#include <WiFi.h>
#include <HTTPClient.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
#include <DHT.h>
#include <math.h>

// ===== WiFi Configuration =====
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// ===== MQTT Configuration =====
const char* mqtt_server = "mqtt.eclipseprojects.io";
const int mqtt_port = 1883;
const char* topicWeather = "weather/data";
const char* topicSensor = "sensors/esp32";
const char* topicPWM = "esp32/pwm";
const char* topicFeedback = "esp32/pwm/feedback";
const char* topicThreshold = "esp32/Thresh";
const char* topicAlert = "alert/BUZZER";
const char* topicTempDHT = "esp32/temp";
const char* topicTempTherm = "esp32/Thermistor";

// ===== Hardware Configuration =====
#define DHTPIN 26
#define DHTTYPE DHT22
#define THERMISTOR_PIN 34
#define FAN_PIN 13
#define LED_PIN 2
#define BUZZER_PIN 5
DHT dht(DHTPIN, DHTTYPE);

// ===== OpenWeatherMap Config =====
const char* apiKey = "0897ec6053fd70b586341d0cc5e0d88a";
const char* city = "Cape Town";
const char* countryCode = "ZA";

// ===== Global Variables =====
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
float tempThreshold = NAN;
bool alertSent = false;

// ===== WiFi Connection =====
void setupWiFi() {
  Serial.print("Connecting to WiFi");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(300);
    Serial.print(".");
  }
  Serial.println(" connected!");
}

// ===== MQTT Reconnect =====
void reconnectMQTT() {
  while (!mqttClient.connected()) {
    Serial.print("Connecting to MQTT...");
    if (mqttClient.connect("ESP32ClientUnified")) {
      Serial.println(" connected.");
      mqttClient.subscribe(topicPWM);
      mqttClient.subscribe(topicThreshold);
    } else {
      Serial.print(" failed. Retry in 3s.\n");
      delay(3000);
    }
  }
}

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

  Serial.printf("MQTT [%s]: %s\n", topic, message.c_str());

  if (strcmp(topic, topicPWM) == 0) {
    int percentage = constrain(message.toInt(), 0, 100);
    int pwmValue = map(percentage, 0, 100, 0, 255);
    analogWrite(FAN_PIN, pwmValue);

    String feedback = "{\"percent\":" + String(percentage) + ",\"pwm\":" + String(pwmValue) + "}";
    mqttClient.publish(topicFeedback, feedback.c_str());
  }

  if (strcmp(topic, topicThreshold) == 0) {
    float newThresh = message.toFloat();
    if (!isnan(newThresh) && newThresh > 0) {
      tempThreshold = newThresh;
      Serial.printf("Updated Threshold: %.2f°C\n", tempThreshold);
    }
  }
}

// ===== Weather Fetching =====
void fetchWeather() {
  String url = "http://api.openweathermap.org/data/2.5/weather?q=" + String(city) + "," + countryCode + "&appid=" + apiKey + "&units=metric";
  HTTPClient http;
  http.begin(url);
  int httpCode = http.GET();

  if (httpCode > 0) {
    String payload = http.getString();
    StaticJsonDocument<1024> doc;
    if (!deserializeJson(doc, payload)) {
      StaticJsonDocument<512> outDoc;
      outDoc["city"] = city;
      outDoc["country"] = countryCode;
      outDoc["temp"] = doc["main"]["temp"];
      outDoc["humidity"] = doc["main"]["humidity"];
      outDoc["description"] = doc["weather"][0]["description"];
      outDoc["wind"] = doc["wind"]["speed"];

      char buffer[512];
      serializeJson(outDoc, buffer);
      mqttClient.publish(topicWeather, buffer);
      Serial.println("Weather published.");
    }
  }
  http.end();
}

// ===== Thermistor Reading =====
float readThermistorC() {
  int analogValue = analogRead(THERMISTOR_PIN);
  float voltage = analogValue * 3.3 / 4095.0;
  float resistance = (3.3 - voltage) * 10000.0 / voltage;
  float tempK = 1.0 / (1.0 / 298.15 + log(resistance / 10000.0) / 3435.0);
  return tempK - 273.15;
}

// ===== Sensor Publishing =====
void publishSensorData() {
  float dhtTemp = dht.readTemperature();
  float dhtHum = dht.readHumidity();
  float thermTemp = readThermistorC();

  if (!isnan(dhtTemp)) {
    char tempBuf[8], humBuf[8], thermBuf[8];
    dtostrf(dhtTemp, 1, 2, tempBuf);
    dtostrf(dhtHum, 1, 2, humBuf);
    dtostrf(thermTemp, 1, 2, thermBuf);

    mqttClient.publish(topicTempDHT, tempBuf);
    mqttClient.publish(topicTempTherm, thermBuf);

    String payload = "{\"dht_temp\":" + String(tempBuf) + ",\"humidity\":" + String(humBuf) + ",\"thermistor\":" + String(thermBuf) + "}";
    mqttClient.publish(topicSensor, payload.c_str());

    Serial.println("Sensor data published.");
  }
}

// ===== Alert Logic =====
void handleAlert(float currentTemp) {
  if (isnan(tempThreshold)) return;

  if (currentTemp > tempThreshold && !alertSent) {
    mqttClient.publish(topicAlert, "HIGH");
    tone(BUZZER_PIN, 1000);
    digitalWrite(LED_PIN, HIGH);
    alertSent = true;
    Serial.println("ALERT: Temperature exceeded threshold!");
  } else if (currentTemp <= tempThreshold && alertSent) {
    mqttClient.publish(topicAlert, "LOW");
    noTone(BUZZER_PIN);
    digitalWrite(LED_PIN, LOW);
    alertSent = false;
    Serial.println("Temperature back to normal.");
  }
}

// ===== Setup =====
void setup() {
  Serial.begin(115200);
  pinMode(FAN_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(LED_PIN, LOW);
  noTone(BUZZER_PIN);
  dht.begin();

  setupWiFi();
  mqttClient.setServer(mqtt_server, mqtt_port);
  mqttClient.setCallback(callback);
}

// ===== Loop =====
unsigned long lastUpdate = 0;
const unsigned long interval = 60000;

void loop() {
  if (!mqttClient.connected()) reconnectMQTT();
  mqttClient.loop();

  unsigned long now = millis();
  if (now - lastUpdate > interval) {
    lastUpdate = now;
    fetchWeather();
    publishSensorData();

    float dhtTemp = dht.readTemperature();
    if (!isnan(dhtTemp)) handleAlert(dhtTemp);
  }
}