ESP32 Telegram Motion Alarm

#include <Arduino.h>
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <HTTPClient.h>

// Enter the Wi-Fi network the ESP32 will use.

// Forward declarations
String urlEncode(const String &text);
bool telegramIsConfigured();
bool sendTelegramMessage(const String &message);
void connectWiFi();
void startAlarm();
void updateBuzzer();

const char *WIFI_SSID = "YOUR_WIFI_NAME";
const char *WIFI_PASSWORD = "YOUR_WIFI_PASSWORD";

// Create a bot with @BotFather in Telegram, then enter its token and your chat ID.
const char *TELEGRAM_BOT_TOKEN = "YOUR_BOT_TOKEN";
const char *TELEGRAM_CHAT_ID = "YOUR_CHAT_ID";

constexpr int PIR_PIN = 27;
constexpr int BUZZER_PIN = 25;
constexpr unsigned long ALERT_COOLDOWN_MS = 60000UL;
constexpr unsigned long BUZZ_DURATION_MS = 3000UL;

bool previousMotion = false;
bool buzzerOn = false;
unsigned long lastAlertMs = 0;
unsigned long buzzerStartedMs = 0;

String urlEncode(const String &text) {
  const char *hex = "0123456789ABCDEF";
  String encoded;
  encoded.reserve(text.length() * 3);
  for (size_t i = 0; i < text.length(); ++i) {
    const uint8_t c = static_cast<uint8_t>(text[i]);
    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
        (c >= '0' && c <= '9') || c == '-' || c == '_' || c == '.' || c == '~') {
      encoded += static_cast<char>(c);
    } else {
      encoded += '%';
      encoded += hex[c >> 4];
      encoded += hex[c & 0x0F];
    }
  }
  return encoded;
}

bool telegramIsConfigured() {
  return String(TELEGRAM_BOT_TOKEN) != "YOUR_BOT_TOKEN" &&
         String(TELEGRAM_CHAT_ID) != "YOUR_CHAT_ID";
}

bool sendTelegramMessage(const String &message) {
  if (WiFi.status() != WL_CONNECTED || !telegramIsConfigured()) return false;

  WiFiClientSecure client;
  client.setInsecure();
  HTTPClient https;
  const String url = String("https://api.telegram.org/bot") + TELEGRAM_BOT_TOKEN +
                     "/sendMessage?chat_id=" + urlEncode(TELEGRAM_CHAT_ID) +
                     "&text=" + urlEncode(message);
  if (!https.begin(client, url)) return false;
  const int httpCode = https.GET();
  https.end();
  return httpCode == HTTP_CODE_OK;
}

void connectWiFi() {
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  Serial.print("Connecting to Wi-Fi");
  const unsigned long startMs = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - startMs < 20000UL) {
    delay(250);
    Serial.print('.');
  }
  Serial.println();
  if (WiFi.status() == WL_CONNECTED) {
    Serial.print("Wi-Fi connected. IP: ");
    Serial.println(WiFi.localIP());
  } else {
    Serial.println("Wi-Fi not connected; local alarm works and Telegram will retry on the next event.");
  }
}

void startAlarm() {
  digitalWrite(BUZZER_PIN, HIGH);
  buzzerOn = true;
  buzzerStartedMs = millis();
}

void updateBuzzer() {
  if (buzzerOn && millis() - buzzerStartedMs >= BUZZ_DURATION_MS) {
    digitalWrite(BUZZER_PIN, LOW);
    buzzerOn = false;
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(PIR_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  digitalWrite(BUZZER_PIN, LOW);
  connectWiFi();
  Serial.println("Motion alarm ready. Let the PIR settle for 30-60 seconds after power-up.");
}

void loop() {
  updateBuzzer();
  const bool motionNow = digitalRead(PIR_PIN) == HIGH;
  const unsigned long now = millis();

  if (motionNow && !previousMotion && now - lastAlertMs >= ALERT_COOLDOWN_MS) {
    lastAlertMs = now;
    startAlarm();
    Serial.println("Motion detected: alarm started.");
    if (sendTelegramMessage("Motion detected by your ESP32 security alarm.")) {
      Serial.println("Telegram alert sent.");
    } else {
      Serial.println("Telegram alert not sent. Check Wi-Fi, token, chat ID, and start the bot chat.");
    }
  }
  previousMotion = motionNow;

  static unsigned long lastReconnectMs = 0;
  if (WiFi.status() != WL_CONNECTED && now - lastReconnectMs >= 30000UL) {
    lastReconnectMs = now;
    WiFi.disconnect();
    WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  }
  delay(20);
}