class MainActivity : AppCompatActivity() {
    lateinit var btn1: Button
    lateinit var btn2:Button
    lateinit var btn3:Button
    lateinit var btn4:Button
    lateinit var btn5:Button
    lateinit var btn6:Button
    lateinit var btn7:Button
    lateinit var btn8:Button
    lateinit var btn9:Button
    lateinit var btnPlus:Button
    lateinit var btnSub:Button
    lateinit var btnMul: Button
    lateinit var btnDiv:Button
    lateinit var btnClr: Button
    lateinit var btnEq: Button

    lateinit var TView: EditText
    lateinit var Display: TextView
    var firstValue: Double=0.0
    var result : Double=0.0
    var secondValue: Double=0.0
    var op:String="null"


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContentView(R.layout.activity_main)

        btn1=findViewById<Button>(R.id.btn1)
        btn2=findViewById<Button>(R.id.btn2)
        btn3=findViewById<Button>(R.id.btn3)
        btn4=findViewById<Button>(R.id.btn4)
        btn5=findViewById<Button>(R.id.btn5)
        btn6=findViewById<Button>(R.id.btn6)
        btn7=findViewById<Button>(R.id.btn7)
        btn8=findViewById<Button>(R.id.btn8)
        btn9=findViewById<Button>(R.id.btn9)
        btnPlus=findViewById<Button>(R.id.btnPlus)
        btnSub=findViewById<Button>(R.id.btnSub)
        btnMul=findViewById<Button>(R.id.btnMul)
        btnDiv=findViewById<Button>(R.id.btnDiv)
        btnClr=findViewById<Button>(R.id.btnCLR)
        btnEq=findViewById<Button>(R.id.btnEq)
        TView=findViewById<EditText>(R.id.Edt1)
        Display=findViewById<TextView>(R.id.Display)
         btn1.setOnClickListener {

            TView.append(btn1.text)

        }
        btn2.setOnClickListener {

            TView.append(btn2.text)
        }
        btn3.setOnClickListener {

            TView.append(btn3.text)
        }
        btn4.setOnClickListener {

            TView.append(btn4.text)
        }
        btn5.setOnClickListener {

            TView.append(btn5.text)
        }
        btn6.setOnClickListener {

            TView.append(btn6.text)
        }
        btn7.setOnClickListener {

            TView.append(btn7.text)
        }
        btn8.setOnClickListener {

            TView.append(btn8.text)
        }
        btn9.setOnClickListener {

            TView.append(btn9.text)
        }
        btnPlus.setOnClickListener {
           firstValue = TView.text.toString().toDouble()
            op="+"
            TView.text.clear()


        }
        btnSub.setOnClickListener {
            firstValue=TView.text.toString().toDouble()
            op="-"
            TView.text.clear()


        }
        btnDiv.setOnClickListener {
            firstValue=TView.text.toString().toDouble()
            op="/"
            TView.text.clear()

        }
        btnMul.setOnClickListener {
            firstValue=TView.text.toString().toDouble()
            op="*"
             TView.text.clear()
        }
        btnClr.setOnClickListener {
            TView.text.clear()
            Display.text=""
            firstValue=0.0
            secondValue=0.0
            op=""

        }
        btnEq.setOnClickListener {
            secondValue = TView.text.toString().toDouble()
               result = when(op){
                   "+"->firstValue+secondValue
                   "-"->firstValue-secondValue
                   "*"->firstValue*secondValue
                   "/"->firstValue/secondValue
                     else -> 0.0
               }
           Display.text=result.toString()
        }

        }


    }