[HSE] [My first Android application] Step 3: implement logic

MainActivity.kt

package your_package_name

import android.os.Bundle
import android.os.CountDownTimer
import android.util.Log
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.appcompat.widget.AppCompatImageView
import com.github.st235.circularprogressbar.CircularProgressBar
import java.util.concurrent.TimeUnit

class MainActivity : AppCompatActivity() {

    private lateinit var timerProgressBar: CircularProgressBar
    private lateinit var timerCounterView: TextView
    private lateinit var playButton: AppCompatImageView

    private lateinit var timer: CountDownTimer

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

        timerProgressBar = findViewById(R.id.timer_progress)
        timerCounterView = findViewById(R.id.timer_text)
        playButton = findViewById(R.id.play_button)

        timerCounterView.text = timeToString(TimeUnit.MINUTES.toMillis(25))

        timer = object : CountDownTimer(TimeUnit.MINUTES.toMillis(25),
                                        1000L) {

            override fun onTick(millisUntilFinished: Long) {
                timerCounterView.text = timeToString(millisUntilFinished)
                val progress = millisUntilFinished.toFloat() / TimeUnit.MINUTES.toMillis(25)

                if (progress < 0 || progress > 1) {
                    Log.d("MainActivity", "Progress is outside of [0, 1]")
                } else {
                    timerProgressBar.progress = progress
                }
            }

            override fun onFinish() {

            }
        }

        playButton.setOnClickListener {
            timer.start()
            playButton.setImageResource(R.drawable.ic_stop)
        }
    }

    private fun timeToString(millis: Long): String {
        val minutes = TimeUnit.MILLISECONDS.toSeconds(millis) / 60
        val seconds = TimeUnit.MILLISECONDS.toSeconds(millis) % 60
        return String.format("%02d:%02d", minutes, seconds)
    }
}