#!/usr/bin/python
# Copyright 2011  Lars Wirzenius
# 
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import cliapp
import os
import tempfile


class FixShebang(cliapp.Application):

    def add_settings(self):
        self.settings.string(['shebang'],  'interpreter path and args')

    def process_input(self, arg):
        name = self.create_tempfile_for(arg)
        temp = open(name, 'w')
        shebang = self.settings['shebang']
        if not shebang:
            raise Exception('You must specify an interpreter with --shebang')
        if not shebang.startswith('#!'):
            shebang = '#!%s' % shebang
        temp.write('%s\n' % shebang)
        f = open(arg)
        line1 = f.readline()
        if line1 and not line1.startswith('#!'):
            temp.write(line1)
        for line in f:
            temp.write(line)
        f.close()
        temp.close()
        os.rename(name, arg)
        
    def create_tempfile_for(self, filename):
        fd, name = tempfile.mkstemp(dir=os.path.dirname(filename))
        os.close(fd)
        return name


if __name__ == '__main__':
    FixShebang().run()