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;

import com.microsoft.azure.storage.core.SR;
import com.microsoft.azure.storage.core.Utility;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.parsers.SAXParser;
import java.io.IOException;
import java.io.InputStream;
import java.util.Stack;
import java.util.UUID;

public class UserDelegationKeyHandler extends DefaultHandler {

    private final Stack<String> elementStack = new Stack<>();
    private final UserDelegationKey key = new UserDelegationKey();

    private StringBuilder sb = new StringBuilder();

    public static UserDelegationKey readUserDelegationKeyFromStream(final InputStream stream)
            throws SAXException, IOException, ParserConfigurationException {
        SAXParser saxParser = Utility.getSAXParser();
        UserDelegationKeyHandler handler = new UserDelegationKeyHandler();
        saxParser.parse(stream, handler);

        return handler.key;
    }

    @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.sb.toString();
        sb = new StringBuilder();
        if (value.isEmpty()) {
            value = null;
        }

        switch (localName) {
            case Constants.SIGNED_OID_ELEMENT:
                try {
                    key.setSignedOid(UUID.fromString(value));
                }
                catch (Exception e) {
                    // no-op
                }
                break;

            case Constants.SIGNED_TID_ELEMENT:
                try {
                    key.setSignedTid(UUID.fromString(value));
                }
                catch (Exception e) {
                    // no-op
                }
                break;

            case Constants.SIGNED_START_ELEMENT:
                try {
                    key.setSignedStart(Utility.parseDate(value));
                }
                catch (Exception e) {
                    // no-op
                }
                break;

            case Constants.SIGNED_EXPIRY_ELEMENT:
                try {
                    key.setSignedExpiry(Utility.parseDate(value));
                }
                catch (Exception e) {
                    // no-op
                }
                break;

            case Constants.SIGNED_VERSION_ELEMENT:
                key.setSignedVersion(value);
                break;

            case Constants.SIGNED_SERVICE_ELEMENT:
                key.setSignedService(value);
                break;

            case Constants.VALUE_ELEMENT:
                key.setValue(value);
                break;

            default:
                break;
        }
    }

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