File: links.py
   1 #!/usr/bin/python3
   2 
   3 # The MIT License (MIT)
   4 #
   5 # Copyright © 2024 pacman64
   6 #
   7 # Permission is hereby granted, free of charge, to any person obtaining a copy
   8 # of this software and associated documentation files (the “Software”), to deal
   9 # in the Software without restriction, including without limitation the rights
  10 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 # copies of the Software, and to permit persons to whom the Software is
  12 # furnished to do so, subject to the following conditions:
  13 #
  14 # The above copyright notice and this permission notice shall be included in
  15 # all copies or substantial portions of the Software.
  16 #
  17 # THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23 # SOFTWARE.
  24 
  25 
  26 from io import TextIOWrapper
  27 from re import compile, Pattern
  28 from sys import argv, exit, stderr, stdin, stdout
  29 
  30 
  31 info = '''
  32 links [options...] [filepaths/URIs...]
  33 
  34 This script finds all web (hyper)links in the input(s) given, specifically
  35 HTTP/HTTPS links, showing each match on its own output line. It can match
  36 multiple links on each input line.
  37 '''
  38 
  39 # no args or a leading help-option arg means show the help message and quit
  40 if len(argv) > 1 and argv[1] in ('-h', '--h', '-help', '--help'):
  41     print(info.strip(), file=stderr)
  42     exit(0)
  43 
  44 
  45 def fail(msg, code: int = 1) -> None:
  46     'Show the error message given, and quit the app right away.'
  47     print(f'\x1b[31m{msg}\x1b[0m', file=stderr)
  48     exit(code)
  49 
  50 
  51 def seems_url(s: str) -> bool:
  52     protocols = ('https://', 'http://', 'file://', 'ftp://', 'data:')
  53     return any(s.startswith(p) for p in protocols)
  54 
  55 
  56 def handle_lines(w, src, links: Pattern) -> None:
  57     for line in src:
  58         for match in links.finditer(line):
  59             w.write(line[match.start():match.end()])
  60             w.write('\n')
  61             w.flush()
  62 
  63 
  64 try:
  65     if argv.count('-') > 1:
  66         msg = 'reading from `-` (standard input) more than once not allowed'
  67         raise ValueError(msg)
  68 
  69     if any(seems_url(e) for e in argv):
  70         from urllib.request import urlopen
  71 
  72     links_src = 'https?://[A-Za-z0-9+_.:%-]+(/[A-Za-z0-9+_.%/,#?&=-]*)*'
  73     links = compile(links_src)
  74 
  75     # handle all named inputs given
  76     for path in argv[1:]:
  77         if path == '-':
  78             handle_lines(stdout, stdin, links)
  79             continue
  80 
  81         if seems_url(path):
  82             with urlopen(path) as inp:
  83                 with TextIOWrapper(inp, encoding='utf-8') as txt:
  84                     handle_lines(stdout, txt, links)
  85             continue
  86 
  87         with open(path, encoding='utf-8') as inp:
  88             handle_lines(stdout, inp, links)
  89 
  90     if len(argv) == 1:
  91         handle_lines(stdout, stdin, links)
  92 except BrokenPipeError:
  93     # quit quietly, instead of showing a confusing error message
  94     stderr.close()
  95 except KeyboardInterrupt:
  96     exit(2)
  97 except Exception as e:
  98     fail(e, 1)