/**
 *    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.
 */

#pragma once

#include <cstdint>
#include <memory>
#include <string>
#include <vector>

#include "mongo/base/status.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/logv2/log_severity_suppressor.h"
#include "mongo/stdx/variant.h"
#include "mongo/transport/service_entry_point.h"
#include "mongo/transport/session.h"
#include "mongo/util/duration.h"
#include "mongo/util/net/cidr.h"

namespace mongo {
class ServiceContext;

/**
 * A basic entry point from the TransportLayer into a server.
 *
 * The server logic is implemented inside of handleRequest() by a subclass.
 * startSession() spawns and detaches a new thread for each incoming connection
 * (transport::Session).
 */
class ServiceEntryPointImpl : public ServiceEntryPoint {
public:
    static constexpr Seconds kSlowSessionWorkflowLogSuppresionPeriod{5};

    explicit ServiceEntryPointImpl(ServiceContext* svcCtx);
    ~ServiceEntryPointImpl();

    ServiceEntryPointImpl(const ServiceEntryPointImpl&) = delete;
    ServiceEntryPointImpl& operator=(const ServiceEntryPointImpl&) = delete;

    void startSession(transport::SessionHandle session) override;

    void endAllSessions(transport::Session::TagMask tags) final;
    void endAllSessionsNoTagMask();

    Status start() final;
    bool shutdown(Milliseconds timeout) final;
    bool shutdownAndWait(Milliseconds timeout);
    bool waitForNoSessions(Milliseconds timeout);

    void appendStats(BSONObjBuilder* bob) const override;

    size_t numOpenSessions() const final;

    size_t maxOpenSessions() const final;

    logv2::LogSeverity slowSessionWorkflowLogSeverity() final;

    void onClientDisconnect(Client* client) final;

    /** `onClientDisconnect` calls this before doing anything else. */
    virtual void derivedOnClientDisconnect(Client* client) {}

protected:
    /** Imbue the new Client with a ServiceExecutorContext. */
    virtual void configureServiceExecutorContext(ServiceContext::UniqueClient& client,
                                                 bool isPrivilegedSession);

private:
    class Sessions;

    ServiceContext* const _svcCtx;

    const size_t _maxSessions;
    size_t _rejectedSessions;

    std::unique_ptr<Sessions> _sessions;

    logv2::SeveritySuppressor _slowSessionWorkflowLogSuppressor{
        kSlowSessionWorkflowLogSuppresionPeriod,
        logv2::LogSeverity::Info(),
        logv2::LogSeverity::Debug(2)};
};

/*
 * Returns true if a session with remote/local addresses should be exempted from maxConns
 */
bool shouldOverrideMaxConns(const transport::SessionHandle& session,
                            const std::vector<stdx::variant<CIDR, std::string>>& exemptions);

}  // namespace mongo