/*
  NTC Thermistor for ESP32 - Child Fever Monitor
  With WiFi, Telegram Bot alerts (loud/urgent) every X minutes while fever persists

  Alert behavior: Sends urgent loud Telegram notification every ALERT_INTERVAL_MINUTES
                  while temperature stays above 38°C
*/

#include <Thermistor.h>
#include <NTC_Thermistor.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <UrlEncode.h>  // Install "URLEncode" by Masood Farquhar from Library Manager

// ============================================================
//   CONFIGURE THESE BEFORE UPLOADING
// ============================================================

// WiFi credentials
const char* WIFI_SSID     = "BS Home1";
const char* WIFI_PASSWORD = "0554418546";

// Telegram Bot - get token from @BotFather, Chat ID from @userinfobot
const String BOT_TOKEN = "8214034828:AAFgHIVpbouWFLBrkr4wVHQSZJFZK9y0NB0";    // e.g. "123456789:ABCDefgh..."
const String CHAT_ID   = "985890015";      // e.g. "987654321"

// How often to re-send the alert while fever persists (in minutes)
#define ALERT_INTERVAL_MINUTES  5

// ============================================================
//   THERMISTOR CONFIG
// ============================================================
#define SENSOR_PIN              D1
#define REFERENCE_RESISTANCE    100000
#define NOMINAL_RESISTANCE      100000
#define NOMINAL_TEMPERATURE     25
#define B_VALUE                 3380
#define ESP32_ANALOG_RESOLUTION 4095
#define ESP32_ADC_VREF_MV       3300
#define NUM_SAMPLES             100

// ============================================================
//   FEVER THRESHOLDS
// ============================================================
#define FEVER_THRESHOLD       33.0   // Alert above this (°C)
#define FEVER_RESET_THRESHOLD 32.5   // Re-arm alert below this (°C)

// ============================================================

Thermistor* thermistor;

unsigned long lastAlertTime   = 0;       // Timestamp of last alert sent
bool          inFeverEpisode  = false;   // True while child is in fever
unsigned long alertIntervalMs = (unsigned long)ALERT_INTERVAL_MINUTES * 60UL * 1000UL;

// -------------------------------------------------------
// WiFi Connection
// -------------------------------------------------------
void connectWiFi() {
  Serial.print("Connecting to WiFi: ");
  Serial.println(WIFI_SSID);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  int attempts = 0;
  while (WiFi.status() != WL_CONNECTED && attempts < 30) {
    delay(500);
    Serial.print(".");
    attempts++;
  }

  if (WiFi.status() == WL_CONNECTED) {
    Serial.println("\nWiFi connected! IP: " + WiFi.localIP().toString());
  } else {
    Serial.println("\nWiFi connection FAILED. Will retry later.");
  }
}

// -------------------------------------------------------
// Send Urgent Telegram Message
// notification_sound = 1  → loud/default sound
// protect_content    = false so user can forward/screenshot
//
// Telegram's "critical" loud alert is achieved by using
// sendMessage with disable_notification=false (default) AND
// sending a second "pinned" copy so it banner-alerts even
// when phone is on silent (via pinChatMessage).
// -------------------------------------------------------
bool sendTelegramUrgentMessage(String message, double tempValue) {
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("[Telegram] Not connected to WiFi, skipping.");
    return false;
  }

  HTTPClient http;

  // --- Step 1: Send the message ---
  String url = "https://api.telegram.org/bot" + BOT_TOKEN +
               "/sendMessage"
               "?chat_id=" + CHAT_ID +
               "&text=" + urlEncode(message) +
               "&parse_mode=HTML"
               "&disable_notification=false";  // Ensures sound/vibration

  http.begin(url);
  int httpCode = http.GET();
  String response = http.getString();
  http.end();

  if (httpCode != 200) {
    Serial.println("[Telegram] Message failed. HTTP: " + String(httpCode));
    Serial.println("[Telegram] Response: " + response);
    return false;
  }

  Serial.println("[Telegram] Urgent message sent.");

  // --- Step 2: Extract message_id from response to pin it ---
  // Simple parse: find "message_id": in the JSON response
  int idIndex = response.indexOf("\"message_id\":");
  if (idIndex != -1) {
    int idStart  = idIndex + 13; // length of "message_id":
    int idEnd    = response.indexOf(',', idStart);
    if (idEnd == -1) idEnd = response.indexOf('}', idStart);
    String messageId = response.substring(idStart, idEnd);
    messageId.trim();

    // --- Step 3: Pin the message so it triggers a loud banner ---
    String pinUrl = "https://api.telegram.org/bot" + BOT_TOKEN +
                    "/pinChatMessage"
                    "?chat_id=" + CHAT_ID +
                    "&message_id=" + messageId +
                    "&disable_notification=false"; // Loud pin notification

    http.begin(pinUrl);
    int pinCode = http.GET();
    http.end();

    if (pinCode == 200) {
      Serial.println("[Telegram] Message pinned (loud banner triggered).");
    } else {
      Serial.println("[Telegram] Pin failed. HTTP: " + String(pinCode));
    }
  }

  return true;
}

// -------------------------------------------------------
// Build and dispatch the fever alert
// -------------------------------------------------------
void sendFeverAlert(double celsius, bool isRepeat) {
  unsigned long minutesInFever = inFeverEpisode
    ? (millis() - lastAlertTime + alertIntervalMs) / 60000UL
    : 0;

  String repeatNote = isRepeat
    ? "⏱️ Fever ongoing for at least <b>" + String(ALERT_INTERVAL_MINUTES) + " more minutes</b>.\n"
    : "";

  String msg = "🚨 <b>FEVER ALERT" + String(isRepeat ? " (ONGOING)" : "") + "!</b>\n\n"
               "🌡️ Temperature: <b>" + String(celsius, 1) + " °C</b>\n" +
               repeatNote +
               "⚠️ Please check on the child <b>immediately!</b>\n\n"
               "📍 ESP32 Fever Monitor";

  sendTelegramUrgentMessage(msg, celsius);
  lastAlertTime = millis();
}

// -------------------------------------------------------
// Average Thermistor Reading
// -------------------------------------------------------
double readAverageCelsius() {
  double sum = 0.0;
  for (int i = 0; i < NUM_SAMPLES; i++) {
    sum += thermistor->readCelsius();
    delay(2);
  }
  return sum / NUM_SAMPLES;
}

// -------------------------------------------------------
// Setup
// -------------------------------------------------------
void setup() {
  Serial.begin(115200);
  delay(1000);

  Serial.println("=== Child Fever Monitor ===");
  Serial.println("Alert interval: every " + String(ALERT_INTERVAL_MINUTES) + " min while fever > " + String(FEVER_THRESHOLD) + "°C");
  Serial.println("---------------------------");

  thermistor = new NTC_Thermistor_ESP32(
    SENSOR_PIN,
    REFERENCE_RESISTANCE,
    NOMINAL_RESISTANCE,
    NOMINAL_TEMPERATURE,
    B_VALUE,
    ESP32_ADC_VREF_MV,
    ESP32_ANALOG_RESOLUTION
  );

  connectWiFi();
}

// -------------------------------------------------------
// Main Loop
// -------------------------------------------------------
void loop() {
  // Reconnect WiFi if dropped
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("WiFi lost, reconnecting...");
    connectWiFi();
  }

  // Read temperature
  const double celsius    = readAverageCelsius();
  const double kelvin     = celsius + 273.15;
  const double fahrenheit = (celsius * 9.0 / 5.0) + 32.0;

  // Serial output
  Serial.print("Temp: ");
  Serial.print(celsius, 2);
  Serial.print(" °C | ");
  Serial.print(kelvin, 2);
  Serial.print(" K | ");
  Serial.print(fahrenheit, 2);
  Serial.print(" °F");

  // --- Fever Detection Logic ---
  if (celsius >= FEVER_THRESHOLD) {
    unsigned long now = millis();
    bool timeToAlert  = (lastAlertTime == 0) || (now - lastAlertTime >= alertIntervalMs);

    if (timeToAlert) {
      Serial.println("  🚨 FEVER! Sending urgent alert...");
      sendFeverAlert(celsius, inFeverEpisode); // isRepeat=true if already in episode
      inFeverEpisode = true;
    } else {
      // Show countdown to next alert
      unsigned long secondsLeft = (alertIntervalMs - (now - lastAlertTime)) / 1000UL;
      Serial.print("  🔴 Fever persists. Next alert in: ");
      Serial.print(secondsLeft);
      Serial.print("s");
    }

  } else if (celsius < FEVER_RESET_THRESHOLD && inFeverEpisode) {
    // Fever broke — send recovery notification and reset
    Serial.print("  ✅ Fever cleared!");
    inFeverEpisode = false;
    lastAlertTime  = 0;

    String recoveryMsg = "✅ <b>Fever Cleared</b>\n\n"
                         "Temperature is now <b>" + String(celsius, 1) + " °C</b>\n"
                         "Back in the normal range. 😊\n\n"
                         "📍 ESP32 Fever Monitor";
    sendTelegramUrgentMessage(recoveryMsg, celsius);

  } else {
    Serial.print("  ✅ Normal.");
  }

  Serial.println();
  delay(500);
}