#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

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

// ---------------- ThingSpeak Configuration ----------------
const char* readAPIKey = "ZI3B01IH4EO2DJGE";   // Replace with your read key
const char* channelID = "3110288";             // Replace with your channel ID

// ---------------- Control Variables ----------------
String lastEntryID = "";
unsigned long lastFetchTime = 0;
const long fetchInterval = 5000; // Check every 5 seconds

void setup() {
  Serial.begin(115200);
  Serial.println("ESP32 ThingSpeak Receiver (Auto Fetch)");
  Serial.println("--------------------------------------");

  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\n✅ WiFi Connected!");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  unsigned long currentTime = millis();

  if (currentTime - lastFetchTime >= fetchInterval) {
    lastFetchTime = currentTime;

    if (WiFi.status() == WL_CONNECTED) {
      HTTPClient http;
      String url = "https://api.thingspeak.com/channels/" + String(channelID) +
                   "/feeds.json?api_key=" + String(readAPIKey) + "&results=1";

      http.begin(url);
      int httpCode = http.GET();

      if (httpCode > 0) {
        String payload = http.getString();

        // Parse JSON
        const size_t capacity = 8 * 1024; // Allocate enough memory
        DynamicJsonDocument doc(capacity);
        DeserializationError error = deserializeJson(doc, payload);

        if (!error) {
          JsonArray feeds = doc["feeds"];
          if (feeds.size() > 0) {
            JsonObject feed = feeds[0];

            String entryID = feed["entry_id"].as<String>();

            if (entryID != lastEntryID) {
              lastEntryID = entryID;

              String device_id = feed["field1"].as<String>();
              String start_lat = feed["field2"].as<String>();
              String start_lon = feed["field3"].as<String>();
              String total_distance_km = feed["field4"].as<String>();
              String timestamp = feed["field5"].as<String>();

              Serial.println("\n--------------------------------------");
              Serial.println("Receiving...");
              Serial.println("Payload Received:");
              Serial.println(device_id + " | " + total_distance_km + " km");
              Serial.println(start_lat + " | " + start_lon);
              Serial.println(timestamp);
              Serial.println("--------------------------------------\n");
            }
          } else {
            Serial.println("⚠️ No feeds available.");
          }
        } else {
          Serial.println("❌ JSON Parse Error");
        }
      } else {
        Serial.println("❌ HTTP Error: " + String(httpCode));
      }

      http.end();
    } else {
      Serial.println("⚠️ WiFi disconnected. Retrying...");
    }
  }
}