/**
*    Copyright (C) 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.
*/

#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kStorage

#include "mongo/platform/basic.h"

#include "mongo/db/repair_database.h"

#include "mongo/base/status.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/bson_validate.h"
#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/database_catalog_entry.h"
#include "mongo/db/catalog/database_holder.h"
#include "mongo/db/catalog/document_validation.h"
#include "mongo/db/catalog/index_create.h"
#include "mongo/db/catalog/index_key_validate.h"
#include "mongo/db/repl/replication_coordinator.h"
#include "mongo/db/storage/mmap_v1/mmap_v1_engine.h"
#include "mongo/db/storage/storage_engine.h"
#include "mongo/util/log.h"
#include "mongo/util/scopeguard.h"

namespace mongo {

using std::endl;
using std::string;

namespace {
Status rebuildIndexesOnCollection(OperationContext* txn,
                                  DatabaseCatalogEntry* dbce,
                                  const std::string& collectionName) {
    CollectionCatalogEntry* cce = dbce->getCollectionCatalogEntry(collectionName);

    std::vector<string> indexNames;
    std::vector<BSONObj> indexSpecs;
    {
        // Fetch all indexes
        cce->getAllIndexes(txn, &indexNames);
        for (size_t i = 0; i < indexNames.size(); i++) {
            const string& name = indexNames[i];
            BSONObj spec = cce->getIndexSpec(txn, name);
            indexSpecs.push_back(spec.removeField("v").getOwned());

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

    // Skip the rest if there are no indexes to rebuild.
    if (indexSpecs.empty())
        return Status::OK();

    std::unique_ptr<Collection> collection;
    std::unique_ptr<MultiIndexBlock> indexer;
    {
        // These steps are combined into a single WUOW to ensure there are no commits without
        // the indexes.
        // 1) Drop all indexes.
        // 2) Open the Collection
        // 3) Start the index build process.

        WriteUnitOfWork wuow(txn);

        {  // 1
            for (size_t i = 0; i < indexNames.size(); i++) {
                Status s = cce->removeIndex(txn, indexNames[i]);
                if (!s.isOK())
                    return s;
            }
        }

        // Indexes must be dropped before we open the Collection otherwise we could attempt to
        // open a bad index and fail.
        // TODO see if MultiIndexBlock can be made to work without a Collection.
        const StringData ns = cce->ns().ns();
        collection.reset(new Collection(txn, ns, cce, dbce->getRecordStore(ns), dbce));

        indexer.reset(new MultiIndexBlock(txn, collection.get()));
        Status status = indexer->init(indexSpecs);
        if (!status.isOK()) {
            // The WUOW will handle cleanup, so the indexer shouldn't do its own.
            indexer->abortWithoutCleanup();
            return status;
        }

        wuow.commit();
    }

    // Iterate all records in the collection. Delete them if they aren't valid BSON. Index them
    // if they are.

    long long numRecords = 0;
    long long dataSize = 0;

    RecordStore* rs = collection->getRecordStore();
    auto cursor = rs->getCursor(txn);
    while (auto record = cursor->next()) {
        RecordId id = record->id;
        RecordData& data = record->data;

        Status status = validateBSON(data.data(), data.size());
        if (!status.isOK()) {
            log() << "Invalid BSON detected at " << id << ": " << status << ". Deleting.";
            cursor->save();  // 'data' is no longer valid.
            {
                WriteUnitOfWork wunit(txn);
                rs->deleteRecord(txn, id);
                wunit.commit();
            }
            cursor->restore();
            continue;
        }

        numRecords++;
        dataSize += data.size();

        // Now index the record.
        // TODO SERVER-14812 add a mode that drops duplicates rather than failing
        WriteUnitOfWork wunit(txn);
        status = indexer->insert(data.releaseToBson(), id);
        if (!status.isOK())
            return status;
        wunit.commit();
    }

    Status status = indexer->doneInserting();
    if (!status.isOK())
        return status;

    {
        WriteUnitOfWork wunit(txn);
        indexer->commit();
        rs->updateStatsAfterRepair(txn, numRecords, dataSize);
        wunit.commit();
    }

    return Status::OK();
}
}  // namespace

Status repairDatabase(OperationContext* txn,
                      StorageEngine* engine,
                      const std::string& dbName,
                      bool preserveClonedFilesOnFailure,
                      bool backupOriginalFiles) {
    DisableDocumentValidation validationDisabler(txn);

    // We must hold some form of lock here
    invariant(txn->lockState()->isLocked());
    invariant(dbName.find('.') == string::npos);

    log() << "repairDatabase " << dbName << endl;

    BackgroundOperation::assertNoBgOpInProgForDb(dbName);

    txn->checkForInterrupt();

    if (engine->isMmapV1()) {
        // MMAPv1 is a layering violation so it implements its own repairDatabase.
        return static_cast<MMAPV1Engine*>(engine)->repairDatabase(
            txn, dbName, preserveClonedFilesOnFailure, backupOriginalFiles);
    }

    // These are MMAPv1 specific
    if (preserveClonedFilesOnFailure) {
        return Status(ErrorCodes::BadValue, "preserveClonedFilesOnFailure not supported");
    }
    if (backupOriginalFiles) {
        return Status(ErrorCodes::BadValue, "backupOriginalFiles not supported");
    }

    // Close the db to invalidate all current users and caches.
    dbHolder().close(txn, dbName);
    ON_BLOCK_EXIT([&dbName, &txn] {
        try {
            // Open the db after everything finishes.
            auto db = dbHolder().openDb(txn, dbName);

            // Set the minimum snapshot for all Collections in this db. This ensures that readers
            // using majority readConcern level can only use the collections after their repaired
            // versions are in the committed view.
            auto replCoord = repl::ReplicationCoordinator::get(txn);
            auto snapshotName = replCoord->reserveSnapshotName(txn);
            replCoord->forceSnapshotCreation();  // Ensure a newer snapshot is created even if idle.

            for (auto&& collection : *db) {
                collection->setMinimumVisibleSnapshot(snapshotName);
            }
        } catch (...) {
            severe() << "Unexpected exception encountered while reopening database after repair.";
            std::terminate();  // Logs additional info about the specific error.
        }
    });

    DatabaseCatalogEntry* dbce = engine->getDatabaseCatalogEntry(txn, dbName);

    std::list<std::string> colls;
    dbce->getCollectionNamespaces(&colls);

    for (std::list<std::string>::const_iterator it = colls.begin(); it != colls.end(); ++it) {
        // Don't check for interrupt after starting to repair a collection otherwise we can
        // leave data in an inconsistent state. Interrupting between collections is ok, however.
        txn->checkForInterrupt();

        log() << "Repairing collection " << *it;

        Status status = engine->repairRecordStore(txn, *it);
        if (!status.isOK())
            return status;

        status = rebuildIndexesOnCollection(txn, dbce, *it);
        if (!status.isOK())
            return status;

        // TODO: uncomment once SERVER-16869
        // engine->flushAllFiles(true);
    }

    return Status::OK();
}
}