package contrib;

import org.jdom.Element;
import org.jdom.Namespace;
import org.jdom.Attribute;
import org.xml.sax.SAXException;
import javax.swing.tree.DefaultMutableTreeNode;

import java.util.List;
import java.util.Iterator;

/**
 * @author Phill Perryman
 *
 * Extends the Element Class from JDOM to provide functionality
 * which is not appropriate for the core library.
 * 
 * The class provides several convenience methods for handling
 * attribute data as well as methods for manipulating the elemment itself.
 */
public class Elementx extends Element implements Comparable {

	// attribute for convenience methods
	Attribute a = null;

	// descriptor
	private static ElementDescriptor descriptor = null;
	private static ElementDescriptor oldDescriptor = null;
	
	/**
	 * Constructor for ExtendedElement.
	 */
	public Elementx() {
		super();
	}

	/**
	 * Constructor for ExtendedElement.
	 * @param arg0
	 * @param arg1
	 */
	public Elementx(String arg0, Namespace arg1) {
		super(arg0, arg1);
	}

	/**
	 * Constructor for ExtendedElement.
	 * @param arg0
	 */
	public Elementx(String arg0) {
		super(arg0);
	}

	/**
	 * Constructor for ExtendedElement.
	 * @param arg0
	 * @param arg1
	 */
	public Elementx(String arg0, String arg1) {
		super(arg0, arg1);
	}

	/**
	 * Constructor for ExtendedElement.
	 * @param arg0
	 * @param arg1
	 * @param arg2
	 */
	public Elementx(String arg0, String arg1, String arg2) {
		super(arg0, arg1, arg2);
	}
	
	/**
	 * Allows the element to be put into a sorted map etc.
	 * 
	 * By using the toString method the descriptor can
	 * be used to control the sorting by attribute
	 * 
	 */
	public int compareTo(Object comp) {
		Elementx e = (Elementx) comp;
		return this.toString().compareTo(e.toString());
	}

	/** 
	 * Allows the toString descriptor to be overidden.
	 * 
	 * Setting the parameter to null will revert to the super
	 * toString method. Note the descriptor is static and so
	 * only one can be in force for all Elements.
	 * 
	 * If the descriptions should be different for diferent
	 * elements then the element descriptor should test the
	 * names of the passed element and respond accordingly.
	 * 
	 * @param the new descriptor
	 * @return the old one or null if none.
	 */
	public static ElementDescriptor setDescriptor(ElementDescriptor newDescriptor) {
		oldDescriptor = descriptor;
		descriptor = newDescriptor;
		return oldDescriptor;
	}

	/**
	 * Allows subclasses to perform validation.
	 * 
	 * This method is called by the SAXHandlerx when
	 * the element has finished parsing. It allows for context
	 * sensitive validation as opposed to the syntactical one
	 * the parser carries out.
	 * 
	 * It can also be used where information about elements 
	 * can usefully be collected while the document is being
	 * parsed.
	 * 
	 * The subclass would overide this method to provide the
	 * functionality.
	 */
	public void validate() throws SAXException {

	}

	// convenience methods

	/**
	 * Converts the attribute value to an int
	 * 
	 * @param name of attribute
	 */
	public int getInt(String attributeName) {
		a = getAttribute(attributeName);
		if (a != null) {
			return Integer.parseInt(a.getValue());
		} else {
			return 0;
		}
	}

	/**
	 * Converts the attribute value to an int
	 * 
	 * @param name of attribute
	 * @param default value if attribute does not exist
	 * @return the int value of the attribute or the default value
	 * if the attribute does not exist
	 */
	public int getInt(String attributeName, int defaultValue) {
		a = getAttribute(attributeName);
		if (a != null) {
			return Integer.parseInt(a.getValue());
		} else {
			return defaultValue;
		}
	}

	/**
	 * Stores the int value into an attribute
	 * 
	 * @param name of attribute
	 * @param value of attribute
	 */
	public void setInt(String attributeName, int value) {
		this.setAttribute(attributeName, value + "");
	}

	/**
	 * Stores the int value into an attribute unless the value
	 * is the default in which case the attribute is removed.
	 * 
	 * This can save space in a stored document where a matching
	 * pair of setInt(name, value, default) and getInt(name, default)
	 * methods are used with the same name and default values.
	 * 
	 * This method is only useful when the application knows the default 
	 * values of attributes or can obtain them. Typically only used
	 * with documents local to an application.
	 *  
	 * @param name of attribute
	 * @param value of attribute
	 * @param default value of the attribute
	 */
	public void setInt(String attributeName, int value, int defaultValue) {
		if (value == defaultValue) {
			a = getAttribute(attributeName);
			if (a != null) {
				this.removeAttribute(a);
			}
		} else {
			this.setAttribute(attributeName, value + "");
		}
	}

	/**
	 * Gets a boolean value from an attribute.
	 * 
	 * Returns true if the attribute has a value of "true" 
	 * otherwise it returns false
	 * 
	 * @param attribute name
	 * @return value of attrubute
	 */
	public boolean getBoolean(String attributeName) {
		a = getAttribute(attributeName);
		if (a != null) {
			if (a.getValue().equals("true")) {
				return true;
			} else {
				return false;
			}
		} else {
			return false;
		}
	}

	/**
	 * Gets a boolean value from an attribute.
	 * 
	 * Returns true if the attribute has a value of "true" 
	 * otherwise it returns the default value
	 * 
	 * @param attribute name
	 * @param default value
	 * @return value of attrubute or default if missing
	 */
	public boolean getBoolean(String attributeName, boolean defaultValue) {
		a = getAttribute(attributeName);
		if (a != null) {
			if (a.getValue().equals("true")) {
				return true;
			} else {
				return false;
			}
		} else {
			return defaultValue;
		}
	}

	/**
	 * Sets the attribute value to a text representation of the
	 * boolean value. The values are explicitly set to "true" or
	 * "false" so that internationalisation is not an issue rather
	 * than use the default toString().
	 * 
	 * @param attribute name
	 * @param attribute value 
	 */
	public void setBoolean(String attributeName, boolean value) {
		if (value) {
			setAttribute(attributeName, "true");
		} else {
			setAttribute(attributeName, "false");
		};
	}

	/**
	 * Stores the boolean value into an attribute unless the value
	 * is the default in which case the attribute is removed.
	 * 
	 * This can save space in a stored document where a matching
	 * pair of setBoolean(name, value, default) and getBoolean(name, default)
	 * methods are used with the same name and default values.
	 * 
	 * This method is only useful when the application knows the default 
	 * values of attributes or can obtain them. Typically only used
	 * with documents local to an application.
	 *  
	 * @param name of attribute
	 * @param value of attribute
	 * @param default value of the attribute
	 */
	public void setBoolean(
		String attributeName,
		boolean value,
		boolean defaultValue) {
		if (value == defaultValue) {
			a = getAttribute(attributeName);
			if (a != null) {
				this.removeAttribute(a);
			}
		} else {
			this.setBoolean(attributeName, value);
		}
	}

	/**
	 * Returns a DefaultMutableTreeNode for use in a JTree which
	 * represents the element
	 * @return DefaultMutableTreeNode
	 */
	public DefaultMutableTreeNode getTreeNode() {
		DefaultMutableTreeNode treeNode = new DefaultMutableTreeNode(this);
		addChildren(treeNode, this);
		return treeNode;
	}

	/**
	 * Internal function to support get tree node
	 */
	private static void addChildren(
		DefaultMutableTreeNode tn,
		Elementx element) {
		DefaultMutableTreeNode node;
		List children = element.getChildren();
		Iterator it = children.iterator();
		while (it.hasNext()) {
			Elementx child = (Elementx) it.next();
			node = new DefaultMutableTreeNode(child);
			tn.add(node);
			addChildren(node, child);
		};
	}

	/**
	 * This method checks to see if an ElementDescriptor has
	 * been set. If it has it uses that to provide the
	 * String representation otherwise it uses Elements toString
	 * functionality.
	 */
	public String toString() {
		if (descriptor == null) {
			return super.toString();
		} else {
			return descriptor.getDescription(this);
		}

	}
}