#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
#include <DFRobotDFPlayerMini.h>
#include <HardwareSerial.h>

// LCD Setup
LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C 20x4 display

// DFPlayer setup
HardwareSerial mp3Serial(1);
#define MP3_RX 16
#define MP3_TX 17
DFRobotDFPlayerMini mp3;

// Keypad setup
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};
byte rowPins[ROWS] = {32, 33, 25, 26};
byte colPins[COLS] = {27, 14, 12, 13};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Switches and buttons
#define SWITCH1 15
#define SWITCH2 2
#define SWITCH3 4
#define SWITCH4 5
#define GREEN_BTN 18
#define RED_BTN 19

// State Variables
bool switchesSet[4];
bool switchesLocked = false;
bool codeLocked = false;
bool countdownStarted = false;
bool waitForReset = false;

String disarmCode = "";
String enteredCode = "";
int timerSeconds = 0;

unsigned long startTime = 0;
unsigned long currentTime = 0;
unsigned long lockoutUntil = 0;

void setup() {
  Serial.begin(115200);
  Serial.println("=== SYSTEM BOOT ===");

  lcd.init();
  lcd.backlight();

  mp3Serial.begin(9600, SERIAL_8N1, MP3_RX, MP3_TX);
  if (mp3.begin(mp3Serial)) {
    mp3.volume(25);
    Serial.println("DFPlayer ready");
  } else {
    Serial.println("ERROR: DFPlayer not detected");
  }

  pinMode(SWITCH1, INPUT_PULLUP);
  pinMode(SWITCH2, INPUT_PULLUP);
  pinMode(SWITCH3, INPUT_PULLUP);
  pinMode(SWITCH4, INPUT_PULLUP);
  pinMode(GREEN_BTN, INPUT_PULLDOWN);
  pinMode(RED_BTN, INPUT_PULLDOWN);

  promptForTimer();
}

void loop() {
  // Always listen for reset
  if (waitForReset && digitalRead(RED_BTN) == HIGH) {
    delay(200);
    Serial.println("RESET TRIGGERED");
    waitForReset = false;
    resetSystem();
    return;
  }

  // STEP 1: Set switches
  if (!switchesLocked) {
    Serial.println("STATE: Waiting for switch config...");
    if (digitalRead(GREEN_BTN) == HIGH) {
      delay(200);
      Serial.println("INPUT: Green button pressed to confirm switches");
      switchesSet[0] = digitalRead(SWITCH1);
      switchesSet[1] = digitalRead(SWITCH2);
      switchesSet[2] = digitalRead(SWITCH3);
      switchesSet[3] = digitalRead(SWITCH4);
      switchesLocked = true;
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Switches Saved");
      delay(1000);
      promptForCode();
    }
  }

  // STEP 2: Code entry
  else if (!codeLocked) {
    char key = keypad.getKey();
    if (key) {
      Serial.print("KEYPAD: ");
      Serial.println(key);
      if (key == '#') {
        codeLocked = true;
        Serial.println("CODE LOCKED IN");
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("Code Saved");
        delay(1000);
        lcd.clear();
        lcd.print("Press GREEN to");
        lcd.setCursor(0, 1);
        lcd.print("start countdown");
      } else if (disarmCode.length() < 6) {
        disarmCode += key;
        lcd.setCursor(0, 1);
        lcd.print("Code: ");
        for (int i = 0; i < disarmCode.length(); i++) lcd.print("*");
      }
    }
  }

  // STEP 3: Start countdown
  else if (!countdownStarted) {
    Serial.println("STATE: Waiting to start timer...");
    if (digitalRead(GREEN_BTN) == HIGH) {
      delay(200);
      Serial.println("EVENT: Timer started");
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Timer Starts Now");
      delay(1000);
      startTime = millis();
      countdownStarted = true;
    }
  }

  // STEP 4: Timer logic
  else if (countdownStarted) {
    currentTime = millis();
    int elapsed = (currentTime - startTime) / 1000;
    int remaining = timerSeconds - elapsed;

    if (remaining <= 0) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("BOOM!");
      Serial.println("EVENT: BOOM!");
      mp3.play(3);
      countdownStarted = false;
      lcd.setCursor(0, 2);
      lcd.print("Press RED to reset");
      waitForReset = true;
      return;
    }

    lcd.setCursor(0, 0);
    lcd.print("Time left: ");
    lcd.print(remaining);
    lcd.print("s   ");

    bool match = switchesMatch();
    lcd.setCursor(0, 1);
    lcd.print("Switches: ");
    lcd.print(match ? "OK   " : "WRONG");

    if (match) {
      lcd.setCursor(0, 2);
      lcd.print("Enter code: ");
      for (int i = 0; i < enteredCode.length(); i++) lcd.print("*");

      lcd.setCursor(0, 3);
      lcd.print("Press # to check");

      if (millis() >= lockoutUntil) {
        char key = keypad.getKey();
        if (key) {
          Serial.print("KEYPAD ENTRY: ");
          Serial.println(key);

          if (key == '#') {
            if (enteredCode == disarmCode) {
              lcd.clear();
              lcd.setCursor(0, 0);
              lcd.print("Bomb Disarmed!");
              Serial.println("EVENT: Bomb disarmed");
              mp3.play(4);
              countdownStarted = false;
              lcd.setCursor(0, 2);
              lcd.print("Press RED to reset");
              waitForReset = true;
            } else {
              lcd.clear();
              lcd.setCursor(0, 0);
              lcd.print("Wrong Code!");
              Serial.println("ERROR: Wrong Code Entered");
              mp3.play(5);
              lockoutUntil = millis() + 5000;
              enteredCode = "";
              lcd.setCursor(0, 2);
              lcd.print("LOCKED 5s...");
            }
          } else if (enteredCode.length() < 6) {
            enteredCode += key;
          }
        }
      } else {
        enteredCode = "";  // Clear buffer during lockout
      }
    } else {
      enteredCode = "";  // Reset if switches are wrong
    }
  }
}

// Prompt for timer
void promptForTimer() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Enter Timer (sec)");
  lcd.setCursor(0, 1);
  lcd.print("Then press #");

  Serial.println("STATE: Waiting for timer...");
  String temp = "";
  while (true) {
    char key = keypad.getKey();
    if (key) {
      Serial.print("KEYPAD TIMER: ");
      Serial.println(key);
      if (key == '#') break;
      if (key >= '0' && key <= '9') {
        temp += key;
        lcd.setCursor(0, 2);
        lcd.print("Time: ");
        lcd.print(temp);
      }
    }
  }

  timerSeconds = temp.toInt();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Timer Set: ");
  lcd.print(timerSeconds);
  lcd.print("s");
  Serial.print("TIMER SET TO: ");
  Serial.println(timerSeconds);
  delay(1000);
  lcd.clear();
  lcd.print("Set switches");
  lcd.setCursor(0, 1);
  lcd.print("Then press GREEN");
}

// Prompt for code
void promptForCode() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Enter Code:");
  Serial.println("STATE: Entering disarm code...");
}

// Compare switch positions
bool switchesMatch() {
  return switchesSet[0] == digitalRead(SWITCH1) &&
         switchesSet[1] == digitalRead(SWITCH2) &&
         switchesSet[2] == digitalRead(SWITCH3) &&
         switchesSet[3] == digitalRead(SWITCH4);
}

// Reset system to initial state
void resetSystem() {
  Serial.println("== SYSTEM RESET ==");
  disarmCode = "";
  enteredCode = "";
  switchesLocked = false;
  codeLocked = false;
  countdownStarted = false;
  lockoutUntil = 0;
  waitForReset = false;
  lcd.clear();
  promptForTimer();
}