#include <WiFi.h>
#include <PubSubClient.h>
#include <HTTPClient.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <HX711.h>
#include <SD.h>
#include <SPI.h>

// OLED
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

// Sensor pins
#define ECG_PIN 36
#define ONE_WIRE_BUS 4
#define DOUT 25
#define CLK 26
#define HR_PIN 35
#define SPO2_PIN 32
#define SYS_PIN 33
#define DIA_PIN 34
#define MOTION_PIN 14

// Buzzer & LED
#define BUZZER_PIN 13
#define LED_PIN 12

// SD card
#define SD_CS 5

// WiFi / MQTT / ThingSpeak
const char* ssid = "Wokwi-GUEST";
const char* password = "";
const char* mqttServer = "broker.hivemq.com";
const int mqttPort = 1883;
const char* patientID = "PT-001";
const char* thingspeakServer = "http://api.thingspeak.com/update";
String apiKey = "J3WIA5NRCOU54Q9I";
//object initialization
WiFiClient espClient;
PubSubClient client(espClient);
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
HX711 scale;

// Helper functions(Timestamp Funtion)
String getTimestamp() {
  char buf[20];
  sprintf(buf, "%04d-%02d-%02d %02d:%02d:%02d", 2025,8,20,22,15,0);
  return String(buf);
}
//Log to SD 
void logToSD(String line) {
  File f = SD.open("/data.csv", FILE_APPEND);
  if (f) { f.println(line); f.close(); Serial.println("Logged to SD"); }
  else Serial.println("SD write error");
}
//MQTT Reconnect
void reconnectMQTT() {
  while (!client.connected()) {
    Serial.print("Connecting to MQTT...");
    if (client.connect(patientID)) Serial.println("Connected");
    else { Serial.print("Failed, rc="); Serial.print(client.state()); Serial.println(" try again in 2s"); delay(2000); }
  }
}
//WiFi Init(WiFi connect to ESP32)
void initWiFi() {
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    Serial.print(".");
    delay(500);
  }
  Serial.println("\nWiFi connected");
}
//ThingSpeak Funtion (Patient data send to ThingSpeak)
void sendToThingSpeak(int hr, int spo2, int sys, int dia, float temp, float weight, int motion, String condition) {
  if (WiFi.status() == WL_CONNECTED) {
    HTTPClient http;
    http.begin(thingspeakServer);
    http.addHeader("Content-Type", "application/x-www-form-urlencoded");
    String post = "api_key=" + apiKey +
      "&field1=" + String(hr) +
      "&field2=" + String(spo2) +
      "&field3=" + String(sys) +
      "&field4=" + String(dia) +
      "&field5=" + String(temp, 2) +
      "&field6=" + String(weight, 2) +
      "&field7=" + String(motion) +
      "&field8=" + condition;
    int code = http.POST(post);
    if (code > 0) Serial.println("Data sent to ThingSpeak successfully");
    else Serial.println("Error sending data to ThingSpeak");
    http.end();
  } else Serial.println("WiFi not connected");
}

void setup() {
  Serial.begin(115200); //Serial Monitor on for debugging
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);  //OLED Displaye initialize
  display.clearDisplay(); display.display();
  sensors.begin(); //DS18B20 temparature sensor on
  scale.begin(DOUT, CLK); //Scale is HX711 Library Object (load cell initialize)
  scale.set_scale(2280.f); // set Calibration factor(convert ADC to kg/g)
  scale.tare();  //reset scale(measure from 0)
  //Set input/output pin mode
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
  pinMode(MOTION_PIN, INPUT);

  SPI.begin();// SD card SPI communication on
  if (!SD.begin(SD_CS)) Serial.println("SD init failed!"); //check SD card connection
  else if (!SD.exists("/data.csv")) { // check previous data.csv file
    File f = SD.open("/data.csv", FILE_WRITE); // open data.csv file in write mode
    if (f) { f.println("Timestamp,PatientID,HR,SpO2,Sys,Dia,Temp,Weight,Motions,Status"); f.close(); } //csv header file formate and .close use for save data right properly
  }
  initWiFi();  //connect ESP32 to Wifi
  client.setServer(mqttServer, mqttPort); //set MQTT broker's IP/port (use data publish/subscribe)
}
// check MQTT is connected to ESP32
void loop() {
  if (!client.connected()) reconnectMQTT();
  client.loop();
//convert Analog sensor value into Digital(0=0v and 4095=3.3v)
  int hr  = map(analogRead(HR_PIN), 0, 4095, 30, 150);  //convert sensor voltage value into bpm
  int spo2 = map(analogRead(SPO2_PIN), 0, 4095, 80, 100);  //convert Spo2 sensor voltage value into Oxygen Saturation (%)
  int sys  = map(analogRead(SYS_PIN), 0, 4095, 70, 190);  //cnvert Systolic Blood Pressure(mmHg)
  int dia  = map(analogRead(DIA_PIN), 0, 4095, 40, 120);  // convert Diastolic Blood Pressure (mmHg)
  int ecg  = analogRead(ECG_PIN); // ecg sensor read direct ADC value
  sensors.requestTemperatures(); // sensor is DallasTemperature library(request to measure temp)
  float temp = sensors.getTempCByIndex(0);// read temp in index 0 (C)
  float weight = scale.get_units(5); if (weight < 0) weight = 0;  //scale is HX711 library take 5 measurement and calculate the mean,if measure (-) value then set 0
  bool motion = digitalRead(MOTION_PIN); // PIR motion sensor. 1 motion detect. 0 no motion.
// check patient condition
  String condition = "Stable";
  if (hr < 40 || hr > 150 || spo2 < 75 || sys < 60 || dia < 40) condition = "CRITICAL";
  else if (hr < 50 || hr > 130 || spo2 < 85 || sys > 180 || dia > 110) condition = "EMERGENCY";
  else if (hr < 60 || hr > 100 || spo2 < 92 || sys > 140 || dia > 90 || temp > 37.5) condition = "WARNING";
//Alarm control
  if (condition == "CRITICAL") { tone(BUZZER_PIN, 1500); digitalWrite(LED_PIN, HIGH); } // sound in 1500 Hz Frequency
  else { noTone(BUZZER_PIN); digitalWrite(LED_PIN, LOW); }
// Show patient data in OLEd display
  display.clearDisplay();  // clear OLED Display
  display.setCursor(0, 0);  // set the writing place
  display.printf("HR:%d SpO2:%d\nBP:%d/%d\nT:%.1f W:%.1f\n ECG:%d\nStatus:%s",
    hr, spo2, sys, dia, temp, weight, condition.c_str());
  display.display();

  String payload = "{\"PatientID\":\"" + String(patientID) + "\"," +
                   "\"HR\":" + String(hr) + "," +
                   "\"SpO2\":" + String(spo2) + "," +
                   "\"Sys\":" + String(sys) + "," +
                   "\"Dia\":" + String(dia) + "," +
                   "\"ECG\":" + String(ecg) + "," +
                   "\"Temp\":" + String(temp, 2) + "," +
                   "\"Weight\":" + String(weight, 2) + "," +
                   "\"Motion\":" + String(motion) + "," +
                   "\"Status\":\"" + condition + "\"}";

  client.publish(("ICU/patient/" + String(patientID)).c_str(), payload.c_str());

  logToSD(getTimestamp() + "," + String(patientID) + "," +
          String(hr) + "," + String(spo2) + "," + String(sys) + "," +
          String(dia) + "," + String(temp, 2) + "," + String(weight, 2) + "," +
          String(motion) + "," + condition);

  Serial.println("Logged to SD");
  Serial.println("Sent: " + payload);

  sendToThingSpeak(hr, spo2, sys, dia, temp, weight, motion, condition);

  delay(2000);
}