/**
 *    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 <memory>
#include <ostream>

#include "mongo/base/string_data.h"
#include "mongo/bson/bsonobjbuilder.h"
#include "mongo/db/process_health/fault_manager_config.h"

namespace mongo {
namespace process_health {

enum class Severity { kOk, kFailure };
static const StringData SeverityStrings[] = {"kOk", "kFailure"};

inline StringBuilder& operator<<(StringBuilder& s, const Severity& sev) {
    return s << SeverityStrings[static_cast<int>(sev)];
}

inline std::ostream& operator<<(std::ostream& s, const Severity& sev) {
    return s << SeverityStrings[static_cast<int>(sev)];
}
/**
 * Immutable class representing current status of an ongoing fault tracked by facet.
 */
class HealthCheckStatus {
public:
    HealthCheckStatus(FaultFacetType type, Severity severity, StringData description)
        : _type(type), _severity(severity), _description(description) {}

    // Constructs a resolved status (no fault detected).
    explicit HealthCheckStatus(FaultFacetType type)
        : _type(type), _severity(Severity::kOk), _description("resolved"_sd) {}

    explicit HealthCheckStatus(HealthObserverTypeEnum type)
        : _type(toFaultFacetType(type)), _severity(Severity::kOk), _description("resolved"_sd) {}

    HealthCheckStatus(const HealthCheckStatus&) = default;
    HealthCheckStatus& operator=(const HealthCheckStatus&) = default;
    HealthCheckStatus(HealthCheckStatus&&) = default;
    HealthCheckStatus& operator=(HealthCheckStatus&&) = default;

    /**
     * @return FaultFacetType of this status.
     */
    FaultFacetType getType() const {
        return _type;
    }

    /**
     * The fault severity value if any.
     *
     * @return Current fault severity
     */
    Severity getSeverity() const {
        return _severity;
    }

    StringData getShortDescription() const {
        return _description;
    }

    void appendDescription(BSONObjBuilder* builder) const;

    BSONObj toBSON() const;

    std::string toString() const;

    // Helpers for severity levels.

    static bool isResolved(Severity severity) {
        return severity == Severity::kOk;
    }

    static bool isActiveFault(Severity severity) {
        return severity == Severity::kFailure;
    }

    bool isActiveFault() const {
        return isActiveFault(getSeverity());
    }

private:
    friend std::ostream& operator<<(std::ostream&, const HealthCheckStatus&);
    friend StringBuilder& operator<<(StringBuilder& s, const HealthCheckStatus& hcs);


    FaultFacetType _type;
    Severity _severity;
    std::string _description;
};

inline void HealthCheckStatus::appendDescription(BSONObjBuilder* builder) const {
    builder->append("type", _type);
    builder->append("description", _description);
    builder->append("severity", _severity);
}

inline StringBuilder& operator<<(StringBuilder& s, const HealthCheckStatus& hcs) {
    BSONObjBuilder bob;
    hcs.appendDescription(&bob);
    return s << bob.obj();
}

inline std::ostream& operator<<(std::ostream& os, const HealthCheckStatus& hcs) {
    BSONObjBuilder bob;
    hcs.appendDescription(&bob);
    return os << bob.obj();
}

inline BSONObj HealthCheckStatus::toBSON() const {
    BSONObjBuilder bob;
    appendDescription(&bob);
    return bob.obj();
}

inline std::string HealthCheckStatus::toString() const {
    BSONObjBuilder bob;
    appendDescription(&bob);
    return bob.obj().toString();
}

}  // namespace process_health
}  // namespace mongo