Implement file download functionality in the Kotlin Bibledit app

[teusbenschop]

The Bibledit app for Android used to have file download functionality.
It could download the exported USFM.zip and the like.

The app has been rewritten in Kotlin.
The download functionality still needs to be made to work in Kotlin too.

Here is the code for the file download functionality in Java

webview.setDownloadListener(new DownloadListener() {
    @Override
    public void onDownloadStart (String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
        DownloadManager.Request request = new DownloadManager.Request (Uri.parse (url));
        request.allowScanningByMediaScanner();
        // Notification once download is completed.
        request.setNotificationVisibility (DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
        Uri uri = Uri.parse (url);
        String filename = uri.getLastPathSegment ();
        request.setDestinationInExternalPublicDir (Environment.DIRECTORY_DOWNLOADS, filename);
        DownloadManager dm = (DownloadManager) getSystemService (DOWNLOAD_SERVICE);
        dm.enqueue (request);
        // Notification that the file is being downloaded.
        Toast.makeText (getApplicationContext(), "Downloading file", Toast.LENGTH_LONG).show ();
    }
});

[teusbenschop]

The file downloader in Kotlin looks like this:

webView.setDownloadListener { url, userAgent, contentDisposition, mimeType, contentLength ->

    // Extract the filename from the Content-Disposition header or from the URL.
    val filename = URLDecoder.decode(getFilename(contentDisposition, url), "UTF-8")

    Log.i("Download", "Download $filename from $url as $userAgent")

    val request = DownloadManager.Request(url.toUri())
    request.apply {
        setTitle(filename)
        setDescription("Downloading file...")
        setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED)
        setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, filename)
        setMimeType(mimeType)
    }

    val downloadManager = getSystemService(DOWNLOAD_SERVICE) as DownloadManager
    downloadManager.enqueue(request)

    Toast.makeText(this, "Downloading $filename $contentLength bytes to the Downloads directory", Toast.LENGTH_LONG).show()
}

private fun getFilename (contentDisposition : String?, url: String) : String {
    return if (contentDisposition != null && contentDisposition.contains("filename")) {
        contentDisposition.substringAfter("filename=").replace("\"", "")
    } else {
        url.substringAfterLast("/")
    }
}