#pragma once
// Include necessary libraries for hardware and communication
#include <WiFi.h>           // For WiFi connectivity
#include <PubSubClient.h>   // For MQTT communication
#include <Wire.h>           // For I2C communication (LCD)
#include <LiquidCrystal_I2C.h> // For LCD display
#include <DHT.h>            // For DHT temperature/humidity sensor
#include <time.h>           // For time synchronization
#include <esp_system.h>     // For ESP32 system functions (restart etc.)

// Pin definitions - mapping hardware components to ESP32 pins
#define BUTTON_PIN 15       // Restart button pin
#define LED1_PIN 19         // Alarm indicator LED
#define LED2_PIN 18         // Status indicator LED
#define DHTPIN 26           // DHT sensor data pin
#define DHTTYPE DHT22       // DHT sensor type (DHT22)
#define BUZZER_PIN 4        // Buzzer for audio alerts
#define GAS_PIN 34          // Gas sensor analog input pin
#define PIR_PIN 27          // PIR motion sensor digital input pin

// Threshold values for alarm triggers
const float TEMP_THRESHOLD_C = 20.0;    // Temperature threshold in Celsius
const float TEMP_THRESHOLD_F = 68.0;    // Temperature threshold in Fahrenheit
const float HUMIDITY_THRESHOLD = 70.0;  // Humidity threshold (%)
const int GAS_THRESHOLD = 900;          // Gas level threshold
const unsigned long MOTION_DELAY = 5000;// Motion detection timeout (5 seconds)

// WiFi and MQTT configuration parameters
const char* ssid = "Wokwi-GUEST";       // WiFi network name
const char* password = "";              // WiFi password
const char* mqtt_server = "broker.hivemq.com"; // MQTT broker address
const char* mqtt_topic_pub = "IOT/Warehouse/sensor"; // Topic for sensor data
const char* mqtt_topic_time = "IOT/Warehouse/time";   // Topic for time data
const char* mqtt_topic_sub = "IOT/Warehouse/control"; // Topic for control commands
const char* mqtt_topic_alarm = "IOT/Warehouse/alarm"; // Topic for alarm status
const char* mqtt_topic_lwt = "IOT/Warehouse/status";  // Topic for device status (LWT)
const char* mqtt_topic_motion = "IOT/Warehouse/motion"; // Topic for motion events

// Create hardware/communication objects
WiFiClient espClient;                   // WiFi client instance
PubSubClient client(espClient);         // MQTT client instance
DHT dht(DHTPIN, DHTTYPE);               // DHT sensor instance
LiquidCrystal_I2C lcd(0x27, 20, 4);     // LCD display instance (I2C addr 0x27, 20x4)

// Global variables to store sensor data
float currentHumidity = 0.0;  
float currentTempC = 0.0; 
float currentTempF = 0.0;  
int currentGasLevel = 0;  

// State variables
bool led1State = false, led2State = false;
unsigned long lastMsg = 0, lastDisplayChange = 0,  // Timers for periodic actions
             alarmStartTime = 0, lastBuzzerToggle = 0,
             lastSensorRead = 0;
const long sensorReadInterval = 2000;   // Read sensors every 2 seconds
const long publishInterval = 2000, displayInterval = 2000; // Publish/display intervals
int displayState = 0;                   // Tracks current LCD display mode
char msg[100];                          // Buffer for MQTT messages
bool welcomeDisplayed = false, isAlarm = false,  // System state flags
     motionDetected = false, motionStateChanged = false;
unsigned long lastMotionTime = 0;       // Last time motion was detected
int buttonState, lastButtonState = HIGH;// Button debounce variables
unsigned long lastDebounceTime = 0, debounceDelay = 50;
bool restartTriggered = false;
uint8_t dot[] = {0x0E, 0x0A, 0x0E, 0x00, 0x00, 0x00, 0x00, 0x00}; // Custom LCD character (degree symbol)

// Function prototypes - declare functions before they're used
void blinkAndRestart();
void checkSensors();
void setup_wifi();
int readGasLevel();
void handlePIR();
void displayWelcome();
void displayDateTime();
void displaySensorData();
void callback(char* topic, byte* payload, unsigned int length);
void controlBuzzer(bool enable);
void handleButton();
void reconnect();

// WiFi connection setup
void setup_wifi() {
  Serial.println("Connecting to WiFi...");
  WiFi.begin(ssid, password);
  
  int wifiRetry = 0;
  while (WiFi.status() != WL_CONNECTED && wifiRetry < 10) { // Retry 10 times
    Serial.print(".");
    delay(500);
    wifiRetry++;
  }
  if (WiFi.status() == WL_CONNECTED) Serial.println("\nWiFi connected!");
  else {
    Serial.println("\nWiFi failed! Restarting...");
    esp_restart();  // Reboot if WiFi fails
  }
}

// Read gas sensor value (analog input)
int readGasLevel() { return analogRead(GAS_PIN); }

// Handle PIR motion sensor detection
void handlePIR() {
  bool currentMotion = digitalRead(PIR_PIN) == HIGH;  // Read current motion state
  
  if (currentMotion) {  // If motion detected
    lastMotionTime = millis();
    if (!motionDetected) {  // New motion detected
      motionDetected = true;
      motionStateChanged = true;
      Serial.println("Motion detected!");
      client.publish(mqtt_topic_motion, "detected");  // Publish motion event
    }
  } else if (motionDetected && millis() - lastMotionTime > MOTION_DELAY) {  // Motion stopped
    motionDetected = false;
    motionStateChanged = true;
    Serial.println("Motion stopped");
    client.publish(mqtt_topic_motion, "stopped");  // Publish motion stopped
  }
}

// Display welcome message on LCD
void displayWelcome() {
  if (!welcomeDisplayed) {
    lcd.clear();
    lcd.print("Hi,Welcome!");
    lcd.setCursor(0, 1);
    lcd.print("Warehouse1,");
    lcd.setCursor(0, 2);
    lcd.print("By Group3!");
    welcomeDisplayed = true;
    delay(2000);  // Show for 2 seconds
  }
}

// Display current date and time on LCD
void displayDateTime() {
  struct tm timeinfo;
  if (getLocalTime(&timeinfo)) {  // If time is synchronized
    char dtbuf[21];
    strftime(dtbuf, sizeof(dtbuf), "%Y-%m-%d %H:%M:%S", &timeinfo);  // Format time
    
    lcd.clear();
    lcd.print("DateTime:");
    lcd.setCursor(0, 1);
    lcd.print(dtbuf);
      
    if (millis() - lastMsg >= publishInterval) {  // Periodically publish time
      lastMsg = millis();
      client.publish(mqtt_topic_time, dtbuf);
    }
  } else {
    lcd.clear();
    lcd.print("Time sync lost!");  // Error if time not available
  }
}

// Read sensors and check for alarm conditions
void checkSensors() {
  unsigned long start = millis();
  // Read sensor data
  currentHumidity = dht.readHumidity();
  currentTempC = dht.readTemperature();
  currentTempF = dht.readTemperature(true);  // true = Fahrenheit
  currentGasLevel = readGasLevel();
  
  if (millis() - start > 1000) {  // Timeout if sensor read takes too long
    Serial.println("Sensor read timeout");
    return;
  }
  
  // Check for DHT sensor errors
  if (isnan(currentHumidity) || isnan(currentTempC) || isnan(currentTempF)) {
    Serial.println(F("DHT read failed!"));
    return;
  }
  
  // Print sensor data to serial monitor
  Serial.printf("Hum: %.1f%%  Temp: %.1f°C / %.1f°F  Gas: %d  Motion: %s\n",
               currentHumidity, currentTempC, currentTempF, currentGasLevel, motionDetected ? "Yes" : "No");
  
  // Check if any alarm thresholds are exceeded
  bool tempAlarm = currentTempC > TEMP_THRESHOLD_C; 
  bool humAlarm = currentHumidity > HUMIDITY_THRESHOLD;  
  bool gasAlarm = currentGasLevel > GAS_THRESHOLD; 
  
  bool newAlarm = tempAlarm || humAlarm || gasAlarm;
  
  if (newAlarm) {  // If alarm condition detected
    if (!isAlarm) {  // New alarm
      isAlarm = true;
      alarmStartTime = millis();
      client.publish(mqtt_topic_alarm, "Alarm");  // Publish alarm status
      const char* alarmType = "";
      float alarmValue = 0;
      const char* alarmUnit = "";
      
      // Determine which alarm was triggered
      if (gasAlarm) {
        alarmType = "Gas";
        alarmValue = currentGasLevel;
      }
      else if (tempAlarm) {
        alarmType = "Temp";
        alarmValue = currentTempC;  
        alarmUnit = "°C";
      }
      else if (humAlarm) {
        alarmType = "Humidity";
        alarmValue = currentHumidity;  
        alarmUnit = "%";
      }
      Serial.printf("Alarm triggered: %s %.1f%s\n", alarmType, alarmValue, alarmUnit);
    }
  } else {  // Alarm condition cleared
    if (isAlarm) {
      isAlarm = false;
      client.publish(mqtt_topic_alarm, "Normal");  // Publish normal status
      Serial.println("Alarm cleared");
    }
  }
}

// Display sensor data on LCD (or alarm message if triggered)
void displaySensorData() {
  if (isAlarm) {  // Show alarm message
    lcd.clear();
    lcd.print("ALARM!");
    lcd.setCursor(0, 1);
    
    // Identify which alarm is active
    bool tempAlarm = currentTempC > TEMP_THRESHOLD_C;
    bool humAlarm = currentHumidity > HUMIDITY_THRESHOLD; 
    bool gasAlarm = currentGasLevel > GAS_THRESHOLD;  
    
    if (gasAlarm) {
      lcd.print("Gas Over!");
      lcd.setCursor(0, 2);
      lcd.print(String(currentGasLevel) + " > " + String(GAS_THRESHOLD));  
    }
    else if (tempAlarm) {
      lcd.print("Temp Over!");
      lcd.setCursor(0, 2);
      lcd.print(String(currentTempC,1));lcd.write(0);lcd.print("C>");  
      lcd.print(String(TEMP_THRESHOLD_C, 1));lcd.write(0);lcd.print("C");
    }
    else if (humAlarm) {
      lcd.print("Humidity Over!");
      lcd.setCursor(0, 2);
      lcd.print(String(currentHumidity) + "% > " + String(HUMIDITY_THRESHOLD) + "%");  
    }
    
    lcd.setCursor(0, 3);
    lcd.print("Motion: ");
    lcd.print(motionDetected ? "Detected" : "None");
  } else {  // Normal operation - show sensor data
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Humidity: "); lcd.print(currentHumidity, 1); lcd.print("%"); 
    
    lcd.setCursor(0, 1);
    lcd.print("Temp: "); lcd.print(currentTempC, 1); lcd.write(0); lcd.print("C/"); 
    lcd.print(currentTempF, 1); lcd.write(0); lcd.print("F"); 

    lcd.setCursor(0, 2);
    lcd.print("Gas Level: "); lcd.print(currentGasLevel); 

    lcd.setCursor(0, 3);
    lcd.print("Motion: "); lcd.print(motionDetected ? "Detected" : "None");
    
    // Periodically publish sensor data via MQTT
    if (millis() - lastMsg >= publishInterval) {
      lastMsg = millis();
      snprintf(msg, sizeof(msg),
               "{\"temp_c\": %.1f, \"temp_f\": %.1f, \"hum\": %.1f, \"gas\": %d, \"motion\": %s}",
               currentTempC, currentTempF, currentHumidity, currentGasLevel, motionDetected ? "true" : "false");
      client.publish(mqtt_topic_pub, msg);
    }
  }
}

// MQTT callback - handles incoming messages
void callback(char* topic, byte* payload, unsigned int length) {
  payload[length] = 0;  // Null-terminate payload
  String command = String((char*)payload);
  command.toUpperCase();
  Serial.print("MQTT command: "); Serial.println(command);
  
  if (command == "RESTART") {  // Handle restart command
    Serial.println("Received restart command");
    blinkAndRestart();
  }
}

// Control buzzer for alarm sounds
void controlBuzzer(bool enable) {
  static int buzzerPattern = 0;
  unsigned long now = millis();

  if (enable && now - lastBuzzerToggle >= 500) {  // Play alarm pattern
    lastBuzzerToggle = now;
    buzzerPattern = (buzzerPattern + 1) % 4;
    switch (buzzerPattern) {
      case 0: tone(BUZZER_PIN, 1000); break;  // Different tones
      case 1: tone(BUZZER_PIN, 1500); break;
      case 2: tone(BUZZER_PIN, 2000); break;
      case 3: noTone(BUZZER_PIN); break;
    }
  } else if (!enable) {  // Turn off buzzer
    noTone(BUZZER_PIN);
  }
}

// Blink LED and restart device
void blinkAndRestart() {
  lcd.clear();
  lcd.print("Restarting...");
  
  // Blink LED before restart
  for (int i = 0; i < 3; i++) {
    digitalWrite(LED2_PIN, LOW);
    delay(300);
    digitalWrite(LED2_PIN, HIGH);
    delay(300);
  }
  
  client.publish(mqtt_topic_lwt, "restarting", true);  // Publish status
  delay(100);
  esp_restart();  // Restart ESP32
}

// Handle button press (with debouncing)
void handleButton() {
  int reading = digitalRead(BUTTON_PIN);

  if (reading != lastButtonState) {  // Button state changed
    lastDebounceTime = millis();
  }

  // Stabilize button reading (debounce)
  if (millis() - lastDebounceTime > debounceDelay && reading != buttonState) {
    buttonState = reading;
    if (buttonState == LOW && !restartTriggered) {  // Button pressed
      restartTriggered = true;
      Serial.println("Button pressed: Restart");
      blinkAndRestart();  // Trigger restart
    }
  }
  lastButtonState = reading;
}

// Reconnect to MQTT broker if disconnected
void reconnect() {
  if (client.connected()) return;  // Already connected

  Serial.println("Connecting to MQTT...");
  // Connect with LWT (Last Will and Testament) message
  if (client.connect("ESP32ClientDevice", mqtt_topic_lwt, 0, true, "offline")) {
    Serial.println("MQTT connected!");
    client.publish(mqtt_topic_lwt, "online", true);  // Publish online status
    client.subscribe(mqtt_topic_sub);  // Subscribe to control commands
    delay(500);
  } else {
    Serial.print("MQTT failed (");
    Serial.print(client.state());
    Serial.println("), retry in 5s...");
    delay(5000);  // Wait before retrying
  }
}

// Initial setup - runs once at startup
void setup() {
  Serial.begin(115200);  // Initialize serial communication
  Serial.println("Starting...");
  // Set pin modes
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(LED1_PIN, OUTPUT);
  pinMode(LED2_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(GAS_PIN, INPUT);
  pinMode(PIR_PIN, INPUT);
  // Initialize pin states
  digitalWrite(LED1_PIN, LOW);
  digitalWrite(LED2_PIN, HIGH);
  digitalWrite(BUZZER_PIN, LOW);
  
  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.createChar(0, dot);  // Create custom degree symbol
  lcd.clear();
  lcd.print("Initializing...");
  delay(1000);

  dht.begin();  // Initialize DHT sensor
  setup_wifi();  // Connect to WiFi
  
  // Configure MQTT
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
  client.setKeepAlive(120);
  client.setSocketTimeout(5000);

  // Configure time synchronization (UTC+8)
  configTime(8 * 3600, 0, "pool.ntp.org");
  struct tm timeinfo;
  int timeRetry = 0;
  while (!getLocalTime(&timeinfo) && timeRetry < 5) {  // Retry time sync
    Serial.println("Waiting for time...");
    delay(1000);
    timeRetry++;
  }
  if (timeRetry < 5) {  // Time sync successful
    Serial.println("Time synced");
    displayWelcome();
    lastDisplayChange = millis();
    lastMsg = 0;
  } else {
    Serial.println("Time sync failed!");
  }

  Serial.println("Entering loop");
}

// Main loop - runs continuously
void loop() {
  client.loop();  // Maintain MQTT connection
  if (!client.connected()) reconnect();  // Reconnect MQTT if needed
  handleButton();  // Check button press
  handlePIR();  // Check motion sensor

  unsigned long now = millis();

  // Read sensors at specified interval
  if (now - lastSensorRead >= sensorReadInterval) {
    lastSensorRead = now;
    checkSensors();
  }

  // Handle alarm indicators
  if (isAlarm) {
    controlBuzzer(true);  // Activate buzzer
    if (now - lastBuzzerToggle >= 250) {  // Blink alarm LED
      lastBuzzerToggle = now;
      digitalWrite(LED1_PIN, !digitalRead(LED1_PIN));
    }
  } else {
    controlBuzzer(false);  // Deactivate buzzer
    digitalWrite(LED1_PIN, LOW);
  }

  // Manage LCD display
  if (isAlarm) {  // Show alarm screen during alarm
    if (now - lastDisplayChange >= 1000) {
      lastDisplayChange = now;
      displaySensorData();
    }
  } else {  // Cycle through normal displays
    if (motionStateChanged && !restartTriggered) {  // Update on motion change
      motionStateChanged = false;
      if (displayState == 1) displayDateTime();
      else if (displayState == 2) displaySensorData();
    }

    // Cycle display modes at interval
    if (now - lastDisplayChange >= displayInterval && !restartTriggered) {
      lastDisplayChange = now;
      displayState = (displayState + 1) % 3;
      switch (displayState) {
        case 0: displayWelcome(); break;
        case 1: displayDateTime(); break;
        case 2: displaySensorData(); break;
      }
    }
  }
}