whatsApp

MainActivity.kt

package com.openwhatsapp

import android.content.Intent
import android.net.Uri
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Toast
import androidx.core.text.isDigitsOnly
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        btn.setOnClickListener {
            val msg =
                "LOL! why are you clicking it continuously. Because you have nothing to do here"
            Toast.makeText(this, msg, Toast.LENGTH_SHORT).show()
        }
        intent.action = Intent.ACTION_PROCESS_TEXT
        val number= intent?.getCharSequenceExtra(Intent.EXTRA_PROCESS_TEXT).toString()
        Log.i("enter1", "done")
        if (number.isDigitsOnly() || number[0] == '+')
            openWhatsapp(number)
        else
            Toast.makeText(this, "Oops! Provide digits only", Toast.LENGTH_SHORT).show()

    }

    private fun openWhatsapp(num: String) {
        val act = Intent(Intent.ACTION_VIEW) // meaning?
        act.setPackage("com.whatsapp")

        val contact: String = if (num[0] == '+')
            num.substring(1)
        else if (num.length == 10)
            "91$num"
        else if (num.length == 11 && num[0] == '0')
            "91" + num.substring(1)
        else
            num
        act.data = Uri.parse("https://wa.me/$contact")
        if (packageManager.resolveActivity(act, 0) != null) {
            startActivity(act)
        } else
            Toast.makeText(this, "Oops! What's App isn't installed", Toast.LENGTH_SHORT).show()
        finish()
    }
}