WiFi Stock Ticker

// WiFi Stock Ticker - fetches a live quote and shows price + change on an OLED.
// In the FluxBench simulator, WiFi "connects" after about a second with a fake IP
// and the Yahoo Finance URL returns simulated quote JSON, so you can watch the
// whole flow work without hardware. On a real ESP32, set your own WiFi below.
#include <WiFi.h>
#include <HTTPClient.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

const char* WIFI_SSID = "YourNetwork";
const char* WIFI_PASS = "YourPassword";
const char* QUOTE_URL = "https://query1.finance.yahoo.com/v8/finance/chart/QQQ?interval=1d&range=1d";

Adafruit_SSD1306 display(128, 64, &Wire, -1);
unsigned long lastFetch = 0;

float readNumber(String body, String key) {
  int k = body.indexOf(key);
  if (k < 0) return 0.0;
  int colon = body.indexOf(":", k);
  int comma = body.indexOf(",", colon);
  if (comma < 0) comma = body.indexOf("}", colon);
  return body.substring(colon + 1, comma).toFloat();
}

void setup() {
  Serial.begin(115200);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("Connecting WiFi...");
  display.display();

  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  while (WiFi.status() != WL_CONNECTED) {
    delay(250);
    Serial.print(".");
  }
  Serial.println();
  Serial.print("Connected! IP: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  if (millis() - lastFetch >= 5000 || lastFetch == 0) {
    lastFetch = millis();
    HTTPClient http;
    http.begin(QUOTE_URL);
    int code = http.GET();
    if (code == 200) {
      String body = http.getString();
      float price = readNumber(body, "regularMarketPrice");
      float prev = readNumber(body, "previousClose");
      float change = price - prev;
      float pct = prev > 0 ? change / prev * 100.0 : 0.0;

      Serial.print("QQQ ");
      Serial.print(price);
      Serial.print("  change ");
      Serial.println(change);

      display.clearDisplay();
      display.setTextSize(1);
      display.setCursor(0, 0);
      display.println("QQQ  (Nasdaq-100)");
      display.setTextSize(2);
      display.setCursor(0, 16);
      display.print("$");
      display.println(price);
      display.setTextSize(1);
      display.setCursor(0, 40);
      if (change >= 0) display.print("+");
      display.print(change);
      display.print(" (");
      if (pct >= 0) display.print("+");
      display.print(pct);
      display.println("%)");
      display.setCursor(0, 54);
      display.print("IP ");
      display.print(WiFi.localIP());
      display.display();
    } else {
      Serial.print("HTTP error ");
      Serial.println(code);
    }
    http.end();
  }
  delay(50);
}