#ifndef MOUSEAPI_H
#define MOUSEAPI_H

#include "OrxonoxPrereqs.h"
#include "util/OgreForwardRefs.h"
#include "graphics/Camera.h"
#include <util/Math.h>
#include <list>
#include <core/input/InputHandler.h>
#include <graphics/Camera.h>
#include <core/GraphicsManager.h>
#include <core/input/InputState.h>
#include <OgreCamera.h>
#include <OgreViewport.h>
#include "CameraManager.h"
#include <functional>
#include "core/GUIManager.h"
#include "core/input/KeyBinderManager.h"
#include "tools/interfaces/Tickable.h"
#include "core/singleton/ScopedSingletonIncludes.h"

/* this class implements a basic mouse-api
 * supported are mouse-clicks (left, right, mousewheel, ...) and scrolling
 *
 * mouse-clicks always are asscociated with an ingame element that has a position and a sphere with a certain radius around it
 * if the cursor is inside this sphere and a button is pressed, a user-defined function will be called
 *
 * scrolling can either be global (independent of where the cursor is) or local (same as a mouse-click)
 * in both cases a user-defined function will be called
 *
 * in short the class works by storing every element that can be clicked / scrolled on in a list
 * everytime a button is clicked or the mousewheel is turned, the list gets traversed and every element checked if it is clicked / scrolled on
 * checking happens by casting a ray from the camera through the mouse-cursor and testing if it intersects the sphere of the element
 *
 * to make it work, one has to add mouseapi in LINK_LIBRARIES in the file CMakeLists.txt of the level
 * see CMakeLists.txt in MouseAPIExample
 */

namespace orxonox
{
typedef uint ClickableElementID;
typedef uint ScrollableElementID;

class MouseAPI : public InputHandler, public Singleton<MouseAPI>,public Tickable
{
friend class Singleton<MouseAPI>;

private:

    // Elements that can be clicked on are stored as clickableElement
    struct clickableElement
    {
        ClickableElementID id;
        Vector3 position;
        float radius;
        std::list<MouseButtonCode::ByEnum> buttons;
        std::function<void(MouseButtonCode::ByEnum button)> onClickedFunction;
        clickableElement(ClickableElementID id,const Vector3& position,float radius,const std::list<MouseButtonCode::ByEnum>& buttons,std::function<void(MouseButtonCode::ByEnum button)> onClickedFunction):id(id),position(position),
            radius(radius), buttons(buttons), onClickedFunction(onClickedFunction){}
    };

    /* Elements that can be "scrolled on" are stored as scrollElement
     * there are 2 diffrent types, hence the overloaded constructor:
     *      1) the function is called whenever one scrolls, independet from position of element and cursor
     *      2) the function is only called when the cursor is placed over the element (identical to the clickableElement)
     */
    struct scrollElement
    {
        ScrollableElementID id;
        bool considerPosition;
        Vector3 position;
        float radius;
        std::function<void(int abs,int rel,const IntVector2& mousePos)> onScrolledFunction;
        // constructor for scrollElement type 1
        scrollElement(ScrollableElementID id,std::function<void(int abs,int rel,const IntVector2& mousePos)> onScrolledFunction):id(id),considerPosition(false),
            onScrolledFunction(onScrolledFunction){}
        // constructor fro scrollElement type 2
        scrollElement(ScrollableElementID id,const Vector3& position, float radius, std::function<void(int abs,int rel,const IntVector2& mousePos)> onScrolledFunction):id(id),considerPosition(true),
            position(position), radius(radius), onScrolledFunction(onScrolledFunction){}
    };

    // pointer to our class (required by singleton)
    static MouseAPI* singletonPtr_s;

    // lists with all our Elements that can be clicked / scrolled on
    std::list<clickableElement> clickEvents;
    std::list<scrollElement> scrollEvents;

    // pointer to the game-camera
    Ogre::Camera *cam ;

    // pointer to our input-state
    InputState* state;

    // true => MouseAPI has been activated, false => MouseAPI has not been activated
    bool active = false;

    Ogre::PanelOverlayElement* cursor;

public:

    MouseAPI();
    ~MouseAPI();

    virtual void tick(float dt) override;

    /* everytime a mousebutton is pressed, this function is called and checks if the cursor is over an element that can be clicked on
     * if yes, the function associated with this element will be called with the corresponding button as argument
     */
    virtual void buttonPressed (MouseButtonCode::ByEnum button) override;

    // not used
    virtual void buttonReleased(MouseButtonCode::ByEnum button)  override{}

    // not used
    virtual void buttonHeld    (MouseButtonCode::ByEnum button) override{}

    // not used
    virtual void mouseMoved    (IntVector2 abs, IntVector2 rel, IntVector2 clippingSize) override;

    /* everytime someone scrolls, this function is called and checks for all scrollElements, wheter a position is required and wheter the curser is over said position
     * if yes, the function associated with this element will be called
     * if there is an element without position-requirement and an element the cursor is over, both their functions will be called
     */
    virtual void mouseScrolled (int abs, int rel) override;

    /* add a clickableElement to the list
     * see mouseapiexample for an example-implementation
     * Arguments:
     *      position: the point that needs to be clicked
     *      radius: radius of the sphere around the position; if the cursor is inside this radius, the function will be executed (because clicking on a single point is pretty hard)
     *      buttons: the function will only be called, if one of these buttons is pressed
     *      onClickedFunction: the function that will be called
     */
    ClickableElementID addClickableElement(const Vector3& position,float radius,const std::list<MouseButtonCode::ByEnum>& buttons,std::function<void(MouseButtonCode::ByEnum button)>  onClickedFunction);

    /* add a scrollElement to the list
     * see mouseapiexample for an example-implementation
     * Arguments:
     *      position: the point the cursor needs to be over
     *      radius: radius of the sphere around the position; if the cursor is inside this radius, the function will be executed
     *      onScrolledFunction: the function that will be called
     */
    ScrollableElementID addScrollElement(const Vector3& position,float radius,std::function<void(int abs,int rel,const IntVector2& mousePos)> onScrolledFunction);

    /* add a scrollElement to the list
     * Arguments:
     *      onScrolledFunction: the function that will be called, no matter where the cursor is
     */
    ScrollableElementID addScrollElement(std::function<void(int abs,int rel,const IntVector2& mousePos)> onScrolledFunction);

    /* change the position of a clickableElement
     * Arguments:
     *      id: the ClickableElementID of the element
     *      position: the new position of the element
     * Return:
     *      true if successfull
     *      false if not successfull
     */
    bool changePositionOfClickableElement(ClickableElementID id,const Vector3& position);

    /* change the position of a scrollElement
     * Arguments:
     *      id: the ScrollableElementID of the element
     *      position: the new position of the element
     * Return:
     *      true if successfull
     *      false if not successfull
     */
    bool changePositionOfScrollableElement(ScrollableElementID id,const Vector3& position);

    /* change the radius of a clickableElement
     * Arguments:
     *      id: the ClickableElementID of the element
     *      radius: the new radius of the element
     * Return:
     *      true if successfull
     *      false if not successfull
     */
    bool changeRadiusOfClickableElement(ClickableElementID id,float radius);

    /* change the radius of a scrollElement
     * Arguments:
     *      id: the ScrollableElementID of the element
     *      radius: the new radius of the element
     * Return:
     *      true if successfull
     *      false if not successfull
     */
    bool changeRadiusOfScrollableElement(ScrollableElementID id,float radius);

    /* remove a clickableElement
     * Arguments:
     *      id: the ClickableElementID of the element
     * Return:
     *      true if successfull
     *      false if not successfull
     */
    bool deleteClickableElement(ClickableElementID id);

    /* remove a scrollElement
     * Arguments:
     *      id: the ScrollableElementID of the element
     * Return:
     *      true if successfull
     *      false if not successfull
     */
    bool deleteScrollableElement(ScrollableElementID id);

    /* get the current radius of a clickableElement
     * Arguments:
     *      id: the ClickableElementID of the element
     */
    float getRadiusClick(ClickableElementID id);

    /* get the current radius of a scrollElement
     * Arguments:
     *      id: the ScrollableElementID of the element
     */
    float getRadiusScroll(ScrollableElementID id);

    /* get the current relative Position of the cursor
     * returns a value between 0 and 1 for both x and y component
     * (0,0) top left corner, (1,1) bottom right corner
     */
    Vector2 getMousePosition();

    /* activate the MouseAPI
     * has to be called after the level has been created (i.e. inside the xml-port
     * can be called multiple times, since the function checks the status of MouseAPI and does nothing if it already is active
     */
    void activate();

    // returns true if MouseAPI is active, false otherwise
    static bool isActive(){return singletonPtr_s != nullptr && getInstance().active;}

    /* deactivate the MouseAPI
     * has to be called, when the level gets closed (i.e. inside the level-destructor)
     * the function does nothing if MouseAPI is not active
     */
    void deactivate();
};
}
#endif // MOUSEAPI_H