/**
 *    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 "mongo/logv2/log_component.h"
#include "mongo/logv2/log_severity.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/platform/mutex.h"

namespace mongo::logv2 {

/**
 * Contains log severities for a list of log components.
 * kDefault always has a log severity defined but it is not necessary to
 * provide log severities for the other components (up to but not including kNumLogComponents).
 */
class LogComponentSettings {
    LogComponentSettings(const LogComponentSettings&) = delete;
    LogComponentSettings& operator=(const LogComponentSettings&) = delete;

public:
    LogComponentSettings();
    ~LogComponentSettings();

    /**
     * Returns true if a minimum log severity has been set for this component.
     * Used by log level commands to query component severity configuration.
     */
    bool hasMinimumLogSeverity(LogComponent component) const;

    /**
     * Gets the minimum log severity for component.
     * Result is defined only if hasMinimumLogSeverity() returns true for component.
     */
    LogSeverity getMinimumLogSeverity(LogComponent component) const;

    /**
     * Sets the minimum log severity for component.
     */
    void setMinimumLoggedSeverity(LogComponent component, LogSeverity severity);

    /**
     * Clears the minimum log severity for component.
     * For kDefault, severity level is initialized to default value.
     */
    void clearMinimumLoggedSeverity(LogComponent component);

    /**
     * Predicate that answers the question, "Should I, the caller, append to you, the log
     * domain, componented messages of the given severity?"  True means yes.
     *
     * If minimum severity levels are not configured, compare 'severity' against the configured
     * level for kDefault.
     */
    bool shouldLog(LogComponent component, LogSeverity severity) const;

private:
    void _setMinimumLoggedSeverityInLock(LogComponent component, LogSeverity severity);

    // A mutex to synchronize writes to the severity arrays. This mutex is to synchronize changes to
    // the entire array, and the atomics are to synchronize individual elements.
    Mutex _mtx = MONGO_MAKE_LATCH("LogComponentSettings::_mtx");

    // True if a log severity is explicitly set for a component.
    // This differentiates between unconfigured components and components that happen to have
    // the same severity as kDefault.
    // This is also used to update the severities of unconfigured components when the severity
    // for kDefault is modified.
    AtomicWord<bool> _hasMinimumLoggedSeverity[LogComponent::kNumLogComponents];

    // Log severities for components.
    // Store numerical values of severities to be cache-line friendly.
    // Set to kDefault minimum logged severity if _hasMinimumLoggedSeverity[i] is false.
    AtomicWord<int> _minimumLoggedSeverity[LogComponent::kNumLogComponents];
};

}  // namespace mongo::logv2