Improvements around external file types (#3887)

* Refactor external file types and extract interface

* Fix ExternalFileType dialog

* Catch exception for not valid paths

* Fix build

* Fix checkstyle

Author: tobiasdiez

src/main/java/org/jabref/gui/actions/EditExternalFileTypesAction.java

@@ -2,19 +2,15 @@
 
 import org.jabref.gui.externalfiletype.ExternalFileTypeEditor;
 
-//TODO: DOES NOT SHOW UP
 public class EditExternalFileTypesAction extends SimpleCommand {
 
     private ExternalFileTypeEditor editor;
 
     @Override
     public void execute() {
         if (editor == null) {
-            editor = new ExternalFileTypeEditor(null);
-            editor.setVisible(true);
-
+            editor = new ExternalFileTypeEditor();
         }
-
+        editor.show();
     }
-
 }

src/main/java/org/jabref/gui/desktop/JabRefDesktop.java

@@ -136,7 +136,13 @@ public static boolean openExternalFileAnyFormat(final BibDatabaseContext databas
             openExternalFilePlatformIndependent(type, filePath);
             return true;
         } else {
-            // No file matched the name, or we did not know the file type.
+            // No file matched the name, try to open it directly using the given app
+            if (type.isPresent()) {
+                openExternalFilePlatformIndependent(type, link);
+                return true;
+            }
+
+            // Run out of ideas what to do...
             return false;
         }
     }

src/main/java/org/jabref/gui/externalfiletype/CustomExternalFileType.java

@@ -0,0 +1,205 @@
+package org.jabref.gui.externalfiletype;
+
+import java.util.Objects;
+
+import javax.swing.JLabel;
+
+import org.jabref.gui.icon.IconTheme;
+import org.jabref.gui.icon.JabRefIcon;
+
+/**
+ * This class defines a type of external files that can be linked to from JabRef.
+ * The class contains enough information to provide an icon, a standard extension
+ * and a link to which application handles files of this type.
+ */
+public class CustomExternalFileType implements ExternalFileType {
+
+    private final JLabel label = new JLabel();
+    private String name;
+    private String extension;
+    private String openWith;
+    private String iconName;
+    private String mimeType;
+    private JabRefIcon icon;
+
+    public CustomExternalFileType(String name, String extension, String mimeType,
+                                  String openWith, String iconName, JabRefIcon icon) {
+        label.setText(null);
+        this.name = name;
+        label.setToolTipText(this.name);
+        this.extension = extension;
+        this.mimeType = mimeType;
+        this.openWith = openWith;
+
+        setIconName(iconName);
+        setIcon(icon);
+    }
+
+    public CustomExternalFileType(ExternalFileType type) {
+        this(type.getName(), type.getExtension(), type.getMimeType(), type.getOpenWithApplication(), "", type.getIcon());
+    }
+
+    /**
+     * Construct an ExternalFileType from a String array. This is used when
+     * reading file type definitions from Preferences, where the available data types are
+     * limited. We assume that the array contains the same values as the main constructor,
+     * in the same order.
+     *
+     * @param val arguments.
+     */
+    public static ExternalFileType buildFromArgs(String[] val) {
+        if ((val == null) || (val.length < 4) || (val.length > 5)) {
+            throw new IllegalArgumentException("Cannot construct ExternalFileType without four elements in String[] argument.");
+        }
+        String name = val[0];
+        String extension = val[1];
+        String openWith;
+        String mimeType;
+        String iconName;
+
+        if (val.length == 4) {
+            // Up to version 2.4b the mime type is not included:
+            mimeType = "";
+            openWith = val[2];
+            iconName = val[3];
+        } else {
+            // When mime type is included, the array length should be 5:
+            mimeType = val[2];
+            openWith = val[3];
+            iconName = val[4];
+        }
+
+        // set icon to default first
+        JabRefIcon icon = IconTheme.JabRefIcons.FILE;
+
+        // check whether there is another icon defined for this file type
+        for (ExternalFileType fileType : ExternalFileTypes.getDefaultExternalFileTypes()) {
+            if (fileType.getName().equals(name)) {
+                icon = fileType.getIcon();
+                break;
+            }
+        }
+
+        return new CustomExternalFileType(name, extension, mimeType, openWith, iconName, icon);
+    }
+
+    @Override
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+        label.setToolTipText(this.name);
+    }
+
+    @Override
+    public String getExtension() {
+        if (extension == null) {
+            return "";
+        }
+        return extension;
+    }
+
+    public void setExtension(String extension) {
+        this.extension = extension;
+    }
+
+    @Override
+    public String getMimeType() {
+        if (mimeType == null) {
+            return "";
+        }
+        return mimeType;
+    }
+
+    public void setMimeType(String mimeType) {
+        this.mimeType = mimeType;
+    }
+
+    @Override
+    public String getOpenWithApplication() {
+        if (openWith == null) {
+            return "";
+        }
+        return openWith;
+    }
+
+    public void setOpenWith(String openWith) {
+        this.openWith = openWith;
+    }
+
+    /**
+     * Obtain a JLabel instance set with this file type's icon. The same JLabel
+     * is returned from each call of this method.
+     *
+     * @return the label.
+     */
+    public JLabel getIconLabel() {
+        return label;
+    }
+
+    /**
+     * Get the string associated with this file type's icon.
+     *
+     * @return The icon name.
+     */
+    public String getIconName() {
+        return iconName;
+    }
+
+    /**
+     * Set the string associated with this file type's icon.
+     *
+     * @param name The icon name to use.
+     */
+    public void setIconName(String name) {
+        this.iconName = name;
+    }
+
+    @Override
+    public JabRefIcon getIcon() {
+        return icon;
+    }
+
+    public void setIcon(JabRefIcon icon) {
+        Objects.requireNonNull(icon);
+        this.icon = icon;
+        label.setIcon(this.icon.getSmallIcon());
+    }
+
+    @Override
+    public String toString() {
+        return getName();
+    }
+
+    public ExternalFileType copy() {
+        return new CustomExternalFileType(name, extension, mimeType, openWith, iconName, icon);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(name, extension, mimeType, openWith, iconName);
+    }
+
+    /**
+     * We define two file type objects as equal if their name, extension, openWith and
+     * iconName are equal.
+     *
+     * @param object The file type to compare with.
+     * @return true if the file types are equal.
+     */
+    @Override
+    public boolean equals(Object object) {
+        if (this == object) {
+            return true;
+        }
+
+        if (object instanceof CustomExternalFileType) {
+            CustomExternalFileType other = (CustomExternalFileType) object;
+            return Objects.equals(name, other.name) && Objects.equals(extension, other.extension) &&
+                    Objects.equals(mimeType, other.mimeType) && Objects.equals(openWith, other.openWith) && Objects.equals(iconName, other.iconName);
+        }
+        return false;
+    }
+}