#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <HX711.h>
#include <EEPROM.h>

// Pin definitions
#define DOUT  4
#define CLK  3

// EEPROM addresses
#define EEPROM_ITEM_NAME 0
#define EEPROM_ITEM_CODE 20
#define EEPROM_ITEM_WEIGHT 40
#define EEPROM_REORDER_LIMIT 44
#define EEPROM_BIN_WEIGHT 48

// HX711
HX711 scale;

// LCD
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Variables
const float calibration=2.380;
const char pass[4] = "1234";
char itemName[20];
char itemCode[8];
float itemWeight;
int reorderLimit;
float binWeight;
float currentWeight;
int numberOfItems;
long timer;
bool limiter = false;

void setup() {
  Serial.begin(9600);
  Serial.print("Enter code: ");

  // Initialize LCD
  lcd.init();
  lcd.backlight();

  // Initialize HX711
  scale.begin(DOUT, CLK);

  // Load data from EEPROM
  EEPROM.get(EEPROM_ITEM_NAME, itemName);
  EEPROM.get(EEPROM_ITEM_CODE, itemCode);
  //EEPROM.get(EEPROM_ITEM_WEIGHT, itemWeight);
  EEPROM.get(EEPROM_REORDER_LIMIT, reorderLimit);
  //EEPROM.get(EEPROM_BIN_WEIGHT, binWeight);

  updateDisplay();
}

void loop() {
  if (Serial.available() > 0) {
    char code[4];
    readSerialString(code, 6);
    Serial.println(code);
    if (pass[0] == code[0])
      if (pass[1] == code[1])
        if (pass[2] == code[2])
          if (pass[3] == code[3])
          {

            Serial.println("Setting Mode");
            handleSerialInput();
          }
          else
          {
            Serial.println("Wrong password!");
            Serial.print("Enter Code: ");
          }
        else
        {
          Serial.println("Wrong password!");
          Serial.print("Enter Code: ");
        }
      else
      {
        Serial.println("Wrong password!");
        Serial.print("Enter Code: ");
      }
    else
    {
      Serial.println("Wrong password!");
      Serial.print("Enter Code: ");
    }
  }

  currentWeight = ((scale.get_units(10)*calibration) - binWeight);
  numberOfItems = (int)(currentWeight / itemWeight);

  updateDisplay();

  if (numberOfItems < reorderLimit) {
    if (timer < millis() - 4000)
    {
      lcd.noBacklight();
      timer = millis();
      limiter = true;
    }
    if (limiter == true)
    {
      if (timer < millis() - 1000)
      {
        lcd.backlight();
        limiter = false;
        timer = millis();
      }
    }
  } else {
    lcd.backlight();
  }
}


void updateDisplay() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Item: ");
  lcd.print(itemName);
  lcd.setCursor(0, 1);
  lcd.print("Code: ");
  lcd.print(itemCode);
  lcd.setCursor(0, 2);
  lcd.print("Reorder Limit: ");
  lcd.print(reorderLimit);
  lcd.setCursor(0, 3);
  lcd.print("Items: ");
  lcd.print(numberOfItems);
  lcd.print(" Wt: ");
  lcd.print(currentWeight, 1);
  lcd.print("g");
}

void handleSerialInput() {
  Serial.print("Enter item name:");
  readSerialString(itemName, 20);
  Serial.println(itemName);
  EEPROM.put(EEPROM_ITEM_NAME, itemName);

  Serial.print("Enter item code:");
  readSerialString(itemCode, 8);
  Serial.println(itemCode);
  EEPROM.put(EEPROM_ITEM_CODE, itemCode);

  Serial.print("Enter item weight (g):");
  itemWeight = readSerialFloat();
  Serial.println(itemWeight);
  EEPROM.put(EEPROM_ITEM_WEIGHT, itemWeight);

  Serial.print("Enter reorder limit:");
  reorderLimit = readSerialInt();
  Serial.println(reorderLimit);
  EEPROM.put(EEPROM_REORDER_LIMIT, reorderLimit);

  Serial.print("Enter bin weight (g):");
  binWeight = readSerialFloat();
  Serial.println(binWeight);
  EEPROM.put(EEPROM_BIN_WEIGHT, binWeight);
  Serial.println("Settings Completed");
  Serial.print("Enter Code: ");
  updateDisplay();
}

void readSerialString(char* buffer, int length) {
  int index = 0;
  while (index < length - 1) {
    if (Serial.available() > 0) {
      char c = Serial.read();
      if (c == '\n') {
        break;
      }
      buffer[index++] = c;
    }
  }
  buffer[index] = '\0';
  Serial.flush();
  delay(200);
}

float readSerialFloat() {
  while(Serial.available())
  Serial.read();
  while (!Serial.available()) { }
  float las=Serial.parseFloat();
  Serial.flush();
  delay(200);
  return las;
}

int readSerialInt() {
  while(Serial.available())
  Serial.read();
  while (Serial.available() == 0) { }
  int las= Serial.parseInt();
  Serial.flush();
  delay(200);
  return las;
}