/*
  Session 5 — Wi-Fi site survey of the college farm (ESP32 + power bank)
  Walk to each candidate node location, wait 10 s, and write down the RSSI of the farm access point.
  RSSI guide: > -60 dBm excellent | -60..-70 good | -70..-80 weak (packet loss) | < -80 use LoRa / ESP-NOW relay
  Output is CSV on the Serial Monitor (or the built-in LED blinks: fast = strong, slow = weak).
*/
#include <WiFi.h>

const char* TARGET_SSID = "KFS-Farm-IoT";
#define LED 2

void setup() {
  Serial.begin(115200);
  pinMode(LED, OUTPUT);
  WiFi.mode(WIFI_STA);
  WiFi.disconnect();
  Serial.println("ms,ssid,rssi_dbm,channel,quality");
}

void loop() {
  int n = WiFi.scanNetworks();
  int best = -127;
  for (int i = 0; i < n; i++) {
    const char* q = WiFi.RSSI(i) > -60 ? "excellent" : WiFi.RSSI(i) > -70 ? "good" : WiFi.RSSI(i) > -80 ? "weak" : "unusable";
    Serial.printf("%lu,%s,%d,%d,%s\n", millis(), WiFi.SSID(i).c_str(), WiFi.RSSI(i), WiFi.channel(i), q);
    if (WiFi.SSID(i) == TARGET_SSID) best = max(best, (int)WiFi.RSSI(i));
  }
  Serial.printf("# %s best RSSI = %d dBm\n", TARGET_SSID, best);
  WiFi.scanDelete();
  int blinkMs = best > -60 ? 100 : best > -70 ? 300 : best > -80 ? 800 : 0;
  for (int i = 0; i < 10 && blinkMs; i++) { digitalWrite(LED, !digitalRead(LED)); delay(blinkMs); }
  digitalWrite(LED, LOW);
  delay(blinkMs ? 2000 : 5000);
}