#ifndef TOOLSELECTOR_H
#define TOOLSELECTOR_H

#include "Tool.h"
#include "../model/MapModelElement.h"
#include "../MapView2D.h"
#include "../model/MapModel.h"


class ToolSelector : public Tool {

	Q_OBJECT

private:

	/** the currently focused MapElement (if any) */
	MapModelElement* focused = nullptr;

	/** whether the mouse-button is currently pressed */
	bool mouseIsDown = false;

public:

	virtual ~ToolSelector() {;}


	virtual void mousePressEvent(MapView2D* m, QMouseEvent* e) override {

		if (e->button() != Qt::MouseButton::LeftButton) {return;}

		mouseIsDown = true;

		const Scaler& s = m->getScaler();
		Point2 p2(s.xsm(e->x()), s.ysm(e->y()));
		//Point3 p3(s.xsm(e->x()), s.ysm(e->y()), 0);

		const float g = m->getScaler().sm(10);					// increase each BBox by 10 px (needed mainly for hor/ver lines)

		// get all elements with bounding-box matchings
		std::vector<MapModelElement*> possible;
		for (MapModelElement* el : m->getModel()->getSelectedLayerElements()) {
			if (!el->getMV2D()) {continue;}
			BBox2 bbox = el->getMV2D()->getBoundingBox();					// elements 3D bbox
			bbox.grow(Point2(g, g));							// grow a little (needed for straight lines)
			if (bbox.contains(p2)) {possible.push_back(el);}	// intersection?
		}

		// among those, find the best-matching one (smallest distance to an intersection)
		auto lambda = [&] (const MapModelElement* el1, const MapModelElement* el2) {return el1->getMV2D()->getMinDistanceXY(p2) < el2->getMV2D()->getMinDistanceXY(p2);};
		auto it = std::min_element(possible.begin(), possible.end(), lambda);
		MapModelElement* el = (it == possible.end()) ? (nullptr) : (*it);



		// focus changed? -> unfocus the old one (if any)
		if (setFocused(el)) {

			;

		} else {

			// focus kept. provide the currently focused element with events
			if (focused) {focused->getMV2D()->mousePressed(m, p2);}

		}

	}

	/** needed eg. when the focused element gets invalid (switching visible layers) */
	void layerChange(MapView2D* m) override {
		(void) m;
		setFocused(nullptr);
	}

private:

	/**
	 * @brief change the currently focused element. throws an event.
	 * @param el the to-be-focused element or null
	 * @return true if the focused element has changed. false otherwise
	 */
	bool setFocused(MapModelElement* el) {

		// whether the focus has changed or not
		const bool focusChanged = (focused != el);

		if (focusChanged) {

			// unfocus the old one (if any)
			if (focused) {focused->getMV2D()->unfocus();}

			// set the currently focused object (if any)
			focused = el;

			// focus the new one (if any)
			if (focused) {focused->getMV2D()->focus();}

			emit onMapElementSelected(el);

		}

		// done
		return focusChanged;

	}

	virtual void mouseMoveEvent(MapView2D* m, QMouseEvent* e) override {

		const Scaler& s = m->getScaler();
		Point2 p2(s.xsm(e->x()), s.ysm(e->y()));

		// mouse pressed?
		if (mouseIsDown) {

			// provide the focused element with the mouse event?
			if (focused) {focused->getMV2D()->mouseMove(m, p2); return;}

		}

	}

	virtual void mouseReleaseEvent(MapView2D* m, QMouseEvent* e) override {

		const Scaler& s = m->getScaler();
		Point2 p2(s.xsm(e->x()), s.ysm(e->y()));

		// provide the focused element with the mouse event?
		if (focused) {focused->getMV2D()->mouseReleased(m, p2);}

		mouseIsDown = false;

	}

	virtual void keyPressEvent(MapView2D* m, QKeyEvent* e) override {
		(void) m;

		if (focused) {

			// pass it to the element which may consume this event
			if (focused->getMV2D()->keyPressEvent(m, e)) {return;}

			// not consumed -> additional options

			// ESCAPE -> unfocus
			if (e->key() == Qt::Key_Escape) {setFocused(nullptr);}

			// DELETE -> delete
			if (e->key() == Qt::Key_Delete) {
				focused->deleteMe();
				setFocused(nullptr);
			}

		}

	}

signals:

	/** map element was selected */
	void onMapElementSelected(MapModelElement* el);

};

#endif // TOOLSELECTOR_H