#include <Wire.h>

#define DHTPIN 2
#define DHTTYPE DHT22
#define PULSE_PIN A0
#define SLOT1_BTN 3
#define SLOT2_BTN 4
#define BUZZER_PIN 5

#define LCD_ADDR 0x27
#define LCD_BACKLIGHT 0x08
#define LCD_ENABLE 0x04
#define LCD_RS 0x01

const unsigned long DOSE_INTERVAL = 20000;
const unsigned long RESPONSE_WINDOW = 8000;
const unsigned long VITALS_CHECK_INTERVAL = 5000;

unsigned long lastDoseTime = 0;
unsigned long doseWindowStart = 0;
bool doseWindowActive = false;
unsigned long lastVitalsCheck = 0;

const int TEMP_HIGH = 38;
const int HR_LOW = 60;
const int HR_HIGH = 100;

bool readDHT22(int &tempC) {
  uint8_t data[5] = {0, 0, 0, 0, 0};

  pinMode(DHTPIN, OUTPUT);
  digitalWrite(DHTPIN, LOW);
  delay(2);
  digitalWrite(DHTPIN, HIGH);
  delayMicroseconds(30);
  pinMode(DHTPIN, INPUT_PULLUP);

  unsigned long t = micros();
  while (digitalRead(DHTPIN) == HIGH) { if (micros() - t > 100) return false; }
  t = micros();
  while (digitalRead(DHTPIN) == LOW) { if (micros() - t > 100) return false; }
  t = micros();
  while (digitalRead(DHTPIN) == HIGH) { if (micros() - t > 100) return false; }

  for (int i = 0; i < 40; i++) {
    t = micros();
    while (digitalRead(DHTPIN) == LOW) { if (micros() - t > 100) return false; }
    t = micros();
    while (digitalRead(DHTPIN) == HIGH) { if (micros() - t > 100) return false; }
    unsigned long len = micros() - t;
    data[i / 8] <<= 1;
    if (len > 40) data[i / 8] |= 1;
  }

  uint8_t checksum = data[0] + data[1] + data[2] + data[3];
  if (checksum != data[4]) return false;

  int rawTemp = ((data[2] & 0x7F) << 8) | data[3];
  tempC = rawTemp / 10;
  if (data[2] & 0x80) tempC = -tempC;
  return true;
}

void lcdWrite4(uint8_t nibble, uint8_t rs) {
  uint8_t data = (nibble & 0xF0) | LCD_BACKLIGHT | (rs ? LCD_RS : 0);
  Wire.beginTransmission(LCD_ADDR);
  Wire.write(data | LCD_ENABLE);
  Wire.endTransmission();
  delayMicroseconds(1);
  Wire.beginTransmission(LCD_ADDR);
  Wire.write(data & ~LCD_ENABLE);
  Wire.endTransmission();
  delayMicroseconds(50);
}

void lcdSend(uint8_t value, uint8_t rs) {
  lcdWrite4(value & 0xF0, rs);
  lcdWrite4((value << 4) & 0xF0, rs);
}

void lcdCommand(uint8_t cmd) { lcdSend(cmd, 0); }
void lcdChar(uint8_t c) { lcdSend(c, 1); }

void lcdInit() {
  delay(50);
  lcdWrite4(0x30, 0); delay(5);
  lcdWrite4(0x30, 0); delayMicroseconds(150);
  lcdWrite4(0x30, 0);
  lcdWrite4(0x20, 0);
  lcdCommand(0x28); 
  lcdCommand(0x0C); 
  lcdCommand(0x06); 
  lcdCommand(0x01); 
  delay(2);
}

void lcdClear() { lcdCommand(0x01); delay(2); }

void lcdSetCursor(uint8_t col, uint8_t row) {
  uint8_t rowOffsets[] = {0x00, 0x40};
  lcdCommand(0x80 | (col + rowOffsets[row]));
}

void lcdPrint(const char* str) {
  while (*str) lcdChar(*str++);
}



void beep(int freqHz, int durationMs) {
  unsigned long periodUs = 1000000UL / freqHz;
  unsigned long halfPeriodUs = periodUs / 2;
  unsigned long cycles = (unsigned long)durationMs * 1000UL / periodUs;
  for (unsigned long i = 0; i < cycles; i++) {
    digitalWrite(BUZZER_PIN, HIGH);
    delayMicroseconds(halfPeriodUs);
    digitalWrite(BUZZER_PIN, LOW);
    delayMicroseconds(halfPeriodUs);
  }
}

void setup() {
  Wire.setSDA(PB7);
  Wire.setSCL(PB6);
  Wire.begin();
  lcdInit();
  pinMode(SLOT1_BTN, INPUT_PULLUP);
  pinMode(SLOT2_BTN, INPUT_PULLUP);
  pinMode(BUZZER_PIN, OUTPUT);

  lcdSetCursor(0, 0);
  lcdPrint("System ready");
  delay(1000);
  lcdClear();
}

void loop() {
  unsigned long now = millis();

  if (now - lastVitalsCheck >= VITALS_CHECK_INTERVAL) {
    lastVitalsCheck = now;
    checkVitals();
  }

  if (!doseWindowActive && (now - lastDoseTime >= DOSE_INTERVAL)) {
    startDoseReminder();
  }

  if (doseWindowActive) {
    handleDoseWindow(now);
  }
}

void checkVitals() {
  int temp = 25; 
  readDHT22(temp);
  int hrRaw = analogRead(PULSE_PIN);
  int heartRate = map(hrRaw, 0, 4095, 50, 130);

  bool abnormal = false;
  if (temp > TEMP_HIGH) abnormal = true;
  if (heartRate < HR_LOW || heartRate > HR_HIGH) abnormal = true;

  if (abnormal) {
    lcdClear();
    lcdSetCursor(0, 0);
    lcdPrint("Abnormal vitals!");
    lcdSetCursor(0, 1);
    lcdPrint("Alerting caregvr");
    triggerAlertTone();
  }

  sendData(temp, heartRate, -1);
}

void startDoseReminder() {
  lastDoseTime = millis();
  doseWindowStart = millis();
  doseWindowActive = true;

  lcdClear();
  lcdSetCursor(0, 0);
  lcdPrint("Time for meds!");
  lcdSetCursor(0, 1);
  lcdPrint("Remove pill now");
  beep(1000, 300);
}

void handleDoseWindow(unsigned long now) {
  bool slot1Taken = (digitalRead(SLOT1_BTN) == LOW);
  bool slot2Taken = (digitalRead(SLOT2_BTN) == LOW);

  if (slot1Taken || slot2Taken) {
    lcdClear();
    lcdSetCursor(0, 0);
    lcdPrint("Dose confirmed");
    beep(1500, 200);
    doseWindowActive = false;
    sendData(-1, -1, 1);
    delay(1000);
    lcdClear();
    return;
  }

  if (now - doseWindowStart >= RESPONSE_WINDOW) {
    lcdClear();
    lcdSetCursor(0, 0);
    lcdPrint("Missed dose!");
    lcdSetCursor(0, 1);
    lcdPrint("Caregiver alert");
    triggerAlertTone();
    doseWindowActive = false;
    sendData(-1, -1, 0);
  }
}

void triggerAlertTone() {
  for (int i = 0; i < 3; i++) {
    beep(2000, 200);
    delay(300);
  }
}


void sendData(int temp, int hr, int doseStatus) {
  (void)temp; (void)hr; (void)doseStatus; 
}