ecommons.waltable/org.eclipse.statet.ecommons.waltable.core/src/org/eclipse/statet/ecommons/waltable/export/FileOutputStreamProvider.java

/*=============================================================================#
 # Copyright (c) 2012, 2021 Original NatTable authors and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0
 # 
 # Contributors:
 #     Original NatTable authors and others - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ecommons.waltable.export;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.OutputStream;
import java.io.PrintStream;

import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.FileDialog;
import org.eclipse.swt.widgets.Shell;

import org.eclipse.statet.internal.ecommons.waltable.WaLTablePlugin;


/**
 * Implementation of IOutputStreamProvider that will open a {@link FileDialog} on requesting
 * an OutputStream, to let a user specify the location to write a file.
 */
public class FileOutputStreamProvider implements IOutputStreamProvider {

	protected String defaultFileName;
	protected String[] defaultFilterNames;
	protected String[] defaultFilterExtensions;

	protected String currentFileName;
	
	public FileOutputStreamProvider(final String defaultFileName, final String[] defaultFilterNames, final String[] defaultFilterExtensions) {
		this.defaultFileName= defaultFileName;
		this.defaultFilterNames= defaultFilterNames;
		this.defaultFilterExtensions= defaultFilterExtensions;
	}
	
	/**
	 * Opens a {@link FileDialog} to let a user choose the location to write the export to,
	 * and returns the corresponding {@link PrintStream} to that file.
	 */
	@Override
	public OutputStream getOutputStream(final Shell shell) {
		final FileDialog dialog= new FileDialog(shell, SWT.SAVE);
		
		String filterPath;
		String relativeFileName;
		
		final int lastIndexOfFileSeparator= this.defaultFileName.lastIndexOf(File.separator);
		if (lastIndexOfFileSeparator >= 0) {
			filterPath= this.defaultFileName.substring(0, lastIndexOfFileSeparator);
			relativeFileName= this.defaultFileName.substring(lastIndexOfFileSeparator + 1);
		} else {
			filterPath= "/"; //$NON-NLS-1$
			relativeFileName= this.defaultFileName;
		}
		
		dialog.setFilterPath(filterPath);
		dialog.setOverwrite(true);

		dialog.setFileName(relativeFileName);
		dialog.setFilterNames(this.defaultFilterNames);
		dialog.setFilterExtensions(this.defaultFilterExtensions);
		this.currentFileName= dialog.open();
		if (this.currentFileName == null) {
			return null;
		}
		
		try {
			return new PrintStream(this.currentFileName);
		} catch (final FileNotFoundException e) {
			WaLTablePlugin.log(new Status(IStatus.ERROR, WaLTablePlugin.BUNDLE_ID,
					"Failed to open or create the file: " + this.currentFileName, e )); //$NON-NLS-1$
			this.currentFileName= null;
			return null;
		}
	}
	
	@Override
	public File getResult() {
		return (this.currentFileName != null) ? new File(this.currentFileName) : null;
	}
}