// engine.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 "../pch.h"
#include "../db/jsobj.h"

namespace mongo {

    struct JSFile {
        const char* name;
        const StringData& source;
    };

    typedef unsigned long long ScriptingFunction;
    typedef BSONObj (*NativeFunction) ( const BSONObj &args, void* data );

    class Scope : boost::noncopyable {
    public:
        Scope();
        virtual ~Scope();

        virtual void reset() = 0;
        virtual void init( const BSONObj * data ) = 0;
        void init( const char * data ) {
            BSONObj o( data );
            init( &o );
        }

        virtual void localConnect( const char * dbName ) = 0;
        virtual void externalSetup() = 0;

        class NoDBAccess {
            Scope * _s;
        public:
            NoDBAccess( Scope * s ) {
                _s = s;
            }
            ~NoDBAccess() {
                _s->rename( "____db____" , "db" );
            }
        };
        NoDBAccess disableDBAccess( const char * why ) {
            rename( "db" , "____db____" );
            return NoDBAccess( this );
        }

        virtual double getNumber( const char *field ) = 0;
        virtual int getNumberInt( const char *field ) { return (int)getNumber( field ); }
        virtual long long getNumberLongLong( const char *field ) { return (long long)getNumber( field ); }
        virtual string getString( const char *field ) = 0;
        virtual bool getBoolean( const char *field ) = 0;
        virtual BSONObj getObject( const char *field ) = 0;

        virtual int type( const char *field ) = 0;

        virtual void append( BSONObjBuilder & builder , const char * fieldName , const char * scopeName );

        virtual void setElement( const char *field , const BSONElement& e ) = 0;
        virtual void setNumber( const char *field , double val ) = 0;
        virtual void setString( const char *field , const char * val ) = 0;
        virtual void setObject( const char *field , const BSONObj& obj , bool readOnly=true ) = 0;
        virtual void setBoolean( const char *field , bool val ) = 0;
        virtual void setFunction( const char *field , const char * code ) = 0;
//        virtual void setThis( const BSONObj * obj ) = 0;

        virtual ScriptingFunction createFunction( const char * code );

        virtual void rename( const char * from , const char * to ) = 0;
        /**
         * @return 0 on success
         */
        virtual int invoke( ScriptingFunction func , const BSONObj* args, const BSONObj* recv, int timeoutMs = 0 , bool ignoreReturn = false, bool readOnlyArgs = false, bool readOnlyRecv = false ) = 0;
        void invokeSafe( ScriptingFunction func , const BSONObj* args, const BSONObj* recv, int timeoutMs = 0 , bool ignoreReturn = false, bool readOnlyArgs = false, bool readOnlyRecv = false ) {
            int res = invoke( func , args , recv, timeoutMs, ignoreReturn, readOnlyArgs, readOnlyRecv );
            if ( res == 0 )
                return;
            throw UserException( 9004 , (string)"invoke failed: " + getError() );
        }
        virtual string getError() = 0;
        virtual bool hasOutOfMemoryException() = 0;

        int invoke( const char* code , const BSONObj* args, const BSONObj* recv, int timeoutMs = 0 );
        void invokeSafe( const char* code , const BSONObj* args, const BSONObj* recv, int timeoutMs = 0 ) {
            if ( invoke( code , args , recv, timeoutMs ) == 0 )
                return;
            throw UserException( 9005 , (string)"invoke failed: " + getError() );
        }

        virtual bool exec( const StringData& code , const string& name , bool printResult , bool reportError , bool assertOnError, int timeoutMs = 0 ) = 0;
        virtual void execSetup( const StringData& code , const string& name = "setup" ) {
            exec( code , name , false , true , true , 0 );
        }

        void execSetup( const JSFile& file) {
            execSetup(file.source, file.name);
        }

        void execCoreFiles();

        virtual bool execFile( const string& filename , bool printResult , bool reportError , bool assertOnError, int timeoutMs = 0 );

        virtual void injectNative( const char *field, NativeFunction func, void* data = 0 ) = 0;

        virtual void gc() = 0;

        void loadStored( bool ignoreNotConnected = false );

        /**
         if any changes are made to .system.js, call this
         right now its just global - slightly inefficient, but a lot simpler
        */
        static void storedFuncMod();

        static int getNumScopes() {
            return _numScopes;
        }

        static void validateObjectIdString( const string &str );

        /** increments the number of times a scope was used */
        void incTimeUsed() { ++_numTimeUsed; }
        /** gets the number of times a scope was used */
        int getTimeUsed() { return _numTimeUsed; }

    protected:

        virtual ScriptingFunction _createFunction( const char * code ) = 0;

        string _localDBName;
        long long _loadedVersion;
        set<string> _storedNames;
        static long long _lastVersion;
        map<string,ScriptingFunction> _cachedFunctions;
        int _numTimeUsed;

        static int _numScopes;
    };

    void installGlobalUtils( Scope& scope );

    class DBClientWithCommands;

    class ScriptEngine : boost::noncopyable {
    public:
        ScriptEngine();
        virtual ~ScriptEngine();

        virtual Scope * newScope() {
            Scope *s = createScope();
            if ( s && _scopeInitCallback )
                _scopeInitCallback( *s );
            installGlobalUtils( *s );
            return s;
        }

        virtual void runTest() = 0;

        virtual bool utf8Ok() const = 0;

        static void setup();

        /** gets a scope from the pool or a new one if pool is empty
         * @param pool An identifier for the pool, usually the db name
         * @return the scope */
        auto_ptr<Scope> getPooledScope( const string& pool );

        /** call this method to release some JS resources when a thread is done */
        void threadDone();

        struct Unlocker { virtual ~Unlocker() {} };
        virtual auto_ptr<Unlocker> newThreadUnlocker() { return auto_ptr< Unlocker >( new Unlocker ); }

        void setScopeInitCallback( void ( *func )( Scope & ) ) { _scopeInitCallback = func; }
        static void setConnectCallback( void ( *func )( DBClientWithCommands& ) ) { _connectCallback = func; }
        static void runConnectCallback( DBClientWithCommands &c ) {
            if ( _connectCallback )
                _connectCallback( c );
        }

        // engine implementation may either respond to interrupt events or
        // poll for interrupts

        // the interrupt functions must not wait indefinitely on a lock
        virtual void interrupt( unsigned opSpec ) {}
        virtual void interruptAll() {}

        static void setGetInterruptSpecCallback( unsigned ( *func )() ) { _getInterruptSpecCallback = func; }
        static bool haveGetInterruptSpecCallback() { return _getInterruptSpecCallback; }
        static unsigned getInterruptSpec() {
            massert( 13474, "no _getInterruptSpecCallback", _getInterruptSpecCallback );
            return _getInterruptSpecCallback();
        }

        static void setCheckInterruptCallback( const char * ( *func )() ) { _checkInterruptCallback = func; }
        static bool haveCheckInterruptCallback() { return _checkInterruptCallback; }
        static const char * checkInterrupt() {
            return _checkInterruptCallback ? _checkInterruptCallback() : "";
        }
        static bool interrupted() {
            const char *r = checkInterrupt();
            return r && r[ 0 ];
        }

    protected:
        virtual Scope * createScope() = 0;

    private:
        void ( *_scopeInitCallback )( Scope & );
        static void ( *_connectCallback )( DBClientWithCommands & );
        static const char * ( *_checkInterruptCallback )();
        static unsigned ( *_getInterruptSpecCallback )();
    };

    bool hasJSReturn( const string& s );

    const char * jsSkipWhiteSpace( const char * raw );

    extern ScriptEngine * globalScriptEngine;
}