#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <Servo.h>

// --- Pin Definitions ---
#define DHT_PIN 2
#define ONEWIRE_BUS_PIN 3
#define SERVO_PIN 9
#define BTN1_PIN 4        // 60 degrees
#define BTN2_PIN 5        // 90 degrees
#define BTN3_PIN 6        // 180 degrees
#define BTN4_PIN 7        // Toggle Sweep Mode

// --- Component Initializations ---
LiquidCrystal_I2C lcd(0x27, 16, 2);
#define DHT_TYPE DHT22
DHT dht(DHT_PIN, DHT_TYPE);
OneWire oneWire(ONEWIRE_BUS_PIN);
DallasTemperature sensors(&oneWire);
Servo myServo;

// --- Timers and State Variables ---
// For passive display
unsigned long previousDisplayMillis = 0;
const long displayInterval = 5000;
int displayState = 0;

// For servo sweep mode
bool isSweeping = false;
unsigned long previousServoMillis = 0;
const int servoInterval = 15; // ms delay between servo steps
int servoPos = 0;
int servoDirection = 1; // 1 for forward, -1 for backward

void setup() {
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("System Ready!");

  dht.begin();
  sensors.begin();

  myServo.attach(SERVO_PIN);
  myServo.write(0);
  delay(1500);

  // Initialize all buttons
  pinMode(BTN1_PIN, INPUT_PULLUP);
  pinMode(BTN2_PIN, INPUT_PULLUP);
  pinMode(BTN3_PIN, INPUT_PULLUP);
  pinMode(BTN4_PIN, INPUT_PULLUP);
}

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

  handleButtons(); // Check for any button presses
  handleServoSweep(currentMillis); // Handle sweep motion if active
  handlePassiveDisplay(currentMillis); // Handle sensor display
}

// --- Main Logic Functions ---

void handleButtons() {
  if (digitalRead(BTN1_PIN) == LOW) {
    isSweeping = false; // Stop sweeping if active
    myServo.write(60);  // Directly control the servo
    delay(50);          // Simple debounce
  }
  if (digitalRead(BTN2_PIN) == LOW) {
    isSweeping = false;
    myServo.write(90);
    delay(50);
  }
  if (digitalRead(BTN3_PIN) == LOW) {
    isSweeping = false;
    myServo.write(180);
    delay(50);
  }
  if (digitalRead(BTN4_PIN) == LOW) {
    isSweeping = !isSweeping; // Toggle sweep mode
    delay(100); // Simple debounce to prevent rapid toggling
  }
}

void handleServoSweep(unsigned long currentMillis) {
  if (isSweeping) {
    if (currentMillis - previousServoMillis >= servoInterval) {
      previousServoMillis = currentMillis;

      servoPos = servoPos + servoDirection;
      myServo.write(servoPos);

      // Reverse direction at the ends
      if (servoPos <= 0 || servoPos >= 180) {
        servoDirection *= -1; // Flips between 1 and -1
      }
    }
  }
}

void handlePassiveDisplay(unsigned long currentMillis) {
  // Check if it's time to switch the display, REGARDLESS of sweep mode
  if (currentMillis - previousDisplayMillis >= displayInterval) {
    previousDisplayMillis = currentMillis;
    displayState = !displayState;

    if (displayState == 0) {
      displayDHT22();
    } else {
      displayDS18B20();
    }
  }
}

// --- Display Functions ---

void displayDHT22() {
  float h = dht.readHumidity();
  float t = dht.readTemperature();

  if (isnan(h) || isnan(t)) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("DHT22 Read Err");
    return;
  }

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Humidity & Temp");
  lcd.setCursor(0, 1);
  lcd.print("T:");
  lcd.print(t, 1);
  lcd.print((char)223);
  lcd.print("C H:");
  lcd.print(h, 1);
  lcd.print("%");
}

void displayDS18B20() {
  sensors.requestTemperatures();
  float tempC = sensors.getTempCByIndex(0);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Probe Temp");
  
  if (tempC == DEVICE_DISCONNECTED_C) {
    lcd.setCursor(0,1);
    lcd.print("Sensor Error");
    return;
  }
  
  lcd.setCursor(0, 1);
  lcd.print("Temp: ");
  lcd.print(tempC, 2);
  lcd.print((char)223);
  lcd.print("C");
}