/**
 *    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 <cstddef>
#include <set>
#include <string>
#include <vector>

#include "mongo/base/string_data.h"
#include "mongo/db/repl/idempotency_scalar_generator.h"
#include "mongo/platform/random.h"

namespace mongo {

class DocumentStructureEnumerator;
class BSONObj;
struct BSONArray;
class BSONObjBuilder;

struct UpdateSequenceGeneratorConfig {
    UpdateSequenceGeneratorConfig(std::set<StringData> fields_,
                                  std::size_t depth_,
                                  std::size_t lengthOfNumericComponent_,
                                  double scalarProbability_ = 0.250,
                                  double docProbability_ = 0.250,
                                  double arrProbability_ = 0.250);

    const std::set<StringData> fields = {};
    const std::size_t depth = 0;
    const std::size_t lengthOfNumericComponent = 0;
    const double scalarProbability = 0.250;
    const double docProbability = 0.250;
    const double arrProbability = 0.250;
};

class UpdateSequenceGenerator {

public:
    UpdateSequenceGenerator(UpdateSequenceGeneratorConfig config,
                            PseudoRandom random,
                            ScalarGenerator* scalarGenerator);

    BSONObj generateUpdate() const;

    std::vector<std::string> getPaths() const;

    friend std::vector<std::string> eliminatePrefixPaths_forTest(
        const std::string& path, const std::vector<std::string>& paths);

    friend std::size_t getPathDepth_forTest(const std::string& path);

private:
    enum class SetChoice : int { kSetScalar, kSetArr, kSetDoc, kNumTotalSetChoices = 3 };

    static std::size_t _getPathDepth(const std::string& path);

    /**
     * Given a path parameter, removes all paths from a copy of the given path vector that are:
     * 1) A prefix of the given path
     * 2) Prefixable by the given path.
     *
     * This function also removes the given path itself from the given path vector, if it exists
     * inside, since a path can prefix itself and therefore qualifies for both #1 and #2 above.
     *
     * A copy of the given path vector is returned after this pruning finishes.
     */
    static std::vector<std::string> _eliminatePrefixPaths(const std::string& path,
                                                          const std::vector<std::string>& paths);

    void _generatePaths(const UpdateSequenceGeneratorConfig& config, const std::string& path);

    std::set<StringData> _getRemainingFields(const std::string& path) const;

    DocumentStructureEnumerator _getValidEnumeratorForPath(const std::string& path) const;

    std::vector<std::string> _getRandomPaths() const;

    BSONObj _generateSet() const;

    SetChoice _determineWhatToSet(const std::string& setPath) const;

    void _appendSetArgToBuilder(const std::string& setPath, BSONObjBuilder* setArgBuilder) const;

    BSONObj _generateUnset() const;

    double _generateNumericToSet() const;

    bool _generateBoolToSet() const;

    BSONArray _generateArrToSet(const std::string& setPath) const;

    BSONObj _generateDocToSet(const std::string& setPath) const;

    std::vector<std::string> _paths;
    const UpdateSequenceGeneratorConfig _config;
    mutable PseudoRandom _random;
    const ScalarGenerator* _scalarGenerator;
};

}  // namespace mongo