"""
download.cobra

Downloads a file specified by a URL to the local file system.

Windows:
> cd \path\to\directory\of\download.cobra
> cobra -c download.cobra
> download http://www.google.com/images/logo_sm.gif
Downloading http://www.google.com/images/logo_sm.gif to logo_sm.gif
Done.

Unix-like:
> cd /path/to/directory/of/download.cobra
> cobra -c Download.cobra
> mono download.exe http://www.google.com/images/logo_sm.gif
Downloading http://www.google.com/images/logo_sm.gif to logo_sm.gif
Done.

You can specify the local filename:
> download http://www.google.com/images/logo_sm.gif GoogleLogo.gif
Downloading http://www.google.com/images/logo_sm.gif to GoogleLogo.gif
Done.

"""

use System.Net

class DownloadFile

	def main
		args = CobraCore.commandLineArgs
		if args.count < 2
			print 'usage: download URL \[LOCALFILENAME]'
			return
		url = args[1]

		# localFileName is derived from the url if missing:
		if args.count > 2
			localFileName = args[2]
		else
			s = url
			if s.endsWith('/'), s = s[:-1]
			i = s.lastIndexOf('/')
			if i <> -1, localFileName = s[i+1:]
			else, print 'Invalid URL.'

		print 'Downloading [url] to [localFileName]'
		Console.out.flush

		try
			WebClient().downloadFile(url, localFileName)
		catch e as Exception
			print e

		print 'Done.'