#!/usr/bin/env python

from __future__ import print_function

import os
import sys


def writeheader(filename, header):
    """
    write a header to filename,
    skip files where first line after optional shebang matches the skip regex
    filename should be the name of the file to write to
    header should be a list of strings
    skip should be a regex
    """
    with open(filename, "r") as f:
        inpt = f.readlines()
    output = []

    # comment out the next 3 lines if you don't wish to preserve shebangs
    if len(inpt) > 0 and inpt[0].startswith("#!"):
        output.append(inpt[0])
        inpt = inpt[1:]

    if inpt[0].strip().startswith("/*"):
        for i, line in enumerate(inpt):
            if line.strip().endswith("*/"):
                inpt = inpt[i + 1:]
                break

    while not inpt[0].strip():
        inpt = inpt[1:]

    output.extend(header)  # add the header
    for line in inpt:
        output.append(line)
    try:
        with open(filename, 'w') as f:
            f.writelines(output)
        print("added header to %s" % filename)
    except IOError as err:
        print("something went wrong trying to add header to %s: %s" % (filename, err))


def main(args=sys.argv):
    with open(os.path.dirname(os.path.realpath(__file__)) + "/copyright-header.txt") as headerfile:
        header = headerfile.readlines()
    for filename in args[1:]:
        writeheader(filename, header)


if __name__ == '__main__':
    # call the main method
    main()