser = new FileChooser();
+        fileChooser.getExtensionFilters().setAll(
+                new FileChooser.ExtensionFilter("Supported Files", "*.hfx")
+        );
+    }
+
+    @Override
+    public void newDocument() {
+        currentFile = null;
+    }
+
+    @Override
+    public boolean open(Stage stage, Consumer<String> contentConsumer) {
+        fileChooser.setTitle(FILE_OPEN_TITLE);
+        if (currentFile != null) {
+            fileChooser.setInitialDirectory(currentFile.getParentFile());
+        }
+        currentFile = fileChooser.showOpenDialog(stage);
+        if (currentFile == null) {
+            return false;
+        }
+        if (!currentFile.exists() || !currentFile.isFile()) {
+            return false;
+        }
+
+        val content = readFile(currentFile);
+        if (content.isEmpty()) {
+            return false;
+        }
+        contentConsumer.accept(content);
+        return true;
+    }
+
+    @Override
+    public void addDocumentListener(DocumentListener listener) {
+        this.listener = listener;
+    }
+
+    private String readFile(File file) {
+        try (InputStream is = new FileInputStream(file)) {
+            return IOStream.readContent(is);
+        } catch (IOException ioe) {
+            if (listener != null) {
+                listener.logError("Unable to open file " + file.getName());
+            }
+            return "";
+        }
+    }
+}

app/src/main/java/com/annimon/hotarufx/io/IOStream.java

@@ -0,0 +1,20 @@
+package com.annimon.hotarufx.io;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import lombok.val;
+
+public class IOStream {
+
+    public static String readContent(InputStream is) throws IOException {
+        val baos = new ByteArrayOutputStream();
+        val bufferSize = 4096;
+        val buffer = new byte[bufferSize];
+        int read;
+        while ((read = is.read(buffer, 0, bufferSize)) != -1)  {
+            baos.write(buffer, 0, read);
+        }
+        return baos.toString("UTF-8");
+    }
+}

app/src/main/java/com/annimon/hotarufx/ui/controller/EditorController.java

@@ -4,12 +4,15 @@ import com.annimon.hotarufx.Main;
 import com.annimon.hotarufx.bundles.BundleLoader;
 import com.annimon.hotarufx.bundles.CompositionBundle;
 import com.annimon.hotarufx.bundles.NodesBundle;
+import com.annimon.hotarufx.io.DocumentListener;
+import com.annimon.hotarufx.io.IOStream;
 import com.annimon.hotarufx.lexer.HotaruLexer;
 import com.annimon.hotarufx.lib.Context;
 import com.annimon.hotarufx.parser.HotaruParser;
 import com.annimon.hotarufx.parser.visitors.InterpreterVisitor;
+import com.annimon.hotarufx.io.DocumentManager;
+import com.annimon.hotarufx.io.FileManager;
 import com.annimon.hotarufx.ui.SyntaxHighlighter;
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.URL;
@@ -27,7 +30,7 @@ import lombok.val;
 import org.fxmisc.richtext.CodeArea;
 import org.fxmisc.richtext.LineNumberFactory;
 
-public class EditorController implements Initializable {
+public class EditorController implements Initializable, DocumentListener {
 
     @FXML
     private CodeArea editor;
@@ -37,7 +40,15 @@ public class EditorController implements Initializable {
     @FXML
     private TitledPane logPane;
 
+    private Stage primaryStage;
     private SyntaxHighlighter syntaxHighlighter;
+    private DocumentManager documentManager;
+
+    @FXML
+    private void handleMenuOpen(ActionEvent event) {
+        documentManager.open(primaryStage,
+                s -> editor.replaceText(0, 0, s));
+    }
 
     @FXML
     private void handleMenuExit(ActionEvent event) {
@@ -81,27 +92,30 @@ public class EditorController implements Initializable {
         editor.setParagraphGraphicFactory(LineNumberFactory.get(editor));
         syntaxHighlighter = new SyntaxHighlighter(editor, Executors.newSingleThreadExecutor());
         syntaxHighlighter.init();
+        documentManager = new FileManager();
         editor.replaceText(0, 0, readProgram("/main.hfx"));
     }
 
+    public void setPrimaryStage(Stage primaryStage) {
+        this.primaryStage = primaryStage;
+    }
+
     public void stop() {
         syntaxHighlighter.release();
     }
 
-    private static String readProgram(String path) {
+    @Override
+    public void logError(String message) {
+        log.insertText(0, message + System.lineSeparator());
+    }
+
+    private String readProgram(String path) {
         val fallbackProgram = "composition(640, 480, 25)";
         try (InputStream is = Main.class.getResourceAsStream(path)) {
             if (is == null) {
                 return fallbackProgram;
             }
-            val baos = new ByteArrayOutputStream();
-            val bufferSize = 4096;
-            val buffer = new byte[bufferSize];
-            int read;
-            while ((read = is.read(buffer, 0, bufferSize)) != -1)  {
-                baos.write(buffer, 0, read);
-            }
-            return baos.toString("UTF-8");
+            return IOStream.readContent(is);
         } catch (IOException ioe) {
             return fallbackProgram;
         }

app/src/main/resources/fxml/Editor.fxml

@@ -21,6 +21,7 @@
         <VBox BorderPane.alignment="CENTER">
             <MenuBar>
                 <Menu mnemonicParsing="false" text="File">
+                    <MenuItem onAction="#handleMenuOpen" text="Open"/>
                     <MenuItem onAction="#handleMenuExit" text="Exit"/>
                 </Menu>
                 <Menu mnemonicParsing="false" text="Composition">