/**
 *
 * Copyright the original author or authors
 *
 * 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 org.jivesoftware.util;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

import org.jivesoftware.smack.packet.Stanza;
import org.jivesoftware.smack.util.XmlUtil;

/**
 * This class can be used in conjunction with a mocked XMPP connection (
 * {@link ConnectionUtils#createMockedConnection(Protocol, org.jxmpp.jid.EntityFullJid, org.jxmpp.jid.DomainBareJid)}) to
 * verify an XMPP protocol. This can be accomplished in the following was:
 * <ul>
 * <li>add responses to packets sent over the mocked XMPP connection by the
 * method to test in the order the tested method awaits them</li>
 * <li>call the method to test</li>
 * <li>call {@link #verifyAll()} to run assertions on the request/response pairs
 * </li>
 * </ul>
 * Example:
 *
 * <pre>
 * <code>
 * public void methodToTest() {
 *   Stanza stanza = new Packet(); // create an XMPP packet
 *   StanzaCollector collector = connection.createStanzaCollector(new StanzaIdFilter());
 *   connection.sendStanza(packet);
 *   Stanza reply = collector.nextResult();
 * }
 *
 * public void testMethod() {
 *   EntityFullJid userJid = JidCreate.entityFullFrom("user@xmpp-server.org");
 *   DomainBareJid serverJid = JidCreate.domainBareFrom("user-server.org");
 *   // create protocol
 *   Protocol protocol = new Protocol();
 *   // create mocked connection
 *   XMPPConnection connection = ConnectionUtils.createMockedConnection(protocol, userJid, serverJid);
 *
 *   // add reply stanza to protocol
 *   Stanza reply = new Packet();
 *   protocol.add(reply);
 *
 *   // call method to test
 *   methodToTest();
 *
 *   // verify protocol
 *   protocol.verifyAll();
 * }
 * </code>
 * </pre>
 *
 * Additionally to adding the response to the protocol instance you can pass
 * verifications that will be executed when {@link #verifyAll()} is invoked.
 * (See {@link Verification} for more details.)
 * <p>
 * If the {@link #printProtocol} flag is set to true {@link #verifyAll()} will
 * also print out the XML messages in the order they are sent to the console.
 * This may be useful to inspect the whole protocol "by hand".
 * </p>
 *
 * @author Henning Staib
 */
public class Protocol {

    /**
     * Set to <code>true</code> to print XML messages to the console while
     * verifying the protocol.
     */
    public boolean printProtocol = false;

    // responses to requests are taken form this queue
    private final Queue<Stanza> responses = new LinkedList<>();

    // list of verifications
    private final List<Verification<?, ?>[]> verificationList = new ArrayList<>();

    // list of requests
    private final List<Stanza> requests = new ArrayList<>();

    // list of all responses
    private final List<Stanza> responsesList = new ArrayList<>();

    /**
     * Adds a responses and all verifications for the request/response pair to
     * the protocol.
     *
     * @param response the response for a request
     * @param verifications verifications for request/response pair
     */
    public void addResponse(Stanza response, Verification<?, ?>... verifications) {
        responses.offer(response);
        verificationList.add(verifications);
        responsesList.add(response);
    }

    /**
     * Verifies the request/response pairs by checking if their numbers match
     * and executes the verification for each pair.
     */
    @SuppressWarnings("unchecked")
    public void verifyAll() {
        // CHECKSTYLE:OFF
        assertEquals(requests.size(), responsesList.size());

        if (printProtocol)
            System.out.println("=================== Start ===============\n");

        for (int i = 0; i < requests.size(); i++) {
            Stanza request = requests.get(i);
            Stanza response = responsesList.get(i);

            if (printProtocol) {
                System.out.println("------------------- Request -------------\n");
                System.out.println(XmlUtil.prettyFormatXml(request.toXML()));
                System.out.println("------------------- Response ------------\n");
                if (response != null) {
                    System.out.println(XmlUtil.prettyFormatXml(response.toXML()));
                }
                else {
                    System.out.println("No response");
                }
            }

            Verification<Stanza, Stanza>[] verifications = (Verification<Stanza, Stanza>[]) verificationList.get(i);
            if (verifications != null) {
                for (Verification<Stanza, Stanza> verification : verifications) {
                    verification.verify(request, response);
                }
            }
        }
        if (printProtocol)
            System.out.println("=================== End =================\n");
        // CHECKSTYLE:ON
    }

    /**
     * Returns the responses queue.
     *
     * @return the responses queue
     */
    protected Queue<Stanza> getResponses() {
        return responses;
    }

    /**
     * Returns a list of all collected requests.
     *
     * @return list of requests
     */
    public List<Stanza> getRequests() {
        return requests;
    }

}