#include <WiFi.h>
#include <PubSubClient.h>
#include "DHT.h"
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <OneWire.h>
#include <DallasTemperature.h>

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

// --- DHT22 Sensor ---
#define DHTPIN 14
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

// --- TMP36GZ Analog Temp Sensor ---
#define ANALOG_TEMP_PIN 34

// --- DS18B20 Setup ---
#define ONE_WIRE_BUS 4
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature ds18b20(&oneWire);

// --- LED & Buzzer Pins ---
const int RED_LED = 23;
const int GREEN_LED = 18;
const int FAN_LED = 5;
const int MQTT_LED = 19;
const int BUZZER = 27;
#define SCREEN_SDA 21
#define SCREEN_SCL 22

// --- Wi-Fi Credentials ---
const char* ssid = "Afrihost Fibre DJ";
const char* password = "0824435505";

// --- MQTT Settings ---
const char* mqttServer = "mqtt.eclipseprojects.io";
const int mqttPort = 1883;
const char* mqttClientID = "ESP32-SensorClient12";
const char* publishTopic = "esp/sensors12";
const char* subscribeTopic = "esp/threshold12";
const char* fanStatusTopic = "esp/fan12/status";

// --- MQTT Client ---
WiFiClient espClient;
PubSubClient client(espClient);

// --- Display and Serial Timing ---
unsigned long lastScreenSwitch = 0;
unsigned long screenInterval = 2500;
int displayIndex = 0;
unsigned long lastSerialPrint = 0;
unsigned long serialInterval = 3000;

// --- Control Variables ---
float thresholdTemp = 1000.0;
bool fanStatus = false;
bool buzzerActive = false;
unsigned long buzzerStartTime = 0;
const unsigned long buzzerDuration = 500;

void connectWiFi() {
  WiFi.begin(ssid, password);
  Serial.println("Connecting to WiFi...");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\nWiFi Connected");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* message, unsigned int length) {
  String incoming = "";
  for (int i = 0; i < length; i++) {
    incoming += (char)message[i];
  }

  Serial.print("Message received [");
  Serial.print(topic);
  Serial.print("]: ");
  Serial.println(incoming);

  if (String(topic) == subscribeTopic) {
    thresholdTemp = incoming.toFloat();
    Serial.print("Updated Threshold: ");
    Serial.println(thresholdTemp);

    digitalWrite(MQTT_LED, HIGH);
    delay(50);
    digitalWrite(MQTT_LED, LOW);
  }

  if (String(topic) == fanStatusTopic) {
    bool isOn = (incoming == "ON");
    if (isOn && !fanStatus) {
      Serial.println("📢 Fan turned ON → Beep + LED ON");
      buzzerActive = true;
      buzzerStartTime = millis();
      digitalWrite(BUZZER, HIGH);
      digitalWrite(FAN_LED, HIGH);
    } else if (!isOn && fanStatus) {
      Serial.println("Fan turned OFF → LED OFF");
      digitalWrite(FAN_LED, LOW);
    }
    fanStatus = isOn;
  }
}

void connectMQTT() {
  client.setServer(mqttServer, mqttPort);
  client.setCallback(callback);
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    if (client.connect(mqttClientID)) {
      Serial.println("connected");
      client.subscribe(subscribeTopic);
      client.subscribe(fanStatusTopic); // subscribe to fan ON/OFF status
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      delay(1000);
    }
  }
}

void setup() {
  Serial.begin(115200);
  dht.begin();
  ds18b20.begin();

  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  pinMode(FAN_LED, OUTPUT);
  pinMode(MQTT_LED, OUTPUT);
  pinMode(BUZZER, OUTPUT);

  digitalWrite(RED_LED, HIGH);
  digitalWrite(GREEN_LED, LOW);
  digitalWrite(FAN_LED, LOW);
  digitalWrite(MQTT_LED, LOW);
  digitalWrite(BUZZER, LOW);

  Wire.begin(SCREEN_SDA, SCREEN_SCL);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("Starting up...");
  display.display();
  delay(2500);

  connectWiFi();
  digitalWrite(GREEN_LED, HIGH);
  connectMQTT();

  display.clearDisplay();
  display.setCursor(0, 0);
  display.println("WiFi OK");
  display.setCursor(0, 16);
  display.println(WiFi.localIP());
  display.display();
  delay(2500);

  lastScreenSwitch = millis();
  lastSerialPrint = millis();
}

void loop() {
  client.loop();

  // --- Read sensors ---
  float tempDHT = dht.readTemperature();
  float humDHT = dht.readHumidity();
  int analogValue = analogRead(ANALOG_TEMP_PIN);
  float voltage = analogValue * (3.3 / 4095.0);
  float analogTemp = (voltage - 0.5) * 100.0;

  ds18b20.requestTemperatures();
  float dsTemps[3];
  for (int i = 0; i < 3; i++) {
    dsTemps[i] = ds18b20.getTempCByIndex(i);
  }

  // --- Handle buzzer timeout ---
  if (buzzerActive && millis() - buzzerStartTime >= buzzerDuration) {
    buzzerActive = false;
    digitalWrite(BUZZER, LOW);
  }

  // --- Serial logging ---
  if (millis() - lastSerialPrint >= serialInterval) {
    lastSerialPrint = millis();
    Serial.println("=== Sensor Readings ===");
    Serial.print("DHT Temp: "); Serial.print(tempDHT); Serial.println(" C");
    Serial.print("Humidity: "); Serial.print(humDHT); Serial.println(" %");
    Serial.print("TMP36 Temp: "); Serial.print(analogTemp); Serial.println(" C");
    for (int i = 0; i < 3; i++) {
      Serial.print("DS18B20 #"); Serial.print(i + 1); Serial.print(": ");
      Serial.print(dsTemps[i]); Serial.println(" C");
    }
    Serial.println(fanStatus ? "FAN ON" : "FAN OFF");
  }

  // --- Publish sensor JSON ---
  String payload = "{";
  payload += "\"temperature\":" + String(tempDHT, 1);
  payload += ",\"humidity\":" + String(humDHT, 1);
  payload += ",\"analogTemp\":" + String(analogTemp, 1);
  for (int i = 0; i < 3; i++) {
    payload += ",\"ds18b20_" + String(i + 1) + "\":" + String(dsTemps[i], 1);
  }
  payload += ",\"fan\":\"" + String(fanStatus ? "on" : "off") + "\"}";
  client.publish(publishTopic, payload.c_str());

  // --- Rotate OLED screen info ---
  if (millis() - lastScreenSwitch >= screenInterval) {
    lastScreenSwitch = millis();
    display.clearDisplay();
    display.setTextSize(1);
    display.setCursor(0, 0);
    switch (displayIndex) {
      case 0:
        display.println("Room Temp:");
        display.setCursor(0, 16);
        isnan(tempDHT) ? display.println("Error") : display.printf("%.1f C", tempDHT);
        break;
      case 1:
        display.println("Room Humidity:");
        display.setCursor(0, 16);
        isnan(humDHT) ? display.println("Error") : display.printf("%.1f %%", humDHT);
        break;
      case 2:
        display.println("TMP36 Temp:");
        display.setCursor(0, 16);
        display.printf("%.1f C", analogTemp);
        break;
      case 3:
        display.println("Intake Temp:");
        display.setCursor(0, 16);
        display.printf("%.1f C", dsTemps[0]);
        break;
      case 4:
        display.println("Exhaust Temp:");
        display.setCursor(0, 16);
        display.printf("%.1f C", dsTemps[1]);
        break;
      case 5:
        display.println("Outside Temp:");
        display.setCursor(0, 16);
        display.printf("%.1f C", dsTemps[2]);
        break;
    }
    display.display();
    displayIndex = (displayIndex + 1) % 6;
  }

  delay(50);
}