/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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/index_builds_coordinator_mongod.h"

#include "mongo/db/catalog/uuid_catalog.h"
#include "mongo/db/curop.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/service_context.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/log.h"
#include "mongo/util/mongoutils/str.h"

namespace mongo {

namespace {

/**
 * Constructs the options for the loader thread pool.
 */
ThreadPool::Options makeDefaultThreadPoolOptions() {
    ThreadPool::Options options;
    options.poolName = "IndexBuildsCoordinatorMongod";
    options.minThreads = 0;
    options.maxThreads = 10;

    // Ensure all threads have a client.
    options.onCreateThread = [](const std::string& threadName) {
        Client::initThread(threadName.c_str());
    };

    return options;
}

}  // namespace

IndexBuildsCoordinatorMongod::IndexBuildsCoordinatorMongod()
    : _threadPool(makeDefaultThreadPoolOptions()) {
    _threadPool.startup();
}

void IndexBuildsCoordinatorMongod::shutdown() {
    // Stop new scheduling.
    _threadPool.shutdown();

    // Signal active builds to stop and wait for them to stop.
    interruptAllIndexBuilds("Index build interrupted due to shutdown.");

    // Wait for active threads to finish.
    _threadPool.join();
}

StatusWith<SharedSemiFuture<ReplIndexBuildState::IndexCatalogStats>>
IndexBuildsCoordinatorMongod::startIndexBuild(OperationContext* opCtx,
                                              CollectionUUID collectionUUID,
                                              const std::vector<BSONObj>& specs,
                                              const UUID& buildUUID) {
    std::vector<std::string> indexNames;
    for (auto& spec : specs) {
        std::string name = spec.getStringField(IndexDescriptor::kIndexNameFieldName);
        if (name.empty()) {
            return Status(
                ErrorCodes::CannotCreateIndex,
                str::stream() << "Cannot create an index for a spec '" << spec
                              << "' without a non-empty string value for the 'name' field");
        }
        indexNames.push_back(name);
    }

    auto nss = UUIDCatalog::get(opCtx).lookupNSSByUUID(collectionUUID);
    auto dbName = nss.db().toString();
    auto replIndexBuildState =
        std::make_shared<ReplIndexBuildState>(buildUUID, collectionUUID, dbName, indexNames, specs);

    Status status = _registerIndexBuild(opCtx, replIndexBuildState);
    if (!status.isOK()) {
        return status;
    }

    // Run index build in-line if we are transitioning between replication modes.
    // While the RSTLExclusive is being held, the async thread in the thread pool is not allowed
    // to take locks.
    if (opCtx->lockState()->isRSTLExclusive()) {
        log() << "Running index build on current thread because we are transitioning between "
                 "replication states: "
              << buildUUID;
        // Sets up and runs the index build. Sets result and cleans up index build.
        _runIndexBuild(opCtx, buildUUID);
        return replIndexBuildState->sharedPromise.getFuture();
    }

    // Task in thread pool should retain the caller's deadline.
    auto deadline = opCtx->getDeadline();
    auto timeoutError = opCtx->getTimeoutError();

    // Task in thread pool should have similar CurOp representation to the caller so that it can be
    // identified as a createIndexes operation.
    BSONObj opDesc;
    {
        stdx::unique_lock<Client> lk(*opCtx->getClient());
        auto curOp = CurOp::get(opCtx);
        opDesc = curOp->opDescription().getOwned();
    }

    status = _threadPool.schedule([ this, buildUUID, deadline, timeoutError, opDesc ]() noexcept {
        auto opCtx = Client::getCurrent()->makeOperationContext();

        opCtx->setDeadlineByDate(deadline, timeoutError);

        {
            stdx::unique_lock<Client> lk(*opCtx->getClient());
            auto curOp = CurOp::get(opCtx.get());
            curOp->setOpDescription_inlock(opDesc);
        }

        // Sets up and runs the index build. Sets result and cleans up index build.
        _runIndexBuild(opCtx.get(), buildUUID);
    });

    // Clean up the index build if we failed to schedule it.
    if (!status.isOK()) {
        stdx::unique_lock<stdx::mutex> lk(_mutex);

        // Unregister the index build before setting the promises, so callers do not see the build
        // again.
        _unregisterIndexBuild(lk, opCtx, replIndexBuildState);

        // Set the promise in case another thread already joined the index build.
        replIndexBuildState->sharedPromise.setError(status);

        return status;
    }

    return replIndexBuildState->sharedPromise.getFuture();
}

Status IndexBuildsCoordinatorMongod::commitIndexBuild(OperationContext* opCtx,
                                                      const std::vector<BSONObj>& specs,
                                                      const UUID& buildUUID) {
    // TODO: not yet implemented.
    return Status::OK();
}

void IndexBuildsCoordinatorMongod::signalChangeToPrimaryMode() {
    stdx::unique_lock<stdx::mutex> lk(_mutex);
    _replMode = ReplState::Primary;
}

void IndexBuildsCoordinatorMongod::signalChangeToSecondaryMode() {
    stdx::unique_lock<stdx::mutex> lk(_mutex);
    _replMode = ReplState::Secondary;
}

void IndexBuildsCoordinatorMongod::signalChangeToInitialSyncMode() {
    stdx::unique_lock<stdx::mutex> lk(_mutex);
    _replMode = ReplState::InitialSync;
}

Status IndexBuildsCoordinatorMongod::voteCommitIndexBuild(const UUID& buildUUID,
                                                          const HostAndPort& hostAndPort) {
    // TODO: not yet implemented.
    return Status::OK();
}

Status IndexBuildsCoordinatorMongod::setCommitQuorum(const NamespaceString& nss,
                                                     const std::vector<StringData>& indexNames,
                                                     const CommitQuorumOptions& newCommitQuorum) {
    // TODO: not yet implemented.
    return Status::OK();
}

Status IndexBuildsCoordinatorMongod::_finishScanningPhase() {
    // TODO: implement.
    return Status::OK();
}

Status IndexBuildsCoordinatorMongod::_finishVerificationPhase() {
    // TODO: implement.
    return Status::OK();
}

Status IndexBuildsCoordinatorMongod::_finishCommitPhase() {
    // TODO: implement.
    return Status::OK();
}

StatusWith<bool> IndexBuildsCoordinatorMongod::_checkCommitQuorum(
    const BSONObj& commitQuorum, const std::vector<HostAndPort>& confirmedMembers) {
    // TODO: not yet implemented.
    return false;
}

void IndexBuildsCoordinatorMongod::_refreshReplStateFromPersisted(OperationContext* opCtx,
                                                                  const UUID& buildUUID) {
    // TODO: not yet implemented.
}

}  // namespace mongo