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

// OLED Display setup
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 32
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// 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'}
};

// KEYPAD PINS: 2,3,4,5,6,7,8,9
byte rowPins[ROWS] = {2, 3, 4, 5};    // Rows: pins 2-5
byte colPins[COLS] = {6, 7, 8, 9};    // Columns: pins 6-9
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Component pins
const int buzzerPin = A2;    // Buzzer
const int greenLED = 12;     // Green LED (shows PUMP STATUS: ON when pump running)
const int redLED = 11;       // Red LED (shows SYSTEM STATUS)
const int relayPin = 10;     // Relay (controls pump)
const int trigPin = A0;      // Ultrasonic trigger
const int echoPin = A1;      // Ultrasonic echo

// Password setup
const String password = "1234";
String inputPassword = "";

// Water tank dimensions
const float tankHeight = 6.0;
const float tankLength = 16.5;
const float tankWidth = 11.5;

// System variables
bool pumpRunning = false;
unsigned long pumpStartTime = 0;
unsigned long lastDisplayUpdate = 0;
bool showingMessage = false;
unsigned long messageTime = 0;

void setup() {
  Serial.begin(9600);
  Serial.println("=== WATER DISPENSER ===");
  
  // Initialize pins
  pinMode(buzzerPin, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(redLED, OUTPUT);
  pinMode(relayPin, OUTPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  
  // Initialize keypad pins (2-9)
  for (int i = 2; i <= 9; i++) {
    pinMode(i, INPUT_PULLUP);
  }
  
  // Initial states
  digitalWrite(relayPin, LOW);    // Relay OFF initially
  digitalWrite(greenLED, LOW);    // Green LED OFF (pump not running)
  digitalWrite(redLED, HIGH);     // Red LED ON (system ready)
  digitalWrite(buzzerPin, LOW);   // Buzzer OFF
  
  // Initialize OLED
  Wire.begin();
  delay(100);
  
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3D)) {
      Serial.println("OLED not found!");
    }
  }
  
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  
  // Show startup screen
  display.clearDisplay();
  display.setCursor(30, 10);
  display.println("WATER DISPENSER");
  display.setCursor(40, 20);
  display.println("SYSTEM");
  display.display();
  
  // Startup beep
  beep(1);
  delay(1000);
  
  // Show main interface
  showMessage("ENTER CODE: 1234", 1500);
  updateMainDisplay();
  
  Serial.println("System Ready!");
  Serial.println("Green LED: Shows PUMP STATUS");
  Serial.println("Red LED: Shows SYSTEM STATUS");
  Serial.println("Enter 1234# to start pump");
  Serial.println("Press ANY button to stop pump");
}

void loop() {
  // Check if message should be cleared
  if (showingMessage && (millis() - messageTime >= 2000)) {
    showingMessage = false;
    updateDisplay();
  }
  
  // Update display every 2 seconds when not showing message
  if (!showingMessage && millis() - lastDisplayUpdate >= 2000) {
    lastDisplayUpdate = millis();
    updateDisplay();
  }
  
  // Check keypad
  char key = keypad.getKey();
  if (key) {
    Serial.print("Key pressed: ");
    Serial.println(key);
    
    // If pump is running, ANY button stops it
    if (pumpRunning) {
      stopPump();
      showMessage("PUMP STOPPED", 1500);
      return;
    }
    
    // If pump not running, handle normal input
    handleKeypress(key);
  }
}

void updateDisplay() {
  if (showingMessage) return;
  
  float waterLevel = getWaterLevel();
  float waterVolume = calculateWaterVolume(waterLevel);
  
  if (pumpRunning) {
    displayPumpRunningScreen();
  } else {
    updateWaterDisplay(waterLevel, waterVolume);
  }
}

float getWaterLevel() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  long duration = pulseIn(echoPin, HIGH, 30000);
  if (duration == 0) return 0.0;
  
  float distance = duration * 0.034 / 2;
  float waterLevel = tankHeight - distance;
  
  waterLevel = constrain(waterLevel, 0, tankHeight);
  return waterLevel;
}

float calculateWaterVolume(float waterLevel) {
  return (tankLength * tankWidth * waterLevel) / 1000.0;
}

void handleKeypress(char key) {
  // Keypress beep
  digitalWrite(buzzerPin, HIGH);
  delay(30);
  digitalWrite(buzzerPin, LOW);
  
  if (key == '#') {
    // Submit password
    checkPassword();
  } 
  else if (key == '*') {
    // Clear input
    inputPassword = "";
    Serial.println("Input cleared");
    showMessage("INPUT CLEARED", 1000);
  }
  else if (key >= '0' && key <= '9') {
    // Add digit to password
    if (inputPassword.length() < 6) {
      inputPassword += key;
      Serial.print("Current input: ");
      Serial.println(inputPassword);
      
      // Show asterisks
      showPasswordEntry();
    }
  }
}

void showPasswordEntry() {
  display.clearDisplay();
  display.setCursor(20, 5);
  display.println("ENTER CODE:");
  display.setCursor(40, 15);
  for (int i = 0; i < inputPassword.length(); i++) {
    display.print("*");
  }
  display.setCursor(10, 25);
  display.println("#=START  *=CLEAR");
  display.display();
}

void checkPassword() {
  Serial.print("Checking password: ");
  Serial.println(inputPassword);
  
  if (inputPassword == password) {
    Serial.println("✓ PASSWORD CORRECT!");
    beep(2);
    startPump();
    inputPassword = "";
  } else {
    Serial.println("✗ WRONG PASSWORD!");
    beep(3);
    showMessage("WRONG CODE", 1500);
    inputPassword = "";
  }
}

void startPump() {
  // MODIFIED: Check water level - changed from 2.0cm to 1.0cm
  float waterLevel = getWaterLevel();
  if (waterLevel < 1.0) {  // Changed from <= 2.0 to < 1.0
    showMessage("LOW WATER!", 2000);
    beep(3);
    return;
  }
  
  Serial.println("Starting pump...");
  pumpRunning = true;
  pumpStartTime = millis();
  
  // Turn ON relay (pump starts)
  digitalWrite(relayPin, HIGH);
  
  // Update LEDs
  digitalWrite(greenLED, HIGH);  // Green ON (pump running)
  digitalWrite(redLED, LOW);     // Red OFF (system busy)
  
  // Show pump started message
  showMessage("PUMP STARTED", 1000);
  
  Serial.println("Pump running. Press ANY button to stop.");
}

void stopPump() {
  Serial.println("Stopping pump...");
  pumpRunning = false;
  
  // Turn OFF relay
  digitalWrite(relayPin, LOW);
  
  // Update LEDs
  digitalWrite(greenLED, LOW);   // Green OFF (pump stopped)
  digitalWrite(redLED, HIGH);    // Red ON (system ready)
  
  // Stop beep
  beep(1);
  
  Serial.println("Pump stopped.");
}

void displayPumpRunningScreen() {
  display.clearDisplay();
  
  // Draw water tank
  display.drawRect(5, 5, 40, 22, SSD1306_WHITE);
  
  // Animated water level (shows its working)
  int animation = (millis() / 500) % 20;
  int waterHeight = animation;
  if (waterHeight > 0) {
    display.fillRect(6, 26 - waterHeight, 38, waterHeight, SSD1306_WHITE);
  }
  
  // Pump status
  display.setCursor(50, 5);
  display.println("PUMP RUNNING");
  
  // Instructions
  display.setCursor(50, 15);
  display.println("PRESS ANY");
  display.setCursor(50, 25);
  display.println("KEY TO STOP");
  
  display.display();
}

void updateMainDisplay() {
  display.clearDisplay();
  display.setCursor(30, 0);
  display.println("WATER DISPENSER");
  display.setCursor(10, 10);
  display.println("STATUS: READY");
  display.setCursor(10, 20);
  display.println("CODE: 1234#");
  display.display();
}

void updateWaterDisplay(float waterLevel, float waterVolume) {
  display.clearDisplay();
  
  // Draw water tank
  display.drawRect(5, 5, 40, 22, SSD1306_WHITE);
  
  // Water level visualization
  int waterHeight = map(waterLevel, 0, tankHeight, 0, 20);
  if (waterHeight > 0) {
    display.fillRect(6, 26 - waterHeight, 38, waterHeight, SSD1306_WHITE);
  }
  
  // Water info
  display.setCursor(50, 5);
  display.print("WATER: ");
  display.print(waterLevel, 1);
  display.println("cm");
  
  display.setCursor(50, 15);
  display.print("VOL: ");
  display.print(waterVolume, 2);
  display.println("L");
  
  // MODIFIED: Status display - changed from < 5.0cm to < 1.0cm
  display.setCursor(50, 25);
  if (waterLevel < 1.0) {  // Changed from < 5.0 to < 1.0
    display.print("REFILL!");
  } else {
    display.print("READY");
  }
  
  display.display();
}

void showMessage(String message, int duration) {
  showingMessage = true;
  messageTime = millis();
  
  display.clearDisplay();
  display.setCursor(10, 12);
  display.println(message);
  display.display();
  
  delay(duration);
  showingMessage = false;
}

void beep(int times) {
  for (int i = 0; i < times; i++) {
    digitalWrite(buzzerPin, HIGH);
    delay(100);
    digitalWrite(buzzerPin, LOW);
    if (i < times - 1) delay(50);
  }
}