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package wahyuros.android.calculator

import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.TextView
import java.lang.NumberFormatException

#Import layout widget so we dont need to call findViewbyId
import kotlinx.android.synthetic.main.activity_main.*

private const val STATE_PENDING_OPERATION = "PendingOperation"
private const val STATE_OPERAND1 = "Operand1"
private const val STATE_OPERAND1_STORED = "Operand1_Stored"


class MainActivity : AppCompatActivity() {
    //Variable to hold operand and type of the calculation
    private var operand1: Double? = null
    private var pendingOperation = "="

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

        val listener = View.OnClickListener { v ->
            val b = v as Button
            newNumber.append(b.text)
        }

        button0.setOnClickListener(listener)
        button1.setOnClickListener(listener)
        button2.setOnClickListener(listener)
        button3.setOnClickListener(listener)
        button4.setOnClickListener(listener)
        button5.setOnClickListener(listener)
        button6.setOnClickListener(listener)
        button7.setOnClickListener(listener)
        button8.setOnClickListener(listener)
        button9.setOnClickListener(listener)
        buttonDot.setOnClickListener(listener)

        val opListener = View.OnClickListener { v ->
            val op = (v as Button).text.toString()
            try {
                val value = newNumber.text.toString().toDouble()
                performOperation(value, op)
            } catch (e: NumberFormatException) {
                newNumber.setText("")
            }
            pendingOperation = op
            operation.text = pendingOperation
        }

        buttonEquals.setOnClickListener(opListener)
        buttonDivide.setOnClickListener(opListener)
        buttonMultiply.setOnClickListener(opListener)
        buttonMinus.setOnClickListener(opListener)
        buttonPlus.setOnClickListener(opListener)
    }

    private fun performOperation(value: Double, operation: String) {
        if (operand1 == null) {
            operand1 = value
        } else {
            if (pendingOperation == "=") {
                pendingOperation = operation
            }

            when (pendingOperation) {
                "=" -> operand1 = value
                "/" -> operand1 = if (value == 0.0) {
                    Double.NaN
                } else {
                    operand1!! / value
                }
                "*" -> operand1 = operand1!! * value
                "+" -> operand1 = operand1!! + value
                "-" -> operand1 = operand1!! - value
            }
        }
        result.setText(operand1.toString())
        newNumber.setText("")
    }

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)
        if (operand1 != null){
            outState.putDouble(STATE_OPERAND1, operand1!!)
            outState.putBoolean(STATE_OPERAND1_STORED, true)
        }
        outState.putString(STATE_PENDING_OPERATION, pendingOperation)
    }

    override fun onRestoreInstanceState(savedInstanceState: Bundle) {
        super.onRestoreInstanceState(savedInstanceState)
        operand1 = if (savedInstanceState.getBoolean(STATE_OPERAND1_STORED,false)){
            savedInstanceState.getDouble(STATE_OPERAND1)
        } else {
            null
        }
        pendingOperation = savedInstanceState.getString(STATE_PENDING_OPERATION)
        operation.text = pendingOperation
    }

}