#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <EEPROM.h>
LiquidCrystal_I2C lcd(0x27, 16, 2); // set the LCD address to 0x27 for a 16 chars and 2 line display

int startPauseButton = 4;
int stopButton = 5;
int relay = 6;
int levelOne = 8;
int levelTwo = 9;
int levelThree = 10;
int levelFour = 11;

int amountInput = 0;
int passInput = 0;

bool prevstartPauseButton = 0;
bool prevstopButton = 0;

double prevMillis = 0;
int rate = 1000;

bool startFlow = 0;
bool threshholdState = 1;
bool startPauseButtonState = 0;
bool stopButtonState = 0;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  lcd.init();
  lcd.backlight();
  pinMode(startPauseButton, INPUT_PULLUP);
  pinMode(stopButton, INPUT_PULLUP);
  pinMode(levelOne, INPUT_PULLUP);
  pinMode(levelTwo, INPUT_PULLUP);
  pinMode(levelThree, INPUT_PULLUP);
  pinMode(levelFour, INPUT_PULLUP);
  if(digitalRead(levelOne) == LOW){
    rate = 1000;
  }
  else if(digitalRead(levelTwo) == LOW){
    rate = 500;
  }
  else if(digitalRead(levelThree) == LOW){
    rate = 333;
  }
  else if(digitalRead(levelFour) == LOW){
    rate = 250;
  }
  pinMode(relay, OUTPUT);
  digitalWrite(relay, LOW);
  lcdPrint("Welcome to", 2, "Gasoline Vendo", 1);
  delay(3000);
  EEPROM.get(0, passInput);
  attachInterrupt(digitalPinToInterrupt(2), readImpulse , FALLING);
  attachInterrupt(digitalPinToInterrupt(3), readImpulse , FALLING);
  if(passInput > 0){
    amountInput = passInput;
  }
  Serial.println(digitalRead(levelOne));
  Serial.println(digitalRead(levelTwo));
  Serial.println(digitalRead(levelThree));
  Serial.println(digitalRead(levelFour));
}

void loop() {
  // put your main code here, to run repeatedly:
  if (threshholdState) {
    if (amountInput >= 5) {
      lcdPrint("Inserted Amount", 0, "P" + String(amountInput), 6);
    }
    else if(amountInput >= 1 && amountInput < 5){
      lcdPrint("Insert More", 2, "P" + String(amountInput), 6);
    }
    else {
      lcdPrint("Insert Coin/Bill", 0, "5/10/20/50/100", 1);
    }
    threshholdState = 0;
    EEPROM.put(0, amountInput);
  }
  if (amountInput >= 5) {
    startPauseButtonPressed();
    while (startFlow) {
      dispense();
    }
  }
  stopButtonClear();
}

void dispense() {
  while (amountInput > 0 && startFlow) {
    while (millis() > (prevMillis + rate)) {
      amountInput -= 1;
      EEPROM.put(0, amountInput);
      startPauseButtonPressed();
      stopButtonPressed();
      prevMillis = millis();
    }
    startPauseButtonPressed();
    stopButtonPressed();
  }
  if (amountInput <= 0) {
    threshholdState = 1;
    amountInput = 0;
    digitalWrite(relay, LOW);
    startFlow = 0;
  }
}
void lcdPrint(String row1, int col1, String row2, int col2) {
  lcd.clear();
  lcd.setCursor(col1, 0);
  lcd.print(row1);
  lcd.setCursor(col2, 1);
  lcd.print(row2);
}
void startPauseButtonPressed() {
  while (digitalRead(startPauseButton) == LOW) {
    Serial.println("LOW");
    if (startPauseButtonState == 0) {
      startFlow = !startFlow;
      Serial.print("startFlow: ");
      Serial.println(startFlow);
      startPauseButtonState = 1;
    }
    if (startFlow) {
      digitalWrite(relay, HIGH);
      lcdPrint("Dispensing Fuel", 0, "Please Wait", 2);
    }
    else {
      digitalWrite(relay, LOW);
      lcdPrint("Dispensing Pause", 0, "", 0);
    }
    delay(20);
  }
  startPauseButtonState = 0;
}
void stopButtonPressed() {
  while (digitalRead(stopButton) == LOW) {
    if (stopButtonState == 0) {
      startFlow = false;
      amountInput = 0;
      digitalWrite(relay, LOW);
      lcdPrint("Dispensing stop", 0, "", 0);
      EEPROM.put(0, amountInput);
      delay(5000);
      threshholdState = 1;
      stopButtonState = 1;
    }
    delay(20);
  }
  stopButtonState = 0;
}

void stopButtonClear(){
  while (digitalRead(stopButton) == LOW) {
    if (stopButtonState == 0) {
      startFlow = false;
      amountInput = 0;
      digitalWrite(relay, LOW);
      EEPROM.put(0, amountInput);
      threshholdState = 1;
      stopButtonState = 1;
    }
    delay(20);
  }
  stopButtonState = 0;
}
void readImpulse(){
  amountInput++; 
  threshholdState = 1;
  delay(10);
}