WhatsApp.kt

private fun openWhatsApp(fileName: String) {
        val smsNumber = mobileNumber
        val isWhatsappInstalled = "com.whatsapp".whatsappInstalledOrNot()

        if (isWhatsappInstalled) {
            val sendIntent = Intent(Intent.ACTION_SEND)
            val outputFile = File(
                requireContext().getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS),
                fileName
            )

            Log.e(TAG, "openWhatsApp: $outputFile")
            Log.e(TAG, "openWhatsApp: ${outputFile.absolutePath}")

            val fileUri: Uri = FileProvider.getUriForFile(
                requireActivity().applicationContext,
                "${requireActivity().applicationContext.packageName}.provider", outputFile
            )
            sendIntent.putExtra(
                "jid",
                PhoneNumberUtils.stripSeparators(smsNumber) + "@s.whatsapp.net"
            ) //phone number without "+" prefix
            sendIntent.setPackage("com.whatsapp")
            sendIntent.action = Intent.ACTION_SEND
            sendIntent.type = "application/pdf"
            sendIntent.putExtra(Intent.EXTRA_STREAM, fileUri)
            if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.LOLLIPOP) {
                sendIntent.addFlags(Intent.FLAG_GRANT_WRITE_URI_PERMISSION or Intent.FLAG_GRANT_READ_URI_PERMISSION)
            } else {
                sendIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
            }
            startActivityForResult(sendIntent, whatsAppCode)
        } else {
            val uri: Uri = Uri.parse("market://details?id=com.whatsapp")
            val goToMarket = Intent(Intent.ACTION_VIEW, uri)
            Toasty.error(
                requireContext(), "WhatsApp not Installed",
                Toast.LENGTH_LONG,
                true
            ).show()
            startActivity(goToMarket)
        }
    }

    private fun String.whatsappInstalledOrNot(): Boolean {
        val pm: PackageManager = requireActivity().packageManager
        var appInstalled = false
        appInstalled = try {
            pm.getPackageInfo(this, PackageManager.GET_ACTIVITIES)
            true
        } catch (e: PackageManager.NameNotFoundException) {
            false
        }
        return appInstalled
    }