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

// ====== WiFi Credentials for Wokwi ======
const char* ssid = "Wokwi-GUEST";
const char* password = "";   // no password

// ====== Backend URL (Render) ======
const char* serverUrl = "https://footzup.onrender.com/api/data";  

// ====== NTP (for timestamps) ======
const char* ntpServer = "pool.ntp.org";
const long gmtOffset_sec = 0;
const int daylightOffset_sec = 0;

void setup() {
  Serial.begin(115200);

  // Connect to WiFi
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("\n✅ WiFi connected");

  // Sync time from NTP
  configTime(gmtOffset_sec, daylightOffset_sec, ntpServer);
}

String getTimestamp() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    Serial.println("❌ Failed to obtain time");
    return "";
  }
  char buf[25];
  strftime(buf, sizeof(buf), "%Y-%m-%dT%H:%M:%SZ", &timeinfo);
  return String(buf);
}

void loop() {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    http.begin(serverUrl);
    http.addHeader("Content-Type", "application/json");

    // ====== Fake sensor values ======
    int steps = random(10, 50);
    float voltage = 3.25 + random(0, 11) / 100.0; // 3.25V–3.35V
    float current = random(100, 500) / 1000.0;
    float power = voltage * current * 1000; // in mW
    String timestamp = getTimestamp();

    // ====== Build JSON manually (lighter than ArduinoJson) ======
    String requestBody = "{";
    requestBody += "\"steps\":" + String(steps) + ",";
    requestBody += "\"voltage\":" + String(voltage, 2) + ",";
    requestBody += "\"current\":" + String(current, 3) + ",";
    requestBody += "\"power\":" + String(power, 1) + ",";
    requestBody += "\"timestamp\":\"" + timestamp + "\"";
    requestBody += "}";

    // ====== Send POST ======
    int httpResponseCode = http.POST(requestBody);

    if (httpResponseCode > 0) {
      Serial.printf("✅ POST OK: %d | Sent -> %s\n", httpResponseCode, requestBody.c_str());
    } else {
      Serial.printf("❌ POST failed: %s\n", http.errorToString(httpResponseCode).c_str());
    }

    http.end();
  } else {
    Serial.println("⚠️ WiFi not connected!");
  }

  delay(3000); // send every 3 seconds
}