/**
 *    Copyright (C) 2013 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.
 */

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kQuery

#include "mongo/platform/basic.h"

#include "mongo/db/exec/shard_filter.h"

#include "mongo/db/exec/filter.h"
#include "mongo/db/exec/scoped_timer.h"
#include "mongo/db/exec/working_set_common.h"
#include "mongo/db/s/collection_metadata.h"
#include "mongo/s/shard_key_pattern.h"
#include "mongo/stdx/memory.h"
#include "mongo/util/log.h"

namespace mongo {

using std::shared_ptr;
using std::unique_ptr;
using std::vector;
using stdx::make_unique;

// static
const char* ShardFilterStage::kStageType = "SHARDING_FILTER";

ShardFilterStage::ShardFilterStage(OperationContext* opCtx,
                                   const shared_ptr<CollectionMetadata>& metadata,
                                   WorkingSet* ws,
                                   PlanStage* child)
    : PlanStage(kStageType, opCtx), _ws(ws), _metadata(metadata) {
    _children.emplace_back(child);
}

ShardFilterStage::~ShardFilterStage() {}

bool ShardFilterStage::isEOF() {
    return child()->isEOF();
}

PlanStage::StageState ShardFilterStage::doWork(WorkingSetID* out) {
    // If we've returned as many results as we're limited to, isEOF will be true.
    if (isEOF()) {
        return PlanStage::IS_EOF;
    }

    StageState status = child()->work(out);

    if (PlanStage::ADVANCED == status) {
        // If we're sharded make sure that we don't return data that is not owned by us,
        // including pending documents from in-progress migrations and orphaned documents from
        // aborted migrations
        if (_metadata) {
            ShardKeyPattern shardKeyPattern(_metadata->getKeyPattern());
            WorkingSetMember* member = _ws->get(*out);
            WorkingSetMatchableDocument matchable(member);
            BSONObj shardKey = shardKeyPattern.extractShardKeyFromMatchable(matchable);

            if (shardKey.isEmpty()) {
                // We can't find a shard key for this document - this should never happen with
                // a non-fetched result unless our query planning is screwed up
                if (!member->hasObj()) {
                    Status status(ErrorCodes::InternalError,
                                  "shard key not found after a covered stage, "
                                  "query planning has failed");

                    // Fail loudly and cleanly in production, fatally in debug
                    error() << status.toString();
                    dassert(false);

                    _ws->free(*out);
                    *out = WorkingSetCommon::allocateStatusMember(_ws, status);
                    return PlanStage::FAILURE;
                }

                // Skip this document with a warning - no shard key should not be possible
                // unless manually inserting data into a shard
                warning() << "no shard key found in document " << member->obj.value().toString()
                          << " "
                          << "for shard key pattern " << _metadata->getKeyPattern() << ", "
                          << "document may have been inserted manually into shard";
            }

            if (!_metadata->keyBelongsToMe(shardKey)) {
                _ws->free(*out);
                ++_specificStats.chunkSkips;
                return PlanStage::NEED_TIME;
            }
        }

        // If we're here either we have shard state and our doc passed, or we have no shard
        // state.  Either way, we advance.
        return status;
    }

    return status;
}

unique_ptr<PlanStageStats> ShardFilterStage::getStats() {
    _commonStats.isEOF = isEOF();
    unique_ptr<PlanStageStats> ret =
        make_unique<PlanStageStats>(_commonStats, STAGE_SHARDING_FILTER);
    ret->children.emplace_back(child()->getStats());
    ret->specific = make_unique<ShardingFilterStats>(_specificStats);
    return ret;
}

const SpecificStats* ShardFilterStage::getSpecificStats() const {
    return &_specificStats;
}

}  // namespace mongo