// commands.h

/*    Copyright 2009 10gen Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

#pragma once

#include <string>
#include <vector>

#include "mongo/base/status.h"
#include "mongo/db/auth/privilege.h"
#include "mongo/db/auth/resource_pattern.h"
#include "mongo/db/client_basic.h"
#include "mongo/db/jsobj.h"

namespace mongo {

    class BSONObj;
    class BSONObjBuilder;
    class Client;
    class Database;
    class Timer;

namespace mutablebson {
    class Document;
}  // namespace mutablebson

    /** mongodb "commands" (sent via db.$cmd.findOne(...))
        subclass to make a command.  define a singleton object for it.
        */
    class Command {
    protected:
        // The type of the first field in 'cmdObj' must be mongo::String. The first field is
        // interpreted as a collection name.
        string parseNsFullyQualified(const string& dbname, const BSONObj& cmdObj) const;
    public:

        // Return the namespace for the command. If the first field in 'cmdObj' is of type
        // mongo::String, then that field is interpreted as the collection name, and is
        // appended to 'dbname' after a '.' character. If the first field is not of type
        // mongo::String, then 'dbname' is returned unmodified.
        virtual string parseNs(const string& dbname, const BSONObj& cmdObj) const;

        // Utility that returns a ResourcePattern for the namespace returned from
        // parseNs(dbname, cmdObj).  This will be either an exact namespace resource pattern
        // or a database resource pattern, depending on whether parseNs returns a fully qualifed
        // collection name or just a database name.
        ResourcePattern parseResourcePattern(const std::string& dbname,
                                             const BSONObj& cmdObj) const;

        const string name;

        /* run the given command
           implement this...

           fromRepl - command is being invoked as part of replication syncing.  In this situation you
                      normally do not want to log the command to the local oplog.

           return value is true if succeeded.  if false, set errmsg text.
        */
        virtual bool run(const string& db, BSONObj& cmdObj, int options, string& errmsg, BSONObjBuilder& result, bool fromRepl = false ) = 0;

        /**
         * This designation for the command is only used by the 'help' call and has nothing to do 
         * with lock acquisition. The reason we need to have it there is because 
         * SyncClusterConnection uses this to determine whether the command is update and needs to
         * be sent to all three servers or just one.
         *
         * Eventually when SyncClusterConnection is refactored out, we can get rid of it.
         */
        virtual bool isWriteCommandForConfigServer() const = 0;

        /* Return true if only the admin ns has privileges to run this command. */
        virtual bool adminOnly() const {
            return false;
        }

        void htmlHelp(stringstream&) const;

        /* Like adminOnly, but even stricter: we must either be authenticated for admin db,
           or, if running without auth, on the local interface.  Used for things which 
           are so major that remote invocation may not make sense (e.g., shutdownServer).

           When localHostOnlyIfNoAuth() is true, adminOnly() must also be true.
        */
        virtual bool localHostOnlyIfNoAuth(const BSONObj& cmdObj) { return false; }

        /* Return true if slaves are allowed to execute the command
           (the command directly from a client -- if fromRepl, always allowed).
        */
        virtual bool slaveOk() const = 0;

        /* Return true if the client force a command to be run on a slave by
           turning on the 'slaveOk' option in the command query.
        */
        virtual bool slaveOverrideOk() const {
            return false;
        }

        /**
         * Override and return fales if the command opcounters should not be incremented on
         * behalf of this command.
         */
        virtual bool shouldAffectCommandCounter() const { return true; }

        virtual void help( stringstream& help ) const;

        /**
         * Checks if the given client is authorized to run this command on database "dbname"
         * with the invocation described by "cmdObj".
         */
        virtual Status checkAuthForCommand(ClientBasic* client,
                                           const std::string& dbname,
                                           const BSONObj& cmdObj);

        /**
         * Redacts "cmdObj" in-place to a form suitable for writing to logs.
         *
         * The default implementation does nothing.
         */
        virtual void redactForLogging(mutablebson::Document* cmdObj);

        /* Return true if a replica set secondary should go into "recovering"
           (unreadable) state while running this command.
         */
        virtual bool maintenanceMode() const { return false; }

        /* Return true if command should be permitted when a replica set secondary is in "recovering"
           (unreadable) state.
         */
        virtual bool maintenanceOk() const { return true; /* assumed true prior to commit */ }

        /** @param webUI expose the command in the web ui as localhost:28017/<name>
            @param oldName an optional old, deprecated name for the command
        */
        Command(StringData _name, bool webUI = false, StringData oldName = StringData());

        virtual ~Command() {}

    protected:

        /**
         * Appends to "*out" the privileges required to run this command on database "dbname" with
         * the invocation described by "cmdObj".  New commands shouldn't implement this, they should
         * implement checkAuthForCommand instead.
         */
        virtual void addRequiredPrivileges(const std::string& dbname,
                                           const BSONObj& cmdObj,
                                           std::vector<Privilege>* out) {
            // The default implementation of addRequiredPrivileges should never be hit.
            fassertFailed(16940);
        }

        BSONObj getQuery( const BSONObj& cmdObj ) {
            if ( cmdObj["query"].type() == Object )
                return cmdObj["query"].embeddedObject();
            if ( cmdObj["q"].type() == Object )
                return cmdObj["q"].embeddedObject();
            return BSONObj();
        }

        static void logIfSlow( const Timer& cmdTimer,  const string& msg);

        static map<string,Command*> * _commands;
        static map<string,Command*> * _commandsByBestName;
        static map<string,Command*> * _webCommands;

    public:
        // Stops all index builds required to run this command and returns index builds killed.
        virtual std::vector<BSONObj> stopIndexBuilds(Database* db, 
                                                     const BSONObj& cmdObj);

        static const map<string,Command*>* commandsByBestName() { return _commandsByBestName; }
        static const map<string,Command*>* webCommands() { return _webCommands; }
        /** @return if command was found */
        static void runAgainstRegistered(const char *ns,
                                         BSONObj& jsobj,
                                         BSONObjBuilder& anObjBuilder,
                                         int queryOptions = 0);
        static Command * findCommand( const string& name );
        // For mongod and webserver.
        static void execCommand(Command* c,
                                Client& client,
                                int queryOptions,
                                const char *ns,
                                BSONObj& cmdObj,
                                BSONObjBuilder& result,
                                bool fromRepl );
        // For mongos
        static void execCommandClientBasic(Command* c,
                                           ClientBasic& client,
                                           int queryOptions,
                                           const char *ns,
                                           BSONObj& cmdObj,
                                           BSONObjBuilder& result,
                                           bool fromRepl );

        // Helper for setting errmsg and ok field in command result object.
        static void appendCommandStatus(BSONObjBuilder& result, bool ok, const std::string& errmsg);

        // @return s.isOK()
        static bool appendCommandStatus(BSONObjBuilder& result, const Status& status);

        // Converts "result" into a Status object.  The input is expected to be the object returned
        // by running a command.  Returns ErrorCodes::CommandResultSchemaViolation if "result" does
        // not look like the result of a command.
        static Status getStatusFromCommandResult(const BSONObj& result);

        // Set by command line.  Controls whether or not testing-only commands should be available.
        static int testCommandsEnabled;

    private:
        /**
         * Checks to see if the client is authorized to run the given command with the given
         * parameters on the given named database.
         *
         * fromRepl is true if this command is running as part of oplog application, which for
         * historic reasons has slightly different authorization semantics.  TODO(schwerin): Check
         * to see if this oddity can now be eliminated.
         *
         * Returns Status::OK() if the command is authorized.  Most likely returns
         * ErrorCodes::Unauthorized otherwise, but any return other than Status::OK implies not
         * authorized.
         */
        static Status _checkAuthorization(Command* c,
                                          ClientBasic* client,
                                          const std::string& dbname,
                                          const BSONObj& cmdObj,
                                          bool fromRepl);
    };

    bool _runCommands(const char *ns, BSONObj& jsobj, BufBuilder &b, BSONObjBuilder& anObjBuilder, bool fromRepl, int queryOptions);

} // namespace mongo
