/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program 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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

/* Client represents a connection to the database (the server-side) and corresponds
   to an open socket (or logical connection if pooling on sockets) from a client.
*/

#include "mongo/platform/basic.h"

#include "mongo/db/client.h"

#include <boost/functional/hash.hpp>
#include <string>
#include <vector>

#include "mongo/base/status.h"
#include "mongo/db/lasterror.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/stdx/thread.h"
#include "mongo/util/concurrency/thread_name.h"
#include "mongo/util/exit.h"
#include "mongo/util/str.h"

namespace mongo {

namespace {
thread_local ServiceContext::UniqueClient currentClient;

void invariantNoCurrentClient() {
    invariant(!haveClient(),
              str::stream() << "Already have client on this thread: "  //
                            << '"' << Client::getCurrent()->desc() << '"');
}
}  // namespace

void Client::initThread(StringData desc, transport::SessionHandle session) {
    initThread(desc, getGlobalServiceContext(), std::move(session));
}

void Client::initThread(StringData desc,
                        ServiceContext* service,
                        transport::SessionHandle session) {
    invariantNoCurrentClient();

    std::string fullDesc;
    if (session) {
        fullDesc = str::stream() << desc << session->id();
    } else {
        fullDesc = desc.toString();
    }

    setThreadName(fullDesc);

    // Create the client obj, attach to thread
    currentClient = service->makeClient(fullDesc, std::move(session));
}

void Client::initKillableThread(StringData desc, ServiceContext* service) {
    initThread(desc, service, nullptr);

    stdx::lock_guard lk(*currentClient);
    currentClient->setSystemOperationKillable(lk);
}

namespace {
int64_t generateSeed(const std::string& desc) {
    size_t seed = 0;
    boost::hash_combine(seed, Date_t::now().asInt64());
    boost::hash_combine(seed, desc);
    return seed;
}
}  // namespace

Client::Client(std::string desc, ServiceContext* serviceContext, transport::SessionHandle session)
    : _serviceContext(serviceContext),
      _session(std::move(session)),
      _desc(std::move(desc)),
      _connectionId(_session ? _session->id() : 0),
      _prng(generateSeed(_desc)) {}

void Client::reportState(BSONObjBuilder& builder) {
    builder.append("desc", desc());

    if (_connectionId) {
        builder.appendNumber("connectionId", _connectionId);
    }

    if (hasRemote()) {
        builder.append("client", getRemote().toString());
    }
}

ServiceContext::UniqueOperationContext Client::makeOperationContext() {
    return getServiceContext()->makeOperationContext(this);
}

void Client::setOperationContext(OperationContext* opCtx) {
    // We can only set the OperationContext once before resetting it.
    invariant(opCtx != nullptr && _opCtx == nullptr);
    _opCtx = opCtx;
}

void Client::resetOperationContext() {
    invariant(_opCtx != nullptr);
    _opCtx = nullptr;
}

std::string Client::clientAddress(bool includePort) const {
    if (!hasRemote()) {
        return "";
    }
    if (includePort) {
        return getRemote().toString();
    }
    return getRemote().host();
}

Client* Client::getCurrent() {
    return currentClient.get();
}

std::unique_ptr<Locker> Client::swapLockState(std::unique_ptr<Locker> locker) {
    scoped_spinlock scopedLock(_lock);
    invariant(_opCtx);
    return _opCtx->swapLockState(std::move(locker), scopedLock);
}

Client& cc() {
    invariant(haveClient());
    return *Client::getCurrent();
}

bool haveClient() {
    return static_cast<bool>(currentClient);
}

ServiceContext::UniqueClient Client::releaseCurrent() {
    invariant(haveClient());
    return std::move(currentClient);
}

void Client::setCurrent(ServiceContext::UniqueClient client) {
    invariantNoCurrentClient();
    currentClient = std::move(client);
}

ThreadClient::ThreadClient(ServiceContext* serviceContext)
    : ThreadClient(getThreadName(), serviceContext, nullptr) {}

ThreadClient::ThreadClient(StringData desc,
                           ServiceContext* serviceContext,
                           transport::SessionHandle session) {
    invariantNoCurrentClient();
    Client::initThread(desc, serviceContext, std::move(session));
}

ThreadClient::~ThreadClient() {
    invariant(currentClient);
    currentClient.reset(nullptr);
}

Client* ThreadClient::get() const {
    return &cc();
}

}  // namespace mongo