// dbclient.cpp - connect to a Mongo database as a database, from C++

/**
*    Copyright (C) 2008 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/>.
*/

#include "stdafx.h"
#include "../db/pdfile.h"
#include "dbclient.h"
#include "../util/builder.h"
#include "../db/jsobj.h"
#include "../db/query.h"
#include "../db/json.h"
#include "../db/instance.h"

/* --- dbclientcommands --- */

inline bool DBClientWithCommands::isOk(const BSONObj& o) { 
	return o.getIntField("ok") == 1;
}

inline bool DBClientWithCommands::runCommand(const char *dbname, BSONObj cmd, BSONObj &info) { 
	string ns = string(dbname) + ".$cmd";
    info = findOne(ns.c_str(), cmd);
	return isOk(info);
}

/* note - we build a bson obj here -- for something that is super common like getlasterror you 
          should have that object prebuilt as that would be faster.
*/
bool DBClientWithCommands::simpleCommand(const char *dbname, BSONObj *info, const char *command) { 
	BSONObj o;
	if( info == 0 )
		info = &o;
	BSONObjBuilder b;
	b.appendInt(command, 1);
	return runCommand(dbname, b.done(), *info);
}

BSONObj ismastercmdobj = fromjson("{ismaster:1}");

bool DBClientWithCommands::isMaster(bool& isMaster, BSONObj *info) {
	BSONObj o;	if( info == 0 )	info = &o;
	bool ok = runCommand("admin", ismastercmdobj, *info);
    isMaster = (info->getIntField("ismaster") == 1);
	return ok;
}

bool DBClientWithCommands::createCollection(const char *ns, unsigned size, bool capped, int max, BSONObj *info) { 
	BSONObj o;	if( info == 0 )	info = &o;
	BSONObjBuilder b;
	b.append("create", ns);
	if( size ) b.append("size", size);
	if( capped ) b.append("capped", true);
	if( max ) b.append("max", max);
	string db = nsToClient(ns);
	return runCommand(db.c_str(), b.done(), *info);
}

bool DBClientWithCommands::copyDatabase(const char *fromdb, const char *todb, const char *fromhost, BSONObj *info) { 
	assert( *fromdb && *todb );
	BSONObj o; if( info == 0 ) info = &o;
	BSONObjBuilder b;
	b.append("copydb", 1);
	b.append("fromhost", fromhost);
	b.append("fromdb", fromdb);
	b.append("todb", todb);
	return runCommand("admin", b.done(), *info);
}

bool DBClientWithCommands::setDbProfilingLevel(const char *dbname, ProfilingLevel level, BSONObj *info ) { 
	BSONObj o; if( info == 0 ) info = &o;

    if( level ) {
        // Create system.profile collection.  If it already exists this does nothing.  
		// TODO: move this into the db instead of here so that all 
		//       drivers don't have to do this.
		string ns = string(dbname) + ".system.profile";
		createCollection(ns.c_str(), 1024 * 1024, true, 0, info);
    }

	BSONObjBuilder b;
	b.append("profile", (int) level);
	return runCommand(dbname, b.done(), *info);
}

BSONObj getprofilingcmdobj; // TODO UNCOMMENT !!! = fromjson("{profile:-1}");

bool DBClientWithCommands::getDbProfilingLevel(const char *dbname, ProfilingLevel& level, BSONObj *info) { 
	BSONObj o; if( info == 0 ) info = &o;
	if( runCommand(dbname, getprofilingcmdobj, *info) ) { 
		level = (ProfilingLevel) info->getIntField("was");
		return true;
	}
	return false;
}

bool DBClientWithCommands::eval(const char *dbname, const char *jscode, BSONObj& info, BSONElement& retValue, BSONObj *args) { 
	BSONObjBuilder b;
	b.appendCode("$eval", jscode);
	if( args ) 
		b.appendArray("args", *args);
	bool ok = runCommand(dbname, b.done(), info);
	if( ok ) 
		retValue = info.getField("retval");
	return ok;
}

bool DBClientWithCommands::eval(const char *dbname, const char *jscode) { 
	BSONObj info;
	BSONElement retValue;
	return eval(dbname, jscode, info, retValue);
}

/* TODO: unit tests should run this? */
void testDbEval() { 
	DBClientConnection c;
	string err;
	if( !c.connect("localhost", err) ) { 
		cout << "can't connect to server " << err << endl;
		return;
	}
	BSONObj info;
	BSONElement retValue;
	BSONObjBuilder b;
	b.append("0", 99);
	BSONObj args = b.done();
	bool ok = c.eval("dwight", "function() { return args[0]; }", info, retValue, &args);
	cout << "eval ok=" << ok << endl;
	cout << "retvalue=" << retValue.toString() << endl;
	cout << "info=" << info.toString() << endl;

	cout << endl;

	int x = 3;
	assert( c.eval("dwight", "function() { return 3; }", x) );

	cout << "***\n";

	BSONObj foo = fromjson("{x:1}");
	cout << foo.toString() << endl;
	int res=0;
	ok = c.eval("dwight", "function(parm1) { return parm1.x; }", foo, res);
	cout << ok << " retval:" << res << endl;
}

int test2() { 
	testDbEval();
	return 0;
}

/* --- dbclientconnection --- */

BSONObj DBClientConnection::findOne(const char *ns, BSONObj query, BSONObj *fieldsToReturn, int queryOptions) {
    auto_ptr<DBClientCursor> c =
        this->query(ns, query, 1, 0, fieldsToReturn, queryOptions);

    massert( "DBClientConnection::findOne: transport error", c.get() );

    if ( !c->more() )
        return BSONObj();

    return c->next().copy();
}

bool DBClientConnection::connect(const char *_serverAddress, string& errmsg) {
    serverAddress = _serverAddress;

    int port = DBPort;
    string ip = hostbyname(_serverAddress);
    if ( ip.empty() )
        ip = serverAddress;

    size_t idx = ip.find( ":" );
    if ( idx != string::npos ) {
        //cout << "port string:" << ip.substr( idx ) << endl;
        port = atoi( ip.substr( idx + 1 ).c_str() );
        ip = ip.substr( 0 , idx );
        ip = hostbyname(ip.c_str());

    }
    if ( ip.empty() )
        ip = serverAddress;

    // we keep around SockAddr for connection life -- maybe MessagingPort
    // requires that?
    server = auto_ptr<SockAddr>(new SockAddr(ip.c_str(), port));
    p = auto_ptr<MessagingPort>(new MessagingPort());

    if ( !p->connect(*server) ) {
        stringstream ss;
        ss << "couldn't connect to server " << serverAddress << " " << ip << ":" << port;
        errmsg = ss.str();
        failed = true;
        return false;
    }
    return true;
}

void DBClientConnection::checkConnection() {
    if ( !failed )
        return;
    if ( lastReconnectTry && time(0)-lastReconnectTry < 2 )
        return;
    if ( !autoReconnect )
        return;

    lastReconnectTry = time(0);
    log() << "trying reconnect to " << serverAddress << endl;
    string errmsg;
    string tmp = serverAddress;
    failed = false;
    if ( !connect(tmp.c_str(), errmsg) )
        log() << "reconnect " << serverAddress << " failed " << errmsg << endl;
    else
        log() << "reconnect " << serverAddress << " ok" << endl;
}

auto_ptr<DBClientCursor> DBClientConnection::query(const char *ns, BSONObj query, int nToReturn,
        int nToSkip, BSONObj *fieldsToReturn, int queryOptions) {
    checkConnection();

    auto_ptr<DBClientCursor> c( new DBClientCursor( new CursorConnector( this ),
                                ns, query, nToReturn, nToSkip,
                                fieldsToReturn, queryOptions ) );
    if ( c->init() )
        return c;
    return auto_ptr< DBClientCursor >( 0 );
}

/* -- DBClientCursor ---------------------------------------------- */

void assembleRequest( const string &ns, BSONObj query, int nToReturn, int nToSkip, BSONObj *fieldsToReturn, int queryOptions, Message &toSend ) {
    // see query.h for the protocol we are using here.
    BufBuilder b;
    int opts = queryOptions;
    assert( (opts&Option_ALLMASK) == opts );
    b.append(opts);
    b.append(ns.c_str());
    b.append(nToSkip);
    b.append(nToReturn);
    query.appendSelfToBufBuilder(b);
    if ( fieldsToReturn )
        fieldsToReturn->appendSelfToBufBuilder(b);
    toSend.setData(dbQuery, b.buf(), b.len());
}

bool DBClientConnection::CursorConnector::send( Message &toSend, Message &response, bool assertOk ) {
    if ( !conn->port().call(toSend, response) ) {
        conn->failed = true;
        if ( assertOk )
            massert("dbclient error communicating with server", false);
        return false;
    }
    return true;
}

void DBClientConnection::CursorConnector::checkResponse( const char *data, int nReturned ) {
    /* check for errors.  the only one we really care about at
     this stage is "not master" */
    if ( conn->clientPaired && nReturned ) {
        BSONObj o(data);
        BSONElement e = o.firstElement();
        if ( strcmp(e.fieldName(), "$err") == 0 &&
                e.type() == String && strncmp(e.valuestr(), "not master", 10) == 0 ) {
            conn->clientPaired->isntMaster();
        }
    }
}

bool DBClientCursor::init() {
    Message toSend;
    assembleRequest( ns, query, nToReturn, nToSkip, fieldsToReturn, opts, toSend );
    if ( !connector->send( toSend, *m, false ) )
        return false;

    dataReceived();
    return true;
}

void DBClientCursor::requestMore() {
    assert( cursorId && pos == nReturned );

    BufBuilder b;
    b.append(opts);
    b.append(ns.c_str());
    b.append(nToReturn);
    b.append(cursorId);

    Message toSend;
    toSend.setData(dbGetMore, b.buf(), b.len());
    auto_ptr<Message> response(new Message());
    connector->send( toSend, *response );

    m = response;
    dataReceived();
}

void DBClientCursor::dataReceived() {
    QueryResult *qr = (QueryResult *) m->data;
    if ( qr->resultFlags() & ResultFlag_CursorNotFound ) {
        // cursor id no longer valid at the server.
        assert( qr->cursorId == 0 );
        cursorId = 0; // 0 indicates no longer valid (dead)
    }
    if ( cursorId == 0 ) {
        // only set initially: we don't want to kill it on end of data
        // if it's a tailable cursor
        cursorId = qr->cursorId;
    }
    nReturned = qr->nReturned;
    pos = 0;
    data = qr->data();

    connector->checkResponse( data, nReturned );
    /* this assert would fire the way we currently work:
        assert( nReturned || cursorId == 0 );
    */
}

bool DBClientCursor::more() {
    if ( pos < nReturned )
        return true;

    if ( cursorId == 0 )
        return false;

    requestMore();
    return pos < nReturned;
}

BSONObj DBClientCursor::next() {
    assert( more() );
    pos++;
    BSONObj o(data);
    data += o.objsize();
    return o;
}

/* ------------------------------------------------------ */

// "./db testclient" to invoke
extern BSONObj emptyObj;
void testClient() {
    cout << "testClient()" << endl;
//	DBClientConnection c(true);
    DBClientPaired c;
    string err;
    if ( !c.connect("10.211.55.2", "1.2.3.4") ) {
//    if( !c.connect("10.211.55.2", err) ) {
        cout << "testClient: connect() failed" << endl;
    }
    else {
        // temp:
        cout << "test query returns: " << c.findOne("foo.bar", fromjson("{}")).toString() << endl;
    }
again:
    cout << "query foo.bar..." << endl;
    auto_ptr<DBClientCursor> cursor =
        c.query("foo.bar", emptyObj, 0, 0, 0, Option_CursorTailable);
    DBClientCursor *cc = cursor.get();
    if ( cc == 0 ) {
        cout << "query() returned 0, sleeping 10 secs" << endl;
        sleepsecs(10);
        goto again;
    }
    while ( 1 ) {
        bool m;
        try {
            m = cc->more();
        } catch (AssertionException&) {
            cout << "more() asserted, sleeping 10 sec" << endl;
            goto again;
        }
        cout << "more: " << m << " dead:" << cc->isDead() << endl;
        if ( !m ) {
            if ( cc->isDead() )
                cout << "cursor dead, stopping" << endl;
            else {
                cout << "Sleeping 10 seconds" << endl;
                sleepsecs(10);
                continue;
            }
            break;
        }
        cout << cc->next().toString() << endl;
    }
}

/* --- class dbclientpaired --- */

string DBClientPaired::toString() {
    stringstream ss;
    ss << "state: " << master << '\n';
    ss << "left:  " << left.toStringLong() << '\n';
    ss << "right: " << right.toStringLong() << '\n';
    return ss.str();
}

DBClientPaired::DBClientPaired() :
        left(true), right(true)
{
    master = NotSetL;
}

/* find which server, the left or right, is currently master mode */
void DBClientPaired::_checkMaster() {
    for ( int retry = 0; retry < 2; retry++ ) {
        int x = master;
        for ( int pass = 0; pass < 2; pass++ ) {
            DBClientConnection& c = x == 0 ? left : right;
            try {
                bool im;
                BSONObj o;
				c.isMaster(im, &o);
                if ( retry )
                    log() << "checkmaster: " << c.toString() << ' ' << o.toString() << '\n';
                if ( im ) {
                    master = (State) (x + 2);
                    return;
                }
            }
            catch (AssertionException&) {
                if ( retry )
                    log() << "checkmaster: caught exception " << c.toString() << '\n';
            }
            x = x^1;
        }
        sleepsecs(1);
    }

    uassert("checkmaster: no master found", false);
}

inline DBClientConnection& DBClientPaired::checkMaster() {
    if ( master > NotSetR ) {
        // a master is selected.  let's just make sure connection didn't die
        DBClientConnection& c = master == Left ? left : right;
        if ( !c.isFailed() )
            return c;
        // after a failure, on the next checkMaster, start with the other
        // server -- presumably it took over. (not critical which we check first,
        // just will make the failover slightly faster if we guess right)
        master = master == Left ? NotSetR : NotSetL;
    }

    _checkMaster();
    assert( master > NotSetR );
    return master == Left ? left : right;
}

bool DBClientPaired::connect(const char *serverHostname1, const char *serverHostname2) {
    string errmsg;
    bool l = left.connect(serverHostname1, errmsg);
    bool r = right.connect(serverHostname2, errmsg);
    master = l ? NotSetL : NotSetR;
    if ( !l && !r ) // it would be ok to fall through, but checkMaster will then try an immediate reconnect which is slow
        return false;
    try {
        checkMaster();
    }
    catch (UserAssertionException&) {
        return false;
    }
    return true;
}

auto_ptr<DBClientCursor> DBClientPaired::query(const char *a, BSONObj b, int c, int d,
        BSONObj *e, int f)
{
    return checkMaster().query(a,b,c,d,e,f);
}

BSONObj DBClientPaired::findOne(const char *a, BSONObj b, BSONObj *c, int d) {
    return checkMaster().findOne(a,b,c,d);
}