#include "HX711_ADC.h"
#include <LiquidCrystal_I2C.h>
#include <Servo.h>

Servo myservo;
HX711_ADC LoadCell(9, 8);
HX711_ADC LoadCell2(3, 2);
LiquidCrystal_I2C lcd(0x27,16,2);
int taree = 6;   //tare
int num = 1;
int pos = 0;
bool InUse = false;
unsigned long prevTime = millis();
long Time = 1000;

void setup()
{
  pinMode (taree, INPUT_PULLUP);
  Serial.begin(9600);
  myservo.attach(7);
  lcd.init();
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Smart Litter Box");
  LoadCell.begin(); 
  LoadCell.start(1000);
  LoadCell.setCalFactor(0.42);
  LoadCell2.begin(); 
  LoadCell2.start(1000);
  LoadCell2.setCalFactor(0.42);
  lcd.clear();
}

void loop() {
  unsigned long currentTime = millis();
  static unsigned long currentTime1 = millis();
  LoadCell.update();
  LoadCell2.update();
  // i = stock weight
  float i = LoadCell.getData();
  // j is used to check whether cat litter box is in use
  // when cat enter the box it must step on a board(pressure sensor built in) in front of the box
  // after the use cat will step on that board again
  // we can use the weight change of j to judge whether the cat leave the box
  float j = LoadCell2.getData();
  switch(num){
    // show stock weight
    case 1:{
      lcd.setCursor(0, 0);
      lcd.print("Cat Litter Stock");
      lcd.setCursor(0,1);
      lcd.print("Stock: ");
      lcd.print(i, 0);
      lcd.print("g  ");
      break;
    }
    // low stock reminder
    case 2:{
      lcd.clear();
      delay(500);
      lcd.setCursor(0, 0);
      lcd.print("   Low Stock    "); 
      delay(500);
      lcd.clear();
      break;
    }
    // clean box
    case 3:{
      lcd.clear();
      delay(200);
      lcd.setCursor(0, 0);
      lcd.print("  Sweeping");
      delay(200);
      lcd.setCursor(10, 0);
      lcd.print(".");
      delay(200);
      lcd.setCursor(11, 0);
      lcd.print(".");
      delay(200);
      lcd.setCursor(12, 0);
      lcd.print(".");
      delay(200);
      lcd.setCursor(13, 0);
      lcd.print(".");
      delay(200);
      for (pos = 0; pos <= 180; pos += 1) {
        myservo.write(pos);             
        delay(15);                       
      }
      for (pos = 180; pos >= 0; pos -= 1) {
        myservo.write(pos);             
        delay(15);                      
      }
      num=1;
      lcd.clear();
      break;
    }
    // too much cat litter reminder
    case 4:{
      lcd.clear();
      delay(500);
      lcd.setCursor(0, 0);
      lcd.print("  Over Loaded   "); 
      delay(500);
      lcd.clear();
      break;
    }
  }
  //before add cat litter press tare to reset the stock scale
  //tare
  if (digitalRead (taree) == LOW)
  {
    lcd.clear();
    lcd.setCursor(3, 0);
    lcd.print("Taring");
    delay(200);
    lcd.setCursor(9, 0);
    lcd.print(".");
    delay(200);
    lcd.setCursor(10, 0);
    lcd.print(".");
    delay(200);
    lcd.setCursor(11, 0);
    lcd.print(".");
    delay(200);
    lcd.setCursor(12, 0);
    lcd.print(".");
    delay(200);
    delay(500);
    LoadCell.start(1000);
    lcd.setCursor(0, 0);
    lcd.print("                ");
    lcd.clear();
  }
  // check if stock is low or overload or cat is in use every 1 second
  if(currentTime - prevTime > Time){
    // if not low stock
    if(i>1000){
      num=1;
    }
    // if low stock
    if (i <=1000){
      num=2;
    }
    // if cat is in use
    if (j>0 && num==1){
      InUse=true;
      delay(5000);
    }
    // after use
    if (j>0 && InUse){
      InUse=false;
      num=3;
    }
    // if overload
    if (i>=20000 && num<4){
      num=4;
    }
    // if not overload
    if(i<20000 && num==4){
      num=1;
      lcd.clear();
      delay(1000);
    }
    prevTime = currentTime;
  }
}