#include <WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>
#include <ArduinoJson.h>
#include <time.h>

// ── WiFi + Cloud ──────────────────────────────────────────────────
const char* WIFI_SSID = "YourNetwork";
const char* WIFI_PASS = "YourPassword";
const char* TB_HOST   = "mqtt.thingsboard.cloud";
const char* TB_TOKEN  = "YOUR_TOKEN";
const char* TELEM     = "v1/devices/me/telemetry";
const char* ATTR      = "v1/devices/me/attributes";
const char* RPC_SUB   = "v1/devices/me/rpc/request/+";
const char* RPC_RESP  = "v1/devices/me/rpc/response/";

// ── Hardware pins ─────────────────────────────────────────────────
#define DHT_PIN    4
#define LDR_PIN   34
#define FAN_PIN   16
#define BUZZ_PIN  17
#define LED_PIN   18
#define STATUS_LED 2

// ── Thresholds ────────────────────────────────────────────────────
const float FAN_ON   = 30.0,  FAN_OFF   = 26.0;
const float BUZZ_ON  = 80.0,  BUZZ_OFF  = 70.0;

// ── State ─────────────────────────────────────────────────────────
bool fanActive   = false, buzzActive   = false;
bool fanOverride = false, buzzOverride = false;  // RPC override flags

// ── Timing ────────────────────────────────────────────────────────
unsigned long lastRead = 0, lastPub = 0;
const long READ_INT = 3000, PUB_INT = 15000;

DHT          dht(DHT_PIN, DHT22);
WiFiClient   wc;
PubSubClient mqtt(wc);

// ── RPC Handler ───────────────────────────────────────────────────
void onRPC(char* topic, byte* payload, unsigned int len) {
  StaticJsonDocument<128> req;
  deserializeJson(req, payload, len);
  String method = req["method"].as<String>();
  String tid = String(topic);
  String rid = tid.substring(tid.lastIndexOf('/') + 1);

  if (method == "setFan") {
    fanOverride = fanActive = req["params"]["state"];
    digitalWrite(FAN_PIN, fanActive ? HIGH : LOW);
    Serial.println(fanActive ? "RPC: Fan ON" : "RPC: Fan OFF");
  } else if (method == "setBuzzer") {
    buzzOverride = buzzActive = req["params"]["state"];
    digitalWrite(BUZZ_PIN, buzzActive ? HIGH : LOW);
  } else if (method == "clearOverrides") {
    fanOverride = buzzOverride = false;
    Serial.println("RPC: Overrides cleared — auto mode restored");
  }
  mqtt.publish((String(RPC_RESP) + rid).c_str(), "{\"result\":\"ok\"}");
}

// ── Connect helpers ───────────────────────────────────────────────
void connectWiFi() {
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  while (WiFi.status() != WL_CONNECTED) delay(500);
  configTime(7200, 0, "pool.ntp.org");   // Rwanda: UTC+2
  Serial.println("Wi-Fi: " + WiFi.localIP().toString());
}

void connectMQTT() {
  while (!mqtt.connected()) {
    if (mqtt.connect("smart-env-01", TB_TOKEN, "")) {
      mqtt.subscribe(RPC_SUB);
      mqtt.publish(ATTR, "{\"firmware\":\"v1.0\",\"location\":\"NEDU-Lab\"}");
    } else { delay(3000); }
  }
}

// ── Automation logic (local — no cloud dependency) ────────────────
void applyAutomation(float temp, float hum) {
  if (fanOverride || buzzOverride) return;   // Manual override active

  // Fan hysteresis control
  if      (!fanActive  && temp >= FAN_ON)  { fanActive  = true;  digitalWrite(FAN_PIN,  HIGH); Serial.println("Auto: Fan ON  (temp=" + String(temp,1) + ")"); }
  else if ( fanActive  && temp <= FAN_OFF) { fanActive  = false; digitalWrite(FAN_PIN,  LOW);  Serial.println("Auto: Fan OFF"); }

  // Buzzer humidity alert
  if      (!buzzActive && hum  >= BUZZ_ON) { buzzActive = true;  digitalWrite(BUZZ_PIN, HIGH); Serial.println("Auto: Buzzer ON (hum=" + String(hum,1) + ")"); }
  else if ( buzzActive && hum  <= BUZZ_OFF){ buzzActive = false; digitalWrite(BUZZ_PIN, LOW);  }
}

// ── Setup ─────────────────────────────────────────────────────────
void setup() {
  Serial.begin(115200);
  dht.begin();
  analogSetAttenuation(ADC_11DB);
  for (int p : {FAN_PIN, BUZZ_PIN, LED_PIN, STATUS_LED}) pinMode(p, OUTPUT);
  connectWiFi();
  mqtt.setServer(TB_HOST, 1883);
  mqtt.setCallback(onRPC);
  connectMQTT();
}

// ── Loop ──────────────────────────────────────────────────────────
void loop() {
  if (!mqtt.connected()) connectMQTT();
  mqtt.loop();
  unsigned long now = millis();

  if (now - lastRead >= READ_INT) {
    lastRead = now;
    float temp = dht.readTemperature();
    float hum  = dht.readHumidity();
    int   ldr  = analogRead(LDR_PIN);

    if (!isnan(temp) && !isnan(hum)) {
      // Auto-brightness: dark room → bright LED
      int brightness = constrain(map(ldr, 100, 3900, 255, 0), 0, 255);
      analogWrite(LED_PIN, brightness);
      applyAutomation(temp, hum);

      if (now - lastPub >= PUB_INT) {
        lastPub = now;
        digitalWrite(STATUS_LED, HIGH);
        StaticJsonDocument<256> doc;
        doc["temperature"] = round(temp * 10) / 10.0;
        doc["humidity"]    = round(hum  * 10) / 10.0;
        doc["light_raw"]   = ldr;
        doc["brightness"]  = brightness;
        doc["fan_state"]   = fanActive  ? 1 : 0;
        doc["buzz_state"]  = buzzActive ? 1 : 0;
        doc["override"]    = (fanOverride || buzzOverride) ? 1 : 0;
        doc["rssi"]        = WiFi.RSSI();
        char payload[256];
        serializeJson(doc, payload);
        mqtt.publish(TELEM, payload);
        Serial.println(payload);
        digitalWrite(STATUS_LED, LOW);
      }
    } else {
      Serial.println("Sensor error — maintaining last state");
    }
  }
}