/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2008 Robert Osfield
 *
 * This library is open source and may be redistributed and/or modified under
 * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
 * (at your option) any later version.  The full license is in LICENSE file
 * included with this distribution, and on the openscenegraph.org website.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * OpenSceneGraph Public License for more details.
*/

// Code by: Jeremy Moles (cubicool) 2007-2008

#ifndef OSGWIDGET_EVENT_INTERFACE
#define OSGWIDGET_EVENT_INTERFACE

#include <list>
#include <osg/ref_ptr>
#include <osg/observer_ptr>
#include <osg/Referenced>

#include <osgWidget/Export>

namespace osgWidget {

class WindowManager;
class Window;
class Widget;

enum EventType
{
    EVENT_NONE          = 0x0000,
    EVENT_FOCUS         = 0x0001,
    EVENT_UNFOCUS       = 0x0002,
    EVENT_MOUSE_ENTER   = 0x0004,
    EVENT_MOUSE_OVER    = 0x0008,
    EVENT_MOUSE_LEAVE   = 0x0010,
    EVENT_MOUSE_DRAG    = 0x0020,
    EVENT_MOUSE_PUSH    = 0x0040,
    EVENT_MOUSE_RELEASE = 0x0080,
    EVENT_MOUSE_SCROLL  = 0x0100,
    EVENT_KEY_DOWN      = 0x0200,
    EVENT_KEY_UP        = 0x0400,
    EVENT_ALL           = 0xFFFF
};

// Helpful wrapper around using the raw types, since it often doesn't make sense to
// use some without the others.
enum EventMask
{
    EVENT_MASK_FOCUS        = EVENT_FOCUS | EVENT_UNFOCUS,
    EVENT_MASK_MOUSE_MOVE   = EVENT_MOUSE_ENTER | EVENT_MOUSE_OVER | EVENT_MOUSE_LEAVE,
    EVENT_MASK_MOUSE_CLICK  = EVENT_MOUSE_PUSH | EVENT_MOUSE_RELEASE,
    EVENT_MASK_MOUSE_DRAG   = EVENT_MASK_MOUSE_MOVE | EVENT_MASK_MOUSE_CLICK | EVENT_MOUSE_DRAG,
    EVENT_MASK_KEY          = EVENT_KEY_UP | EVENT_KEY_DOWN
};

class OSGWIDGET_EXPORT Event
{
    public:
        EventType type;
        double     x;
        double     y;
        int        key;
        int        keyMask;

        Event(WindowManager* wm, EventType _type = EVENT_NONE):
        type    (_type),
        x       (0.0f),
        y       (0.0f),
        key     (-1),
        keyMask (-1),
        _wm     (wm),
        _window (0),
        _widget (0),
        _data   (0) {
        }

        Event& makeType(EventType _type) {
            if(_type != EVENT_NONE) type = _type;

            return *this;
        }

        Event& makeMouse(double _x, double _y, EventType _type = EVENT_NONE) {
            x = _x;
            y = _y;

            if(_type != EVENT_NONE) type = _type;

            return *this;
        }

        Event& makeKey(int _key, int _keyMask, EventType _type = EVENT_NONE) {
            key     = _key;
            keyMask = _keyMask;

            if(_type != EVENT_NONE) type = _type;

            return *this;
        }

        WindowManager* getWindowManager() { return _wm; }

        const WindowManager* getWindowManager() const {
            return _wm;
        }

        Window* getWindow() {
            return _window;
        }

        const Window* getWindow() const {
            return _window;
        }

        Widget* getWidget() {
            return _widget;
        }

        const Widget* getWidget() const {
            return _widget;
        }

        void* getData() {
            return _data;
        }

        const void* getData() const {
            return _data;
        }

        void setData(void* data) {
            _data = data;
        }

    protected:

        friend class WindowManager;
        friend class Window;

        WindowManager* _wm;
        Window*        _window;
        Widget*        _widget;
        void*          _data;

};

// The Callback interface was inspired by the CEGUI project:
//
//     http://www.cegui.org.uk/wiki/index.php/Main_Page
//
// It's a great little way to cleanly implement callbacks for events, although
// I did change the names a bit to make them more appropriate for OSG. MANY THANKS
// to the CEGUI project!

// The CallbackInterface, which the highest-level functor keeps a pointer to.
struct CallbackInterface: public osg::Referenced
{
    virtual ~CallbackInterface() {}

    virtual const char* className() const { return "osgWidget::CallbackInterface"; }

    virtual bool operator()(Event&) = 0;
};

// The object that facilitates a class method as a callback.
template<typename T>
class ObjectCallback: public CallbackInterface
{
    public:
        typedef bool (T::*ObjectCallbackType)(Event&);

        ObjectCallback(ObjectCallbackType callback, T* obj):
        _object   (obj),
        _callback (callback) {}

        virtual bool operator()(Event& ev) {
            return (_object->*_callback)(ev);
        }

    private:
        T*                 _object;
        ObjectCallbackType _callback;
};

// The object that facilitates general functions as callbacks.
template<typename T>
class FunctionCallback: public CallbackInterface
{
    public:
        FunctionCallback(T* callback):
        _callback(callback) {
        }

        virtual bool operator()(Event& ev) {
            return (*_callback)(ev);
        }
    protected:
        T* _callback;
};

// The highlevel functor.
class OSGWIDGET_EXPORT Callback: public osg::Referenced
{
    public:
        Callback(): _type(EVENT_NONE), _data(0), _callback(0) {}
        Callback(const Callback& rhs): osg::Referenced(rhs), _type(rhs._type), _data(rhs._data), _callback(rhs._callback) {}

        virtual const char* className() const { return "osgWidget::Callback"; }

        // The more traditional style of OSG Callbacks.
        Callback(EventType type, void* data=0):
        _type     (type),
        _data     (data),
        _callback (0) {
        }

        // Creates a Callback that is bound to a member function.
        template<typename T>
        Callback(bool (T::*function)(Event&), T* obj, EventType type, void* data=0):
        _type     (type),
        _data     (data),
        _callback (new ObjectCallback<T>(function, obj)) {
        }

        // Creates a Callback that is bound to a functor pointer.
        template<typename T>
        Callback(T* functor, EventType type, void* data=0):
        _type     (type),
        _data     (data),
        _callback (new FunctionCallback<T>(functor)) {
        }

        virtual ~Callback() {}

        virtual bool operator()(Event& ev) {
            if(!_callback) return false;

            return (*_callback)(ev);
        }

        EventType getType() const {
            return _type;
        }

        void* getData() {
            return _data;
        }

        const void* getData() const {
            return _data;
        }

    protected:
        EventType _type;
        void*     _data;

        // We use a ref_ptr here so that we don't have to worry about memory.
        osg::ref_ptr<CallbackInterface> _callback;

};


class OSGWIDGET_EXPORT EventInterface
{
    public:
        EventInterface(): _eventMask(EVENT_NONE) {}

        EventInterface(const EventInterface& ei):
        _eventMask (ei._eventMask),
        _callbacks (ei._callbacks) {}

        virtual ~EventInterface() {}

        // These functions take as their final argument the WindowManager which issued the
        // request. This is sometimes useful to get information about key state, etc.

        // Notify the EventInterface object that is has been focused or unfocused; since
        // this isn't always bound to a mouse event (i.e., if you want to be able to use
        // the TAB key to focus), we need separate events here.
        virtual bool focus   (const WindowManager*) { return false; }
        virtual bool unfocus (const WindowManager*) { return false; }

        // Mouse events, pretty self-explanatory.
        virtual bool mouseEnter   (double, double, const WindowManager*) { return false; }
        virtual bool mouseOver    (double, double, const WindowManager*) { return false; }
        virtual bool mouseLeave   (double, double, const WindowManager*) { return false; }
        virtual bool mouseDrag    (double, double, const WindowManager*) { return false; }
        virtual bool mousePush    (double, double, const WindowManager*) { return false; }
        virtual bool mouseRelease (double, double, const WindowManager*) { return false; }
        virtual bool mouseScroll  (double, double, const WindowManager*) { return false; }

        // These functions pass the osgGA::GUIEventAdapter::KeySymbol and KeyModMask and,
        // as above, the WindowManager.
        virtual bool keyDown (int, int, const WindowManager*) { return false; }
        virtual bool keyUp   (int, int, const WindowManager*) { return false; }

        void setEventMask(unsigned int mask) {
            _eventMask = mask;
        }

        void addEventMask(unsigned int mask) {
            _eventMask |= mask;
        }

        void removeEventMask(unsigned int mask) {
            _eventMask ^= mask;
        }

        unsigned int getEventMask() const {
            return _eventMask;
        }

        typedef std::list<osg::ref_ptr<Callback> > CallbackList;

        inline CallbackList& getCallbacks() { return _callbacks; }
        inline const CallbackList& getCallbacks() const { return _callbacks; }

        void addCallback(Callback* cb) {
            _callbacks.push_back(cb);
        }

        bool callCallbacks(Event& ev) {
            if(ev.type == EVENT_NONE || !(_eventMask & ev.type)) return false;

            for(CallbackList::iterator i = _callbacks.begin(); i != _callbacks.end(); i++) {
                // This is the OLD method; testing a new method below.
                // if(i->getType() == ev.type && (*i)(ev)) return true;

                if(i->get()->getType() & ev.type) {
                    ev.setData(i->get()->getData());

                    if((*i->get())(ev)) return true;
                }
            }

            return false;
        }

        bool callMethodAndCallbacks(Event& ev) {
            if(ev.type == EVENT_NONE || !(_eventMask & ev.type)) return false;

            bool handled = false;

            if(ev.type == EVENT_FOCUS) handled = focus(ev.getWindowManager());

            else if(ev.type == EVENT_UNFOCUS) handled = unfocus(ev.getWindowManager());

            else if(ev.type == EVENT_MOUSE_ENTER)
                handled = mouseEnter(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_MOUSE_OVER)
                handled = mouseOver(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_MOUSE_LEAVE)
                handled = mouseLeave(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_MOUSE_DRAG)
                handled = mouseDrag(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_MOUSE_PUSH)
                handled = mousePush(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_MOUSE_RELEASE)
                handled = mouseRelease(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_MOUSE_SCROLL)
                handled = mouseScroll(ev.x, ev.y, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_KEY_DOWN)
                handled = keyDown(ev.key, ev.keyMask, ev.getWindowManager())
            ;

            else if(ev.type == EVENT_KEY_UP)
                handled = keyUp(ev.key, ev.keyMask, ev.getWindowManager())
            ;

            else return false;

            return callCallbacks(ev) || handled;
        }

        bool canFocus   () const { return (_eventMask & EVENT_FOCUS) != 0; }
        bool canUnfocus () const { return (_eventMask & EVENT_UNFOCUS) != 0; }

        bool canMouseEnter   () const { return (_eventMask & EVENT_MOUSE_ENTER) != 0; }
        bool canMouseOver    () const { return (_eventMask & EVENT_MOUSE_OVER) != 0; }
        bool canMouseLeave   () const { return (_eventMask & EVENT_MOUSE_LEAVE) != 0; }
        bool canMouseDrag    () const { return (_eventMask & EVENT_MOUSE_DRAG) != 0; }
        bool canMousePush    () const { return (_eventMask & EVENT_MOUSE_PUSH) != 0; }
        bool canMouseRelease () const { return (_eventMask & EVENT_MOUSE_RELEASE) != 0; }
        bool canMouseScroll  () const { return (_eventMask & EVENT_MOUSE_SCROLL) != 0; }

        bool canKeyDown () const { return (_eventMask & EVENT_KEY_DOWN) != 0; }
        bool canKeyUp   () const { return (_eventMask & EVENT_KEY_UP) != 0; }

    private:

        unsigned int _eventMask;
        CallbackList _callbacks;

};

}

#endif