/*
 * IR Remote Password Lock System
 * ================================
 * - Default password: 1234
 * - User can change password (stored in EEPROM)
 * - Green LED = Unlocked, Red LED = Locked
 * - LCD displays status and input
 *
 * BUTTONS:
 *   0-9    : Enter password digits
 *   PLAY   : Confirm / Submit password
 *   POWER  : Lock the system
 *   MENU   : Enter change-password mode (when unlocked)
 *   C      : Clear current input
 *   BACK   : Cancel operation
 */
#include <IRremote.hpp>
#include <LiquidCrystal.h>
#include <EEPROM.h>
// ───── Pin Definitions ─────
#define IR_RECEIVE_PIN  2
#define GREEN_LED_PIN   10   // Unlocked indicator
#define RED_LED_PIN     11   // Locked indicator
// ───── EEPROM Addresses ─────
#define EEPROM_FLAG_ADDR   0    // Flag to check if password was saved before
#define EEPROM_LEN_ADDR    1    // Password length
#define EEPROM_PASS_ADDR   2    // Password digits start here
#define EEPROM_FLAG_VALUE  42   // Magic number to detect first boot
// ───── Constants ─────
#define MAX_PASS_LEN  8
#define DEFAULT_PASS  "1234"
// ───── System States ─────
enum State {
  STATE_LOCKED,
  STATE_UNLOCKED,
  STATE_CHANGE_PASS_OLD,    // Ask for old password before changing
  STATE_CHANGE_PASS_NEW,    // Enter new password
  STATE_CHANGE_PASS_CONFIRM // Confirm new password
};
// ───── Global Variables ─────
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);
State currentState = STATE_LOCKED;
char storedPassword[MAX_PASS_LEN + 1];  // Stored password
char inputBuffer[MAX_PASS_LEN + 1];     // Current input
char newPassBuffer[MAX_PASS_LEN + 1];   // New password buffer (for change)
int inputIndex = 0;
int failedAttempts = 0;
unsigned long lockoutTime = 0;
bool lockedOut = false;
// ───── Function Prototypes ─────
void loadPasswordFromEEPROM();
void savePasswordToEEPROM(const char* password);
void setLEDs(bool unlocked);
void displayLocked();
void displayUnlocked();
void displayInput();
void processDigit(char digit);
void submitPassword();
void clearInput();
void handleLockedState(int command);
void handleUnlockedState(int command);
void handleChangePassOld(int command);
void handleChangePassNew(int command);
void handleChangePassConfirm(int command);
int getDigitFromCommand(int command);
// =====================================================
//  SETUP
// =====================================================
void setup() {
  Serial.begin(9600);
  // Initialize pins
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  // Initialize IR receiver
  IrReceiver.begin(IR_RECEIVE_PIN);
  // Initialize LCD
  lcd.begin(16, 2);
  // Load password from EEPROM (or set default)
  loadPasswordFromEEPROM();
  // Start in locked state
  currentState = STATE_LOCKED;
  setLEDs(false);
  displayLocked();
  Serial.println("IR Password Lock Ready");
  Serial.print("Current password: ");
  Serial.println(storedPassword);
}
// =====================================================
//  MAIN LOOP
// =====================================================
void loop() {
  // Handle lockout after too many failed attempts
  if (lockedOut) {
    if (millis() - lockoutTime >= 30000) {  // 30 second lockout
      lockedOut = false;
      failedAttempts = 0;
      lcd.clear();
      lcd.print("Lockout expired");
      delay(1000);
      displayLocked();
    } else {
      // Blink red LED during lockout
      digitalWrite(RED_LED_PIN, (millis() / 250) % 2);
      return;
    }
  }
  // Check for IR signal
  if (IrReceiver.decode()) {
    int command = IrReceiver.decodedIRData.command;
    // Route to appropriate state handler
    switch (currentState) {
      case STATE_LOCKED:
        handleLockedState(command);
        break;
      case STATE_UNLOCKED:
        handleUnlockedState(command);
        break;
      case STATE_CHANGE_PASS_OLD:
        handleChangePassOld(command);
        break;
      case STATE_CHANGE_PASS_NEW:
        handleChangePassNew(command);
        break;
      case STATE_CHANGE_PASS_CONFIRM:
        handleChangePassConfirm(command);
        break;
    }
    IrReceiver.resume();
  }
}
// =====================================================
//  EEPROM FUNCTIONS
// =====================================================
void loadPasswordFromEEPROM() {
  // Check if a password has been saved before
  if (EEPROM.read(EEPROM_FLAG_ADDR) == EEPROM_FLAG_VALUE) {
    int len = EEPROM.read(EEPROM_LEN_ADDR);
    if (len > 0 && len <= MAX_PASS_LEN) {
      for (int i = 0; i < len; i++) {
        storedPassword[i] = EEPROM.read(EEPROM_PASS_ADDR + i);
      }
      storedPassword[len] = '\0';
      Serial.println("Password loaded from EEPROM");
      return;
    }
  }
  // No valid password found — use default
  strcpy(storedPassword, DEFAULT_PASS);
  savePasswordToEEPROM(storedPassword);
  Serial.println("Default password set and saved to EEPROM");
}
void savePasswordToEEPROM(const char* password) {
  int len = strlen(password);
  EEPROM.update(EEPROM_FLAG_ADDR, EEPROM_FLAG_VALUE);
  EEPROM.update(EEPROM_LEN_ADDR, len);
  for (int i = 0; i < len; i++) {
    EEPROM.update(EEPROM_PASS_ADDR + i, password[i]);
  }
  Serial.println("Password saved to EEPROM");
}
// =====================================================
//  LED CONTROL
// =====================================================
void setLEDs(bool unlocked) {
  if (unlocked) {
    digitalWrite(GREEN_LED_PIN, HIGH);
    digitalWrite(RED_LED_PIN, LOW);
  } else {
    digitalWrite(GREEN_LED_PIN, LOW);
    digitalWrite(RED_LED_PIN, HIGH);
  }
}
// =====================================================
//  LCD DISPLAY FUNCTIONS
// =====================================================
void displayLocked() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("== LOCKED ==");
  lcd.setCursor(0, 1);
  lcd.print("Enter Password:");
  clearInput();
}
void displayUnlocked() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("** UNLOCKED **");
  lcd.setCursor(0, 1);
  lcd.print("MENU=ChgPw PWR=Lk");
}
void displayInput() {
  // Show asterisks for entered digits on the second line
  lcd.setCursor(0, 1);
  lcd.print("                ");  // Clear line
  lcd.setCursor(0, 1);
  for (int i = 0; i < inputIndex; i++) {
    lcd.print('*');
  }
  // Show cursor blink effect
  if (inputIndex < MAX_PASS_LEN) {
    lcd.print('_');
  }
}
void displayChangePrompt(const char* line1) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(line1);
  clearInput();
  displayInput();
}
// =====================================================
//  INPUT HANDLING
// =====================================================
void clearInput() {
  memset(inputBuffer, 0, sizeof(inputBuffer));
  inputIndex = 0;
}
void processDigit(char digit) {
  if (inputIndex < MAX_PASS_LEN) {
    inputBuffer[inputIndex] = digit;
    inputIndex++;
    inputBuffer[inputIndex] = '\0';
    displayInput();
    // Brief feedback beep could go here
  }
}
// =====================================================
//  STATE: LOCKED
// =====================================================
void handleLockedState(int command) {
  int digit = getDigitFromCommand(command);
  if (digit >= 0) {
    // Number pressed — add to input
    processDigit('0' + digit);
  }
  else if (command == 168) {  // PLAY = Submit
    if (inputIndex == 0) return;
    if (strcmp(inputBuffer, storedPassword) == 0) {
      // Correct password!
      currentState = STATE_UNLOCKED;
      failedAttempts = 0;
      setLEDs(true);
      lcd.clear();
      lcd.setCursor(2, 0);
      lcd.print("ACCESS");
      lcd.setCursor(2, 1);
      lcd.print("GRANTED!");
      delay(1500);
      displayUnlocked();
    } else {
      // Wrong password
      failedAttempts++;
      setLEDs(false);
      lcd.clear();
      lcd.setCursor(2, 0);
      lcd.print("WRONG!");
      lcd.setCursor(0, 1);
      lcd.print("Attempts: ");
      lcd.print(failedAttempts);
      delay(1500);
      // Lockout after 3 failed attempts
      if (failedAttempts >= 3) {
        lockedOut = true;
        lockoutTime = millis();
        lcd.clear();
        lcd.setCursor(0, 0);
        lcd.print("!! LOCKOUT !!");
        lcd.setCursor(0, 1);
        lcd.print("Wait 30 seconds");
        // Blink both LEDs rapidly for warning
        for (int i = 0; i < 10; i++) {
          digitalWrite(RED_LED_PIN, HIGH);
          delay(100);
          digitalWrite(RED_LED_PIN, LOW);
          delay(100);
        }
        digitalWrite(RED_LED_PIN, HIGH);
      } else {
        displayLocked();
      }
    }
  }
  else if (command == 176) {  // C = Clear
    clearInput();
    displayLocked();
  }
}
// =====================================================
//  STATE: UNLOCKED
// =====================================================
void handleUnlockedState(int command) {
  if (command == 162) {  // POWER = Lock
    currentState = STATE_LOCKED;
    setLEDs(false);
    lcd.clear();
    lcd.setCursor(2, 0);
    lcd.print("LOCKING...");
    delay(1000);
    displayLocked();
  }
  else if (command == 226) {  // MENU = Change password
    currentState = STATE_CHANGE_PASS_OLD;
    displayChangePrompt("Old Password:");
  }
}
// =====================================================
//  STATE: CHANGE PASSWORD — Enter Old Password
// =====================================================
void handleChangePassOld(int command) {
  int digit = getDigitFromCommand(command);
  if (digit >= 0) {
    processDigit('0' + digit);
  }
  else if (command == 168) {  // PLAY = Submit
    if (strcmp(inputBuffer, storedPassword) == 0) {
      // Old password correct → ask for new password
      currentState = STATE_CHANGE_PASS_NEW;
      displayChangePrompt("New Password:");
    } else {
      lcd.clear();
      lcd.print("Wrong old pass!");
      delay(1500);
      currentState = STATE_UNLOCKED;
      displayUnlocked();
    }
  }
  else if (command == 194 || command == 176) {  // BACK or C = Cancel
    currentState = STATE_UNLOCKED;
    displayUnlocked();
  }
}
// =====================================================
//  STATE: CHANGE PASSWORD — Enter New Password
// =====================================================
void handleChangePassNew(int command) {
  int digit = getDigitFromCommand(command);
  if (digit >= 0) {
    processDigit('0' + digit);
  }
  else if (command == 168) {  // PLAY = Submit
    if (inputIndex < 1) {
      lcd.clear();
      lcd.print("Min 1 digit!");
      delay(1000);
      displayChangePrompt("New Password:");
      return;
    }
    // Store new password temporarily
    strcpy(newPassBuffer, inputBuffer);
    currentState = STATE_CHANGE_PASS_CONFIRM;
    displayChangePrompt("Confirm New Pw:");
  }
  else if (command == 194 || command == 176) {  // BACK or C = Cancel
    currentState = STATE_UNLOCKED;
    displayUnlocked();
  }
}
// =====================================================
//  STATE: CHANGE PASSWORD — Confirm New Password
// =====================================================
void handleChangePassConfirm(int command) {
  int digit = getDigitFromCommand(command);
  if (digit >= 0) {
    processDigit('0' + digit);
  }
  else if (command == 168) {  // PLAY = Submit
    if (strcmp(inputBuffer, newPassBuffer) == 0) {
      // Passwords match — save!
      strcpy(storedPassword, newPassBuffer);
      savePasswordToEEPROM(storedPassword);
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Password Changed");
      lcd.setCursor(0, 1);
      lcd.print("Saved to EEPROM!");
      // Success LED blink
      for (int i = 0; i < 5; i++) {
        digitalWrite(GREEN_LED_PIN, LOW);
        delay(150);
        digitalWrite(GREEN_LED_PIN, HIGH);
        delay(150);
      }
      delay(1000);
      currentState = STATE_UNLOCKED;
      setLEDs(true);
      displayUnlocked();
    } else {
      lcd.clear();
      lcd.print("Mismatch! Retry");
      delay(1500);
      currentState = STATE_CHANGE_PASS_NEW;
      displayChangePrompt("New Password:");
    }
  }
  else if (command == 194 || command == 176) {  // BACK or C = Cancel
    currentState = STATE_UNLOCKED;
    displayUnlocked();
  }
}
// =====================================================
//  IR COMMAND → DIGIT MAPPING
// =====================================================
int getDigitFromCommand(int command) {
  switch (command) {
    case 104: return 0;
    case 48:  return 1;
    case 24:  return 2;
    case 122: return 3;
    case 16:  return 4;
    case 56:  return 5;
    case 90:  return 6;
    case 66:  return 7;
    case 74:  return 8;
    case 82:  return 9;
    default:  return -1;
  }
}