#include <Arduino.h>
#include "pins.h"

class Button {
	protected:
	unsigned int m_mask;
	unsigned int m_debounceTime;
	bool m_debouncing;
	unsigned long m_debounceEnd;
	bool m_pressed;

	void startDebounce() {
		m_debouncing = true;
		m_debounceEnd = millis() + m_debounceTime;
	}

	public:
	static unsigned int state;
	Button(unsigned int index, unsigned int debounceTime=4) {
		m_mask = 1 << index;
		m_debounceTime = debounceTime;
		m_debouncing = false;
		m_pressed = false;
	}

	void update(unsigned int pins) {
		if (m_debouncing) {
			if (millis() > m_debounceEnd) {
				/* done debouncing, continue */
				m_debouncing = false;
			}
			else {
				/* still debouncing, ignore changes */
				return;
			}
		}
		
		if ((m_mask & pins)) {
			/* pressed */
			if (m_pressed) {
				/* already marked */
			}
			else {
				/* update state */
				m_pressed = true;
				state = state | m_mask;
				startDebounce();
			}
		}
		else {
			/* released */
			if (!m_pressed) {
				/* already marked, ignore */
			}
			else {
				/* update state */
				m_pressed = false;
				state = state & ~m_mask;
				startDebounce();
			}
		}
	}
};
unsigned int Button::state = 0;

Button buttons[] = {
	Button(0),
	Button(1),
	Button(2),
	Button(3),
	Button(4),
	Button(5),
	Button(6),
	Button(7),
	Button(8),
	Button(9),
	Button(10),
	Button(11),
};

/* pin bitmask order: xxxx 1234 5678 9*0# */
unsigned int ReadPins() {
	byte col1 = 1 - digitalRead(COL_1);	
	byte col2 = 1 - digitalRead(COL_2);	
	byte col3 = 1 - digitalRead(COL_3);	

	byte row1 = 1 - digitalRead(ROW_1);
	byte row2 = 1 - digitalRead(ROW_2);
	byte row3 = 1 - digitalRead(ROW_3);
	byte row4 = 1 - digitalRead(ROW_4);

	#define BUILD_ROW(row, c1, c2, c3) \
		( ((row & c1) << 2) | ((row & c2) << 1) | (row & c3) )

	byte row1_buttons = BUILD_ROW(row1, col1, col2, col3);
	byte row2_buttons = BUILD_ROW(row2, col1, col2, col3);
	byte row3_buttons = BUILD_ROW(row3, col1, col2, col3);
	byte row4_buttons = BUILD_ROW(row4, col1, col2, col3);

	return 0 | 
		(row1_buttons << 9) | 
		(row2_buttons << 6) | 
		(row3_buttons << 3) | 
		(row4_buttons << 0);
}

void setup() {
	pinMode(COL_1, INPUT_PULLUP);
	pinMode(COL_2, INPUT_PULLUP);
	pinMode(COL_3, INPUT_PULLUP);

	pinMode(ROW_1, INPUT_PULLUP);
	pinMode(ROW_2, INPUT_PULLUP);
	pinMode(ROW_3, INPUT_PULLUP);
	pinMode(ROW_4, INPUT_PULLUP);

	Serial.begin(115200);
}


void PrintPin(unsigned int pins, int index, const char *msg) {
	if (pins & (1 << index)) {
		Serial.print(msg);
	}
}


void loop() {
	unsigned int pins = ReadPins();
	for (int i=0; i<12; i++) {
		buttons[i].update(pins);
	}

	if (Button::state != 0) {
		Serial.print("buttons: ");
		PrintPin(Button::state, 11, "1");
		PrintPin(Button::state, 10, "2");
		PrintPin(Button::state, 9, "3");
		PrintPin(Button::state, 8, "4");
		PrintPin(Button::state, 7, "5");
		PrintPin(Button::state, 6, "6");
		PrintPin(Button::state, 5, "7");
		PrintPin(Button::state, 4, "8");
		PrintPin(Button::state, 3, "9");
		PrintPin(Button::state, 2, "*");
		PrintPin(Button::state, 1, "0");
		PrintPin(Button::state, 0, "#");
		Serial.println();
		Button::state = 0;
	}
}