/*
 *  Copyright (c) 2020, The OpenThread Authors.
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. Neither the name of the copyright holder nor the
 *     names of its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * @file
 *   This file includes connection definition for RESTful HTTP server.
 */

#ifndef OTBR_REST_CONNECTION_HPP_
#define OTBR_REST_CONNECTION_HPP_

#include "openthread-br/config.h"

#include <string.h>
#include <unistd.h>

#include "common/mainloop.hpp"
#include "rest/parser.hpp"
#include "rest/resource.hpp"

using std::chrono::steady_clock;

namespace otbr {
namespace rest {

/**
 * This class implements a Connection class of each socket connection.
 */
class Connection : public MainloopProcessor
{
public:
    /**
     * The constructor is to initialize a socket connection instance.
     *
     * @param[in] aStartTime  The reference start time of a connection which
     *                        is set when created for the first time and maybe
     *                        reset when transfer to wait callback or wait write
     *                        state.
     * @param[in] aResource   A pointer to the resource handler.
     * @param[in] aFd         The file descriptor for the connection.
     */
    Connection(steady_clock::time_point aStartTime, Resource *aResource, int aFd);

    /**
     * The desctructor destroys the connection instance.
     */
    ~Connection(void) override;

    /**
     * This method initializes the connection.
     */
    void Init(void);

    void Update(MainloopContext &aMainloop) override;
    void Process(const MainloopContext &aMainloop) override;

    /**
     * This method indicates whether this connection no longer need to be processed.
     *
     * @retval TRUE   This connection could be released in next loop.
     * @retval FALSE  This connection still needs to be processed in next loop.
     */
    bool IsComplete(void) const;

private:
    void UpdateReadFdSet(fd_set &aReadFdSet, int &aMaxFd) const;
    void UpdateWriteFdSet(fd_set &aWriteFdSet, int &aMaxFd) const;
    void UpdateTimeout(timeval &aTimeout) const;
    void ProcessWaitRead(const fd_set &aReadFdSet);
    void ProcessWaitCallback(void);
    void ProcessWaitWrite(const fd_set &aWriteFdSet);
    void Write(void);
    void Handle(void);
    void Disconnect(void);

    // Timestamp used for each check point of a connection
    steady_clock::time_point mTimeStamp;

    // File descriptor for this connection
    int mFd;

    // Enum indicates the state of this connection
    ConnectionState mState;

    // Response instance binded to this connection
    Response mResponse;

    // Request instance binded to this connection
    Request mRequest;

    // HTTP parser instance
    Parser mParser;

    // Resource handler instance
    Resource *mResource;

    // Write buffer in case write multiple times
    std::string mWriteContent;
};

} // namespace rest
} // namespace otbr

#endif // OTBR_REST_CONNECTION_HPP_