Copyright Microsoft Corporation
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
/**
 * Copyright Microsoft Corporation
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.microsoft.azure.storage.file;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Stack;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;

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

import com.microsoft.azure.storage.Constants;
import com.microsoft.azure.storage.core.SR;
import com.microsoft.azure.storage.core.Utility;

RESERVED FOR INTERNAL USE. A class used to deserialize a list of file ranges.
/**
 * RESERVED FOR INTERNAL USE. A class used to deserialize a list of file ranges.
 */
final class FileRangeHandler extends DefaultHandler {

    private final Stack<String> elementStack = new Stack<String>();
    private StringBuilder bld = new StringBuilder();

    private final ArrayList<FileRange> fileRanges = new ArrayList<FileRange>();

    private long startOffset;
    private long endOffset;

    
Returns an ArrayList of File Ranges for the given stream.
Throws:
SAXException – 
ParserConfigurationException – 
IOException – 
Returns:
an ArrayList of File Ranges for the given stream./**
     * Returns an ArrayList of File Ranges for the given stream.
     * 
     * @return an ArrayList of File Ranges for the given stream.
     * @throws SAXException
     * @throws ParserConfigurationException
     * @throws IOException
     */
    protected static ArrayList<FileRange> getFileRanges(InputStream streamRef) throws ParserConfigurationException,
            SAXException, IOException {
        SAXParser saxParser = Utility.getSAXParser();
        FileRangeHandler handler = new FileRangeHandler();
        saxParser.parse(streamRef, handler);

        return handler.fileRanges;
    }

    @Override
    public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
        this.elementStack.push(localName);
    }

    @Override
    public void endElement(String uri, String localName, String qName) throws SAXException {
        String currentNode = this.elementStack.pop();

        // if the node popped from the stack and the localName don't match, the xml document is improperly formatted
        if (!localName.equals(currentNode)) {
            throw new SAXException(SR.INVALID_RESPONSE_RECEIVED);
        }

        String value = this.bld.toString();
        if (value.isEmpty()) {
            value = null;
        }

        if (FileConstants.FILE_RANGE_ELEMENT.equals(currentNode)) {
            final FileRange fileRangeRef = new FileRange(this.startOffset, this.endOffset);
            this.fileRanges.add(fileRangeRef);
        }
        else if (FileConstants.START_ELEMENT.equals(currentNode)) {
            this.startOffset = Long.parseLong(value);
        }
        else if (Constants.END_ELEMENT.equals(currentNode)) {
            this.endOffset = Long.parseLong(value);
        }

        this.bld = new StringBuilder();
    }

    @Override
    public void characters(char ch[], int start, int length) throws SAXException {
        this.bld.append(ch, start, length);
    }
}