/*  -*- C++ -*-
 *  Copyright (C) 2003,2005 Thiago Macieira <thiago@kde.org>
 *
 *
 *  Permission is hereby granted, free of charge, to any person obtaining
 *  a copy of this software and associated documentation files (the
 *  "Software"), to deal in the Software without restriction, including
 *  without limitation the rights to use, copy, modify, merge, publish,
 *  distribute, sublicense, and/or sell copies of the Software, and to
 *  permit persons to whom the Software is furnished to do so, subject to
 *  the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included
 *  in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifndef KSERVERSOCKET_H
#define KSERVERSOCKET_H

#include <QtCore/QObject>
#include "k3socketbase.h"
#include "k3streamsocket.h"

namespace KNetwork
{

class KStreamSocket;
class KResolver;
class KResolverResults;

class KServerSocketPrivate;
/**
 * @class KServerSocket k3serversocket.h k3serversocket.h
 * @brief A server socket for accepting connections.
 *
 * This class provides functionality for creating a socket to
 * listen for incoming connections and subsequently accept them.
 *
 * To use this class, you must first set the parameters for the listening
 * socket's address, then place it in listening mode.
 *
 * A typical example would look like:
 * \code
 *   QString service = "http";
 *   KServerSocket *ss = new KServerSocket(service);
 *   connect(ss, SIGNAL(readyAccept()), this, SLOT(slotReadyAccept()));
 *   connect(ss, SIGNAL(gotError(int)), this, SLOT(slotSocketError(int)));
 *   ss->listen();
 * \endcode
 *
 * In this case, this class will place the socket into listening mode on the
 * service pointed to by @p service and will emit the readyAccept() signal
 * when a connection is ready for accepting. The called slot is responsible for
 * calling accept().
 *
 * The location of the services file (where @p service is looked up)
 * is defined by _PATH_SERVICES in /usr/include/netdb.h.  This is
 * usually set to /etc/services.
 * See RFC 1700 for more information on services.
 * You can specify @p service as a port number directly, rather than as a service
 * name.  This is discouraged as it prevents the end user from easily modifying
 * the port number.
 *
 * For another example of usage, this below code attempts to make a connection on any port within a range:
 * \code
 *   KServerSocket *ss = new KServerSocket();
 *   ss->setFamily(KResolver::InetFamily);
 *   bool found = false;
 *   for( unsigned int port = firstport; port <= lastport; ++port) {
 *     ss->setAddress( QString::number( port ) );
 *     bool success = ss->listen();
 *     if( found = ( success && ss->error() ==
 *                              KSocketBase::NoError ) )
 *       break;
 *     ss->close();
 *   }
 *   if( !found ) {
 *     // Couldn't connect to any port.
 *   } else {
 *     connect(ss, SIGNAL(readyAccept()), this, SLOT(slotReadyAccept()));
 *     connect(ss, SIGNAL(gotError(int)), this, SLOT(slotSocketError(int)));
 *     ss->listen();
 *   }
 * \endcode
 *
 * The called slot slotReadyAccept() is responsible for calling
 * accept().
 *
 * It is important to note that accept() can return either an
 * object of type KNetwork::KStreamSocket or
 * KNetwork::KBufferedSocket (default). If you want to accept a
 * non-buffered socket, you must first call setAcceptBuffered.
 *
 * @warning If you use KServerSocket in an auxiliary (non-GUI) thread,
 *          you need to accept only KNetwork::KStreamSocket objects.
 *
 * @see KNetwork::KStreamSocket, KNetwork::KBufferedSocket
 * @author Thiago Macieira <thiago@kde.org>
 * @deprecated Use KSocketFactory or KLocalSocket instead
 */
class KDELIBS4SUPPORT_DEPRECATED_EXPORT KServerSocket: public QObject, public KPassiveSocketBase
{
    Q_OBJECT
public:
    /**
     * Default constructor.
     *
     * If the binding address isn't changed by setAddress, this socket will
     * bind to all interfaces on this node and the port will be selected by the
     * operating system.
     *
     * @param parent      the parent QObject object
     */
    KServerSocket(QObject *parent = nullptr);

    /**
     * Construct this object specifying the service to listen on.
     *
     * If the binding address isn't changed by setAddress, this socket will
     * bind to all interfaces and will listen on the port specified by
     * @p service.  This is either a service name (e.g. 'www') or a port
     * number (e.g. '80').
     *
     * The location of the services file (where @p service is looked up)
     * is defined by _PATH_SERVICES in /usr/include/netdb.h.  This is
     * usually set to /etc/services.
     * See RFC 1700 for more information on services.
     *
     * @param service     the service name to listen on
     * @param parent      the parent QObject object
     */
    KDELIBS4SUPPORT_DEPRECATED explicit KServerSocket(const QString &service, QObject *parent = nullptr);

    /**
     * Construct this object specifying the node and service names to listen on.
     *
     * If the binding address isn't changed by setAddress, this socket will
     * bind to the interface specified by @p node and the port specified by
     * @p service.  This is either a service name (e.g. 'www') or a port
     * number (e.g. '80').
     *
     * The location of the services file (where @p service is looked up)
     * is defined by _PATH_SERVICES in /usr/include/netdb.h.  This is
     * usually set to /etc/services.
     * See RFC 1700 for more information on services.
     *
     * @param node        the node to bind to
     * @param service     the service port to listen on
     * @param parent      the parent QObject object
     */
    KServerSocket(const QString &node, const QString &service,
                  QObject *parent = nullptr);

    /**
     * Destructor. This will close the socket, if open.
     *
     * Note, however, that accepted sockets do not get closed when this
     * object closes.
     */
    ~KServerSocket();

protected:
    /**
     * Sets the socket options. Reimplemented from KSocketBase.
     */
    bool setSocketOptions(int opts) override;

public:
    /**
     * Returns the internal KResolver object used for
     * looking up the host name and service.
     *
     * This can be used to set extra options to the
     * lookup process other than the default values, as well
     * as obtaining the error codes in case of lookup failure.
     */
    KResolver &resolver() const;

    /**
     * Returns the internal list of resolved results for the binding address.
     */
    const KResolverResults &resolverResults() const;

    /**
     * Enables or disables name resolution. If this flag is set to true,
     * the bind() operation will trigger name lookup
     * operations (i.e., converting a hostname into its binary form).
     * If the flag is set to false, those operations will instead
     * try to convert a string representation of an address without
     * attempting name resolution.
     *
     * This is useful, for instance, when IP addresses are in
     * their string representation (such as "1.2.3.4") or come
     * from other sources like KSocketAddress.
     *
     * @param enable  whether to enable
     */
    void setResolutionEnabled(bool enable);

    /**
     * Sets the allowed families for the resolutions.
     *
     * @param families        the families that we want/accept
     * @see KResolver::SocketFamilies for possible values
     */
    void setFamily(int families);

    /**
     * Sets the address on which we will listen. The port to listen on is given by
     * @p service, and we will bind to all interfaces. To let the operating system choose a
     * port, set the service to "0".  @p service can either be a service name
     * (e.g. 'www') or a port number (e.g. '80').
     *
     * The location of the services file (where @p service is looked up)
     * is defined by _PATH_SERVICES in /usr/include/netdb.h.  This is
     * usually set to /etc/services.
     * See RFC 1700 for more information on services.
     *
     * @param service     the service name to listen on
     */
    void setAddress(const QString &service);

    /**
     * @overload
     * Sets the address on which we will listen. This will cause the socket to listen
     * only on the interface given by @p node and on the port given by @p service.
     * @p service can either be a service name (e.g. 'www') or a port number
     * (e.g. '80').
     *
     * The location of the services file (where @p service is looked up)
     * is defined by _PATH_SERVICES in /usr/include/netdb.h.  This is
     * usually set to /etc/services.
     * See RFC 1700 for more information on services.
     *
     * @param node        the node to bind to
     * @param service     the service port to listen on
     */
    void setAddress(const QString &node, const QString &service);

    /**
     * Sets the timeout for accepting. When you call accept(),
     * it will wait at most @p msecs milliseconds or return with an error
     * (returning a NULL object).
     *
     * @param msecs       the time in milliseconds to wait, 0 to wait forever
     */
    void setTimeout(int msecs);

    /**
     * Starts the lookup for peer and local hostnames as
     * well as their services.
     *
     * If the blocking mode for this object is on, this function will
     * wait for the lookup results to be available (by calling the
     * KResolver::wait() method on the resolver objects).
     *
     * When the lookup is done, the signal hostFound() will be
     * emitted (only once, even if we're doing a double lookup).
     * If the lookup failed (for any of the two lookups) the
     * gotError() signal will be emitted with the appropriate
     * error condition (see KSocketBase::SocketError).
     *
     * This function returns true on success and false on error. Note that
     * this is not the lookup result!
     */
    virtual bool lookup();

    /**
     * Binds this socket to the given nodename and service,
     * or use the default ones if none are given.
     *
     * Upon successful binding, the bound() signal will be
     * emitted. If an error is found, the gotError()
     * signal will be emitted.
     *
     * This function returns true on success.
     *
     * @param node    the nodename
     * @param service the service
     */
    virtual bool bind(const QString &node, const QString &service);

    /**
     * Binds the socket to the given service name.
     * @overload
     *
     * @param service the service
     */
    virtual bool bind(const QString &service);

    /**
     * Binds the socket to the addresses previously set with setAddress().
     * @overload
     *
     */
    virtual bool bind();

    /**
     * Connect this socket to this specific address. Reimplemented from KSocketBase.
     *
     * Unlike bind(const QString&, const QString&) above, this function
     * really does bind the socket. No lookup is performed. The bound() signal
     * will be emitted.
     */
    bool bind(const KResolverEntry &address) override;

    /**
     * Puts this socket into listening mode. Reimplemented from KPassiveSocketBase.
     *
     * Placing a socket into listening mode means it will be able to receive incoming
     * connections through the accept() method.
     *
     * If you do not call this method but call accept() directly, the socket will
     * be placed into listening mode automatically.
     *
     * @param backlog     the number of connection the system is to
     *                            queue without accept() being called
     * @returns true if the socket is now in listening mode.
     */
    bool listen(int backlog = 5) override; // 5 is arbitrary

    /**
     * Closes this socket.
     */
    void close() override;

    /**
     * Toggles whether the accepted socket will be buffered or not.
     * That is, the accept() function will always return a KStreamSocket
     * object or descended from it. If buffering is enabled, the class
     * to be returned will be KBufferedSocket.
     *
     * By default, this flag is set to true.
     *
     * @param enable      whether to set the accepted socket to
     *                buffered mode
     */
    void setAcceptBuffered(bool enable);

    /**
     * Accepts one incoming connection and return the associated, open
     * socket.
     *
     * If this function cannot accept a new connection, it will return NULL.
     * The specific object class returned by this function may vary according
     * to the implementation: derived classes may return specialized objects
     * descended from KStreamSocket.
     *
     * @sa KBufferedSocket
     * @sa setAcceptBuffered
     */
    KStreamSocket *accept() override;

    /**
     * Returns this socket's local address.
     */
    KSocketAddress localAddress() const override;

    /**
     * Returns this socket's externally-visible address if know.
     */
    KSocketAddress externalAddress() const override;

private Q_SLOTS:
    void lookupFinishedSlot();

Q_SIGNALS:
    /**
     * This signal is emitted when this object finds an error.
     * The @p code parameter contains the error code that can
     * also be found by calling error().
     */
    void gotError(int code);

    /**
     * This signal is emitted when the lookup is successfully completed.
     */
    void hostFound();

    /**
     * This signal is emitted when the socket successfully binds
     * to an address.
     *
     * @param local   the local address we bound to
     */
    void bound(const KNetwork::KResolverEntry &local);

    /**
     * This signal is emitted when the socket completes the
     * closing/shut down process.
     */
    void closed();

    /**
     * This signal is emitted whenever the socket is ready for
     * accepting -- i.e., there is at least one connection waiting to
     * be accepted.
     */
    void readyAccept();

protected:
    /**
     * Convenience function to set this object's error code to match
     * that of the socket device.
     */
    void copyError();

private:
    bool doBind();
    bool doListen();

private:
    KServerSocket(const KServerSocket &);
    KServerSocket &operator=(const KServerSocket &);

    KServerSocketPrivate *const d;
};

}               // namespace KNetwork

#endif
