// ESP32 Smart Irrigation (local, no Blynk)
// Publishes telemetry to MQTT and listens to "cmd" to toggle pump.
// Moisture (%): potentiometer on ADC34; thirst = 100 - moisture
// Temp/RH: DHT22 on GPIO15 (cached reads; optional)
// Pump LED/relay: GPIO25
// Auto mode is handled by the server (FastAPI). This device just measures & obeys cmd.

#include <WiFi.h>
#include <PubSubClient.h>
#include <ArduinoJson.h>
#include <DHTesp.h>

// ---------- CONFIG ----------
const char* WIFI_SSID = "Wokwi-GUEST";
const char* WIFI_PASS = "";

// Use a public broker so Wokwi can reach it (your server will also connect here)
#define MQTT_HOST "test.mosquitto.org"
#define MQTT_PORT 1883

// Area / topics
const char* AREA_ID = "area-tn-001";
String TOPIC_TELE; // chrab/<area>/telemetry
String TOPIC_CMD;  // chrab/<area>/cmd
String TOPIC_CFG;  // chrab/<area>/cfg   (optional: {"SAMPLE_MS":3000})

const uint32_t DEFAULT_SAMPLE_MS = 3000;

// Pins
const int PIN_SOIL = 34;   // potentiometer
const int PIN_DHT  = 15;   // DHT22
const int PIN_PUMP = 25;   // LED/relay (HIGH=ON)

// ---------- STATE ----------
WiFiClient espClient;
PubSubClient mqtt(espClient);
DHTesp dht;

unsigned long lastPub = 0;
unsigned long lastDht = 0;
uint32_t SAMPLE_MS = DEFAULT_SAMPLE_MS;

bool pumpOn = false;

// Tank & NPK simple sim
float waterLevel = 80.0f;     // %
float Nppm = 20.0f, Pppm = 10.0f, Kppm = 15.0f;

// DHT cache
float tC_cache = 25.0f;
float rh_cache = 55.0f;

// ---------- WIFI ----------
void wifiConnect() {
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  Serial.print("[WiFi] Connecting");
  while (WiFi.status() != WL_CONNECTED) { delay(350); Serial.print("."); }
  Serial.println("\n[WiFi] Connected: " + WiFi.localIP().toString());
}

// ---------- MQTT ----------
void onMqttMessage(char* topic, uint8_t* payload, unsigned int len) {
  String t = topic;
  if (t == TOPIC_CMD) {
    if (len > 0 && payload[0] == '1') {
      pumpOn = true;
      Serial.println("[CMD] PUMP=ON");
    } else {
      pumpOn = false;
      Serial.println("[CMD] PUMP=OFF");
    }
  } else if (t == TOPIC_CFG) {
    // optional: { "SAMPLE_MS": 3000 }
    StaticJsonDocument<128> doc;
    DeserializationError e = deserializeJson(doc, payload, len);
    if (!e) {
      if (doc.containsKey("SAMPLE_MS")) {
        SAMPLE_MS = (uint32_t)doc["SAMPLE_MS"].as<uint32_t>();
        Serial.printf("[CFG] SAMPLE_MS=%u\n", SAMPLE_MS);
      }
    }
  }
}

void mqttConnect() {
  mqtt.setServer(MQTT_HOST, MQTT_PORT);
  mqtt.setCallback(onMqttMessage);
  Serial.print("[MQTT] Connecting");
  while (!mqtt.connected()) {
    String cid = String("esp32-irrig-") + String((uint32_t)ESP.getEfuseMac(), HEX);
    if (mqtt.connect(cid.c_str())) {
      Serial.println("\n[MQTT] Connected");
      mqtt.subscribe(TOPIC_CMD.c_str(), 1);
      mqtt.subscribe(TOPIC_CFG.c_str(), 1);
      Serial.println("[MQTT] Subscribed: " + TOPIC_CMD + " , " + TOPIC_CFG);
    } else {
      Serial.print(".");
      delay(600);
    }
  }
  mqtt.setBufferSize(512);
}

// ---------- HELPERS ----------
int readMoisturePct() {
  // Pot 0..4095 -> 0..100 (invert so clockwise increases "moist")
  int raw = analogRead(PIN_SOIL);
  raw = constrain(raw, 0, 4095);
  int pct = map(raw, 4095, 0, 0, 100);
  return constrain(pct, 0, 100);
}

void readDHT(float &tC, float &rh) {
  unsigned long now = millis();
  if (now - lastDht >= 2100) {
    TempAndHumidity th = dht.getTempAndHumidity();
    if (!isnan(th.temperature)) tC_cache = th.temperature;
    if (!isnan(th.humidity))    rh_cache = th.humidity;
    lastDht = now;
  }
  tC = tC_cache; rh = rh_cache;
}

void simTankAndNPK(bool pump) {
  // very simple: tank drains when pumping, leaks slowly when off
  // NPK drift a bit; dilute when pumping
  float dtm = SAMPLE_MS / 60000.0f; // minutes per step
  if (pump && waterLevel > 0.5f) {
    waterLevel -= 3.0f * dtm;   // %/min
    Nppm -= 0.05f * dtm; Pppm -= 0.03f * dtm; Kppm -= 0.04f * dtm;
  } else {
    waterLevel -= 0.05f * dtm;  // slow leak
  }
  if (waterLevel < 0) waterLevel = 0; if (waterLevel > 100) waterLevel = 100;
  // keep NPK reasonable
  if (Nppm < 5) Nppm = 5; if (Nppm > 60) Nppm = 60;
  if (Pppm < 3) Pppm = 3; if (Pppm > 40) Pppm = 40;
  if (Kppm < 5) Kppm = 5; if (Kppm > 80) Kppm = 80;
}

void publishTelemetry(int moisture, float tC, float rh) {
  StaticJsonDocument<256> doc;
  doc["ts"] = "";                 // server stamps actual time
  doc["area_id"] = AREA_ID;
  doc["moist"] = moisture;
  doc["temp_c"] = tC;
  doc["rh"]     = rh;
  doc["water_level"] = waterLevel;
  doc["N"] = Nppm; doc["P"] = Pppm; doc["K"] = Kppm;
  doc["last_pump"] = pumpOn ? 1 : 0;

  char buf[256];
  size_t n = serializeJson(doc, buf, sizeof(buf));
  bool ok = mqtt.publish(TOPIC_TELE.c_str(),
                         reinterpret_cast<const uint8_t*>(buf),
                         n, false);
  Serial.print("[PUB] "); Serial.print(TOPIC_TELE); Serial.print(" "); Serial.println(buf);
  if (ok) Serial.println("[PUB->MQTT] sent");
}

// ---------- ARDUINO ----------
void setup() {
  Serial.begin(115200);
  pinMode(PIN_PUMP, OUTPUT);
  digitalWrite(PIN_PUMP, LOW);

  analogReadResolution(12);
  dht.setup(PIN_DHT, DHTesp::DHT22);

  TOPIC_TELE = String("chrab/") + AREA_ID + "/telemetry";
  TOPIC_CMD  = String("chrab/") + AREA_ID + "/cmd";
  TOPIC_CFG  = String("chrab/") + AREA_ID + "/cfg";

  wifiConnect();
  mqttConnect();

  lastPub = millis();
  lastDht = 0;
}

void loop() {
  if (!mqtt.connected()) mqttConnect();
  mqtt.loop();

  float tC, rh;
  readDHT(tC, rh);

  unsigned long now = millis();
  if (now - lastPub >= SAMPLE_MS) {
    lastPub = now;

    int moist = readMoisturePct();
    // pump indicator mirrors last command from server
    digitalWrite(PIN_PUMP, pumpOn ? HIGH : LOW);

    simTankAndNPK(pumpOn);
    publishTelemetry(moist, tC, rh);
  }
}