process_md

#!/usr/bin/env python3

import re
import sys

include_file_re = re.compile(r'^<!-- include "([^"]*)" -->\n$')
end_include_re = re.compile(r'^<!-- end_include -->\n$')


def find_include_file(line):
    m = include_file_re.match(line)
    return m.group(1) if m else None


def find_end_include(line):
    return end_include_re.match(line)


def include(filename):
    with open(filename) as f:
        return """```
%s```
<!-- end_include -->
""" % f.read()


def fast_forward_to_end_include(it):
    for line in it:
        if find_end_include(line):
            break
    return it


def main(argv):
    assert len(argv) == 2

    filename = argv[1]
    contents = ""
    with open(filename, "r") as f:
        it = f.__iter__()
        for line in it:
            contents += line
            include_filename = find_include_file(line)
            if include_filename is not None:
                contents += include(include_filename)
                it = fast_forward_to_end_include(it)

    with open(filename, "w") as f:
        f.write(contents)

if __name__ == "__main__":
    main(sys.argv)