/**
 *    Copyright (C) 2021-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.
 */

#pragma once

#include <boost/move/utility_core.hpp>
#include <boost/none.hpp>
#include <boost/optional/optional.hpp>
#include <boost/smart_ptr/intrusive_ptr.hpp>
#include <set>

#include "mongo/base/string_data.h"
#include "mongo/bson/bsonelement.h"
#include "mongo/db/exec/document_value/document.h"
#include "mongo/db/exec/document_value/value.h"
#include "mongo/db/pipeline/dependencies.h"
#include "mongo/db/pipeline/document_source.h"
#include "mongo/db/pipeline/expression_context.h"
#include "mongo/db/pipeline/pipeline.h"
#include "mongo/db/pipeline/stage_constraints.h"
#include "mongo/db/pipeline/variables.h"
#include "mongo/db/query/query_shape/serialization_options.h"

namespace mongo {

/**
 * This stage will take a list of oplog entry documents as input and forge a no-op pre- or
 * post-image to be returned before the document for each 'findAndModify' oplog entry that has the
 * the 'needsRetryImage' field or each 'applyOps' oplog entry with a 'findAndModify' operation entry
 * that has the 'needsRetryImage' field. This stage also downconverts 'findAndModify' or 'applyOps'
 * oplog entry documents by stripping the 'needsRetryImage' field and appending the appropriate
 * 'preImageOpTime' or 'postImageOpTime' field. If 'includeCommitTransactionTimestamp' is true,
 * the forged pre- or post-image oplog entry document for each 'applyOps' oplog entry document that
 * comes with a transaction commit timestamp will have the commit timestamp attached to it.
 */
class DocumentSourceFindAndModifyImageLookup : public DocumentSource {
public:
    static constexpr StringData kStageName = "$_internalFindAndModifyImageLookup"_sd;
    static constexpr StringData kIncludeCommitTransactionTimestampFieldName =
        "includeCommitTransactionTimestamp"_sd;

    static boost::intrusive_ptr<DocumentSourceFindAndModifyImageLookup> create(
        const boost::intrusive_ptr<ExpressionContext>& expCtx,
        bool includeCommitTransactionTimestamp = false);

    static boost::intrusive_ptr<DocumentSourceFindAndModifyImageLookup> createFromBson(
        BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& expCtx);

    DepsTracker::State getDependencies(DepsTracker* deps) const final;

    void addVariableRefs(std::set<Variables::Id>* refs) const final {}

    DocumentSource::GetModPathsReturn getModifiedPaths() const final;

    Value serialize(const SerializationOptions& opts = SerializationOptions{}) const final;

    StageConstraints constraints(Pipeline::SplitState pipeState) const final;

    boost::optional<DistributedPlanLogic> distributedPlanLogic() final {
        return boost::none;
    }

    const char* getSourceName() const override {
        return DocumentSourceFindAndModifyImageLookup::kStageName.rawData();
    }

    DocumentSourceType getType() const override {
        return DocumentSourceType::kFindAndModifyImageLookup;
    }

protected:
    DocumentSource::GetNextResult doGetNext() override;

private:
    DocumentSourceFindAndModifyImageLookup(const boost::intrusive_ptr<ExpressionContext>& expCtx,
                                           bool includeCommitTransactionTimestamp);

    // Downconverts 'findAndModify' or 'applyOps' entries with 'needsRetryImage'. If an oplog entry
    // document has 'needsRetryImage' set, we downconvert and stash the document as
    // '_stashedDownconvertedDoc' and then forge a no-op pre- or post-image document and return it.
    Document _downConvertIfNeedsRetryImage(Document inputDoc);

    // Set to true if the input oplog entry documents can have a transaction commit timestamp
    // attached to it.
    bool _includeCommitTransactionTimestamp;

    // Represents the stashed downconverted 'findAndModify' or 'applyOps' oplog entry document.
    // This indicates that the previous document emitted was a forged pre- or post-image.
    boost::optional<Document> _stashedDownconvertedDoc;
};

}  // namespace mongo
