/*
  Session 6 — ESP-NOW sensor node (star topology, no router needed in the field)
  Sends a struct to the gateway every 60 s; retries 3 times if the delivery callback reports failure.
  Set GATEWAY_MAC to the MAC printed by s06_espnow_gateway. Use the SAME Wi-Fi channel as the gateway.
  Compatible with ESP32 Arduino core 3.x (esp_now_send_cb_t uses wifi_tx_info_t). For core 2.x change the
  callback signature to:  void onSent(const uint8_t *mac, esp_now_send_status_t status)
*/
#include <WiFi.h>
#include <esp_now.h>
#include <esp_wifi.h>
#include <DHT.h>

uint8_t GATEWAY_MAC[] = {0x24, 0x6F, 0x28, 0xAA, 0xBB, 0xCC};   // <-- edit
const uint8_t CHANNEL = 6;
const uint8_t NODE_NUM = 2;                                     // 1..20, unique per node

typedef struct __attribute__((packed)) {
  uint8_t node;
  uint32_t seq;
  float temp;
  float hum;
  uint16_t soilRaw;
  float battery;
} Reading;

DHT dht(4, DHT22);
Reading msg;
volatile bool lastOk = false;

void onSent(const wifi_tx_info_t *info, esp_now_send_status_t status) { lastOk = (status == ESP_NOW_SEND_SUCCESS); }

void setup() {
  Serial.begin(115200);
  dht.begin();
  WiFi.mode(WIFI_STA);
  esp_wifi_set_channel(CHANNEL, WIFI_SECOND_CHAN_NONE);
  if (esp_now_init() != ESP_OK) { Serial.println("ESP-NOW init failed"); ESP.restart(); }
  esp_now_register_send_cb(onSent);
  esp_now_peer_info_t peer = {};
  memcpy(peer.peer_addr, GATEWAY_MAC, 6);
  peer.channel = CHANNEL;
  esp_now_add_peer(&peer);
  Serial.print("node MAC: "); Serial.println(WiFi.macAddress());
}

void loop() {
  msg.node = NODE_NUM;
  msg.seq++;
  msg.temp = dht.readTemperature();
  msg.hum = dht.readHumidity();
  msg.soilRaw = analogRead(34);
  msg.battery = analogReadMilliVolts(33) * 2 / 1000.0;
  for (int attempt = 1; attempt <= 3; attempt++) {     // handle temporary loss
    lastOk = false;
    esp_now_send(GATEWAY_MAC, (uint8_t *)&msg, sizeof(msg));
    delay(60);
    if (lastOk) break;
    Serial.printf("seq %lu attempt %d failed\n", msg.seq, attempt);
    delay(200 * attempt);                                  // back-off
  }
  Serial.printf("seq %lu sent=%s\n", msg.seq, lastOk ? "OK" : "LOST");
  delay(60000);
}