inc/button_factory.hpp

#pragma once

#include "button_config.hpp"
#include "button_interface.hpp"

#include <phosphor-logging/elog-errors.hpp>

#include <unordered_map>

using buttonIfCreatorMethod = std::function<std::unique_ptr<ButtonIface>(
    sdbusplus::bus_t& bus, EventPtr& event, ButtonConfig& buttonCfg)>;

/**
 * @brief This is abstract factory for the creating phosphor buttons objects
 * based on the button  / formfactor type given.
 */

class ButtonFactory
{
  public:
    static ButtonFactory& instance()
    {
        static ButtonFactory buttonFactoryObj;
        return buttonFactoryObj;
    }

    /**
     * @brief this method creates a key and value pair element
     * for the given button interface where key is the form factor
     * name and the value is lambda method to return
     * the instance of the button interface.
     * This key value pair is stored in the Map buttonIfaceRegistry.
     */

    template <typename T>
    void addToRegistry()
    {
        buttonIfaceRegistry[T::getFormFactorName()] =
            [](sdbusplus::bus_t& bus, EventPtr& event,
               ButtonConfig& buttonCfg) {
                return std::make_unique<T>(bus, T::getDbusObjectPath().c_str(),
                                           event, buttonCfg);
            };
    }

    template <typename T>
    void addToRegistry(size_t index)
    {
        auto indexStr = std::to_string(index);
        buttonIfaceRegistry[T::getFormFactorName() + indexStr] =
            [=](sdbusplus::bus_t& bus, EventPtr& event,
                ButtonConfig& buttonCfg) {
                return std::make_unique<T>(
                    bus, (T::getDbusObjectPath() + indexStr).c_str(), event,
                    buttonCfg);
            };
    }

    /**
     * @brief this method returns the button interface object
     *    corresponding to the button formfactor name provided
     */
    std::unique_ptr<ButtonIface>
        createInstance(const std::string& name, sdbusplus::bus_t& bus,
                       EventPtr& event, ButtonConfig& buttonCfg)
    {
        // find matching name in the registry and call factory method.
        auto objectIter = buttonIfaceRegistry.find(name);
        if (objectIter != buttonIfaceRegistry.end())
        {
            return objectIter->second(bus, event, buttonCfg);
        }
        else
        {
            return nullptr;
        }
    }

  private:
    // This map is the registry for keeping supported button interface types.
    std::unordered_map<std::string, buttonIfCreatorMethod> buttonIfaceRegistry;
};

template <class T>
class ButtonIFRegister
{
  public:
    ButtonIFRegister()
    {
        // register the class factory function
        ButtonFactory::instance().addToRegistry<T>();
    }

    explicit ButtonIFRegister(size_t count)
    {
        // register the class factory function
        // The index, 'countIter', starts at 1 and increments,
        // representing slot_1 through slot_N.
        for (size_t countIter = 1; countIter <= count; countIter++)
        {
            ButtonFactory::instance().addToRegistry<T>(countIter);
        }
    }
};