// Copyright (C) 2018 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#ifndef QWASMCOMPOSITOR_H
#define QWASMCOMPOSITOR_H

#include "qwasmwindowstack.h"

#include <QtGui/qregion.h>
#include <qpa/qplatformwindow.h>

#include <QtOpenGL/qopengltextureblitter.h>
#include <QtGui/qpalette.h>
#include <QtGui/qpainter.h>
#include <QtGui/qinputdevice.h>
#include <QtCore/private/qstdweb_p.h>

#include <QPointer>
#include <QPointingDevice>

#include <emscripten/html5.h>
#include <emscripten/emscripten.h>
#include <emscripten/bind.h>

QT_BEGIN_NAMESPACE

struct PointerEvent;
class QWasmWindow;
class QWasmScreen;
class QOpenGLContext;
class QOpenGLTexture;
class QWasmEventTranslator;

class QWasmCompositor : public QObject
{
    Q_OBJECT
public:
    QWasmCompositor(QWasmScreen *screen);
    ~QWasmCompositor();
    void initEventHandlers();
    void deregisterEventHandlers();
    void destroy();

    enum QWasmSubControl {
        SC_None =                  0x00000000,
        SC_TitleBarSysMenu =       0x00000001,
        SC_TitleBarMinButton =     0x00000002,
        SC_TitleBarMaxButton =     0x00000004,
        SC_TitleBarCloseButton =   0x00000008,
        SC_TitleBarNormalButton =  0x00000010,
        SC_TitleBarLabel =         0x00000100
    };
    Q_DECLARE_FLAGS(SubControls, QWasmSubControl)

    enum QWasmStateFlag {
        State_None =               0x00000000,
        State_Enabled =            0x00000001,
        State_Raised =             0x00000002,
        State_Sunken =             0x00000004
    };
    Q_DECLARE_FLAGS(StateFlags, QWasmStateFlag)

    enum ResizeDimension {
        Left = 1,
        Right = 1 << 1,
        Top = 1 << 2,
        Bottom = 1 << 3
    };

    enum ResizeMode {
        ResizeNone,
        ResizeTopLeft = Top | Left,
        ResizeTop = Top,
        ResizeTopRight = Top | Right,
        ResizeRight = Right,
        ResizeBottomRight = Bottom | Right,
        ResizeBottom = Bottom,
        ResizeBottomLeft = Bottom | Left,
        ResizeLeft = Left
    };

    struct QWasmTitleBarOptions {
        QRect rect;
        Qt::WindowFlags flags;
        int state;
        QPalette palette;
        QString titleBarOptionsString;
        QWasmCompositor::SubControls subControls;
        QIcon windowIcon;
    };

    struct QWasmFrameOptions {
        QRect rect;
        int lineWidth;
        QPalette palette;
    };

    void setEnabled(bool enabled);

    void addWindow(QWasmWindow *window);
    void removeWindow(QWasmWindow *window);

    void setVisible(QWasmWindow *window, bool visible);
    void raise(QWasmWindow *window);
    void lower(QWasmWindow *window);

    int windowCount() const;

    QWindow *windowAt(QPoint globalPoint, int padding = 0) const;
    QWindow *keyWindow() const;

    static QWasmTitleBarOptions makeTitleBarOptions(const QWasmWindow *window);
    static QRect titlebarRect(QWasmTitleBarOptions tb, QWasmCompositor::SubControls subcontrol);

    QWasmScreen *screen();
    QOpenGLContext *context();

    enum UpdateRequestDeliveryType { ExposeEventDelivery, UpdateRequestDelivery };
    void requestUpdateAllWindows();
    void requestUpdateWindow(QWasmWindow *window, UpdateRequestDeliveryType updateType = ExposeEventDelivery);
    void requestUpdate();
    void deliverUpdateRequests();
    void deliverUpdateRequest(QWasmWindow *window, UpdateRequestDeliveryType updateType);
    void handleBackingStoreFlush();
    bool processKeyboard(int eventType, const EmscriptenKeyboardEvent *keyEvent);
    bool processWheel(int eventType, const EmscriptenWheelEvent *wheelEvent);
    int handleTouch(int eventType, const EmscriptenTouchEvent *touchEvent);

    bool processMouseEnter(const EmscriptenMouseEvent *mouseEvent);
    bool processMouseLeave();
    void enterWindow(QWindow* window, const QPoint &localPoint, const QPoint &globalPoint);
    void leaveWindow(QWindow* window);

private slots:
    void frame();

private:
    class WindowManipulation {
    public:
        enum class Operation {
            None,
            Move,
            Resize,
        };

        WindowManipulation(QWasmScreen* screen);

        void onPointerDown(const PointerEvent& event, QWindow* windowAtPoint);
        void onPointerMove(const PointerEvent& event);
        void onPointerUp(const PointerEvent& event);

        Operation operation() const;

    private:
        struct ResizeState {
            ResizeMode m_resizeMode;
            QPoint m_originInScreenCoords;
            QRect m_initialWindowBounds;
            const QPoint m_minShrink;
            const QPoint m_maxGrow;
        };
        struct MoveState {
            QPoint m_lastPointInScreenCoords;
        };
        struct OperationState
        {
            int pointerId;
            QPointer<QWindow> window;
            std::variant<ResizeState, MoveState> operationSpecific;
        };

        void resizeWindow(const QPoint& amount);

        QWasmScreen *m_screen;

        std::unique_ptr<OperationState> m_state;
    };

    void onTopWindowChanged(QWasmWindow *window);
    void drawWindow(QOpenGLTextureBlitter *blitter, QWasmScreen *screen, const QWasmWindow *window);
    void drawWindowContent(QOpenGLTextureBlitter *blitter, QWasmScreen *screen,
                           const QWasmWindow *window);
    void blit(QOpenGLTextureBlitter *blitter, QWasmScreen *screen, const QOpenGLTexture *texture, QRect targetGeometry);

    void drawWindowDecorations(QOpenGLTextureBlitter *blitter, QWasmScreen *screen,
                               const QWasmWindow *window);

    static QPalette makeWindowPalette();

    void drawFrameWindow(QWasmFrameOptions options, QPainter *painter);
    void drawTitlebarWindow(QWasmTitleBarOptions options, QPainter *painter);
    void drawShadePanel(QWasmTitleBarOptions options, QPainter *painter);
    void drawItemPixmap(QPainter *painter, const QRect &rect,
                                    int alignment, const QPixmap &pixmap) const;

    static int keyboard_cb(int eventType, const EmscriptenKeyboardEvent *keyEvent, void *userData);
    static int focus_cb(int eventType, const EmscriptenFocusEvent *focusEvent, void *userData);
    static int wheel_cb(int eventType, const EmscriptenWheelEvent *wheelEvent, void *userData);

    bool processPointer(const PointerEvent& event);
    bool deliverEventToTarget(const PointerEvent& event, QWindow *eventTarget);

    static int touchCallback(int eventType, const EmscriptenTouchEvent *ev, void *userData);

    WindowManipulation m_windowManipulation;
    QWasmWasmWindowStack m_windowStack;

    QScopedPointer<QOpenGLContext> m_context;
    QScopedPointer<QOpenGLTextureBlitter> m_blitter;

    QHash<const QWasmWindow *, bool> m_windowVisibility;
    QRegion m_globalDamage; // damage caused by expose, window close, etc.
    bool m_needComposit = false;
    bool m_inFlush = false;
    bool m_isEnabled = true;
    QSize m_targetSize;
    qreal m_targetDevicePixelRatio = 1;
    QMap<QWasmWindow *, UpdateRequestDeliveryType> m_requestUpdateWindows;
    bool m_requestUpdateAllWindows = false;
    int m_requestAnimationFrameId = -1;
    bool m_inDeliverUpdateRequest = false;

    QPointer<QWindow> m_pressedWindow;
    QPointer<QWindow> m_lastMouseTargetWindow;

    std::unique_ptr<qstdweb::EventCallback> m_pointerDownCallback;
    std::unique_ptr<qstdweb::EventCallback> m_pointerMoveCallback;
    std::unique_ptr<qstdweb::EventCallback> m_pointerUpCallback;
    std::unique_ptr<qstdweb::EventCallback> m_pointerLeaveCallback;
    std::unique_ptr<qstdweb::EventCallback> m_pointerEnterCallback;

    std::unique_ptr<QPointingDevice> m_touchDevice;

    QMap <int, QPointF> m_pressedTouchIds;

    bool m_isResizeCursorDisplayed = false;

    std::unique_ptr<QWasmEventTranslator> m_eventTranslator;

    bool m_mouseInCanvas = false;
    QPointer<QWindow> m_windowUnderMouse;
};
Q_DECLARE_OPERATORS_FOR_FLAGS(QWasmCompositor::SubControls)

QT_END_NAMESPACE

#endif