/**
 *    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.
 */

#pragma once

#include <type_traits>

#include "mongo/bson/bsonelement.h"
#include "mongo/db/pipeline/document_source_list_local_sessions.h"
#include "mongo/db/pipeline/document_source_match.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
#include "mongo/util/intrusive_counter.h"

namespace mongo {

/**
 * $listSessions: { allUsers: true/false, users: [ {user:"jsmith", db:"test"}, ... ] }
 * Return all sessions in the config.system.sessions collection
 * or just sessions for the currently logged in user. (Default: false)
 *
 * This is essentially an alias for {$match:{"_id.uid": myid}} or {$match:{}}
 * with appropriate constraints on stage positioning and security checks
 * based on ActionType::ListSessions
 */
class DocumentSourceListSessions final : public DocumentSourceMatch {
public:
    DocumentSourceListSessions(const DocumentSourceListSessions& other,
                               const boost::intrusive_ptr<ExpressionContext>& newExpCtx)
        : DocumentSourceMatch(other, newExpCtx), _allUsers(other._allUsers), _users(other._users) {}

    virtual boost::intrusive_ptr<DocumentSource> clone(
        const boost::intrusive_ptr<ExpressionContext>& newExpCtx) const {
        return make_intrusive<std::decay_t<decltype(*this)>>(*this, newExpCtx);
    }

    static constexpr StringData kStageName = "$listSessions"_sd;

    class LiteParsed final : public LiteParsedDocumentSource {
    public:
        static std::unique_ptr<LiteParsed> parse(const NamespaceString& nss,
                                                 const BSONElement& spec) {
            return std::make_unique<LiteParsed>(
                spec.fieldName(),
                listSessionsParseSpec(DocumentSourceListSessions::kStageName, spec));
        }

        explicit LiteParsed(std::string parseTimeName, const ListSessionsSpec& spec)
            : LiteParsedDocumentSource(std::move(parseTimeName)), _spec(spec) {}

        stdx::unordered_set<NamespaceString> getInvolvedNamespaces() const final {
            return stdx::unordered_set<NamespaceString>();
        }

        PrivilegeVector requiredPrivileges(bool isMongos,
                                           bool bypassDocumentValidation) const final {
            return listSessionsRequiredPrivileges(_spec);
        }

        bool isInitialSource() const final {
            return true;
        }

        bool allowedToPassthroughFromMongos() const final {
            return _spec.getAllUsers();
        }

    private:
        const ListSessionsSpec _spec;
    };

    const char* getSourceName() const final {
        return DocumentSourceListSessions::kStageName.rawData();
    }

    Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final;

    StageConstraints constraints(Pipeline::SplitState pipeState) const final {
        return {StreamType::kStreaming,
                PositionRequirement::kFirst,
                HostTypeRequirement::kNone,
                DiskUseRequirement::kNoDiskUse,
                FacetRequirement::kNotAllowed,
                TransactionRequirement::kNotAllowed,
                LookupRequirement::kAllowed,
                UnionRequirement::kAllowed};
    }

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

private:
    DocumentSourceListSessions(const BSONObj& query,
                               const boost::intrusive_ptr<ExpressionContext>& pExpCtx,
                               const bool allUsers,
                               const boost::optional<std::vector<mongo::ListSessionsUser>>& users)
        : DocumentSourceMatch(query, pExpCtx), _allUsers(allUsers), _users(users) {}

    bool _allUsers;
    boost::optional<std::vector<mongo::ListSessionsUser>> _users;
};

}  // namespace mongo