/* *************************************************************************
 
 IT Mill Toolkit 

 Development of Browser User Interfaces Made Easy

 Copyright (C) 2000-2006 IT Mill Ltd
 
 *************************************************************************

 This product is distributed under commercial license that can be found
 from the product package on license.pdf. Use of this product might 
 require purchasing a commercial license from IT Mill Ltd. For guidelines 
 on usage, see licensing-guidelines.html

 *************************************************************************
 
 For more information, contact:
 
 IT Mill Ltd                           phone: +358 2 4802 7180
 Ruukinkatu 2-4                        fax:   +358 2 4802 7181
 20540, Turku                          email:  info@itmill.com
 Finland                               company www: www.itmill.com
 
 Primary source for information and releases: www.itmill.com

 ********************************************************************** */

package com.itmill.toolkit.ui;

import java.lang.reflect.Method;

import com.itmill.toolkit.data.Property;
import com.itmill.toolkit.data.util.ObjectProperty;
import com.itmill.toolkit.terminal.PaintException;
import com.itmill.toolkit.terminal.PaintTarget;

/**
 * Label component for showing non-editable short texts.
 * 
 * The label content can be set to the modes specified by the final members
 * CONTENT_*
 * 
 * <p>
 * The contents of the label may contain simple formatting:
 * <ul>
 * <li> <b>&lt;b></b> Bold
 * <li> <b>&lt;i></b> Italic
 * <li> <b>&lt;u></b> Underlined
 * <li> <b>&lt;br/></b> Linebreak
 * <li> <b>&lt;ul>&lt;li>item 1&lt;/li>&lt;li>item 2&lt;/li>&lt;/ul></b> List
 * of items
 * </ul>
 * The <b>b</b>,<b>i</b>,<b>u</b> and <b>li</b> tags can contain all the
 * tags in the list recursively.
 * </p>
 * 
 * @author IT Mill Ltd.
 * @version
 * @VERSION@
 * @since 3.0
 */
public class Label extends AbstractComponent implements Property,
		Property.Viewer, Property.ValueChangeListener,
		Property.ValueChangeNotifier, Comparable {

	/**
	 * Content mode, where the label contains only plain text. The getValue()
	 * result is coded to XML when painting.
	 */
	public static final int CONTENT_TEXT = 0;

	/**
	 * Content mode, where the label contains preformatted text.
	 */
	public static final int CONTENT_PREFORMATTED = 1;

	/**
	 * Formatted content mode, where the contents is XML restricted to the UIDL
	 * 1.0 formatting markups.
	 */
	public static final int CONTENT_UIDL = 2;

	/**
	 * Content mode, where the label contains XHTML. Contents is then enclosed
	 * in DIV elements having namespace of
	 * "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd".
	 */
	public static final int CONTENT_XHTML = 3;

	/**
	 * Content mode, where the label contains well-formed or well-balanced XML.
	 * Each of the root elements must have their default namespace specified.
	 */
	public static final int CONTENT_XML = 4;

	/**
	 * Content mode, where the label contains RAW output. Output is not required
	 * to comply to with XML. In Web Adapter output is inserted inside the
	 * resulting HTML document as-is. This is useful for some specific purposes
	 * where possibly broken HTML content needs to be shown, but in most cases
	 * XHTML mode should be preferred.
	 */
	public static final int CONTENT_RAW = 5;

	/**
	 * The default content mode is plain text.
	 */
	public static final int CONTENT_DEFAULT = CONTENT_TEXT;

	/** Array of content mode names that are rendered in UIDL as mode attribute. */
	private static final String[] CONTENT_MODE_NAME = { "text", "pre", "uidl",
			"xhtml", "xml", "raw" };

	private Property dataSource;

	private int contentMode = CONTENT_DEFAULT;

	/**
	 * Creates an empty Label.
	 */
	public Label() {
		setPropertyDataSource(new ObjectProperty("", String.class));
	}

	/**
	 * Creates a new instance of Label with text-contents.
	 * 
	 * @param content
	 */
	public Label(String content) {
		setPropertyDataSource(new ObjectProperty(content, String.class));
	}

	/**
	 * Creates a new instance of Label with text-contents read from given
	 * datasource.
	 * 
	 * @param contentSource
	 */
	public Label(Property contentSource) {
		setPropertyDataSource(contentSource);
	}

	/**
	 * Creates a new instance of Label with text-contents.
	 * 
	 * @param content
	 * @param contentMode
	 */
	public Label(String content, int contentMode) {
		setPropertyDataSource(new ObjectProperty(content, String.class));
		setContentMode(contentMode);
	}

	/**
	 * Creates a new instance of Label with text-contents read from given
	 * datasource.
	 * 
	 * @param contentSource
	 * @param contentMode
	 */
	public Label(Property contentSource, int contentMode) {
		setPropertyDataSource(contentSource);
		setContentMode(contentMode);
	}

	/**
	 * Get the component UIDL tag.
	 * 
	 * @return the Component UIDL tag as string.
	 */
	public String getTag() {
		return "label";
	}

	/**
	 * Set the component to read-only. Readonly is not used in label.
	 * 
	 * @param readOnly
	 *            True to enable read-only mode, False to disable it.
	 */
	public void setReadOnly(boolean readOnly) {
		if (dataSource == null)
			throw new IllegalStateException("Datasource must be se");
		dataSource.setReadOnly(readOnly);
	}

	/**
	 * Is the component read-only ? Readonly is not used in label - this returns
	 * allways false.
	 * 
	 * @return <code>true</code> if the component is in read only mode.
	 */
	public boolean isReadOnly() {
		if (dataSource == null)
			throw new IllegalStateException("Datasource must be se");
		return dataSource.isReadOnly();
	}

	/**
	 * Paints the content of this component.
	 * 
	 * @param target
	 *            the Paint Event.
	 * @throws PaintException
	 *             if the Paint Operation fails.
	 */
	public void paintContent(PaintTarget target) throws PaintException {
		if (contentMode != CONTENT_TEXT)
			target.addAttribute("mode", CONTENT_MODE_NAME[contentMode]);
		if (contentMode == CONTENT_TEXT)
			target.addText(toString());
		else if (contentMode == CONTENT_UIDL)
			target.addUIDL(toString());
		else if (contentMode == CONTENT_XHTML) {
			target.startTag("data");
			target.addXMLSection("div", toString(),
					"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd");
			target.endTag("data");
		} else if (contentMode == CONTENT_PREFORMATTED) {
			target.startTag("pre");
			target.addText(toString());
			target.endTag("pre");
		} else if (contentMode == CONTENT_XML) {
			target.addXMLSection("data", toString(), null);
		} else if (contentMode == CONTENT_RAW) {
			target.startTag("data");
			target.addAttribute("escape", false);
			target.addCharacterData(toString());
			target.endTag("data");
		}

	}

	/**
	 * Gets the value of the label. Value of the label is the XML contents of
	 * the label.
	 * 
	 * @return the Value of the label.
	 */
	public Object getValue() {
		if (dataSource == null)
			throw new IllegalStateException("Datasource must be se");
		return dataSource.getValue();
	}

	/**
	 * Set the value of the label. Value of the label is the XML contents of the
	 * label.
	 * 
	 * @param newValue
	 *            the New value of the label.
	 */
	public void setValue(Object newValue) {
		if (dataSource == null)
			throw new IllegalStateException("Datasource must be se");
		this.dataSource.setValue(newValue);
	}

	/**
	 * @see java.lang.Object#toString()
	 */
	public String toString() {
		if (dataSource == null)
			throw new IllegalStateException("Datasource must be se");
		return dataSource.toString();
	}

	/**
	 * Gets the type of the Property.
	 * 
	 * @see com.itmill.toolkit.data.Property#getType()
	 */
	public Class getType() {
		if (dataSource == null)
			throw new IllegalStateException("Datasource must be se");
		return dataSource.getType();
	}

	/**
	 * Gets the viewing data-source property.
	 * 
	 * @return the data source property.
	 * @see com.itmill.toolkit.data.Property.Viewer#getPropertyDataSource()
	 */
	public Property getPropertyDataSource() {
		return dataSource;
	}

	/**
	 * Sets the property as data-source for viewing.
	 * 
	 * @param newDataSource
	 *            the new data source Property
	 * @see com.itmill.toolkit.data.Property.Viewer#setPropertyDataSource(com.itmill.toolkit.data.Property)
	 */
	public void setPropertyDataSource(Property newDataSource) {
		// Stops listening the old data source changes
		if (dataSource != null
				&& Property.ValueChangeNotifier.class
						.isAssignableFrom(dataSource.getClass()))
			((Property.ValueChangeNotifier) dataSource).removeListener(this);

		// Sets the new data source
		dataSource = newDataSource;

		// Listens the new data source if possible
		if (dataSource != null
				&& Property.ValueChangeNotifier.class
						.isAssignableFrom(dataSource.getClass()))
			((Property.ValueChangeNotifier) dataSource).addListener(this);
	}

	/**
	 * Gets the content mode of the Label.
	 * 
	 * <p>
	 * Possible content modes include:
	 * <ul>
	 * <li><b>CONTENT_TEXT</b> Content mode, where the label contains only
	 * plain text. The getValue() result is coded to XML when painting.</li>
	 * <li><b>CONTENT_PREFORMATTED</b> Content mode, where the label contains
	 * preformatted text.</li>
	 * <li><b>CONTENT_UIDL</b> Formatted content mode, where the contents is
	 * XML restricted to the UIDL 1.0 formatting markups.</li>
	 * <li><b>CONTENT_XHTML</b> Content mode, where the label contains XHTML.
	 * Contents is then enclosed in DIV elements having namespace of
	 * "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd".</li>
	 * <li><b>CONTENT_XML</b> Content mode, where the label contains
	 * well-formed or well-balanced XML. Each of the root elements must have
	 * their default namespace specified.</li>
	 * <li><b>CONTENT_RAW</b> Content mode, where the label contains RAW
	 * output. Output is not required to comply to with XML. In Web Adapter
	 * output is inserted inside the resulting HTML document as-is. This is
	 * useful for some specific purposes where possibly broken HTML content
	 * needs to be shown, but in most cases XHTML mode should be preferred.</li>
	 * </ul>
	 * </p>
	 * 
	 * @return the Content mode of the label.
	 */
	public int getContentMode() {
		return contentMode;
	}

	/**
	 * Sets the content mode of the Label.
	 * 
	 * <p>
	 * Possible content modes include:
	 * <ul>
	 * <li><b>CONTENT_TEXT</b> Content mode, where the label contains only
	 * plain text. The getValue() result is coded to XML when painting.</li>
	 * <li><b>CONTENT_PREFORMATTED</b> Content mode, where the label contains
	 * preformatted text.</li>
	 * <li><b>CONTENT_UIDL</b> Formatted content mode, where the contents is
	 * XML restricted to the UIDL 1.0 formatting markups.</li>
	 * <li><b>CONTENT_XHTML</b> Content mode, where the label contains XHTML.
	 * Contents is then enclosed in DIV elements having namespace of
	 * "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd".</li>
	 * <li><b>CONTENT_XML</b> Content mode, where the label contains
	 * well-formed or well-balanced XML. Each of the root elements must have
	 * their default namespace specified.</li>
	 * <li><b>CONTENT_RAW</b> Content mode, where the label contains RAW
	 * output. Output is not required to comply to with XML. In Web Adapter
	 * output is inserted inside the resulting HTML document as-is. This is
	 * useful for some specific purposes where possibly broken HTML content
	 * needs to be shown, but in most cases XHTML mode should be preferred.</li>
	 * </ul>
	 * </p>
	 * 
	 * @param contentMode
	 *            the New content mode of the label.
	 */
	public void setContentMode(int contentMode) {
		if (contentMode >= CONTENT_TEXT && contentMode <= CONTENT_RAW)
			this.contentMode = contentMode;
	}

	/* Value change events ****************************************** */

	private static final Method VALUE_CHANGE_METHOD;

	static {
		try {
			VALUE_CHANGE_METHOD = Property.ValueChangeListener.class
					.getDeclaredMethod("valueChange",
							new Class[] { Property.ValueChangeEvent.class });
		} catch (java.lang.NoSuchMethodException e) {
			// This should never happen
			throw new java.lang.RuntimeException();
		}
	}

	/**
	 * Value change event
	 * 
	 * @author IT Mill Ltd.
	 * @version
	 * @VERSION@
	 * @since 3.0
	 */
	public class ValueChangeEvent extends Component.Event implements
			Property.ValueChangeEvent {

		/**
		 * Serial generated by eclipse.
		 */
		private static final long serialVersionUID = 3906084563938586935L;

		/**
		 * New instance of text change event
		 * 
		 * @param source
		 *            the Source of the event.
		 */
		public ValueChangeEvent(Label source) {
			super(source);
		}

		/**
		 * Gets the Property that has been modified.
		 * 
		 * @see com.itmill.toolkit.data.Property.ValueChangeEvent#getProperty()
		 */
		public Property getProperty() {
			return (Property) getSource();
		}
	}

	/**
	 * Adds the value change listener.
	 * 
	 * @param listener
	 *            the Listener to be added.
	 * @see com.itmill.toolkit.data.Property.ValueChangeNotifier#addListener(com.itmill.toolkit.data.Property.ValueChangeListener)
	 */
	public void addListener(Property.ValueChangeListener listener) {
		addListener(Label.ValueChangeEvent.class, listener, VALUE_CHANGE_METHOD);
	}

	/**
	 * Removes the value change listener.
	 * 
	 * @param listener
	 *            the Listener to be removed.
	 * @see com.itmill.toolkit.data.Property.ValueChangeNotifier#removeListener(com.itmill.toolkit.data.Property.ValueChangeListener)
	 */
	public void removeListener(Property.ValueChangeListener listener) {
		removeListener(Label.ValueChangeEvent.class, listener,
				VALUE_CHANGE_METHOD);
	}

	/**
	 * Emits the options change event.
	 */
	protected void fireValueChange() {
		// Set the error message
		fireEvent(new Label.ValueChangeEvent(this));
		requestRepaint();
	}

	/**
	 * Listens the value change events from data source.
	 * 
	 * @see com.itmill.toolkit.data.Property.ValueChangeListener#valueChange(Property.ValueChangeEvent)
	 */
	public void valueChange(Property.ValueChangeEvent event) {
		fireValueChange();
	}

	/**
	 * Compares the Label to other objects.
	 * 
	 * <p>
	 * Labels can be compared to other labels for sorting label contents. This
	 * is especially handy for sorting table columns.
	 * </p>
	 * 
	 * <p>
	 * In RAW, PREFORMATTED and TEXT modes, the label contents are compared as
	 * is. In XML, UIDL and XHTML modes, only CDATA is compared and tags
	 * ignored. If the other object is not a Label, its toString() return value
	 * is used in comparison.
	 * </p>
	 * 
	 * @param other
	 *            the Other object to compare to.
	 * @return a negative integer, zero, or a positive integer as this object is
	 *         less than, equal to, or greater than the specified object.
	 * @see java.lang.Comparable#compareTo(java.lang.Object)
	 */
	public int compareTo(Object other) {

		String thisValue;
		String otherValue;

		if (contentMode == CONTENT_XML || contentMode == CONTENT_UIDL
				|| contentMode == CONTENT_XHTML)
			thisValue = stripTags(toString());
		else
			thisValue = toString();

		if (other instanceof Label
				&& (((Label) other).getContentMode() == CONTENT_XML
						|| ((Label) other).getContentMode() == CONTENT_UIDL || ((Label) other)
						.getContentMode() == CONTENT_XHTML))
			otherValue = stripTags(other.toString());
		else
			otherValue = other.toString();

		return thisValue.compareTo(otherValue);
	}

	/**
	 * Strips the tags from the XML.
	 * 
	 * @param xml
	 *            the String containing a XML snippet.
	 * @return the original XML without tags.
	 */
	private String stripTags(String xml) {

		StringBuffer res = new StringBuffer();

		int processed = 0;
		int xmlLen = xml.length();
		while (processed < xmlLen) {
			int next = xml.indexOf('<', processed);
			if (next < 0)
				next = xmlLen;
			res.append(xml.substring(processed, next));
			if (processed < xmlLen) {
				next = xml.indexOf('>', processed);
				if (next < 0)
					next = xmlLen;
				processed = next + 1;
			}
		}

		return res.toString();
	}

}