// SPDX-License-Identifier: GPL-3.0-or-later
// SPDX-FileCopyrightText: 2024 A-La-Karte Contributors

#include "gamepadmanager.h"

#include <QCoreApplication>
#include <QString>

#include <memory>

#define SDL_MAIN_HANDLED 1
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>

namespace
{
constexpr int PollIntervalMs = 16;
constexpr int RepeatIntervalMs = 150;
constexpr qint16 AxisThreshold = 16000;

QString buttonLabelToString(SDL_GamepadButtonLabel label)
{
    switch (label) {
    case SDL_GAMEPAD_BUTTON_LABEL_A:
        return QStringLiteral("A");
    case SDL_GAMEPAD_BUTTON_LABEL_B:
        return QStringLiteral("B");
    case SDL_GAMEPAD_BUTTON_LABEL_X:
        return QStringLiteral("X");
    case SDL_GAMEPAD_BUTTON_LABEL_Y:
        return QStringLiteral("Y");
    case SDL_GAMEPAD_BUTTON_LABEL_CROSS:
        return QStringLiteral("Cross");
    case SDL_GAMEPAD_BUTTON_LABEL_CIRCLE:
        return QStringLiteral("Circle");
    case SDL_GAMEPAD_BUTTON_LABEL_SQUARE:
        return QStringLiteral("Square");
    case SDL_GAMEPAD_BUTTON_LABEL_TRIANGLE:
        return QStringLiteral("Triangle");
    default:
        return QString();
    }
}

GamepadManager::ControllerStyle controllerStyleFromTypeVendor(SDL_GamepadType type, Uint16 vendor)
{
    switch (type) {
    case SDL_GAMEPAD_TYPE_XBOX360:
    case SDL_GAMEPAD_TYPE_XBOXONE:
        return GamepadManager::XboxController;
    case SDL_GAMEPAD_TYPE_PS3:
    case SDL_GAMEPAD_TYPE_PS4:
    case SDL_GAMEPAD_TYPE_PS5:
        return GamepadManager::PlayStationController;
    case SDL_GAMEPAD_TYPE_NINTENDO_SWITCH_PRO:
    case SDL_GAMEPAD_TYPE_NINTENDO_SWITCH_JOYCON_LEFT:
    case SDL_GAMEPAD_TYPE_NINTENDO_SWITCH_JOYCON_RIGHT:
    case SDL_GAMEPAD_TYPE_NINTENDO_SWITCH_JOYCON_PAIR:
        return GamepadManager::NintendoController;
    default:
        break;
    }

    if (vendor == 0x045E) {
        return GamepadManager::XboxController;
    }
    if (vendor == 0x054C) {
        return GamepadManager::PlayStationController;
    }
    if (vendor == 0x057E) {
        return GamepadManager::NintendoController;
    }

    if (type == SDL_GAMEPAD_TYPE_STANDARD) {
        return GamepadManager::GenericController;
    }

    return GamepadManager::UnknownController;
}
}

GamepadManager *GamepadManager::s_instance = nullptr;

GamepadManager::GamepadManager(QObject *parent)
    : QObject(parent)
{
    SDL_SetMainReady();

    m_sdlInitialized = SDL_Init(SDL_INIT_GAMEPAD);

    connect(QCoreApplication::instance(), &QCoreApplication::aboutToQuit, this, [this]() {
        m_pollTimer.stop();
        m_repeatTimer.stop();
        closeGamepad();
        if (m_sdlInitialized) {
            SDL_Quit();
            m_sdlInitialized = false;
        }
    });

    m_pollTimer.setInterval(PollIntervalMs);
    connect(&m_pollTimer, &QTimer::timeout, this, &GamepadManager::pollEvents);

    m_repeatTimer.setInterval(RepeatIntervalMs);
    connect(&m_repeatTimer, &QTimer::timeout, this, &GamepadManager::processInput);

    if (m_sdlInitialized) {
        SDL_SetGamepadEventsEnabled(true);
        openFirstAvailableGamepad();
        m_pollTimer.start();
    }
}

GamepadManager *GamepadManager::instance()
{
    if (!s_instance) {
        s_instance = new GamepadManager();
    }
    return s_instance;
}

GamepadManager *GamepadManager::create(QQmlEngine *engine, QJSEngine *scriptEngine)
{
    Q_UNUSED(engine)
    Q_UNUSED(scriptEngine)
    return instance();
}

bool GamepadManager::connected() const
{
    return m_connected;
}

bool GamepadManager::active() const
{
    return m_active;
}

GamepadManager::ControllerStyle GamepadManager::controllerStyle() const
{
    return m_controllerStyle;
}

QString GamepadManager::confirmButtonLabel() const
{
    return m_confirmButtonLabel;
}

QString GamepadManager::backButtonLabel() const
{
    return m_backButtonLabel;
}

QString GamepadManager::detailsButtonLabel() const
{
    return m_detailsButtonLabel;
}

QString GamepadManager::searchButtonLabel() const
{
    return m_searchButtonLabel;
}

void GamepadManager::setActive(bool active)
{
    if (m_active != active) {
        m_active = active;
        Q_EMIT activeChanged();
    }
}

void GamepadManager::openFirstAvailableGamepad()
{
    if (!m_sdlInitialized || m_gamepad) {
        return;
    }

    int count = 0;
    std::unique_ptr<SDL_JoystickID[], decltype(&SDL_free)> ids(SDL_GetGamepads(&count), SDL_free);
    if (!ids || count <= 0) {
        return;
    }

    const SDL_JoystickID instanceId = ids[0];

    if (SDL_IsGamepad(instanceId)) {
        openGamepad(static_cast<int>(instanceId));
    }
}

void GamepadManager::openGamepad(int deviceId)
{
    if (!m_sdlInitialized || m_gamepad) {
        return;
    }

    SDL_Gamepad *pad = SDL_OpenGamepad(static_cast<SDL_JoystickID>(deviceId));
    if (!pad) {
        return;
    }

    m_gamepad = pad;
    m_gamepadId = deviceId;
    m_connected = true;
    Q_EMIT connectedChanged();
    updateControllerInfo();
}

void GamepadManager::closeGamepad()
{
    if (!m_gamepad) {
        return;
    }

    SDL_CloseGamepad(m_gamepad);
    m_gamepad = nullptr;
    m_gamepadId = 0;
    m_connected = false;
    setActive(false);
    m_leftX = 0;
    m_leftY = 0;
    m_leftDirX = 0;
    m_leftDirY = 0;
    m_repeatTimer.stop();
    Q_EMIT connectedChanged();
    updateControllerInfo();
}

void GamepadManager::updateControllerInfo()
{
    ControllerStyle style = UnknownController;
    QString confirmLabel;
    QString backLabel;
    QString detailsLabel;
    QString searchLabel;

    if (m_gamepad) {
        const SDL_GamepadType type = SDL_GetGamepadType(m_gamepad);
        const Uint16 vendor = SDL_GetGamepadVendor(m_gamepad);
        style = controllerStyleFromTypeVendor(type, vendor);

#if SDL_VERSION_ATLEAST(3, 2, 0)
        confirmLabel = buttonLabelToString(SDL_GetGamepadButtonLabel(m_gamepad, SDL_GAMEPAD_BUTTON_SOUTH));
        backLabel = buttonLabelToString(SDL_GetGamepadButtonLabel(m_gamepad, SDL_GAMEPAD_BUTTON_EAST));
        detailsLabel = buttonLabelToString(SDL_GetGamepadButtonLabel(m_gamepad, SDL_GAMEPAD_BUTTON_WEST));
        searchLabel = buttonLabelToString(SDL_GetGamepadButtonLabel(m_gamepad, SDL_GAMEPAD_BUTTON_NORTH));
#endif

        if (confirmLabel.isEmpty() || backLabel.isEmpty() || detailsLabel.isEmpty() || searchLabel.isEmpty()) {
            if (style == PlayStationController) {
                if (confirmLabel.isEmpty()) {
                    confirmLabel = QStringLiteral("Cross");
                }
                if (backLabel.isEmpty()) {
                    backLabel = QStringLiteral("Circle");
                }
                if (detailsLabel.isEmpty()) {
                    detailsLabel = QStringLiteral("Square");
                }
                if (searchLabel.isEmpty()) {
                    searchLabel = QStringLiteral("Triangle");
                }
            } else if (style == NintendoController) {
                if (confirmLabel.isEmpty()) {
                    confirmLabel = QStringLiteral("B");
                }
                if (backLabel.isEmpty()) {
                    backLabel = QStringLiteral("A");
                }
                if (detailsLabel.isEmpty()) {
                    detailsLabel = QStringLiteral("Y");
                }
                if (searchLabel.isEmpty()) {
                    searchLabel = QStringLiteral("X");
                }
            } else {
                if (confirmLabel.isEmpty()) {
                    confirmLabel = QStringLiteral("A");
                }
                if (backLabel.isEmpty()) {
                    backLabel = QStringLiteral("B");
                }
                if (detailsLabel.isEmpty()) {
                    detailsLabel = QStringLiteral("X");
                }
                if (searchLabel.isEmpty()) {
                    searchLabel = QStringLiteral("Y");
                }
            }
        }
    }

    const bool changed = (style != m_controllerStyle) || (confirmLabel != m_confirmButtonLabel) || (backLabel != m_backButtonLabel)
        || (detailsLabel != m_detailsButtonLabel) || (searchLabel != m_searchButtonLabel);

    m_controllerStyle = style;
    m_confirmButtonLabel = confirmLabel;
    m_backButtonLabel = backLabel;
    m_detailsButtonLabel = detailsLabel;
    m_searchButtonLabel = searchLabel;

    if (changed) {
        Q_EMIT controllerInfoChanged();
    }
}

void GamepadManager::pollEvents()
{
    if (!m_sdlInitialized) {
        return;
    }

    SDL_Event e;
    while (SDL_PollEvent(&e)) {
        switch (e.type) {
        case SDL_EVENT_GAMEPAD_ADDED: {
            if (!m_gamepad) {
                openGamepad(static_cast<int>(e.gdevice.which));
            }
            break;
        }
        case SDL_EVENT_GAMEPAD_REMOVED: {
            if (m_gamepad && static_cast<int>(e.gdevice.which) == m_gamepadId) {
                closeGamepad();
                openFirstAvailableGamepad();
            }
            break;
        }
        case SDL_EVENT_GAMEPAD_AXIS_MOTION: {
            if (!m_gamepad || static_cast<int>(e.gaxis.which) != m_gamepadId) {
                break;
            }

            if (e.gaxis.axis == SDL_GAMEPAD_AXIS_LEFTX) {
                m_leftX = e.gaxis.value;
            } else if (e.gaxis.axis == SDL_GAMEPAD_AXIS_LEFTY) {
                m_leftY = e.gaxis.value;
            } else {
                break;
            }

            const qint8 dirX = (m_leftX < -AxisThreshold) ? -1 : (m_leftX > AxisThreshold ? 1 : 0);
            const qint8 dirY = (m_leftY < -AxisThreshold) ? -1 : (m_leftY > AxisThreshold ? 1 : 0);

            if (dirX != 0 || dirY != 0) {
                setActive(true);
            }

            if (dirY != m_leftDirY) {
                m_leftDirY = dirY;
                if (dirY < 0) {
                    Q_EMIT navigateUp();
                } else if (dirY > 0) {
                    Q_EMIT navigateDown();
                }
            }

            if (dirX != m_leftDirX) {
                m_leftDirX = dirX;
                if (dirX < 0) {
                    Q_EMIT navigateLeft();
                } else if (dirX > 0) {
                    Q_EMIT navigateRight();
                }
            }

            if (m_leftDirX != 0 || m_leftDirY != 0) {
                if (!m_repeatTimer.isActive()) {
                    m_repeatTimer.start();
                }
            } else {
                m_repeatTimer.stop();
            }

            break;
        }
        case SDL_EVENT_GAMEPAD_BUTTON_DOWN: {
            if (!m_gamepad || static_cast<int>(e.gbutton.which) != m_gamepadId) {
                break;
            }

            setActive(true);

            switch (static_cast<SDL_GamepadButton>(e.gbutton.button)) {
            case SDL_GAMEPAD_BUTTON_SOUTH:
                Q_EMIT selectPressed();
                break;
            case SDL_GAMEPAD_BUTTON_EAST:
            case SDL_GAMEPAD_BUTTON_BACK:
                Q_EMIT backPressed();
                break;
            case SDL_GAMEPAD_BUTTON_WEST:
                Q_EMIT detailsPressed();
                break;
            case SDL_GAMEPAD_BUTTON_LEFT_SHOULDER:
                Q_EMIT leftBumperPressed();
                break;
            case SDL_GAMEPAD_BUTTON_RIGHT_SHOULDER:
                Q_EMIT rightBumperPressed();
                break;
            case SDL_GAMEPAD_BUTTON_START:
                Q_EMIT menuPressed();
                break;
            case SDL_GAMEPAD_BUTTON_NORTH:
                Q_EMIT searchPressed();
                break;
            case SDL_GAMEPAD_BUTTON_DPAD_UP:
                Q_EMIT navigateUp();
                break;
            case SDL_GAMEPAD_BUTTON_DPAD_DOWN:
                Q_EMIT navigateDown();
                break;
            case SDL_GAMEPAD_BUTTON_DPAD_LEFT:
                Q_EMIT navigateLeft();
                break;
            case SDL_GAMEPAD_BUTTON_DPAD_RIGHT:
                Q_EMIT navigateRight();
                break;
            default:
                break;
            }
            break;
        }
        default:
            break;
        }
    }
}

void GamepadManager::processInput()
{
    if (!m_gamepad) {
        return;
    }

    if (m_leftY < -AxisThreshold) {
        Q_EMIT navigateUp();
    } else if (m_leftY > AxisThreshold) {
        Q_EMIT navigateDown();
    }

    if (m_leftX < -AxisThreshold) {
        Q_EMIT navigateLeft();
    } else if (m_leftX > AxisThreshold) {
        Q_EMIT navigateRight();
    }
}