short.py now reads files and stdin

links/short.py

@@ -1,8 +1,23 @@
 #!/usr/bin/env python3
 
+"""
+short.py generates unique short URLs.
+
+This script reads lines from stdin or files named as arguments, then:
+
+1. retrieves or creates new short URLs, taking into account existing RedirectTemp
+   directives in custom.htacess or short.htacess;
+2. appends RedirectTemp directives for newly created short URLs to short.htacess;
+3. outputs the list of (short, long) URLs retrieved or created.
+
+"""
+
+import fileinput
 import itertools
 from collections.abc import Iterator
+from time import strftime
 
+BASE_DOMAIN = 'fpy.li'
 
 def load_redirects():
     redirects = {}
@@ -25,52 +40,55 @@ def load_redirects():
 SDIGITS = '23456789abcdefghjkmnpqrstvwxyz'
 
 
-def gen_short() -> Iterator[str]:
+def gen_short(start_len=1) -> Iterator[str]:
     """
-    Generate every possible sequence of SDIGITS.
+    Generate every possible sequence of SDIGITS, starting with start_len
     """
-    length = 1
+    length = start_len
     while True:
         for short in itertools.product(SDIGITS, repeat=length):
             yield ''.join(short)
         length += 1
 
 
-def gen_free_short(redirects: dict) -> Iterator[str]:
+def gen_unused_short(redirects: dict) -> Iterator[str]:
     """
-    Generate next available short URL.
+    Generate next available short URL of len >= 2.
     """
-    for short in gen_short():
+    for short in gen_short(2):
         if short not in redirects:
             yield short
 
 
 def shorten(urls: list[str], redirects: dict, targets: dict) -> list[tuple[str,str]]:
-    """return (short, long) pairs, updating short.htaccess as needed""'
-    iter_short = gen_free_short(redirects)
+    """return (short, long) pairs, appending directives to short.htaccess as needed"""
+    iter_short = gen_unused_short(redirects)
     pairs = []
+    timestamp = strftime('%Y-%m-%d %H:%M:%S')
     with open('short.htaccess', 'a') as fp:
         for long in urls:
-            assert 'fpy.li' not in long, f"{long} is a fpy.li URL"
+            assert BASE_DOMAIN not in long, f"{long} is a {BASE_DOMAIN} URL"
             if long in targets:
                 short = targets[long]
             else:
                 short = next(iter_short)
-                redirects[short] = url
-                targets[url] = short
-                fp.write(f"RedirectTemp /{short} {url}\n")
+                redirects[short] = long
+                targets[long] = short
+                if timestamp:
+                    fp.write(f'\n# appended: {timestamp}\n')
+                    timestamp = None
+                fp.write(f'RedirectTemp /{short} {long}\n')
             pairs.append((short, long))
             
     return pairs
 
 
 def main():
-    from random import randrange
-    urls = [f'https://example.com/{randrange(100000)}.html' for n in range(7)]
-
+    """read URLS from filename arguments or stdin"""
+    urls = [line.strip() for line in fileinput.input(encoding="utf-8")]
     redirects, targets = load_redirects()
     for short, long in shorten(urls, redirects, targets):
-    		print(f'fpy.li/{short}\t{long}')
+    		print(f'{BASE_DOMAIN}/{short}\t{long}')
 
 
 if __name__ == '__main__':