How to Build Live Train Status App in Android?

package com.droidcon.kotlinapplication

import android.app.DatePickerDialog
import android.os.Bundle
import kotlinx.coroutines.GlobalScope
import android.view.View
import android.widget.Button
import android.widget.EditText
import android.widget.ProgressBar

import okhttp3.OkHttpClient
import okhttp3.Request

import android.widget.TextView
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
import org.jsoup.Jsoup
import java.text.SimpleDateFormat
import java.util.Calendar
import java.util.Date

class MainActivity : AppCompatActivity() {

    // on the below line creating a variable 
      // for train status text view.
    private lateinit var trainStatusTV: TextView

    // on the below line creating a variable for 
      // button to get live train status.
    private lateinit var getTrainStatusBtn: Button

    // on the below line creating a variable for edit text
      // for entering train number.
    private lateinit var trainNumberEdt: EditText

    // on the below line creating a variable for progress bar
      // for displaying loading indicator.
    private lateinit var loadingPB: ProgressBar

    // on the below line creating a text view
      // for displaying a date.
    private lateinit var dateTV: TextView

    // on the below line creating an integer 
      // variable for year, month as well as day.
    private var mYear = 0

    // on the below line creating an integer 
      // variable for year, month as well as day.
    private var mMonth = 0

    // on the below line creating an integer 
      // variable for year, month as well as day.
    private var mDay = 0

    private var formattedDate = ""

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

        // on the below line initializing all the variables.
        trainStatusTV = findViewById(R.id.idTVTrainStatus)
        getTrainStatusBtn = findViewById(R.id.btnView)
        trainNumberEdt = findViewById(R.id.idEdtTrainNumber)
        loadingPB = findViewById(R.id.idPBLoading)
        dateTV = findViewById(R.id.idTVDate)

        // on the below line adding a click listener for our get train status button.
        // on the below line adding a click listener for our get train status button.
        getTrainStatusBtn.setOnClickListener(View.OnClickListener {
            // on the below line checking if the train number edit text 
              // is not empty as well as date text view is not equal to select date.
            if (!trainNumberEdt.getText().toString().isEmpty() && dateTV.getText()
                    .toString() != "Select Date"
            ) {
                // on the below line we are calling our async task 
                  // to make api call to get live train status.
                checkTrainStatus(trainNumberEdt.getText().toString(), formattedDate)
            } else {
                // on the below line displaying a toast message 
                  // to enter train number as well as date,
                Toast.makeText(
                    this@MainActivity,
                    "Please enter the train number as well as date..",
                    Toast.LENGTH_SHORT
                ).show()
            }
        })

        // on the below line adding a click listener for our date text view.
        // on the below line calling a pick date method.
        dateTV.setOnClickListener { 
            pickDate()
        }
    }

    // on the below line creating a date picker
      // method to pick the date.
    private fun pickDate() {

        // on the below line creating a variable for 
          // calendar and getting instance for the same.
        val c = Calendar.getInstance()
        // on the below line getting current 
          // date with day, month and year.
        mYear = c[Calendar.YEAR]
        mMonth = c[Calendar.MONTH]
        mDay = c[Calendar.DAY_OF_MONTH]
        // on the below line creating and initializing 
          // variable for date picker dialog.
        val datePickerDialog = DatePickerDialog(
            this,
            { view, year, monthOfYear, dayOfMonth -> // on the below line we are getting the date from date picker dialog.
                val dateFormat = dayOfMonth.toString() + "-" + (monthOfYear + 1) + "-" + year
                // on the below line we are specifying the input date
                  // format and output date format.
                val inputDateFormat = SimpleDateFormat("dd-MM-yyyy")
                val outputDateFormat = SimpleDateFormat("yyyyMMdd")

                // on the below line parsing input date.
                var inputDate: Date? = null
                try {
                    // on the below line parsing the date.
                    inputDate = inputDateFormat.parse(dateFormat)
                    // Format the parsed date to the desired output format
                    val outputDateStr = outputDateFormat.format(inputDate)
                    // on the below line setting date in a variable.
                    formattedDate = outputDateStr
                } catch (e: Exception) {
                    // on the below line handling exception while parsing the date.
                    e.printStackTrace()
                }
                // on the below line setting date to our text view.
                dateTV.text = dayOfMonth.toString() + "-" + (monthOfYear + 1) + "-" + year
            }, mYear, mMonth, mDay
        )
        // on the below line calling date picker dialog show method to display the dialog.
        datePickerDialog.show()
    }

    // on the below line creating a method to check train status. 
    fun checkTrainStatus(trainNumber: String, date: String) {
        // on the below line changing visibility for progress bar. 
        loadingPB.visibility = View.VISIBLE

        // on the below line calling global scope. 
        GlobalScope.launch(Dispatchers.IO) {
            // on the below line specifying try and catch block. 
            try {
                // on the below line creating url for making call for web page. 
                val url = "https://runningstatus.in/status/$trainNumber-on-$date"
                // on the below line creating a variable for http client and initializing it. 
                val client = OkHttpClient()
                // on the below line creating and initializing variable for request. 
                val request = Request.Builder().url(url).build()
                // on the below line making a new call. 
                val response = client.newCall(request).execute()
                // on the below line getting the response. 
                val responseBody = response.body?.string()
                // on the below line getting train status by parsing data to inside parse train status method. 
                val trainStatus = parseTrainStatus(responseBody)

                // on the below line changing visibility for the progress bar and setting train status to our text view. 
                withContext(Dispatchers.Main) {
                    loadingPB.visibility = View.GONE
                    trainStatusTV.text = trainStatus
                }
                // on the below line handling the exception. 
            } catch (e: Exception) {
                e.printStackTrace()
                // on the below line handling error. 
                withContext(Dispatchers.Main) {
                    loadingPB.visibility = View.GONE
                    trainStatusTV.text = "Please enter a valid train number.."
                }
            }
        }
    }

    // on the below line creating a method to parse the response. 
    private fun parseTrainStatus(responseBody: String?): String {
        // on the below line creating and initializing variable for jsoup. 
        val document = Jsoup.parse(responseBody)
        // on the below line getting first element for card header. 
        val cardHeaderElement = document.select("div.card-header").first()
        // on the below line checking if card header element is not null. 
        if (cardHeaderElement != null) {
            // on the below line removing small and a tag. 
            cardHeaderElement.select("small").remove()
            cardHeaderElement.select("a").remove()
            // on the below line returning the text result. 
            return cardHeaderElement.text()
        } else {
            // on the below line returning the error message. 
            return "Please enter a valid train number.."
        }
    }

}