#ifndef UI_LIST_H
#define UI_LIST_H

#undef min
#undef max
#include <vector>
#include <string>

#include "UIElement.h"
#include "UIButton.h"

class UIListModel {

	std::vector<std::string> entries;

public:

	void add(const std::string& str) {
		entries.push_back(str);
	}

	void remove(const size_t idx) {
		entries.erase(entries.begin()+idx);
	}

	size_t size() const {
		return entries.size();
	}

	const std::string& get(const size_t idx) const {
		return entries[idx];
	}

};




class UIList : public UIElement, public UIButton::Listener {

public:

	class Listener {
	public:
		virtual void onSelected(UIList* lst, int idx) = 0;
	};

private:

	UIListModel model;
	int offset = 0;
	int selectedIndex = -1;

	UIButton btnUp;
	UIButton btnDown;

	static constexpr const int btnW = 32;

	Color cRect = Color::fromRGB(0,0,0);
	Color cNormalBG = Color::fromRGB(230,230,230);
	Color cSelectedBG = Color::fromRGB(190,190,255);
	Color cText = Color::fromRGB(0,0,0);

	Listener* listener = nullptr;

	static constexpr const char* TAG = "UIList";

public:

	/** ctor */
	UIList() : btnUp("<"), btnDown(">") {
		addChild(&btnUp);
		addChild(&btnDown);
		btnUp.setListener(this);
		btnDown.setListener(this);
	}

	void setListener(Listener* l) {
		this->listener = l;
	}

//	UIListModel& getModel() {
//		setNeedsRedraw();
//		return model;
//	}

//	const UIListModel& getModel() const {
//		return model;
//	}

	void add(const std::string& str) {
		model.add(str);
		btnUp.setVisible(needsScroll());
		btnDown.setVisible(needsScroll());
		setNeedsRedraw();
	}

	void remove(const size_t idx) {
		model.remove(idx);
		if (idx == selectedIndex) {
			selectedIndex = -1;
			if (listener) {listener->onSelected(this, selectedIndex);}
		} else if (idx < selectedIndex) {
			--selectedIndex;
			if (listener) {listener->onSelected(this, selectedIndex);}
		}
		if (offset > maxOffset()) {offset = maxOffset();}
		btnUp.setVisible(needsScroll());
		btnDown.setVisible(needsScroll());
		setNeedsRedraw();
	}

	size_t size() const {
		return model.size();
	}

	const std::string& get(const size_t idx) const {
		return model.get(idx);
	}

	int getSelectedIndex() const {
		return this->selectedIndex;
	}

	void reLayout() override {
		int h = rect.h / 2 - 1;
		btnUp.setRect(rect.x+rect.w-btnW-1,		rect.y+1,	btnW, h);
		btnDown.setRect(rect.x+rect.w-btnW-1,	rect.y+h+2,	btnW, h);
	}

	virtual void draw(UIPainter& p) override {

		debugMod(TAG, "draw()");
		debugMod4(TAG, "rect: %d %d %d %d", rect.x, rect.y, rect.w, rect.h);

		const uint8_t oy = (elementHeight() - fnt_f1.getHeight()) / 2;
		const uint16_t entryW = rect.w - (needsScroll() ? btnW : 0);

		// outline rectangle
		p.setFG(cNormalBG);
		p.fillRect(rect.x+1, rect.y+1, entryW, rect.h-2);
		p.setFG(cRect);
		p.drawRect(rect);

		// display as many elements as fit within the list's height
		for (unsigned int i = 0; i < elementsVisible(); ++i) {

			// determine position (y-coordinate)
			const uint16_t y = i * elementHeight();

			// determine element from model
			const int idx = i+offset;
			const bool selected = idx == selectedIndex;

			// draw background depending on selection
			//p.setFG( selected ? cSelectedBG : cNormalBG );
			//p.fillRect(UIRect(rect.x+1, rect.y+y+1, entryW-1, elementHeight()-1));
			if (selected) {
				p.setFG( cSelectedBG );
				p.fillRect(UIRect(rect.x+1, rect.y+y+1, entryW-1, elementHeight()-1));
			}

			// draw text
			p.setFG(cText);
			p.drawText(rect.x+3, rect.y + y + oy, model.get(idx).c_str());

		}



	}

	virtual void onTouchDown(uint16_t, uint16_t y) override {
		unsigned int idx = y / elementHeight() + offset;
		this->selectedIndex = (idx < numElements()) ? (idx) : (-1);
		debugMod1(TAG, "selected: %d", selectedIndex);
		setNeedsRedraw();
		if (listener) {listener->onSelected(this, selectedIndex);}
	}

	virtual void onTouch(uint16_t, uint16_t) override {

	}

	virtual void onTouchUp() override {

	}

	virtual void onClick(UIButton* btn) override {
		if (btn == &btnUp) {
			if (offset > 0) {--offset; setNeedsRedraw();}
		} else if (btn == &btnDown) {
			if (offset < maxOffset()) {++offset; setNeedsRedraw();}
		}
	}

private:

	unsigned int elementHeight() const {return 16;}
	unsigned int maxElementsVisible() const {return rect.h / elementHeight();}
	unsigned int elementsVisible() const {return std::min(maxElementsVisible(), numElements());}
	unsigned int numElements() const {return model.size();}
	unsigned int maxOffset() const {return numElements()-maxElementsVisible();}
	bool needsScroll() const {return numElements() > maxElementsVisible();}

};

#endif // UI_LIST_H