/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2017, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This 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 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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 software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.wildfly.extension.undertow.handlers;

import io.undertow.server.HttpHandler;
import io.undertow.server.handlers.ResponseCodeHandler;
import io.undertow.server.handlers.proxy.LoadBalancingProxyClient;
import io.undertow.server.handlers.proxy.ProxyHandler;
import io.undertow.util.Headers;
import org.jboss.as.controller.AttributeDefinition;
import org.jboss.as.controller.OperationContext;
import org.jboss.as.controller.OperationFailedException;
import org.jboss.as.controller.PersistentResourceDefinition;
import org.jboss.as.controller.SimpleAttributeDefinitionBuilder;
import org.jboss.as.controller.client.helpers.MeasurementUnit;
import org.jboss.as.controller.registry.AttributeAccess;
import org.jboss.dmr.ModelNode;
import org.jboss.dmr.ModelType;
import org.wildfly.extension.undertow.Constants;

import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

/**
 * @author Stuart Douglas
 */
public class ReverseProxyHandler extends Handler {


    public static final AttributeDefinition PROBLEM_SERVER_RETRY = new SimpleAttributeDefinitionBuilder(Constants.PROBLEM_SERVER_RETRY, ModelType.INT)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(30))
            .setMeasurementUnit(MeasurementUnit.SECONDS)
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();

    public static final AttributeDefinition SESSION_COOKIE_NAMES = new SimpleAttributeDefinitionBuilder(Constants.SESSION_COOKIE_NAMES, ModelType.STRING)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode("JSESSIONID"))
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();
    public static final AttributeDefinition CONNECTIONS_PER_THREAD = new SimpleAttributeDefinitionBuilder(Constants.CONNECTIONS_PER_THREAD, ModelType.INT)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(40))
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();

    public static final AttributeDefinition MAX_REQUEST_TIME = new SimpleAttributeDefinitionBuilder(Constants.MAX_REQUEST_TIME, ModelType.INT)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(-1))
            .setMeasurementUnit(MeasurementUnit.MILLISECONDS)
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();

    public static final AttributeDefinition REQUEST_QUEUE_SIZE = new SimpleAttributeDefinitionBuilder(Constants.REQUEST_QUEUE_SIZE, ModelType.INT)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(10))
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();


    public static final AttributeDefinition CACHED_CONNECTIONS_PER_THREAD = new SimpleAttributeDefinitionBuilder(Constants.CACHED_CONNECTIONS_PER_THREAD, ModelType.INT)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(5))
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();

    public static final AttributeDefinition CONNECTION_IDLE_TIMEOUT = new SimpleAttributeDefinitionBuilder(Constants.CONNECTION_IDLE_TIMEOUT, ModelType.INT)
            .setRequired(false)
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(60000))
            .setMeasurementUnit(MeasurementUnit.MILLISECONDS)
            .setFlags(AttributeAccess.Flag.RESTART_ALL_SERVICES)
            .build();

    public static final AttributeDefinition MAX_RETRIES = new SimpleAttributeDefinitionBuilder(Constants.MAX_RETRIES, ModelType.INT)
            .setRequired(false)
            .setRestartAllServices()
            .setAllowExpression(true)
            .setDefaultValue(new ModelNode(1L))
            .build();

    public static final ReverseProxyHandler INSTANCE = new ReverseProxyHandler();

    private ReverseProxyHandler() {
        super(Constants.REVERSE_PROXY);
    }

    @Override
    public Collection<AttributeDefinition> getAttributes() {
        return Arrays.asList(CONNECTIONS_PER_THREAD, SESSION_COOKIE_NAMES,
                PROBLEM_SERVER_RETRY, REQUEST_QUEUE_SIZE, MAX_REQUEST_TIME,
                CACHED_CONNECTIONS_PER_THREAD, CONNECTION_IDLE_TIMEOUT,
                MAX_RETRIES);
    }

    @Override
    protected List<? extends PersistentResourceDefinition> getChildren() {
        return Collections.<PersistentResourceDefinition>singletonList(ReverseProxyHandlerHost.INSTANCE);
    }

    @Override
    public HttpHandler createHandler(final OperationContext context, ModelNode model) throws OperationFailedException {

        String sessionCookieNames = SESSION_COOKIE_NAMES.resolveModelAttribute(context, model).asString();
        int connectionsPerThread = CONNECTIONS_PER_THREAD.resolveModelAttribute(context, model).asInt();
        int problemServerRetry = PROBLEM_SERVER_RETRY.resolveModelAttribute(context, model).asInt();
        int maxTime = MAX_REQUEST_TIME.resolveModelAttribute(context, model).asInt();
        int requestQueueSize = REQUEST_QUEUE_SIZE.resolveModelAttribute(context, model).asInt();
        int cachedConnectionsPerThread = CACHED_CONNECTIONS_PER_THREAD.resolveModelAttribute(context, model).asInt();
        int connectionIdleTimeout = CONNECTION_IDLE_TIMEOUT.resolveModelAttribute(context, model).asInt();
        int maxRetries = MAX_RETRIES.resolveModelAttribute(context, model).asInt();


        final LoadBalancingProxyClient lb = new LoadBalancingProxyClient(exchange -> {
            //we always create a new connection for upgrade requests
            return exchange.getRequestHeaders().contains(Headers.UPGRADE);
        })
                .setConnectionsPerThread(connectionsPerThread)
                .setMaxQueueSize(requestQueueSize)
                .setSoftMaxConnectionsPerThread(cachedConnectionsPerThread)
                .setTtl(connectionIdleTimeout)
                .setProblemServerRetry(problemServerRetry);
        String[] sessionIds = sessionCookieNames.split(",");
        for (String id : sessionIds) {
            lb.addSessionCookieName(id);
        }

        return ProxyHandler.builder()
                .setProxyClient(lb)
                .setMaxRequestTime(maxTime)
                .setNext(ResponseCodeHandler.HANDLE_404)
                .setRewriteHostHeader(false)
                .setReuseXForwarded(false)
                .setMaxConnectionRetries(maxRetries)
                .build();
    }
}
