/*
 * HA-JDBC: High-Availability JDBC
 * Copyright (C) 2014  Paul Ferraro
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.hajdbc.xml;

import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.util.StreamReaderDelegate;

import net.sf.hajdbc.util.Strings;
import net.sf.hajdbc.util.SystemProperties;

public class PropertyReplacementFilter extends StreamReaderDelegate
{
	private static final Pattern PATTERN = Pattern.compile("\\$\\{([^\\}]+)\\}");

	private final Properties properties;
	
	public PropertyReplacementFilter(XMLStreamReader reader)
	{
		this(reader, SystemProperties.getSystemProperties());
	}

	public PropertyReplacementFilter(XMLStreamReader reader, Properties properties)
	{
		super(reader);
		this.properties = properties;
	}

	@Override
	public String getAttributeValue(int index)
	{
		return this.replace(super.getAttributeValue(index));
	}

	@Override
	public String getAttributeValue(String namespaceUri, String localName)
	{
		return this.replace(super.getAttributeValue(namespaceUri, localName));
	}

	@Override
	public String getElementText() throws XMLStreamException
	{
		return this.replace(super.getElementText());
	}
	
	@Override
	public String getText()
	{
		return this.replace(super.getText());
	}

	@Override
	public char[] getTextCharacters()
	{
		return this.replace(String.valueOf(super.getTextCharacters())).toCharArray();
	}

	@Override
	public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length) throws XMLStreamException
	{
		throw new UnsupportedOperationException();
	}

	private String replace(String input)
	{
		if (input == null) return null;

		Matcher matcher = PATTERN.matcher(input);

		if (!matcher.find()) return input;

		StringBuilder builder = new StringBuilder();
		int tail = 0;
		
		do
		{
			builder.append(input, tail, matcher.start());
			
			String group = matcher.group(1);
			
			if (group.equals("/"))
			{
				builder.append(Strings.FILE_SEPARATOR);
			}
			else if (group.equals(":"))
			{
				builder.append(Strings.PATH_SEPARATOR);
			}
			else
			{
				String key = group;
				String defaultValue = null;
				
				int index = group.indexOf(":");
				
				if (index > 0)
				{
					key = group.substring(0, index);
					defaultValue = group.substring(index + 1);
				}
				
				String value = this.getProperty(key.split(","), defaultValue);
				
	  			builder.append((value != null) ? value : matcher.group());
			}
			
			tail = matcher.end();
		}
		while (matcher.find());
		
		builder.append(input, tail, input.length());
		
		return builder.toString();
	}
	
	private String getProperty(String[] keys, String defaultValue)
	{
		for (String key: keys)
		{
			String value = this.properties.getProperty(key.trim());
			
			if (value != null) return value;
		}

		return defaultValue;
	}
}