/*    Copyright 2012 10gen Inc.
 *
 *    This program is free software: you can redistribute it and/or  modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    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
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    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 GNU Affero General 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 <string>
#include <vector>

#include "mongo/client/dbclientinterface.h"
#include "mongo/db/jsobj.h"
#include "mongo/platform/unordered_map.h"
#include "mongo/rpc/unique_message.h"
#include "mongo/util/concurrency/spin_lock.h"

namespace mongo {

    const std::string IdentityNS("local.me");
    const BSONField<std::string> HostField("host");

    /**
     * A very simple mock that acts like a database server. Every object keeps track of its own
     * InstanceID, which initially starts at zero and increments every time it is restarted.
     * This is primarily used for simulating the state of which old connections won't be able
     * to talk to the sockets that has already been closed on this server.
     *
     * Note: All operations on this server are protected by a lock.
     */
    class MockRemoteDBServer {
    public:
        typedef size_t InstanceID;

        /**
         * Creates a new mock server. This can also be setup to work with the
         * ConnectionString class by using mongo::MockConnRegistry as follows:
         *
         * ConnectionString::setConnectionHook(MockConnRegistry::get()->getConnStrHook());
         * MockRemoteDBServer server("$a:27017");
         * MockConnRegistry::get()->addServer(&server);
         *
         * This allows clients using the ConnectionString::connect interface to create
         * connections to this server. The requirements to make this hook fully functional are:
         *
         * 1. hostAndPort of this server should start with $.
         * 2. No other instance has the same hostAndPort as this.
         *
         * This server will also contain the hostAndPort inside the IdentityNS
         * collection. This is convenient for testing query routing.
         *
         * @param hostAndPort the host name with port for this server.
         *
         * @see MockConnRegistry
         */
        MockRemoteDBServer(const std::string& hostAndPort);
        virtual ~MockRemoteDBServer();

        //
        // Connectivity methods
        //

        /**
         * Set a delay for calls to query and runCommand
         */
        void setDelay(long long milliSec);

        /**
         * Shuts down this server. Any operations on this server with an InstanceID
         * less than or equal to the current one will throw a mongo::SocketException.
         * To bring the server up again, use the reboot method.
         */
        void shutdown();

        /**
         * Increments the instanceID of this server.
         */
        void reboot();

        /**
         * @return true if this server is running
         */
        bool isRunning() const;

        //
        // Mocking methods
        //

        /**
         * Sets the reply for a command.
         *
         * @param cmdName the name of the command
         * @param replyObj the exact reply for the command
         */
        void setCommandReply(const std::string& cmdName,
                const mongo::BSONObj& replyObj);

        /**
         * Sets the reply for a command.
         *
         * @param cmdName the name of the command.
         * @param replySequence the sequence of replies to cycle through every time
         *     the given command is requested. This is useful for setting up a
         *     sequence of response when the command can be called more than once
         *     that requires different results when calling a method.
         */
        void setCommandReply(const std::string& cmdName,
                const std::vector<mongo::BSONObj>& replySequence);

        /**
         * Inserts a single document to this server.
         *
         * @param ns the namespace to insert the document to.
         * @param obj the document to insert.
         * @param flags ignored.
         */
        void insert(const std::string& ns, BSONObj obj, int flags = 0);

        /**
         * Removes documents from this server.
         *
         * @param ns the namespace to remove documents from.
         * @param query ignored.
         * @param flags ignored.
         */
        void remove(const std::string& ns, Query query, int flags = 0);

        //
        // DBClientBase methods
        //
        bool runCommand(InstanceID id, const std::string& dbname,
                const mongo::BSONObj& cmdObj,
                mongo::BSONObj &info, int options = 0);

        rpc::UniqueReply runCommandWithMetadata(InstanceID id,
                                                StringData database,
                                                StringData commandName,
                                                const BSONObj& metadata,
                                                const BSONObj& commandArgs);

        mongo::BSONArray query(InstanceID id,
                const std::string &ns,
                mongo::Query query = mongo::Query(),
                int nToReturn = 0,
                int nToSkip = 0,
                const mongo::BSONObj* fieldsToReturn = 0,
                int queryOptions = 0,
                int batchSize = 0);

        //
        // Getters
        //

        InstanceID getInstanceID() const;
        mongo::ConnectionString::ConnectionType type() const;
        double getSoTimeout() const;

        /**
         * @return the exact std::string address passed to hostAndPort parameter of the
         *     constructor. In other words, doesn't automatically append a
         *     'default' port if none is specified.
         */
        std::string getServerAddress() const;
        std::string toString();

        //
        // Call counters
        //

        size_t getCmdCount() const;
        size_t getQueryCount() const;
        void clearCounters();

    private:
        /**
         * A very simple class for cycling through a set of BSONObj
         */
        class CircularBSONIterator {
        public:
            /**
             * Creates a new iterator with a deep copy of the vector.
             */
            CircularBSONIterator(const std::vector<mongo::BSONObj>& replyVector);
            mongo::BSONObj next();

        private:
            std::vector<mongo::BSONObj>::iterator _iter;
            std::vector<mongo::BSONObj> _replyObjs;
        };

        /**
         * Checks whether the instance of the server is still up.
         *
         * @throws mongo::SocketException if this server is down
         */
        void checkIfUp(InstanceID id) const;

        typedef unordered_map<std::string, std::shared_ptr<CircularBSONIterator> > CmdToReplyObj;
        typedef unordered_map<std::string, std::vector<BSONObj> > MockDataMgr;

        bool _isRunning;

        const std::string _hostAndPort;
        long long _delayMilliSec;

        //
        // Mock replies
        //
        CmdToReplyObj _cmdMap;
        MockDataMgr _dataMgr;

        //
        // Op Counters
        //
        size_t _cmdCount;
        size_t _queryCount;

        // Unique id for every restart of this server used for rejecting requests from
        // connections that are still "connected" to the old instance
        InstanceID _instanceID;

        // protects this entire instance
        mutable mongo::SpinLock _lock;
    };
}