// drop_indexes.cpp

/**
*    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::kCommand

#include "mongo/platform/basic.h"

#include <string>
#include <vector>

#include "mongo/db/background.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/catalog/collection_catalog_entry.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/catalog/drop_indexes.h"
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/catalog/index_create.h"
#include "mongo/db/catalog/index_key_validate.h"
#include "mongo/db/client.h"
#include "mongo/db/commands.h"
#include "mongo/db/concurrency/write_conflict_exception.h"
#include "mongo/db/curop.h"
#include "mongo/db/db_raii.h"
#include "mongo/db/dbdirectclient.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/index_builder.h"
#include "mongo/db/op_observer.h"
#include "mongo/db/repl/replication_coordinator_global.h"
#include "mongo/db/service_context.h"
#include "mongo/util/log.h"

namespace mongo {

using std::endl;
using std::string;
using std::stringstream;
using std::vector;

/* "dropIndexes" is now the preferred form - "deleteIndexes" deprecated */
class CmdDropIndexes : public BasicCommand {
public:
    virtual bool slaveOk() const {
        return false;
    }
    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
        return true;
    }
    virtual void help(stringstream& help) const {
        help << "drop indexes for a collection";
    }
    virtual void addRequiredPrivileges(const std::string& dbname,
                                       const BSONObj& cmdObj,
                                       std::vector<Privilege>* out) {
        ActionSet actions;
        actions.addAction(ActionType::dropIndex);
        out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
    }

    CmdDropIndexes() : BasicCommand("dropIndexes", "deleteIndexes") {}
    bool run(OperationContext* opCtx,
             const string& dbname,
             const BSONObj& jsobj,
             BSONObjBuilder& result) {
        const NamespaceString nss = parseNsCollectionRequired(dbname, jsobj);
        return appendCommandStatus(result, dropIndexes(opCtx, nss, jsobj, &result));
    }

} cmdDropIndexes;

class CmdReIndex : public ErrmsgCommandDeprecated {
public:
    virtual bool slaveOk() const {
        return true;
    }  // can reindex on a secondary
    virtual bool supportsWriteConcern(const BSONObj& cmd) const override {
        return false;
    }
    virtual void help(stringstream& help) const {
        help << "re-index a collection";
    }
    virtual void addRequiredPrivileges(const std::string& dbname,
                                       const BSONObj& cmdObj,
                                       std::vector<Privilege>* out) {
        ActionSet actions;
        actions.addAction(ActionType::reIndex);
        out->push_back(Privilege(parseResourcePattern(dbname, cmdObj), actions));
    }
    CmdReIndex() : ErrmsgCommandDeprecated("reIndex") {}

    bool errmsgRun(OperationContext* opCtx,
                   const string& dbname,
                   const BSONObj& jsobj,
                   string& errmsg,
                   BSONObjBuilder& result) {
        DBDirectClient db(opCtx);

        const NamespaceString toReIndexNs = parseNsCollectionRequired(dbname, jsobj);

        LOG(0) << "CMD: reIndex " << toReIndexNs;

        Lock::DBLock dbXLock(opCtx, dbname, MODE_X);
        OldClientContext ctx(opCtx, toReIndexNs.ns());

        Collection* collection = ctx.db()->getCollection(opCtx, toReIndexNs);
        if (!collection) {
            if (ctx.db()->getViewCatalog()->lookup(opCtx, toReIndexNs.ns()))
                return appendCommandStatus(
                    result, {ErrorCodes::CommandNotSupportedOnView, "can't re-index a view"});
            else
                return appendCommandStatus(
                    result, {ErrorCodes::NamespaceNotFound, "collection does not exist"});
        }

        BackgroundOperation::assertNoBgOpInProgForNs(toReIndexNs.ns());

        const auto featureCompatibilityVersion =
            serverGlobalParams.featureCompatibility.version.load();
        const auto defaultIndexVersion =
            IndexDescriptor::getDefaultIndexVersion(featureCompatibilityVersion);

        vector<BSONObj> all;
        {
            vector<string> indexNames;
            collection->getCatalogEntry()->getAllIndexes(opCtx, &indexNames);
            all.reserve(indexNames.size());

            for (size_t i = 0; i < indexNames.size(); i++) {
                const string& name = indexNames[i];
                BSONObj spec = collection->getCatalogEntry()->getIndexSpec(opCtx, name);

                {
                    BSONObjBuilder bob;

                    for (auto&& indexSpecElem : spec) {
                        auto indexSpecElemFieldName = indexSpecElem.fieldNameStringData();
                        if (IndexDescriptor::kIndexVersionFieldName == indexSpecElemFieldName) {
                            // We create a new index specification with the 'v' field set as
                            // 'defaultIndexVersion'.
                            bob.append(IndexDescriptor::kIndexVersionFieldName,
                                       static_cast<int>(defaultIndexVersion));
                        } else {
                            bob.append(indexSpecElem);
                        }
                    }

                    all.push_back(bob.obj());
                }

                const BSONObj key = spec.getObjectField("key");
                const Status keyStatus =
                    index_key_validate::validateKeyPattern(key, defaultIndexVersion);
                if (!keyStatus.isOK()) {
                    errmsg = str::stream()
                        << "Cannot rebuild index " << spec << ": " << keyStatus.reason()
                        << " For more info see http://dochub.mongodb.org/core/index-validation";
                    return false;
                }
            }
        }

        result.appendNumber("nIndexesWas", all.size());

        {
            WriteUnitOfWork wunit(opCtx);
            collection->getIndexCatalog()->dropAllIndexes(opCtx, true);
            wunit.commit();
        }

        MultiIndexBlock indexer(opCtx, collection);
        // do not want interruption as that will leave us without indexes.

        auto indexInfoObjs = indexer.init(all);
        if (!indexInfoObjs.isOK()) {
            return appendCommandStatus(result, indexInfoObjs.getStatus());
        }

        auto status = indexer.insertAllDocumentsInCollection();
        if (!status.isOK()) {
            return appendCommandStatus(result, status);
        }

        {
            WriteUnitOfWork wunit(opCtx);
            indexer.commit();
            wunit.commit();
        }

        // Do not allow majority reads from this collection until all original indexes are visible.
        // This was also done when dropAllIndexes() committed, but we need to ensure that no one
        // tries to read in the intermediate state where all indexes are newer than the current
        // snapshot so are unable to be used.
        auto replCoord = repl::ReplicationCoordinator::get(opCtx);
        auto snapshotName = replCoord->reserveSnapshotName(opCtx);
        replCoord->forceSnapshotCreation();  // Ensures a newer snapshot gets created even if idle.
        collection->setMinimumVisibleSnapshot(snapshotName);

        result.append("nIndexes", static_cast<int>(indexInfoObjs.getValue().size()));
        result.append("indexes", indexInfoObjs.getValue());

        return true;
    }
} cmdReIndex;
}