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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.unicode;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;

import static com.globalmentor.java.Objects.*;

import com.globalmentor.swing.*;
import com.globalmentor.swing.text.TextComponents;
import com.globalmentor.text.Unicode;
import com.globalmentor.unicode.*;

/**
 * A status bar showing Unicode code point value, name, and category.
 * @author Garret Wilson
 */
public class UnicodeStatusBar extends StatusBar {

	/** The last known position in a document, or -1 if not known. */
	private int position = -1;

	/** @return The last known position in a document, or -1 if not known. */
	protected int getPosition() {
		return position;
	};

	/** The label for a Unicode character value. */
	protected final JLabel unicodeCharacterValueLabel;

	/** The label for a Unicode character name. */
	protected final JLabel unicodeCharacterNameLabel;

	/**
	 * The caret listener that updates the status bar in response to a caret event.
	 * @see #updateStatus(CaretEvent)
	 */
	protected final CaretListener caretListener = new CaretListener() {

		public void caretUpdate(final CaretEvent caretEvent) {
			updateStatus(caretEvent);
		}
	};

	/**
	 * The document listener that updates the status bar in response to a document event.
	 * @see #updateStatus(DocumentEvent)
	 */
	protected final DocumentListener documentListener = new DocumentListener() {

		public void insertUpdate(final DocumentEvent documentEvent) {
			updateStatus(documentEvent);
		}

		public void removeUpdate(final DocumentEvent documentEvent) {
			updateStatus(documentEvent);
		}

		public void changedUpdate(final DocumentEvent documentEvent) {
			updateStatus(documentEvent);
		}
	};

	/**
	 * The document change listener that updates the document listener in response to a document change.
	 * @see #onDocumentChange(Document, Document)
	 */
	protected final PropertyChangeListener documentPropertyChangeListener = new PropertyChangeListener() {

		public void propertyChange(final PropertyChangeEvent propertyChangeEvent) {
			onDocumentChange(asInstance(propertyChangeEvent.getOldValue(), Document.class), asInstance(propertyChangeEvent.getNewValue(), Document.class));
		}
	};

	/** Default constructor. */
	public UnicodeStatusBar() {
		this(true); //construct a panel and initialize it	
	}

	/**
	 * Constructor with optional initialization.
	 * @param initialize true if the toolbar should initialize itself by calling the initialization methods.
	 */
	public UnicodeStatusBar(final boolean initialize) {
		super("Unicode Character Information", false); //construct the parent class without initializing it	//TODO i18n
		unicodeCharacterValueLabel = createStatusLabel(); //create a label for the Unicode character value
		unicodeCharacterNameLabel = createStatusLabel(); //create a label for the Unicode character name
		if(initialize) //if we should initialize
			initialize(); //initialize the panel
	}

	/** Initializes the user interface. */
	public void initializeUI() {
		super.initializeUI(); //do the default user interface initialization
		addStatusComponent(unicodeCharacterValueLabel); //add the Unicode character value label
		addStatusComponent(unicodeCharacterNameLabel); //add the Unicode character name label
	}

	/** The currently displayed Unicode character, or null if no character is currently being displayed. */
	private UnicodeCharacter unicodeCharacter = null;

	/** @return The currently displayed Unicode character, or null if no character is currently being displayed. */
	public UnicodeCharacter getUnicodeCharacter() {
		return unicodeCharacter;
	}

	/** The currently displayed Unicode code point, or -1 if no code point is currently being displayed. */
	private int codePoint = -1;

	/** @return The currently displayed Unicode code point, or -1 if no code point is currently being displayed. */
	public int getCodePoint() {
		return codePoint;
	}

	/**
	 * Sets the Unicode character status by changing the displayed code point.
	 * @param codePoint The Unicode code point, or -1 for no code point.
	 */
	public void setCodePoint(final int codePoint) {
		if(getCodePoint() != codePoint) { //if the code point is really changing
			this.codePoint = codePoint; //save the code point
			unicodeCharacter = codePoint >= 0 ? UnicodeData.getUnicodeCharacter(codePoint) : null; //if a code point was indicated, try to get a character corresponding to the code point
			if(codePoint >= 0) { //if a valid code point was indicated
				unicodeCharacterValueLabel.setText(Unicode.getCodePointString(codePoint)); //show the Unicode character value
				if(unicodeCharacter != null) { //if we found Unicode character information
					unicodeCharacterNameLabel.setText(unicodeCharacter.getUniqueCharacterName()); //show the Unicode character name
				} else { //if we didn't find a Unicode character
					unicodeCharacterNameLabel.setText(""); //show no Unicode character name			
				}
			} else { //if we don't have a valid Unicode code point
				unicodeCharacterValueLabel.setText(""); //show no Unicode character value
				unicodeCharacterNameLabel.setText(""); //show no Unicode character name			
			}
		}
	}

	/**
	 * Updates the status, such as the Unicode character information labels, for the text component character at the caret position.
	 * @param textComponent The text component that holds Unicode characters.
	 */
	public void updateStatus(final JTextComponent textComponent) {
		updateStatus(textComponent.getDocument(), textComponent.getCaretPosition()); //update the status for the text component for the character at the given position
	}

	/**
	 * Updates the status, such as the Unicode character information labels, for the text component character at the given position. The given position is saved.
	 * @param document The document that holds Unicode characters.
	 * @param position The position for which the status should be shown.
	 */
	public void updateStatus(final Document document, final int position) {
		try {
			final String unicodeString = document.getText(position, 1); //get the single character at the given position
			setCodePoint(unicodeString.charAt(0)); //set the code point to the character at the given position
		} catch(BadLocationException e) { //if the caret isn't at a valid position
			unicodeCharacter = null; //show that we don't have a Unicode character
		}
		this.position = position; //save the position
	}

	/**
	 * Updates the status when a text component caret is updated by updating the Unicode status labels to represent the character under the caret.
	 * @param caretEvent The event that holds information about the caret change.
	 * @see #updateStatus(JTextComponent, int)
	 */
	protected void updateStatus(final CaretEvent caretEvent) {
		final Object source = caretEvent.getSource(); //get the source of the event
		if(source instanceof JTextComponent) { //if a text component made the change
			updateStatus(((JTextComponent)source).getDocument(), caretEvent.getDot()); //update the status for the character under the new cursor position
		}
	}

	/**
	 * Updates the status when a text component document is changed if that change appears under the cursor.
	 * @param documentEvent The event that holds information about the document change.
	 * @see #updateStatus(JTextComponent, int)
	 */
	protected void updateStatus(final DocumentEvent documentEvent) {
		final int position = getPosition(); //get our current position
		final int eventOffset = documentEvent.getOffset(); //get the event's offset
		if(position >= eventOffset && position < eventOffset + documentEvent.getLength()) { //if our position is within the event range			
			updateStatus(documentEvent.getDocument(), position); //update the status for the current character under the position
		}
	}

	/**
	 * Updates the document changes listeners based upon the change of document.
	 * @param oldDocument The old document, or null if there was no previous document.
	 * @param newDocument The new document, or null if there is no new document.
	 */
	protected void onDocumentChange(final Document oldDocument, final Document newDocument) {
		if(oldDocument != null) { //if there was a previous document
			oldDocument.removeDocumentListener(documentListener); //stop listening for document changes from the old document
		}
		if(newDocument != null) { //if there is a new document
			newDocument.addDocumentListener(documentListener); //listen for document changes in the new document
		}
	}

	/**
	 * Attaches this status bar to a text component so that it will be updated when the text component changes.
	 * @param textComponent The text component to which the status bar should be attached.
	 */
	public void attach(final JTextComponent textComponent) {
		textComponent.addCaretListener(caretListener); //listen for caret events
		textComponent.getDocument().addDocumentListener(documentListener); //listen for document changes in the document
		textComponent.addPropertyChangeListener(TextComponents.DOCUMENT_PROPERTY, documentPropertyChangeListener); //listen for document changes
		updateStatus(textComponent); //update the status for the text component, which will save the current caret position
	}

	/**
	 * Detaches this status bar from a text component so that it will no longer be be updated when the text component changes.
	 * @param textComponent The text component from which the status bar should be detached.
	 */
	public void detach(final JTextComponent textComponent) {
		textComponent.removeCaretListener(caretListener); //stop listening for caret events
		textComponent.getDocument().removeDocumentListener(documentListener); //stop listening for document changes in the document
		textComponent.removePropertyChangeListener(TextComponents.DOCUMENT_PROPERTY, documentPropertyChangeListener); //listen for document changes
		position = -1; //show that we no longer represent a valid position
	}
}