#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_FeatherOLED.h>


#define DEBUG 0

#define BUTTON_HOLD_TIME 500
#define BUTTON_PRESS_TIME 20

#define UP_BUTTON 31
#define ENTER_BUTTON 30
#define DOWN_BUTTON 27

Adafruit_FeatherOLED oled = Adafruit_FeatherOLED();

static const unsigned char PROGMEM arrow[] =
{ B10000000,
  B11000000,
  B11100000,
  B11000000,
  B10000000};
//oled.drawBitmap(0, 1, arrow, 8, 5, 1);


enum buttonStates {
	OPEN,
	CLOSED,
	CHECK_PRESSED,
	PRESSED,
	HELD,
	NUM_BUTTONSTATES
};

enum screenStates {
	PRESSURE,
	SETTINGS,
	NUM_SCREENSTATES
};

enum buttonStates upButton = OPEN;
enum buttonStates enterButton = OPEN;
enum buttonStates downButton = OPEN;

int pressureSetPoint = 69;

void setup()
{
  Serial.begin(115200);

  oled.init();

  pinMode(UP_BUTTON, INPUT_PULLUP);
  pinMode(ENTER_BUTTON, INPUT); // Has external pullup
  pinMode(DOWN_BUTTON, INPUT_PULLUP);
}

void loop() {
	pollButtons();
	runUI();
}

void runUI() {
	static enum screenStates screenState = PRESSURE;

	oled.clearDisplay();

	switch (screenState) {
		case PRESSURE:
			if (enterButton == HELD) screenState = SETTINGS;

			if (upButton == PRESSED) {
				pressureSetPoint++;
			} else if (downButton == PRESSED) {
				pressureSetPoint--;
			} else if (upButton == HELD) {
				pressureSetPoint++;
				delay(75);
			} else if (downButton == HELD) {
				pressureSetPoint--;
				delay(75);
			}


			oled.setCursor(0,0);
			oled.setTextSize(3);
			oled.print(pressureSetPoint);

			oled.display();

			break;
	}
}

void pollButtons() {
	static unsigned long upButtonTime = 0;
	static unsigned long enterButtonTime = 0;
	static unsigned long downButtonTime = 0;

	processButtonState(UP_BUTTON, upButton, upButtonTime);
	processButtonState(ENTER_BUTTON, enterButton, enterButtonTime);
	processButtonState(DOWN_BUTTON, downButton, downButtonTime);

	if (DEBUG) {
		if (upButton == PRESSED) {
			Serial.println("up button pressed");
		} else if (upButton == HELD) {
			Serial.println("up button held");
		}
			
		if (enterButton == PRESSED) {
			Serial.println("enter button pressed");
		} else if (enterButton == HELD) {
			Serial.println("enter button held");
		}
			
		if (downButton == PRESSED) {
			Serial.println("down button pressed");
		} else if (downButton == HELD) {
			Serial.println("down button held");
		}
	}
}

void processButtonState(int buttonPin, buttonStates &buttonState, unsigned long &buttonTime) {
	bool pinState = !digitalRead(buttonPin);

	switch(buttonState) {
		case OPEN:
			if (pinState) {
				buttonState = CLOSED;
				buttonTime = millis();
			}
			break;
		case CLOSED:
			if (millis() >= buttonTime + BUTTON_HOLD_TIME) {
				buttonState = HELD;
			}
			if (pinState) {
				;
			} else {
				buttonState = CHECK_PRESSED;
			}
			break;
		case CHECK_PRESSED:
			if (millis() >= buttonTime + BUTTON_PRESS_TIME) {
				buttonState = PRESSED;
			} else {
				buttonState = OPEN;
			}
			break;
		case PRESSED:
			buttonState = OPEN;
			break;
		case HELD:
			if (!pinState) {
				buttonState = OPEN;
			}
			break;
		default:
			break;
	}
}