#!/usr/bin/env python

import os, sys
import getopt
import re

def usage():
	print """usage: %s [OPTION] FILE...

 -e  launch editor after creating files. Uses editor from $EDITOR envvar.
 -f  overwrite existing files
 -h  show this help and exit""" % (os.path.basename(sys.argv[0]))

def main():
	try:
		opts, args = getopt.getopt(sys.argv[1:], "efh")
	except getopt.GetoptError, err:
		print str(err)
		usage()
		sys.exit(2)

	if len(args) < 1:
		usage()
		sys.exit(2)

	overwrite = False
	launch_editor = False
	for o, a in opts:
		if o == "-e":
			launch_editor = True
		elif o == "-f":
			overwrite = True
		elif o == "-h":
			usage()
			sys.exit()
		else:
			assert False, "unhandled option"

	p = re.compile('[a-zA-Z0-9._-]+\.h')
	for f in args:
		if not p.match(f):
			print "Invalid header filename '%s'. Header not created" % f
			continue

		if not overwrite and os.path.exists(f):
			print "Header file '%s' already exists. Use -f to override." % f
			continue

		print "Creating %s..." % f
		q = re.compile('[.-]')
		define = q.sub('_', f.upper())
		f = open(f, 'w')
		f.write('#ifndef _%s_\n' % define)
		f.write('#define _%s_\n\n' % define)
		f.write('/* TODO: Your code here */\n\n')
		f.write('#endif /* _%s_ */' % define)
		f.close()

	if launch_editor:
		editor = os.getenv("EDITOR")
		if editor is None:
			editor = "vi"

		# Fork an editor for each file as not all editors support
		# editing multiple files at once (e.g. splitted view in vim)
		for f in args:
			print "Editing header '%s' with '%s'" % (f, editor)

			pid = os.fork()
			if pid == 0:	# child process
				os.execvp(editor, [editor, f])
				sys.exit(0)
			else:		# parent process
				os.waitpid(pid, 0)

if __name__ == '__main__':
	main()