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/*
 * Copyright © 1996-2009 GlobalMentor, Inc. 
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.globalmentor.swing;

import java.awt.Component;
import java.io.*;
import java.net.URI;
import java.util.prefs.Preferences;

import javax.swing.*;

import com.globalmentor.io.*;
import com.globalmentor.log.Log;
import static com.globalmentor.net.URIs.*;

import com.globalmentor.net.ResourceSelector;
import com.globalmentor.rdf.*;
import com.globalmentor.util.prefs.PreferencesUtilities;

/**
 * An implementation of a resource selector that selects resources from a file system and returns RDF resources as descriptions of selected files.
 * @author Garret Wilson
 */
public class FileRDFResourceSelector extends DefaultURIAccessible implements ResourceSelector {

	/** The preference for storing the current directory. */
	protected final String CURRENT_DIRECTORY_PREFERENCE = PreferencesUtilities.getPreferenceName(getClass(), "current.directory");

	/** The preferences that should be used for this object, or null if the default preferences for this class should be used. */
	private Preferences preferences = null;

	/**
	 * @return The preferences that should be used for this object, or the default preferences for this class if no preferences are specifically set.
	 * @throws SecurityException Thrown if a security manager is present and it denies RuntimePermission("preferences").
	 */
	public Preferences getPreferences() throws SecurityException {
		return preferences != null ? preferences : Preferences.userNodeForPackage(getClass()); //return the user preferences node for whatever class extends this one 
	}

	/**
	 * Sets the preferences to be used for this panel.
	 * @param preferences The preferences that should be used for this panel, or null if the default preferences for this class should be used
	 */
	public void setPreferences(final Preferences preferences) {
		this.preferences = preferences; //store the preferences
	}

	/** The component to serve as a parent for file dialogs. */
	private final Component parentComponent;

	/** @return The component to serve as a parent for file dialogs. */
	protected Component getParentComponent() {
		return parentComponent;
	}

	/**
	 * Parent component constructor.
	 * @param parentComponent The component to serve as a parent for file dialogs.
	 */
	public FileRDFResourceSelector(final Component parentComponent) {
	this.parentComponent = parentComponent; //save the parent component
	}

	/**
	 * Retrieves a description of the resource with the given reference URI.
	 * @param referenceURI The reference URI of the resource in question.
	 * @return A description of the identified resource.
	 * @throws IOException Thrown if there is an error retrieving the resource description.
	 */
	public RDFResource getResource(final URI referenceURI) throws IOException {
		return new DefaultRDFResource(referenceURI); //create a default resource from the reference URI
		/*TODO convert to Marmot
				if(FILE_SCHEME.equals(referenceURI.getScheme())) {	//if this is a file:// URI 
					final File file=new File(referenceURI);	//create a new file from the reference URI
					return new RDFFileProcessor().createResource(file);	//return a resource representing the selected file
				}
				else {	//if this is not a file URI
					return new DefaultRDFResource(referenceURI);	//create a default resource from the reference URI
				}
		*/
	}

	/**
	 * Selects a resource for input.
	 * @param oldResource The currently selected resource, if applicable, or null if there is no selected resource.
	 * @return The selected resource, or null if selection was canceled.
	 * @throws SecurityException Thrown if selecting an input resource is not allowed.
	 * @throws IOException Thrown if there is an error locating a resource.
	 */
	public RDFResource selectInputResource(final RDFResource oldResource) throws SecurityException, IOException {
		//if we were given a resource with a valid file URI, create a file from that URI and get the parent directory of that file
		File currentDirectory = oldResource != null && oldResource.getURI() != null && FILE_SCHEME.equals(oldResource.getURI().getScheme()) ? new File(
				oldResource.getURI()).getParentFile() //get the parent file
				: null; //if this was not a file URI, we can't get the current directory
		if(currentDirectory == null) { //if we don't know the current directory, try to use the one from the preferences
			try {
				final Preferences preferences = getPreferences(); //get the preferences
				final String currentDirectoryString = preferences.get(CURRENT_DIRECTORY_PREFERENCE, null); //get the current directory from the preferences
				if(currentDirectoryString != null) { //if we know a current directory from the preferences
					currentDirectory = new File(currentDirectoryString); //create a file with the current directory
				}
			} catch(SecurityException securityException) { //if we can't access preferences
				Log.warn(securityException); //warn of the security problem			
			}
		}
		final JFileChooser fileChooser = new JFileChooser(currentDirectory); //create a new dialog for listing files
		final int option = fileChooser.showOpenDialog(getParentComponent()); //show the open dialog
		if(option == JFileChooser.APPROVE_OPTION) { //if they chose a file
			try {
				final Preferences preferences = getPreferences(); //get the preferences
				preferences.put(CURRENT_DIRECTORY_PREFERENCE, fileChooser.getCurrentDirectory().toString()); //store the current directory name in the preferences
			} catch(SecurityException securityException) { //if we can't access preferences
				Log.warn(securityException); //warn of the security problem			
			}
			final File selectedFile = fileChooser.getSelectedFile(); //get the file they chose
			if(selectedFile != null) { //if they chose a file
				return getResource(Files.toURI(selectedFile)); //convert the file into a URI and create a resource to describe it
			}
		}
		return null; //show that we couldn't select a file	

	}

	/**
	 * Selects a resource for output.
	 * @param oldResource The currently selected resource, if applicable, or null if there is no selected resource.
	 * @return The selected resource, or null if selection was canceled.
	 * @throws SecurityException Thrown if selecting an output resource is not allowed.
	 * @throws IOException Thrown if there is an error locating a resource.
	 */
	public RDFResource selectOutputResource(final RDFResource oldResource) throws SecurityException, IOException {
		throw new UnsupportedOperationException(); //indicate that this operation is not yet supported 
	}

}