#pragma once
#include <WiFi.h>           // For WiFi connectivity
#include <PubSubClient.h>   // For MQTT communication
#include <Wire.h>           // For I2C communication (LCD)
#include <LiquidCrystal_I2C.h> // For controlling I2C LCD
#include <DHT.h>            // For DHT temperature/humidity sensor
#include <time.h>           // For time synchronization
#include <esp_system.h>     // For ESP32 system functions (e.g., restart)

// Pin definitions
#define BUTTON_PIN 15       // Button pin (for restart)
#define LED1_PIN 19         // LED1 pin (alarm indicator)
#define LED2_PIN 18         // LED2 pin (status indicator)
#define DHTPIN 26           // DHT sensor pin
#define DHTTYPE DHT22       // DHT sensor type (DHT22)
#define BUZZER_PIN 4        // Buzzer pin (alarm sound)
#define GAS_PIN 34          // Gas sensor pin (analog input)
#define PIR_PIN 27          // PIR motion sensor pin

// Thresholds for alarms
const float TEMP_THRESHOLD_C = 20.0;  // Temperature threshold (°C)
const float TEMP_THRESHOLD_F = 68.0;  // Temperature threshold (°F)
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 (ms)

// WiFi & MQTT configuration
const char* ssid = "Wokwi-GUEST";     // WiFi SSID
const char* password = "";            // WiFi password
const char* mqtt_server = "broker.hivemq.com"; // MQTT broker address
const char* mqtt_topic_pub = "IOT/Warehouse/sensor"; // Sensor data topic
const char* mqtt_topic_time = "IOT/Warehouse/time";  // Time data topic
const char* mqtt_topic_sub = "IOT/Warehouse/control";// Control commands topic
const char* mqtt_topic_alarm = "IOT/Warehouse/alarm";// Alarm status topic
const char* mqtt_topic_lwt = "IOT/Warehouse/status"; // Last Will & Testament topic
const char* mqtt_topic_motion = "IOT/Warehouse/motion";// Motion status topic

// Object instances
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 instance (I2C addr 0x27, 20x4 display)

// Global state variables
bool led1State = false, led2State = false; // LED states
unsigned long lastMsg = 0, lastDisplayChange = 0, // Timestamps for events
             alarmStartTime = 0, lastBuzzerToggle = 0,
             lastSensorRead = 0;
const long sensorReadInterval = 2000; // Sensor read interval (ms)
const long publishInterval = 2000, displayInterval = 2000; // Publish/display intervals
int displayState = 0;                 // LCD display state (0:Welcome,1:Time,2:Sensors)
char msg[100];                        // MQTT message buffer
bool welcomeDisplayed = false, isAlarm = false, // Flags for welcome, alarm
     motionDetected = false, motionStateChanged = false; // Motion detection flags
unsigned long lastMotionTime = 0;     // Last motion detection timestamp
int buttonState, lastButtonState = HIGH; // Button debounce states
unsigned long lastDebounceTime = 0, debounceDelay = 50; // Button debounce timing
bool restartTriggered = false;        // Restart trigger flag
uint8_t dot[] = {0x0E, 0x0A, 0x0E, 0x00, 0x00, 0x00, 0x00, 0x00}; // Custom LCD character (°)

// Function prototypes
void blinkAndRestart();               // Blink LED then restart
void checkSensors();                  // Read sensors & check alarms
void setup_wifi();                    // Initialize WiFi
int readGasLevel();                   // Read gas sensor value
void handlePIR();                     // Handle PIR motion sensor
void displayWelcome();                // Show welcome message on LCD
void displayDateTime();               // Show date/time on LCD
void displaySensorData();             // Show sensor data on LCD
void callback(char* topic, byte* payload, unsigned int length); // MQTT callback
void controlBuzzer(bool enable);      // Control buzzer (alarm sound)
void handleButton();                  // Handle button press (restart)
void reconnect();                     // Reconnect to MQTT broker

// Initialize WiFi connection
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 { // Restart if WiFi fails
    Serial.println("\nWiFi failed! Restarting...");
    esp_restart();
  }
}

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

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

// Show welcome message on LCD (once)
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);
  }
}

// Display date/time on LCD and publish to MQTT
void displayDateTime() {
  struct tm timeinfo;
  if (getLocalTime(&timeinfo)) { // If time is synced
    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) { // Publish periodically
      lastMsg = millis();
      client.publish(mqtt_topic_time, dtbuf);
    }
  } else { // Time sync failed
    lcd.clear();
    lcd.print("Time sync lost!");
  }
}

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

// Display sensor data on LCD (show alarm info if triggered)
void displaySensorData() {
  float h = dht.readHumidity();
  float c = dht.readTemperature();
  float f = dht.readTemperature(true);
  int gas = readGasLevel();

  if (isAlarm) { // Show alarm info
    lcd.clear();
    lcd.print("ALARM!");
    lcd.setCursor(0, 1);
    
    bool tempAlarm = c > TEMP_THRESHOLD_C;
    bool humAlarm = h > HUMIDITY_THRESHOLD;
    bool gasAlarm = gas > GAS_THRESHOLD;
    
    if (gasAlarm) {
      lcd.print("Gas Over!");
      lcd.setCursor(0, 2);
      lcd.print(String(gas) + " > " + String(GAS_THRESHOLD));
    }
    else if (tempAlarm) {
    lcd.print("Temp Over!");
    lcd.setCursor(0, 2);
    lcd.print(String(c,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(h) + "% > " + String(HUMIDITY_THRESHOLD) + "%");
    }
    
    lcd.setCursor(0, 3);
    lcd.print("Motion: ");
    lcd.print(motionDetected ? "Detected" : "None");
  } else { // Show normal sensor data
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("Humidity: "); lcd.print(h, 1); lcd.print("%");
    
    lcd.setCursor(0, 1);
    lcd.print("Temp: "); lcd.print(c, 1); lcd.write(0); lcd.print("C/");
    lcd.print(f, 1); lcd.write(0); lcd.print("F");

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

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

// MQTT callback (handle received commands)
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 (variable tone for alarm)
void controlBuzzer(bool enable) {
  static int buzzerPattern = 0;
  unsigned long now = millis();

  if (enable && now - lastBuzzerToggle >= 500) { // Change tone every 500ms
    lastBuzzerToggle = now;
    buzzerPattern = (buzzerPattern + 1) % 4;
    switch (buzzerPattern) {
      case 0: tone(BUZZER_PIN, 1000); break; // 1kHz tone
      case 1: tone(BUZZER_PIN, 1500); break; // 1.5kHz tone
      case 2: tone(BUZZER_PIN, 2000); break; // 2kHz tone     
      case 3: tone(BUZZER_PIN, 3000); break; // 3kHz tone
      case 4: noTone(BUZZER_PIN); break;     // Stop
    }
  } else if (!enable) { // Stop buzzer
    noTone(BUZZER_PIN);
  }
}

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

// Handle button press (with debounce) to trigger restart
void handleButton() {
  int reading = digitalRead(BUTTON_PIN);

  if (reading != lastButtonState) { // Reset debounce timer on state change
    lastDebounceTime = millis();
  }

  // Check if button state is stable (debounced)
  if (millis() - lastDebounceTime > debounceDelay && reading != buttonState) {
    buttonState = reading;
    if (buttonState == LOW && !restartTriggered) { // Button pressed
      restartTriggered = true;
      Serial.println("Button pressed: Restart");
      blinkAndRestart();
    }
  }
  lastButtonState = reading;
}

// Reconnect to MQTT broker if disconnected
void reconnect() {
  if (client.connected()) return; // Do nothing if already connected

  Serial.println("Connecting to MQTT...");
  // Connect with LWT (Last Will & Testament)
  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 topic
    delay(500);
  } else { // Retry if connection fails
    Serial.print("MQTT failed (");
    Serial.print(client.state());
    Serial.println("), retry in 5s...");
    delay(5000);
  }
}

// Initial setup (run once)
void setup() {
  Serial.begin(115200);
  Serial.println("Starting...");
  // Initialize pins
  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);
  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(); // Start DHT sensor
  setup_wifi(); // Connect to WiFi
  
  // Configure MQTT
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);
  client.setKeepAlive(120);
  client.setSocketTimeout(5000);

  // Sync time with NTP server (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 { // Time sync failed
    Serial.println("Time sync failed!");
  }

  Serial.println("Entering loop");
}

// Main loop (run continuously)
void loop() {
  client.loop(); // Process MQTT messages
  if (!client.connected()) reconnect(); // Reconnect MQTT if needed
  handleButton(); // Check button press
  handlePIR(); // Check motion sensor

  unsigned long now = millis();

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

  // Handle alarm state (buzzer and LED)
  if (isAlarm) {
    controlBuzzer(true);
    if (now - lastBuzzerToggle >= 250) { // Blink LED1 every 250ms
      lastBuzzerToggle = now;
      digitalWrite(LED1_PIN, !digitalRead(LED1_PIN));
    }
  } else { // No alarm: turn off buzzer and LED1
    controlBuzzer(false);
    digitalWrite(LED1_PIN, LOW);
  }

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

    // Cycle display states 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;
      }
    }
  }
}