SettingInterface.h

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/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *     http://aws.amazon.com/apache2.0/
 *
 * or in the "license" file accompanying this file. This file is distributed
 * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */
#ifndef ALEXA_CLIENT_SDK_SETTINGS_INCLUDE_SETTINGS_SETTINGINTERFACE_H_
#define ALEXA_CLIENT_SDK_SETTINGS_INCLUDE_SETTINGS_SETTINGINTERFACE_H_

#include <atomic>
#include <memory>
#include <mutex>
#include <string>
#include <type_traits>
#include <unordered_set>

#include <AVSCommon/Utils/GuardedValue.h>
#include <AVSCommon/Utils/Logger/LogEntry.h>
#include <AVSCommon/Utils/Logger/LoggerUtils.h>

#include "Settings/SetSettingResult.h"
#include "Settings/SettingObserverInterface.h"

namespace alexaClientSDK {
namespace settings {

template <typename ValueT>
class SettingInterface {
public:
    using ValueType = ValueT;

    using ObserverType = SettingObserverInterface<SettingInterface<ValueType>>;

    virtual ~SettingInterface() = default;

    virtual SetSettingResult setLocalChange(const ValueType& value) = 0;

    virtual bool setAvsChange(const ValueType& value) = 0;

    virtual bool clearData(const ValueType& value) = 0;

    inline ValueType get() const;

    inline ValueType getDefault() const;

    inline bool addObserver(std::shared_ptr<ObserverType> observer);

    inline void removeObserver(std::shared_ptr<ObserverType>& observer);

protected:
    SettingInterface(const ValueType& value);

    void notifyObservers(SettingNotifications notification);

    std::mutex m_observerMutex;

    std::unordered_set<std::shared_ptr<ObserverType>> m_observers;

    using GuardedValue = avsCommon::utils::GuardedValue<ValueType>;

    using LogEntry = avsCommon::utils::logger::LogEntry;

    typename std::conditional<std::is_scalar<ValueType>::value, std::atomic<ValueType>, GuardedValue>::type m_value;

    const ValueType m_defaultValue;
};

template <typename ValueT>
ValueT SettingInterface<ValueT>::get() const {
    return m_value;
}

template <typename ValueT>
ValueT SettingInterface<ValueT>::getDefault() const {
    return m_defaultValue;
}

template <typename ValueT>
bool SettingInterface<ValueT>::addObserver(std::shared_ptr<ObserverType> observer) {
    if (observer) {
        std::lock_guard<std::mutex>{m_observerMutex};
        m_observers.insert(observer);
        return true;
    }
    avsCommon::utils::logger::acsdkError(LogEntry("SettingInterface", "addObserverFailed").d("reason", "nullObserver"));
    return false;
}

template <typename ValueT>
void SettingInterface<ValueT>::notifyObservers(SettingNotifications notification) {
    std::lock_guard<std::mutex>{m_observerMutex};
    for (auto& observer : m_observers) {
        ValueT value = m_value;
        observer->onSettingNotification(value, notification);
    }
}

template <typename ValueT>
void SettingInterface<ValueT>::removeObserver(std::shared_ptr<ObserverType>& observer) {
    std::lock_guard<std::mutex>{m_observerMutex};
    m_observers.erase(observer);
}

template <typename ValueT>
SettingInterface<ValueT>::SettingInterface(const ValueT& value) : m_value(value), m_defaultValue{value} {
}

}  // namespace settings
}  // namespace alexaClientSDK

#endif  // ALEXA_CLIENT_SDK_SETTINGS_INCLUDE_SETTINGS_SETTINGINTERFACE_H_