/**
 *    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.
 */

#include "mongo/platform/basic.h"

#include "mongo/db/dbdirectclient.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/db/repl/oplog_entry.h"
#include "mongo/db/transaction_history_iterator.h"
#include "mongo/logger/redaction.h"
#include "mongo/util/mongoutils/str.h"

namespace mongo {

TransactionHistoryIterator::TransactionHistoryIterator(repl::OpTime startingOpTime)
    : _nextOpTime(std::move(startingOpTime)) {}

bool TransactionHistoryIterator::hasNext() const {
    return !_nextOpTime.isNull();
}

repl::OplogEntry TransactionHistoryIterator::next(OperationContext* opCtx) {
    invariant(hasNext());

    DBDirectClient client(opCtx);
    auto oplogBSON = client.findOne(NamespaceString::kRsOplogNamespace.ns(),
                                    _nextOpTime.asQuery(),
                                    nullptr,
                                    QueryOption_OplogReplay);

    uassert(ErrorCodes::IncompleteTransactionHistory,
            str::stream() << "oplog no longer contains the complete write history of this "
                             "transaction, log with opTime "
                          << _nextOpTime.toBSON()
                          << " cannot be found",
            !oplogBSON.isEmpty());

    auto oplogEntry = uassertStatusOK(repl::OplogEntry::parse(oplogBSON));
    const auto& oplogPrevTsOption = oplogEntry.getPrevWriteOpTimeInTransaction();
    uassert(
        ErrorCodes::FailedToParse,
        str::stream() << "Missing prevTs field on oplog entry of previous write in transcation: "
                      << redact(oplogBSON),
        oplogPrevTsOption);

    _nextOpTime = oplogPrevTsOption.value();

    return oplogEntry;
}

}  // namespace mongo