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/*
   Copyright The Narayana Authors
   SPDX-License-Identifier: Apache-2.0
 */

package com.arjuna.common.util.propertyservice;

import java.util.Properties;

import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

/**
 *
 * @author Gytis Trikleris
 *
 */
public final class SaxHandler extends DefaultHandler {

    private final Properties properties;

    private boolean isEntry;

    private String currentKey;

    private StringBuffer currentBuffer;

    public SaxHandler() {
        properties = new Properties();
        isEntry = false;
        currentKey = null;
        currentBuffer = null;
    }

    /**
     * Returns copy of the properties read from the handled XML.
     *
     * @return Properties read from the handled XML.
     */
    public Properties getProperties() {
        Properties propertiesCopy = new Properties();
        propertiesCopy.putAll(properties);

        return propertiesCopy;
    }

    /**
     * Handles open tag, if its name is entry and has attribute key.
     */
    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        if (qName.toLowerCase().equals("entry") && attributes.getLength() > 0) {
            currentKey = getAttributeValue("key", attributes);
            if (currentKey != null) {
                isEntry = true;
                currentBuffer = new StringBuffer();
            }
        }
    }

    /**
     * Handles close tag, if its name is entry.
     */
    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        if (qName.toLowerCase().equals("entry") && isEntry) {
            properties.put(currentKey, currentBuffer.toString().trim());
            currentKey = null;
            currentBuffer = null;
            isEntry = false;
        }
    }

    /**
     * Handles text content of the entry tag.
     */
    @Override
    public void characters(char ch[], int start, int length) throws SAXException {
        if (isEntry) {
            currentBuffer.append(ch, start, length);
        }
    }

    /**
     * Returns attribute's value from the attributes container based on the name.
     *
     * @param name
     * @param attributes
     * @return String value of the attribute if such attribute exists and null otherwise.
     */
    private String getAttributeValue(final String name, final Attributes attributes) {
        for (int i = 0; i < attributes.getLength(); i++) {
            if (attributes.getQName(i).toLowerCase().equals(name.toLowerCase())) {
                return attributes.getValue(i);
            }
        }

        return null;
    }

}