#!/usr/bin/env python
# encoding: UTF-8

from __future__ import absolute_import, division

import os
import re
import sys

MAN_NAME_RE = re.compile(r'/man/(?:[^/]+/)?man([^/]+)/[^/]+.\1$')
MAX_LEN = 1024
SO_RE = re.compile(r'^\.so\s+(.*)$')

SUFFIXES = {
    'xz': '.xz',
    'bzip2': '.bz2',
    'gzip': '.gz',
}

def process_file(name, suffix):
    full_name = os.path.abspath(name)
    m = MAN_NAME_RE.search(full_name)
    if not m:
        return False
    category = m.group(1)
    dir_name = 'man' + category
    with open(name, 'r') as f:
        s = f.read(MAX_LEN+1)
        if len(s) > MAX_LEN:
            return False
    lines = [line for line in s.rstrip().split('\n') if not line.startswith('.\\"')]
    if len(lines) != 1:
        return False
    m = SO_RE.search(lines[0])
    if not m:
        return False
    link = m.group(1)
    if link.startswith('/') or link.count('/') > 1:
        return False
    if link.startswith(dir_name+'/'):
        link = link[len(dir_name)+1:]
    elif '/' in link:
        link = '../' + link
    os.unlink(name)
    os.symlink(link + suffix, name + suffix)
    print 'Converted {} into a symlink to {}'.format(full_name, link)
    return True

def main(args=[]):
    try:
        dashes = args.index('--')
    except ValueError:
        compressor = []
        all_files = args
    else:
        compressor = args[:dashes]
        all_files = args[dashes+1:]
    if compressor:
        suffix = SUFFIXES.get(compressor[0], '')
    else:
        suffix = ''
    files = []
    for name in all_files:
        if not process_file(name, suffix):
            files.append(name)
    if not compressor or not files:
        return 0
    os.execvp(compressor[0], compressor + files)
    return 1

if __name__ == '__main__':
    sys.exit(main(sys.argv[1:]))