/**
 *    Copyright (C) 2013-2014 MongoDB 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.
 */

/**
 * This file tests db/exec/fetch.cpp.  Fetch goes to disk so we cannot test outside of a dbtest.
 */


#include "mongo/client/dbclientcursor.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/dbdirectclient.h"
#include "mongo/db/exec/fetch.h"
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/exec/queued_data_stage.h"
#include "mongo/db/json.h"
#include "mongo/db/matcher/expression_parser.h"
#include "mongo/db/operation_context_impl.h"
#include "mongo/dbtests/dbtests.h"

namespace QueryStageFetch {

    using std::shared_ptr;
    using std::unique_ptr;
    using std::set;

    class QueryStageFetchBase {
    public:
        QueryStageFetchBase() : _client(&_txn) {
        
        }

        virtual ~QueryStageFetchBase() {
            _client.dropCollection(ns());
        }

        void getLocs(set<RecordId>* out, Collection* coll) {
            auto cursor = coll->getCursor(&_txn);
            while (auto record = cursor->next()) {
                out->insert(record->id);
            }
        }

        void insert(const BSONObj& obj) {
            _client.insert(ns(), obj);
        }

        void remove(const BSONObj& obj) {
            _client.remove(ns(), obj);
        }

        static const char* ns() { return "unittests.QueryStageFetch"; }

    protected:
        OperationContextImpl _txn;
        DBDirectClient _client;
    };


    //
    // Test that a WSM with an obj is passed through verbatim.
    //
    class FetchStageAlreadyFetched : public QueryStageFetchBase {
    public:
        void run() {
            OldClientWriteContext ctx(&_txn, ns());
            Database* db = ctx.db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                WriteUnitOfWork wuow(&_txn);
                coll = db->createCollection(&_txn, ns());
                wuow.commit();
            }

            WorkingSet ws;

            // Add an object to the DB.
            insert(BSON("foo" << 5));
            set<RecordId> locs;
            getLocs(&locs, coll);
            ASSERT_EQUALS(size_t(1), locs.size());

            // Create a mock stage that returns the WSM.
            unique_ptr<QueuedDataStage> mockStage(new QueuedDataStage(&ws));

            // Mock data.
            {
                WorkingSetMember mockMember;
                mockMember.state = WorkingSetMember::LOC_AND_UNOWNED_OBJ;
                mockMember.loc = *locs.begin();
                mockMember.obj = coll->docFor(&_txn, mockMember.loc);
                // Points into our DB.
                mockStage->pushBack(mockMember);

                mockMember.state = WorkingSetMember::OWNED_OBJ;
                mockMember.loc = RecordId();
                mockMember.obj = Snapshotted<BSONObj>(SnapshotId(), BSON("foo" << 6));
                ASSERT_TRUE(mockMember.obj.value().isOwned());
                mockStage->pushBack(mockMember);
            }

            unique_ptr<FetchStage> fetchStage(new FetchStage(&_txn, &ws, mockStage.release(),
                                                           NULL, coll));

            WorkingSetID id = WorkingSet::INVALID_ID;
            PlanStage::StageState state;

            // Don't bother doing any fetching if an obj exists already.
            state = fetchStage->work(&id);
            ASSERT_EQUALS(PlanStage::ADVANCED, state);
            state = fetchStage->work(&id);
            ASSERT_EQUALS(PlanStage::ADVANCED, state);

            // No more data to fetch, so, EOF.
            state = fetchStage->work(&id);
            ASSERT_EQUALS(PlanStage::IS_EOF, state);
        }
    };

    //
    // Test matching with fetch.
    //
    class FetchStageFilter : public QueryStageFetchBase {
    public:
        void run() {
            ScopedTransaction transaction(&_txn, MODE_IX);
            Lock::DBLock lk(_txn.lockState(), nsToDatabaseSubstring(ns()), MODE_X);
            OldClientContext ctx(&_txn, ns());
            Database* db = ctx.db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                WriteUnitOfWork wuow(&_txn);
                coll = db->createCollection(&_txn, ns());
                wuow.commit();
            }

            WorkingSet ws;

            // Add an object to the DB.
            insert(BSON("foo" << 5));
            set<RecordId> locs;
            getLocs(&locs, coll);
            ASSERT_EQUALS(size_t(1), locs.size());

            // Create a mock stage that returns the WSM.
            unique_ptr<QueuedDataStage> mockStage(new QueuedDataStage(&ws));

            // Mock data.
            {
                WorkingSetMember mockMember;
                mockMember.state = WorkingSetMember::LOC_AND_IDX;
                mockMember.loc = *locs.begin();

                // State is loc and index, shouldn't be able to get the foo data inside.
                BSONElement elt;
                ASSERT_FALSE(mockMember.getFieldDotted("foo", &elt));
                mockStage->pushBack(mockMember);
            }

            // Make the filter.
            BSONObj filterObj = BSON("foo" << 6);
            StatusWithMatchExpression swme = MatchExpressionParser::parse(filterObj);
            verify(swme.isOK());
            unique_ptr<MatchExpression> filterExpr(swme.getValue());

            // Matcher requires that foo==6 but we only have data with foo==5.
            unique_ptr<FetchStage> fetchStage(
                     new FetchStage(&_txn, &ws, mockStage.release(), filterExpr.get(), coll));

            // First call should return a fetch request as it's not in memory.
            WorkingSetID id = WorkingSet::INVALID_ID;
            PlanStage::StageState state;

            // Normally we'd return the object but we have a filter that prevents it.
            state = fetchStage->work(&id);
            ASSERT_EQUALS(PlanStage::NEED_TIME, state);

            // No more data to fetch, so, EOF.
            state = fetchStage->work(&id);
            ASSERT_EQUALS(PlanStage::IS_EOF, state);
        }
    };

    class All : public Suite {
    public:
        All() : Suite( "query_stage_fetch" ) { }

        void setupTests() {
            add<FetchStageAlreadyFetched>();
            add<FetchStageFilter>();
        }
    };

    SuiteInstance<All> queryStageFetchAll;

}  // namespace QueryStageFetch