// Bitcoin tracer, ktery zobrazuje soucasnou cenu a jeji zmenu. Pokud cena 5x za sebou spadla, rozsviti se led.
#include <ezButton.h> 
#include <Adafruit_SSD1306.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#define SCREEN_WIDTH 128 // Sirka
#define SCREEN_HEIGHT 64 // Vyska
#define OLED_RESET     -1 // Reset
#define SCREEN_ADDRESS 0x3C // Pozicovani
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
#define DEBOUNCE_TIME 50

const int ledPin = 12;
ezButton buttonPIN(18); // zamezeni efektu zadrceni
int i = 0;

#define SSID "Wokwi-GUEST"; // jmeno wifi
#define WIFI_PASSWORD ""; // heslo wifi
const char* ssid = "Wokwi-GUEST"; // znovu jmeno wifi pro ukazatel
const char* password = ""; // znovu heslo wifi pro ukazatel

// cena ziskana ze stranky coindesk - https://www.coindesk.com/price/bitcoin
const String url = "http://api.coindesk.com/v1/bpi/currentprice/BTC.json";
const String cryptoCode = "BTC";

// Ikona bitcoinu
const unsigned char bitcoinIcon [] PROGMEM = {
0x00, 0x7e, 0x00, 0x03, 0xff, 0xc0, 0x07, 0x81, 0xe0, 0x0e, 0x00, 0x70, 0x18, 0x28, 0x18, 0x30, 
0x28, 0x0c, 0x70, 0xfc, 0x0e, 0x60, 0xfe, 0x06, 0x60, 0xc7, 0x06, 0xc0, 0xc3, 0x03, 0xc0, 0xc7, 
0x03, 0xc0, 0xfe, 0x03, 0xc0, 0xff, 0x03, 0xc0, 0xc3, 0x83, 0xc0, 0xc1, 0x83, 0x60, 0xc3, 0x86, 
0x60, 0xff, 0x06, 0x70, 0xfe, 0x0e, 0x30, 0x28, 0x0c, 0x18, 0x28, 0x18, 0x0e, 0x00, 0x70, 0x07, 
0x81, 0xe0, 0x03, 0xff, 0xc0, 0x00, 0x7e, 0x00
};

HTTPClient http;
String lastPrice;
String staracena;

void setup() {
  Serial.begin(115200);
  pinMode(ledPin, OUTPUT);
  buttonPIN.setDebounceTime(DEBOUNCE_TIME);

  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;); 
  }

  display.clearDisplay();
  display.setTextSize(1);           
  display.setTextColor(SSD1306_WHITE);      
  display.setCursor(0,0); 
  display.println("Pripojovani k WiFi...");
  display.display();

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
  }

  Serial.print("Pripojeno k: ");
  Serial.println(ssid);

  display.print("Pripojeno k ");
  display.println(ssid);
  display.display();
  delay(4500);
}

void loop() {
  buttonPIN.loop();
  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("Ziskavam data...");

    // Po zmacknuti tlacitka led zhasne a vynuluje se "trend".
    if (buttonPIN.isPressed()) {
      digitalWrite(ledPin, LOW);
      i = 0;
    }

    // ziskavani dat
    http.begin(url);
    int httpCode = http.GET();
      StaticJsonDocument<768> doc;
      DeserializationError error = deserializeJson(doc, http.getString());

      if (error) {
        Serial.print(F("deserializeJson failed: "));
        Serial.println(error.f_str());
        delay(2500);
        return;
      }

      // zpracovani dat
      String BTCUSDPrice = doc["bpi"]["USD"]["rate_float"].as<String>();
      if(BTCUSDPrice == lastPrice) {
        Serial.print("Stala cena: ");
        Serial.println(BTCUSDPrice);
        delay(5000);
        return;
      } else {
        staracena = lastPrice;
        lastPrice = BTCUSDPrice;
        Serial.print("Nova cena: ");
        Serial.println(lastPrice);
      }
      http.end();

      // Display
      display.clearDisplay();
      display.drawBitmap(52, 20, bitcoinIcon, 24, 24, WHITE);
      display.display();

      // Cena
      display.setTextSize(2);
      printpr("$" + BTCUSDPrice, 00, 50);

      // Stonks/notstonks
      bool isUp = lastPrice > staracena;
      String percentChange;
      if (isUp) {
        percentChange = "Stonks";
        i++;
      } else {
        percentChange = "NotStonks";
        i--;
        if (i < -5) digitalWrite(ledPin, HIGH); // Pokud "trend rustu" bude zaporny sestkrat, rozsviti se ledka.
      }
      display.setTextSize(2);
      printpr(percentChange, 0, 0);
      display.display();
    
    delay(1250);
  }
}

void printpr(const String buf, int x, int y) // tisk hodnot
{
  int16_t x1, y1;
  uint16_t w, h;
  display.getTextBounds(buf, x, y, &x1, &y1, &w, &h);
  display.setCursor((x - w / 2) + (128 / 2), y);
  display.print(buf);
}