code

#include <WiFi.h>
#include <HTTPClient.h>
#include <WiFiClientSecure.h>
#include <time.h>
#include "esp_sleep.h"

// ================= WIFI =================
const char* ssid = "HUAWEI-2.4G-Mfy4";
const char* password = "VabeC8a3";

// ================= URL =================
const char* url =
"https://urniki.easistent.com/urniki/5a42718f4a77f1f87d5f03d0634b3c6eaef7312c/razredi/679032/dijak/9032618";

#define uS_TO_S 1000000ULL

// ================= TIME =================
String getTodayDate() {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) return "";

  char buf[11];
  strftime(buf, sizeof(buf), "%Y-%m-%d", &timeinfo);
  return String(buf);
}

// ================= SCRAPER =================
void fetchTodaySubjects(String date) {

  WiFiClientSecure client;
  client.setInsecure();
  client.setTimeout(15);

  HTTPClient http;
  http.begin(client, url);
  http.setTimeout(20000);

  http.addHeader("User-Agent", "Mozilla/5.0");
  http.addHeader("Accept", "*/*");
  http.addHeader("Cache-Control", "no-cache");

  int httpCode = http.GET();
  Serial.println("HTTP code: " + String(httpCode));

  if (httpCode <= 0) {
    Serial.println("HTTP failed");
    http.end();
    return;
  }

  WiFiClient* stream = http.getStreamPtr();
  if (!stream) {
    Serial.println("Stream null");
    http.end();
    return;
  }

  String buf = "";
  buf.reserve(32768);

  int subjectCount = 0;
  bool headerPrinted = false;

  while (http.connected() || stream->available()) {

    while (stream->available()) {
      buf += (char)stream->read();
      if (buf.length() > 32000) buf = buf.substring(16000);
    }

    String searchTd = "ednevnik-seznam_ur_teden-td-";
    int pos = 0;

    while ((pos = buf.indexOf(searchTd, pos)) != -1) {

      int dashAfterNum = buf.indexOf("-", pos + searchTd.length());
      if (dashAfterNum == -1) { pos++; continue; }

      String afterPrefix = buf.substring(pos + searchTd.length(), dashAfterNum);
      String dateInId = buf.substring(dashAfterNum + 1, dashAfterNum + 11);

      if (dateInId != date) { pos++; continue; }

      int tdEnd = buf.indexOf("</td>", pos);
      if (tdEnd == -1) break;

      String cell = buf.substring(pos, tdEnd);

      if (cell.indexOf("class=\"hidden") != -1) {
        buf = buf.substring(tdEnd + 5);
        pos = 0;
        continue;
      }

      int periodNum = afterPrefix.toInt();
      String periodLabel = (periodNum == 0) ? "Predura" : String(periodNum) + ". ura";

      String subject = "";
      int titlePos = cell.indexOf("ednevnik-title");

      while (titlePos != -1) {
        int spanPos = cell.indexOf("<span", titlePos);
        if (spanPos == -1) break;

        int textStart = cell.indexOf(">", spanPos) + 1;
        int textEnd = cell.indexOf("<", textStart);

        if (textStart > 0 && textEnd > textStart) {
          String text = cell.substring(textStart, textEnd);
          text.trim();

          if (text.length() > 0 && text.length() <= 6) {
            subject = text;
            break;
          }
        }

        titlePos = cell.indexOf("ednevnik-title", titlePos + 1);
      }

      String status = "";
      if (cell.indexOf("odpadla") != -1) status = " (ODPADLA)";
      else if (cell.indexOf("nadomescanje") != -1) status = " (NADOMESCANJE)";

      if (subject.length() > 0) {
        if (!headerPrinted) {
          Serial.println("\n--- TODAY (" + date + ") ---");
          headerPrinted = true;
        }

        Serial.println(periodLabel + ": " + subject + status);
        subjectCount++;
      }

      buf = buf.substring(tdEnd + 5);
      pos = 0;
    }
  }

  http.end();

  Serial.println("\n--- DONE (" + String(subjectCount) + ") ---");
}

// ================= UPDATE =================
void updateSchedule() {
  String today = getTodayDate();

  if (today == "") {
    Serial.println("No time yet!");
    return;
  }

  fetchTodaySubjects(today);
}

// ================= WIFI =================
void connectWiFi() {
  WiFi.begin(ssid, password);

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

  Serial.println("\nWiFi OK");
}

// ================= TIME SYNC =================
void syncTime() {
  configTime(3600, 3600, "pool.ntp.org");

  Serial.print("Syncing time");

  struct tm timeinfo;
  while (!getLocalTime(&timeinfo)) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("\nTime OK");
}

// ================= SLEEP UNTIL 09:00 =================
void goToSleep() {
  struct tm timeinfo;

  if (!getLocalTime(&timeinfo)) {
    Serial.println("Time fail, sleeping 1h");
    esp_sleep_enable_timer_wakeup(3600ULL * uS_TO_S);
    esp_deep_sleep_start();
  }

  int nowSeconds = timeinfo.tm_hour * 3600 +
                   timeinfo.tm_min * 60 +
                   timeinfo.tm_sec;

  int targetSeconds = 7 * 3600; // 09:00

  int sleepSeconds = targetSeconds - nowSeconds;

  if (sleepSeconds <= 0) {
    sleepSeconds += 24 * 3600;
  }

  Serial.println("Sleeping for " + String(sleepSeconds) + " seconds");

  esp_sleep_enable_timer_wakeup((uint64_t)sleepSeconds * uS_TO_S);
  esp_deep_sleep_start();
}

// ================= SETUP =================
void setup() {
  Serial.begin(115200);
  delay(500);

  Serial.println("\nBOOT");

  connectWiFi();
  syncTime();

  Serial.println("Running update...");
  updateSchedule();

  goToSleep();
}

// ================= LOOP =================
void loop() {}