/*=========================================================================

  Program:   FusionViewer
  Module:    $RCSfile: Configuration.java,v $
  Language:  Java
  Date:      $Date: 2007/02/02 19:26:29 $
  Version:   $Revision: 1.2 $
  
  Copyright (c) Insightful Corporation.  All rights reserved.
  See Copyright.txt for details.
  
  This software is distributed WITHOUT ANY WARRANTY; without even
  the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  PURPOSE.  See the above copyright notice for more information.

=========================================================================*/

package org.fusionviewer.io;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import org.fusionviewer.ui.ViewArrangement;
import org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.Format;
import org.jdom.output.XMLOutputter;



/**\class Configuration
 *\brief Saves and loads application settings from an XML file.
 */
public class Configuration {
	private File m_configFile;								// Location of the configuration file
	private FileHistory m_fileHistory = new FileHistory();	// List of files recently opened
	private int m_lastDisplayLayout = FUSION_LAYOUT;
	private int m_lastImageOrientation = ViewArrangement.AXIAL;

	public final static int FUSION_LAYOUT = 1;
	public final static int LINKED_CURSOR_LAYOUT = 2;

	private final static String DOCUMENT = "Configuration";
	private final static String FILE_HISTORY_TAG = "RecentFiles";
	private final static String DISPLAY_MODE_TAG = "DisplayMode";
	private final static String IMAGE_ORIENTATION_TAG = "ImageOrientation";

	private final static String FUSION_LAYOUT_STRING = "Fusion";
	private final static String LINKED_CURSOR_LAYOUT_STRING = "Linked Cursor";
	
	private final static String AXIAL_ORIENTATION_STRING = "Axial";
	private final static String SAGITTAL_ORIENTATION_STRING = "Sagittal";
	private final static String CORONAL_ORIENTATION_STRING = "Coronal";

	private static Configuration m_configuration;				// Singleton instance
	
	/**
	 * Return the single instance of the Configuration object
	 * 
	 * @return a Configuration
	 */
	public static synchronized Configuration getConfiguration() {
		if (m_configuration == null) {
			try {
				// Try loading an existing configuration file
				m_configuration = new Configuration();
			} catch (IOException e) {
				// If the load failed, create a new default Configuration
				m_configuration = new Configuration(true);
			}
		}
		
		return m_configuration;
	}
	
	/*
	 * Create a new Configuration, loading a configuration file if it exists.
	 */
	private Configuration() throws IOException {
		m_configFile = new File(Env.PREFERENCES_DIRECTORY, Env.CONFIG);
		if (m_configFile.exists())
			load();
	}
	
	/*
	 * Create a new Configuration with the default settings.
	 */
	private Configuration(boolean noLoad) {
		m_configFile = new File(Env.PREFERENCES_DIRECTORY, Env.CONFIG);
	}
	
	/**
	 * Saves the application configuration.
	 *
	 * @throws IOException
	 */
	public void save() throws IOException {
		Element rootElement = new Element(DOCUMENT);
		Document doc = new Document(rootElement);
		
		// Add display mode
		Element displayModeElement = new Element(DISPLAY_MODE_TAG);

		if (m_lastDisplayLayout == FUSION_LAYOUT)
			displayModeElement.addContent(FUSION_LAYOUT_STRING);
		else if (m_lastDisplayLayout == LINKED_CURSOR_LAYOUT)
			displayModeElement.addContent(LINKED_CURSOR_LAYOUT_STRING);
		else
			displayModeElement.addContent(FUSION_LAYOUT_STRING);

		rootElement.addContent(displayModeElement);
		
		// Add image orientation
		Element imageOrientationElement = new Element(IMAGE_ORIENTATION_TAG);

		if (m_lastImageOrientation == ViewArrangement.AXIAL)
			imageOrientationElement.addContent(AXIAL_ORIENTATION_STRING);
		else if (m_lastImageOrientation == ViewArrangement.SAGITTAL)
			imageOrientationElement.addContent(SAGITTAL_ORIENTATION_STRING);
		else if (m_lastImageOrientation == ViewArrangement.CORONAL)
			imageOrientationElement.addContent(CORONAL_ORIENTATION_STRING);
		else
			imageOrientationElement.addContent(AXIAL_ORIENTATION_STRING);
		
		rootElement.addContent(imageOrientationElement);

		// Add file history
		Element fileList = new Element(FILE_HISTORY_TAG);
		m_fileHistory.getFileHistoryAsXml(fileList);
		rootElement.addContent(fileList);

		// Write XML text to a file
		XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat());
		FileWriter writer = new FileWriter(m_configFile);
		try {
			outputter.output(doc, writer);
		} finally {
			writer.close();
		}
	}
		
	/*
	 * Loads the application configuration.
	 */
	private void load() throws IOException {
		try {
			SAXBuilder builder = new SAXBuilder();
			Document doc = builder.build(m_configFile);
			Element root = doc.getRootElement();

			String displayMode = root.getChildTextTrim(DISPLAY_MODE_TAG);
			if (displayMode != null) {
				if (displayMode.compareToIgnoreCase(FUSION_LAYOUT_STRING) == 0)
					m_lastDisplayLayout = FUSION_LAYOUT;
				else if (displayMode.compareToIgnoreCase(LINKED_CURSOR_LAYOUT_STRING) == 0)
					m_lastDisplayLayout = LINKED_CURSOR_LAYOUT;
			}
			
			String imageOrientation = root.getChildTextTrim(IMAGE_ORIENTATION_TAG);
			if (imageOrientation != null) {
				if (imageOrientation.compareToIgnoreCase(AXIAL_ORIENTATION_STRING) == 0)
					m_lastImageOrientation = ViewArrangement.AXIAL;
				else if (imageOrientation.compareToIgnoreCase(SAGITTAL_ORIENTATION_STRING) == 0)
					m_lastImageOrientation = ViewArrangement.SAGITTAL;
				else if (imageOrientation.compareToIgnoreCase(CORONAL_ORIENTATION_STRING) == 0)
					m_lastImageOrientation = ViewArrangement.CORONAL;
			}
			
			m_fileHistory.readFromXml(root.getChild(FILE_HISTORY_TAG));
		} catch (JDOMException e) {
			throw new IOException(e.getMessage());
		}
	}
	
	/**
	 * Return a list of recently opened file pairs.
	 * 
	 * @return file history list
	 */
	public FileHistory getFileHistory() {
		return m_fileHistory;
	}

	/**
	 * Return the last display layout type used (fusion or linked cursor).
	 * 
	 * @return display layout
	 */
	public int getLastDisplayLayout() {
		return m_lastDisplayLayout;
	}

	/**
	 * Set the last display layout type used (fusion or linked cursor).
	 * 
	 * @param layout display layout
	 */
	public void setLastDisplayLayout(int layout) {
		if ((layout != FUSION_LAYOUT) && (layout != LINKED_CURSOR_LAYOUT))
			throw new IllegalArgumentException("Unknown layout type " + Integer.toString(layout));

		m_lastDisplayLayout = layout;
	}

	/**
	 * Get the last image orientation used
	 * 
	 * @return image orientation as defined in ViewArrangement
	 */
	public int getLastImageOrientation() {
		return m_lastImageOrientation;
	}

	/**
	 * Set the last image orientation used
	 * 
	 * @param orientation image orientation as defined in ViewArrangement
	 */
	public void setLastImageOrientation(int orientation) {
		if ((orientation != ViewArrangement.AXIAL) && (orientation != ViewArrangement.SAGITTAL) &&
				(orientation != ViewArrangement.CORONAL))
			throw new IllegalArgumentException("Unknown orientation " + Integer.toString(orientation));
		
		m_lastImageOrientation = orientation;
	}
}