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

#define RST_PIN 27
#define SS_PIN 5 
#define OLED_SDA 21
#define OLED_SCL 22
#define OLED_RST -1
#define OLED_ADDR 0x3C
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define GRANTED_LED_PIN 16
#define DENIED_LED_PIN 2
#define BUZZER_PIN 25
#define ROWS 4
#define COLS 4
#define MAX_UIDS 4
#define interuptpin 4

// Keypad Setup
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {17, 13, 12, 14};
byte colPins[COLS] = {27, 26, 33, 32};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Oled Setup
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RST);

// Password Setup
String presetPassword = "11111";
String registerPassword = "12345";
String userInputPassword = "";
bool isPasswordCorrect = false;

int state = 1;
String accessgranted = "1";
String accessdenied = "2";
String UIDregister = "3";
char uidString[20];

void displayDoorLocked() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.println("DOOR LOCKED");
  display.display();
}

void setup() {
  Serial.begin(115200);
  Wire.begin(OLED_SDA, OLED_SCL);
  display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR);
  displayDoorLocked();
  pinMode(19, INPUT_PULLUP);
  pinMode(18, INPUT_PULLUP);
  pinMode(GRANTED_LED_PIN, OUTPUT);
  pinMode(DENIED_LED_PIN, OUTPUT);
  digitalWrite(GRANTED_LED_PIN, LOW);
  digitalWrite(DENIED_LED_PIN, LOW);
  pinMode(BUZZER_PIN, OUTPUT);
}

void clearUserInputPassword() {
  userInputPassword = "";
}

void addUserInputPassword(char key) {
  if (userInputPassword.length() < presetPassword.length()) {
    userInputPassword += key;
  }
}

void displayEnterPassword() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.println("Enter");
  display.setCursor(0, 20);
  display.println("Password:");
  display.display();
}

void displayScanCard() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.println("Scan Card!");
  display.display();
}

void displayUserInputPassword() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("Enter");
  display.setCursor(0, 20);
  display.println("Password:");
  display.setCursor(0, 40);
  for (int i = 0; i < userInputPassword.length(); i++) {
    display.print('*');
  }
  display.display();
}

void displayCurrentPassword() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("Enter");
  display.setCursor(0, 20);
  display.println("Password:");
  display.setCursor(0, 40);
  display.println(userInputPassword);
  display.display();
  delay(500);
}

void displayAccessGranted() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.println("Access Granted!");
  display.display();
  digitalWrite(GRANTED_LED_PIN, HIGH);
  digitalWrite(DENIED_LED_PIN, LOW);
  tone(BUZZER_PIN, 1000,2000);
  delay(1000);
  digitalWrite(GRANTED_LED_PIN, LOW);
  display.clearDisplay();
  display.display();
}

void displayAccessDenied() {
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.println("Access Denied!");
  display.display();
  digitalWrite(GRANTED_LED_PIN, LOW);
  digitalWrite(DENIED_LED_PIN, HIGH);
  delay(1000);
  digitalWrite(DENIED_LED_PIN, LOW);
  display.clearDisplay();
  display.display();
}


void getUserInput(){
  displayEnterPassword();
  while (true){
    char key = keypad.getKey();
    if (key != NO_KEY) {
      switch (key) {
        case '#':
          return;
        case '*':
          clearUserInputPassword();
          break;
        case 'A':
          displayCurrentPassword();
          break;
        default:
          addUserInputPassword(key);
          break;
      }
    }
    displayUserInputPassword();
  }
}

int checkPassword() {
  if (userInputPassword == presetPassword) {
    return 1;
  }
  else if (userInputPassword == registerPassword){
    return 2;
  } 
  else {
    return 3;
  }
}

void registerUID(){

  if (digitalRead(18)==1){
    display.clearDisplay();
    display.setCursor(0, 0);
    display.setTextSize(2);
    display.setTextColor(SSD1306_WHITE);
    display.println("UID is registered!");
    display.display();
    digitalWrite(GRANTED_LED_PIN, LOW);
    digitalWrite(DENIED_LED_PIN, HIGH);
    delay(1000);
    digitalWrite(DENIED_LED_PIN,LOW);
  }
  else{
    display.clearDisplay();
    display.setCursor(0, 0);
    display.setTextSize(2);
    display.setTextColor(SSD1306_WHITE);
    display.println("Succesfully registered!");
    display.display();
    digitalWrite(GRANTED_LED_PIN, HIGH);
    digitalWrite(DENIED_LED_PIN, LOW);
    delay(2000);
    digitalWrite(GRANTED_LED_PIN, LOW);
  }
}

void loop() {
  switch(state){
    case 0:{
      displayScanCard();
      if (digitalRead(19)==1) {
          display.clearDisplay();
          display.setCursor(0, 0);
          display.setTextSize(2);
          display.setTextColor(SSD1306_WHITE);
          display.println("Valid UID!");
          display.display();
          delay(2000);
          state=1;
          displayAccessGranted();
          displayDoorLocked();
          return;
        }
        else {
          state=1;
          display.clearDisplay();
          display.setCursor(0, 0);
          display.setTextSize(2);
          display.setTextColor(SSD1306_WHITE);
          display.println("Invalid UID!");
          display.display();
          delay(2000);
          displayAccessDenied();
          displayDoorLocked();
          return;
        }
      break; 
    }

    case 1:{
      displayDoorLocked();
      clearUserInputPassword();
      char key = keypad.getKey();
      if (key != NO_KEY) {
        getUserInput();
        int A = checkPassword();
        if (A==1){
          state=0;
          display.clearDisplay();
          display.setCursor(0, 0);
          display.setTextSize(2);
          display.setTextColor(SSD1306_WHITE);
          display.println("Valid Password!");
          display.display();
          delay(2000);
          return;
        }

        if (A==2){
          state=2;
          display.clearDisplay();
          display.setCursor(0, 0);
          display.setTextSize(2);
          display.setTextColor(SSD1306_WHITE);
          display.println("Pairing.....");
          display.display();
          delay(2000);
          return;
        }

        if (A==3){
          state=1;
          display.clearDisplay();
          display.setCursor(0, 0);
          display.setTextSize(2);
          display.setTextColor(SSD1306_WHITE);
          display.println("Invalid Password!");
          display.display();
          delay(2000);
          return;
        }
      }
      break;
    }

    case 2:{
      if (digitalRead(19)==1) {
        registerUID();
        state = 1;
        delay(2000);
        displayDoorLocked();
      }

      char key = keypad.getKey();
      if (key == 'B') {
        state = 1;
        delay(2000);
        displayDoorLocked();
      }
      break;
    }
  }
}