#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include "loadingAnimation.h"

#define DHTPIN 4               // DHT sensor pin
#define DHTTYPE DHT11
#define BUTTON_PIN 2           // Button pin
#define DEBOUNCE_DELAY 50      // Short delay for debounce
#define HOLD_DELAY 1000        // Hold delay to enter submenu (1 second)

LiquidCrystal_I2C lcd(0x27, 16, 2);
DHT dht(DHTPIN, DHTTYPE);

byte customChar[] = {
  B01010,
  B10101,
  B01010,
  B10101,
  B01010,
  B10101,
  B01010,
  B10101
};

enum MenuState { MENU, SUBMENU };
MenuState currentState = MENU;

const char* menuItems[] = {"Temperature", "Humidity", "Option 1", "Message"};
int selectedItem = 0;
unsigned long buttonPressStart = 0; // Tracks the start time of a button press
bool buttonHeld = false;

void clearSerialBuffer(); 

void setup() {
  lcd.begin(16, 2);
  lcd.backlight();
  Serial.begin(9600); // Start serial communication at 9600 baud
  lcd.createChar(0, customChar);
  dht.begin();

  pinMode(BUTTON_PIN, INPUT_PULLUP);  // Button with internal pull-up resistor
  loadingAnimation(lcd);

  lcd.clear();
  displayMenu();
}

void loop() {
  int buttonState = digitalRead(BUTTON_PIN);

  if (buttonState == LOW) {
    // Button is pressed; check for long hold
    if (buttonPressStart == 0) {
      buttonPressStart = millis();  // Record the time the button was first pressed
    }

    // Check if button is held
    if (!buttonHeld && millis() - buttonPressStart > HOLD_DELAY) {
      buttonHeld = true;
      handleButtonHold();
    }
  } else {
    // Button released
    if (buttonHeld) {
      // Reset hold state on release
      buttonHeld = false;
    } else if (buttonPressStart != 0 && millis() - buttonPressStart < HOLD_DELAY) {
      // If it was a short press, handle as a normal press
      handleButtonPress();
    }

    // Reset button press start time 
    buttonPressStart = 0;
  }

  // Check for real-time updates in specific submenus
  if (currentState == SUBMENU) {
    switch (selectedItem) {
      case 0:  // Temperature submenu
        displayTemperature();
        break;
      case 1:  // Humidity submenu
        displayHumidity();
        break;
      case 3:  // Message submenu
        readFromLCD(); // Continuously read data while in "Message" submenu
        break;
    }
  }

  delay(DEBOUNCE_DELAY);
}

void handleButtonPress() {
  if (currentState == MENU) {
    // Move the ">" indicator down to the next item
    selectedItem = (selectedItem + 1) % (sizeof(menuItems) / sizeof(menuItems[0]));
    displayMenu();
  }
}

void handleButtonHold() {
  if (currentState == MENU) {
    // Enter the selected submenu
    currentState = SUBMENU;
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("< Main Menu");

    // Show specific information for Temperature, Humidity, or read message
    switch (selectedItem) {
      case 0:
        displayTemperature();
        break;
      case 1:
        displayHumidity();
        break;
      case 2:
        displayHumidity(); // Assuming this is intentional; adjust as needed
        break;
      case 3:
        readFromLCD();     
        break;
    }
  } else {
    // Return to main menu
    currentState = MENU;
    displayMenu();
  }
}

void displayMenu() {
  lcd.clear();
  for (int i = 0; i < 2; i++) {  // Display 2 lines at a time
    int index = (selectedItem + i) % (sizeof(menuItems) / sizeof(menuItems[0]));
    lcd.setCursor(0, i);
    lcd.print((i == 0) ? "> " : "  ");
    lcd.print(menuItems[index]);
  }
}

void displayTemperature() {
  lcd.setCursor(0, 1);
  float temperature = dht.readTemperature();
  if (isnan(temperature)) {
    lcd.print("Sensor error!   ");
  } else {
    lcd.print("Temp: ");
    lcd.print(temperature);
    lcd.print("\xDF""C    "); // Clear any leftover characters
  }
}

void displayHumidity() {
  lcd.setCursor(0, 1);
  float humidity = dht.readHumidity();
  if (isnan(humidity)) {
    lcd.print("Sensor error!   ");
  } else {
    lcd.print("Hum: ");
    lcd.print(humidity);
    lcd.print("%    "); // Clear any leftover characters
  }
}

void readFromLCD() {
  if (Serial.available() > 0) {
    lcd.setCursor(0, 1);
    lcd.print("                "); // Clear the previous message
    
    // Read new input
    String input = Serial.readStringUntil('\n');  // Read until newline character
    lcd.setCursor(0, 1); // Set cursor back to the second line
    lcd.print(input); // Print the new input
  }
}

void serialFlush(){
  while(Serial.available() > 0) {
    char t = Serial.read();
  }
}