/*
 *    Copyright (C) 2010 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/>.
 */

// strategy_sharded.cpp

#include "pch.h"
#include "request.h"
#include "chunk.h"
#include "cursors.h"
#include "stats.h"
#include "client.h"

#include "../client/connpool.h"
#include "../db/commands.h"

// error codes 8010-8040

namespace mongo {

    class ShardStrategy : public Strategy {

        virtual void queryOp( Request& r ) {
            QueryMessage q( r.d() );

            log(3) << "shard query: " << q.ns << "  " << q.query << endl;

            if ( q.ntoreturn == 1 && strstr(q.ns, ".$cmd") )
                throw UserException( 8010 , "something is wrong, shouldn't see a command here" );

            ChunkManagerPtr info = r.getChunkManager();
            assert( info );

            Query query( q.query );

            set<Shard> shards;
            info->getShardsForQuery( shards , query.getFilter()  );

            set<ServerAndQuery> servers;
            for ( set<Shard>::iterator i = shards.begin(); i != shards.end(); i++ ) {
                servers.insert( ServerAndQuery( i->getConnString() , BSONObj() ) );
            }

            if ( logLevel > 4 ) {
                StringBuilder ss;
                ss << " shard query servers: " << servers.size() << '\n';
                for ( set<ServerAndQuery>::iterator i = servers.begin(); i!=servers.end(); i++ ) {
                    const ServerAndQuery& s = *i;
                    ss << "       " << s.toString() << '\n';
                }
                log() << ss.str() << endl;
            }

            ClusteredCursor * cursor = 0;

            BSONObj sort = query.getSort();

            if ( sort.isEmpty() ) {
                cursor = new SerialServerClusteredCursor( servers , q );
            }
            else {
                cursor = new ParallelSortClusteredCursor( servers , q , sort );
            }

            assert( cursor );

            try {
                cursor->init();

                log(5) << "   cursor type: " << cursor->type() << endl;
                shardedCursorTypes.hit( cursor->type() );

                if ( query.isExplain() ) {
                    BSONObj explain = cursor->explain();
                    replyToQuery( 0 , r.p() , r.m() , explain );
                    delete( cursor );
                    return;
                }
            }
            catch(...) {
                delete cursor;
                throw;
            }

            ShardedClientCursorPtr cc (new ShardedClientCursor( q , cursor ));
            if ( ! cc->sendNextBatch( r ) ) {
                return;
            }
            log(6) << "storing cursor : " << cc->getId() << endl;
            cursorCache.store( cc );
        }

        virtual void getMore( Request& r ) {
            int ntoreturn = r.d().pullInt();
            long long id = r.d().pullInt64();

            log(6) << "want cursor : " << id << endl;

            ShardedClientCursorPtr cursor = cursorCache.get( id );
            if ( ! cursor ) {
                log(6) << "\t invalid cursor :(" << endl;
                replyToQuery( ResultFlag_CursorNotFound , r.p() , r.m() , 0 , 0 , 0 );
                return;
            }

            if ( cursor->sendNextBatch( r , ntoreturn ) ) {
                // still more data
                cursor->accessed();
                return;
            }

            // we've exhausted the cursor
            cursorCache.remove( id );
        }

        void _insert( Request& r , DbMessage& d, ChunkManagerPtr manager ) {

            while ( d.moreJSObjs() ) {
                BSONObj o = d.nextJsObj();
                if ( ! manager->hasShardKey( o ) ) {

                    bool bad = true;

                    if ( manager->getShardKey().partOfShardKey( "_id" ) ) {
                        BSONObjBuilder b;
                        b.appendOID( "_id" , 0 , true );
                        b.appendElements( o );
                        o = b.obj();
                        bad = ! manager->hasShardKey( o );
                    }

                    if ( bad ) {
                        log() << "tried to insert object without shard key: " << r.getns() << "  " << o << endl;
                        throw UserException( 8011 , "tried to insert object without shard key" );
                    }

                }

                // Many operations benefit from having the shard key early in the object
                o = manager->getShardKey().moveToFront(o);

                const int maxTries = 30;

                bool gotThrough = false;
                for ( int i=0; i<maxTries; i++ ) {
                    try {
                        ChunkPtr c = manager->findChunk( o );
                        log(4) << "  server:" << c->getShard().toString() << " " << o << endl;
                        insert( c->getShard() , r.getns() , o );

                        r.gotInsert();
                        if ( r.getClientInfo()->autoSplitOk() )
                            c->splitIfShould( o.objsize() );
                        gotThrough = true;
                        break;
                    }
                    catch ( StaleConfigException& ) {
                        log( i < ( maxTries / 2 ) ) << "retrying insert because of StaleConfigException: " << o << endl;
                        r.reset();
                        manager = r.getChunkManager();
                    }
                    sleepmillis( i * 200 );
                }

                assert( gotThrough );

            }
        }

        void _update( Request& r , DbMessage& d, ChunkManagerPtr manager ) {
            int flags = d.pullInt();

            BSONObj query = d.nextJsObj();
            uassert( 13506 ,  "$atomic not supported sharded" , query["$atomic"].eoo() );
            uassert( 10201 ,  "invalid update" , d.moreJSObjs() );
            BSONObj toupdate = d.nextJsObj();

            BSONObj chunkFinder = query;

            bool upsert = flags & UpdateOption_Upsert;
            bool multi = flags & UpdateOption_Multi;

            if (upsert) {
                uassert(8012, "can't upsert something without shard key",
                        (manager->hasShardKey(toupdate) ||
                         (toupdate.firstElement().fieldName()[0] == '$' && manager->hasShardKey(query))));

                BSONObj key = manager->getShardKey().extractKey(query);
                BSONForEach(e, key) {
                    uassert(13465, "shard key in upsert query must be an exact match", getGtLtOp(e) == BSONObj::Equality);
                }
            }

            bool save = false;
            if ( ! manager->hasShardKey( query ) ) {
                if ( multi ) {
                }
                else if ( strcmp( query.firstElement().fieldName() , "_id" ) || query.nFields() != 1 ) {
                    throw UserException( 8013 , "can't do non-multi update with query that doesn't have the shard key" );
                }
                else {
                    save = true;
                    chunkFinder = toupdate;
                }
            }


            if ( ! save ) {
                if ( toupdate.firstElement().fieldName()[0] == '$' ) {
                    BSONObjIterator ops(toupdate);
                    while(ops.more()) {
                        BSONElement op(ops.next());
                        if (op.type() != Object)
                            continue;
                        BSONObjIterator fields(op.embeddedObject());
                        while(fields.more()) {
                            const string field = fields.next().fieldName();
                            uassert(13123,
                                    str::stream() << "Can't modify shard key's value field" << field
                                    << " for collection: " << manager->getns(),
                                    ! manager->getShardKey().partOfShardKey(field));
                        }
                    }
                }
                else if ( manager->hasShardKey( toupdate ) ) {
                    uassert( 8014,
                             str::stream() << "cannot modify shard key for collection: " << manager->getns(),
                             manager->getShardKey().compare( query , toupdate ) == 0 );
                }
                else {
                    uasserted(12376,
                              str::stream() << "shard key must be in update object for collection: " << manager->getns() );
                }
            }

            if ( multi ) {
                set<Shard> shards;
                manager->getShardsForQuery( shards , chunkFinder );
                int * x = (int*)(r.d().afterNS());
                x[0] |= UpdateOption_Broadcast;
                for ( set<Shard>::iterator i=shards.begin(); i!=shards.end(); i++) {
                    doWrite( dbUpdate , r , *i , false );
                }
            }
            else {
                int left = 5;
                while ( true ) {
                    try {
                        ChunkPtr c = manager->findChunk( chunkFinder );
                        doWrite( dbUpdate , r , c->getShard() );
                        if ( r.getClientInfo()->autoSplitOk() )
                            c->splitIfShould( d.msg().header()->dataLen() );
                        break;
                    }
                    catch ( StaleConfigException& e ) {
                        if ( left <= 0 )
                            throw e;
                        left--;
                        log() << "update failed b/c of StaleConfigException, retrying "
                              << " left:" << left << " ns: " << r.getns() << " query: " << query << endl;
                        r.reset( false );
                        manager = r.getChunkManager();
                    }
                }
            }

        }

        void _delete( Request& r , DbMessage& d, ChunkManagerPtr manager ) {

            int flags = d.pullInt();
            bool justOne = flags & 1;

            uassert( 10203 ,  "bad delete message" , d.moreJSObjs() );
            BSONObj pattern = d.nextJsObj();
            uassert( 13505 ,  "$atomic not supported sharded" , pattern["$atomic"].eoo() );

            set<Shard> shards;
            int left = 5;

            while ( true ) {
                try {
                    manager->getShardsForQuery( shards , pattern );
                    log(2) << "delete : " << pattern << " \t " << shards.size() << " justOne: " << justOne << endl;
                    if ( shards.size() == 1 ) {
                        doWrite( dbDelete , r , *shards.begin() );
                        return;
                    }
                    break;
                }
                catch ( StaleConfigException& e ) {
                    if ( left <= 0 )
                        throw e;
                    left--;
                    log() << "delete failed b/c of StaleConfigException, retrying "
                          << " left:" << left << " ns: " << r.getns() << " patt: " << pattern << endl;
                    r.reset( false );
                    shards.clear();
                    manager = r.getChunkManager();
                }
            }

            if ( justOne && ! pattern.hasField( "_id" ) )
                throw UserException( 8015 , "can only delete with a non-shard key pattern if can delete as many as we find" );

            for ( set<Shard>::iterator i=shards.begin(); i!=shards.end(); i++) {
                int * x = (int*)(r.d().afterNS());
                x[0] |= RemoveOption_Broadcast;
                doWrite( dbDelete , r , *i , false );
            }
        }

        virtual void writeOp( int op , Request& r ) {
            const char *ns = r.getns();
            log(3) << "write: " << ns << endl;

            DbMessage& d = r.d();
            ChunkManagerPtr info = r.getChunkManager();
            assert( info );

            if ( op == dbInsert ) {
                _insert( r , d , info );
            }
            else if ( op == dbUpdate ) {
                _update( r , d , info );
            }
            else if ( op == dbDelete ) {
                _delete( r , d , info );
            }
            else {
                log() << "sharding can't do write op: " << op << endl;
                throw UserException( 8016 , "can't do this write op on sharded collection" );
            }

        }
    };

    Strategy * SHARDED = new ShardStrategy();
}