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

// Wi-Fi credentials for Wokwii
const char* ssid = "Wokwi-GUEST";
const char* password = "";

// ThingSpeak settings
String apiKey = "9H07YXCDRDA5NARD";
const char* server = "http://api.thingspeak.com/update";

// Pins
const int attendanceButtonPin = 15;  // Button to mark attendance
const int resetButtonPin = 16;       // Button to reset session
const int ledPin = 2;                // Confirmation LED
const int buzzerPin = 4;             // Confirmation buzzer

// System variables
bool attendanceMarked = false;
int attendanceCount = 0;
const int expectedStudents = 5;      // Simulated class size for percentage calculation

// Button state tracking for edge detection
int lastAttendanceButtonState = HIGH;
int lastResetButtonState = HIGH;

// Time settings for Uganda 
const long gmtOffset_sec = 3 * 3600;
const int daylightOffset_sec = 0;

// Send heartbeat data every 20 seconds
unsigned long lastSendTime = 0;
const unsigned long sendInterval = 20000;

// Connect to Wi-Fi
void connectWiFi() {
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");

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

  Serial.println("\nWiFi connected");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
}

// Sync time using NTP
void syncTime() {
  configTime(gmtOffset_sec, daylightOffset_sec, "pool.ntp.org", "time.nist.gov");

  struct tm timeinfo;
  while (!getLocalTime(&timeinfo)) {
    Serial.println("Waiting for time sync...");
    delay(1000);
  }

  Serial.println("Time synchronized");
}

// Get current hour and minute
bool getCurrentTime(int &hourNow, int &minuteNow) {
  struct tm timeinfo;
  if (!getLocalTime(&timeinfo)) {
    return false;
  }

  hourNow = timeinfo.tm_hour;
  minuteNow = timeinfo.tm_min;
  return true;
}

// Simple rule-based "AI" risk score
int calculateRiskScore() {
  int hourNow, minuteNow;

  if (!getCurrentTime(hourNow, minuteNow)) {
    return 0; // If time is unavailable, keep it safe
  }

  float attendanceRate = (attendanceCount * 100.0) / expectedStudents;

  // Example class schedule: 8:00 AM
  if (hourNow < 8) {
    return 0; // Class has not started
  }

  if (hourNow == 8 && minuteNow <= 15) {
    return (attendanceRate < 60.0) ? 1 : 0;
  }

  if (hourNow == 8 && minuteNow > 15) {
    return (attendanceRate < 80.0) ? 1 : 0;
  }

  if (hourNow > 8 && hourNow < 10) {
    return (attendanceRate < 80.0) ? 1 : 0;
  }

  return (attendanceRate < 60.0) ? 1 : 0;
}

// Send data to ThingSpeak
void sendToThingSpeak(int riskScore) {
  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("WiFi not connected");
    return;
  }

  float attendanceRate = (attendanceCount * 100.0) / expectedStudents;
  int hourNow, minuteNow;
  getCurrentTime(hourNow, minuteNow);

  HTTPClient http;
  String url = String(server) +
               "?api_key=" + apiKey +
               "&field1=" + String(attendanceCount) +
               "&field2=" + String(attendanceRate, 1) +
               "&field3=" + String(riskScore) +
               "&field4=" + String(hourNow * 100 + minuteNow);

  http.begin(url);
  int httpResponseCode = http.GET();

  Serial.print("ThingSpeak HTTP response: ");
  Serial.println(httpResponseCode);

  http.end();
}

void setup() {
  Serial.begin(115200);

  pinMode(attendanceButtonPin, INPUT_PULLUP);
  pinMode(resetButtonPin, INPUT_PULLUP);
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);

  digitalWrite(ledPin, LOW);
  digitalWrite(buzzerPin, LOW);

  connectWiFi();
  syncTime();

  Serial.println("System ready");
  sendToThingSpeak(0); // send initial status
}

void loop() {
  int attendanceButtonState = digitalRead(attendanceButtonPin);
  int resetButtonState = digitalRead(resetButtonPin);

  // Attendance button: detect new press only
  if (attendanceButtonState == LOW && lastAttendanceButtonState == HIGH) {
    if (!attendanceMarked) {
      attendanceMarked = true;
      attendanceCount++;

      digitalWrite(ledPin, HIGH);
      digitalWrite(buzzerPin, HIGH);
      delay(200);
      digitalWrite(buzzerPin, LOW);

      Serial.println("Attendance Marked");

      int riskScore = calculateRiskScore();
      sendToThingSpeak(riskScore);
    } else {
      Serial.println("Duplicate Ignored");
    }
  }

  // Reset button: start a new class/day
  if (resetButtonState == LOW && lastResetButtonState == HIGH) {
    attendanceMarked = false;
    attendanceCount = 0;
    digitalWrite(ledPin, LOW);

    Serial.println("New session started");

    int riskScore = calculateRiskScore();
    sendToThingSpeak(riskScore);
  }

  // Heartbeat update every 20 seconds
  if (millis() - lastSendTime >= sendInterval) {
    lastSendTime = millis();
    int riskScore = calculateRiskScore();
    sendToThingSpeak(riskScore);
  }

  lastAttendanceButtonState = attendanceButtonState;
  lastResetButtonState = resetButtonState;

  delay(20);
}