// Copyright 2017 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#pragma once

#include <memory>
#include <string>
#include <tuple>
#include <unordered_map>
#include <utility>
#include "common/logging/log.h"
#include "common/param_package.h"
#include "common/vector_math.h"

namespace Input {

/// An abstract class template for an input device (a button, an analog input, etc.).
template <typename StatusType>
class InputDevice {
public:
    virtual ~InputDevice() = default;
    virtual StatusType GetStatus() const {
        return {};
    }
};

/// An abstract class template for a factory that can create input devices.
template <typename InputDeviceType>
class Factory {
public:
    virtual ~Factory() = default;
    virtual std::unique_ptr<InputDeviceType> Create(const Common::ParamPackage&) = 0;
};

namespace Impl {

template <typename InputDeviceType>
using FactoryListType = std::unordered_map<std::string, std::shared_ptr<Factory<InputDeviceType>>>;

template <typename InputDeviceType>
struct FactoryList {
    static FactoryListType<InputDeviceType> list;
};

template <typename InputDeviceType>
FactoryListType<InputDeviceType> FactoryList<InputDeviceType>::list;

} // namespace Impl

/**
 * Registers an input device factory.
 * @tparam InputDeviceType the type of input devices the factory can create
 * @param name the name of the factory. Will be used to match the "engine" parameter when creating
 *     a device
 * @param factory the factory object to register
 */
template <typename InputDeviceType>
void RegisterFactory(const std::string& name, std::shared_ptr<Factory<InputDeviceType>> factory) {
    auto pair = std::make_pair(name, std::move(factory));
    if (!Impl::FactoryList<InputDeviceType>::list.insert(std::move(pair)).second) {
        LOG_ERROR(Input, "Factory '{}' already registered", name);
    }
}

/**
 * Unregisters an input device factory.
 * @tparam InputDeviceType the type of input devices the factory can create
 * @param name the name of the factory to unregister
 */
template <typename InputDeviceType>
void UnregisterFactory(const std::string& name) {
    if (Impl::FactoryList<InputDeviceType>::list.erase(name) == 0) {
        LOG_ERROR(Input, "Factory '{}' not registered", name);
    }
}

/**
 * Create an input device from given paramters.
 * @tparam InputDeviceType the type of input devices to create
 * @param params a serialized ParamPackage string contains all parameters for creating the device
 */
template <typename InputDeviceType>
std::unique_ptr<InputDeviceType> CreateDevice(const std::string& params) {
    const Common::ParamPackage package(params);
    const std::string engine = package.Get("engine", "null");
    const auto& factory_list = Impl::FactoryList<InputDeviceType>::list;
    const auto pair = factory_list.find(engine);
    if (pair == factory_list.end()) {
        if (engine != "null") {
            LOG_ERROR(Input, "Unknown engine name: {}", engine);
        }
        return std::make_unique<InputDeviceType>();
    }
    return pair->second->Create(package);
}

/**
 * A button device is an input device that returns bool as status.
 * true for pressed; false for released.
 */
using ButtonDevice = InputDevice<bool>;

/**
 * An analog device is an input device that returns a tuple of x and y coordinates as status. The
 * coordinates are within the unit circle. x+ is defined as right direction, and y+ is defined as up
 * direction
 */
using AnalogDevice = InputDevice<std::tuple<float, float>>;

/**
 * A motion device is an input device that returns a tuple of accelerometer state vector and
 * gyroscope state vector.
 *
 * For both vectors:
 *   x+ is the same direction as LEFT on D-pad.
 *   y+ is normal to the touch screen, pointing outward.
 *   z+ is the same direction as UP on D-pad.
 *
 * For accelerometer state vector
 *   Units: g (gravitational acceleration)
 *
 * For gyroscope state vector:
 *   Orientation is determined by right-hand rule.
 *   Units: deg/sec
 */
using MotionDevice = InputDevice<std::tuple<Math::Vec3<float>, Math::Vec3<float>>>;

/**
 * A touch device is an input device that returns a tuple of two floats and a bool. The floats are
 * x and y coordinates in the range 0.0 - 1.0, and the bool indicates whether it is pressed.
 */
using TouchDevice = InputDevice<std::tuple<float, float, bool>>;

} // namespace Input