/*******************************************************************************
 * Copyright (c) 2004 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/

package org.eclipse.birt.report.model.util;

import java.util.Date;

import org.eclipse.birt.report.model.api.util.StringUtil;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;

/**
 * Abstract parse state for the <code>XMLParserHandler</code> class. Derived
 * classes create parse states based on this class.
 * 
 * @see ParseState
 * @see AnyElementState
 */

public abstract class AbstractParseState
{

	/**
	 * SAX context string.
	 */

	protected String context;

	/**
	 * The name of the element being parsed.
	 */

	protected String elementName = null;

	/**
	 * Accumulates any text that appears within the element tags.
	 */

	protected StringBuffer text = new StringBuffer( );
	

	/**
	 * Sets the element name.
	 * 
	 * @param name
	 *            the name of the element.
	 */

	public void setElementName( String name )
	{

		this.elementName = name;

	}

	/**
	 * Jumps to the specified state that the current state needs to go.
	 * 
	 * @return the other state.
	 */

	public AbstractParseState jumpTo( )
	{

		return null;
	}

	/**
	 * Called to parse attributes. This is the first method called after the
	 * state is created.Returns the value of attribute name.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @throws XMLParserException
	 *             if any parse exception
	 * @see org.xml.sax.helpers.DefaultHandler#startElement
	 */

	public void parseAttrs( Attributes attrs ) throws XMLParserException
	{
	}

	/**
	 * Start a new tag. Derived classes override this to create a state to
	 * handle the element. Call this method to issue an error for, and ignore,
	 * any unrecognized tags.
	 * 
	 * @param tagName
	 *            the name of the starting element
	 * @return the state to parse the given tag
	 * @see org.xml.sax.helpers.DefaultHandler#startElement
	 */

	public AbstractParseState startElement( String tagName )
	{
		getHandler( ).getErrorHandler( ).semanticError(
				new XMLParserException( XMLParserException.DESIGN_EXCEPTION_UNKNOWN_TAG ) );
		return new AnyElementState( getHandler( ) );
	}

	/**
	 * Returns the parser handler. Required to be implemented by derived states.
	 * States will implement this differently depending on whether the state is
	 * a normal or inner class.
	 * 
	 * @return the XML parser handler
	 */

	public abstract XMLParserHandler getHandler( );

	/**
	 * Called when a child element is ending.
	 * 
	 * @param state
	 *            the child state that is ending
	 */

	public void endElement( AbstractParseState state )
	{
	}

	/**
	 * Called when the element for this state is ending.
	 * 
	 * @throws SAXException
	 *             if the SAX exception is encountered.
	 * @throws 
	 * @see org.xml.sax.helpers.DefaultHandler#endElement
	 */

	public void end( ) throws SAXException
	{
	}

	/**
	 * Utility method to parse a Boolean attribute.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @param attrName
	 *            the name of the attribute to parse
	 * @param defaultValue
	 *            the default value if the attribute is not provided
	 * @return the parsed Boolean value
	 */

	public boolean getBooleanAttrib( Attributes attrs, String attrName,
			boolean defaultValue )
	{
		return parseBoolean( attrs.getValue( attrName ), defaultValue );
	}

	/**
	 * Parse a boolean string.
	 * 
	 * @param value
	 *            the XML string to parse
	 * @param defaultValue
	 *            the default value if the string is null or blank
	 * @return the parsed Boolean value
	 */

	public boolean parseBoolean( String value, boolean defaultValue )
	{
		value = StringUtil.trimString( value );
		if ( value == null )
			return defaultValue;
		else if ( value.equalsIgnoreCase( "true" ) ) //$NON-NLS-1$ 
			return true;
		else if ( value.equalsIgnoreCase( "false" ) ) //$NON-NLS-1$ 
			return false;
		getHandler( ).getErrorHandler( ).semanticError(
				new XMLParserException( XMLParserException.DESIGN_EXCEPTION_INVALID_BOOLEAN ) );
		return defaultValue;
	}

	/**
	 * Parses an integer attribute.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @param attrName
	 *            the name of the attribute to parse
	 * @return the parsed attribute, or 0 if the attribute is not present
	 */

	public int getIntAttrib( Attributes attrs, String attrName )
	{
		return getIntAttrib( attrs, attrName, 0 );
	}

	/**
	 * Parses an integer attribute.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @param attrName
	 *            the name of the attribute to parse
	 * @param defaultValue
	 *            default value to return if the attribute is not present
	 * @return the parsed integer value
	 */

	public int getIntAttrib( Attributes attrs, String attrName, int defaultValue )
	{
		String value = attrs.getValue( attrName );
		if ( value == null )
			return defaultValue;
		try
		{
			Integer result = Integer.decode( value );
			return result.intValue( );
		}
		catch ( NumberFormatException e )
		{
			getHandler( )
					.getErrorHandler( ).semanticError(
							new XMLParserException(
									XMLParserException.DESIGN_EXCEPTION_INVALID_INTEGER ) );
			return 0;
		}
	}

	/**
	 * Parse a string value. Normalizes the string: blank strings are converted
	 * to a null string.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @param attrName
	 *            the name of the attribute to parse
	 * @return the parsed string
	 */

	protected String getAttrib( Attributes attrs, String attrName )
	{
		return StringUtil.trimString( attrs.getValue( attrName ) );
	}

	/**
	 * Parse a date value. The date is assumed to be in the XML date format.
	 * 
	 * @param attrs
	 *            the SAX attributes object
	 * @param attrName
	 *            the name of the attribute to parse
	 * @return the parsed date
	 */

	protected Date getDateAttrib( Attributes attrs, String attrName )
	{
		assert false;
		return null;
	}

}