Add support for vim decrypted view of cheatsheat files.

cheat

@@ -21,13 +21,14 @@ cheat.py -- cheat allows you to create and view interactive cheatsheets on the
 
 import os
 import sys
+import magic
 import argparse
 import subprocess
 from textwrap import dedent
 
 DEFAULT_CHEAT_DIR = os.environ.get('DEFAULT_CHEAT_DIR') or \
-                    os.path.join(os.path.expanduser('~'), '.cheat')
-USE_PYGMENTS      = False
+    os.path.join(os.path.expanduser('~'), '.cheat')
+USE_PYGMENTS = False
 
 # NOTE remove this check if it is confirmed to work on windows
 if os.name == 'posix' and 'CHEATCOLORS' in os.environ:
@@ -40,8 +41,9 @@ if os.name == 'posix' and 'CHEATCOLORS' in os.environ:
     except ImportError:
         pass
 
+
 def pretty_print(filename):
-    "Applies syntax highlighting to a cheatsheet and writes it to stdout"
+    """Applies syntax highlighting to a cheatsheet and writes it to stdout"""
     try:
         if os.path.splitext(filename)[1]:
             lexer = get_lexer_for_filename(filename)
@@ -58,6 +60,7 @@ def pretty_print(filename):
     fmt = TerminalFormatter()
     highlight(code, lexer, fmt, sys.stdout)
 
+
 class CheatSheets(object):
 
     dirs = None
@@ -107,19 +110,20 @@ class CheatSheets(object):
         # arguments have been given
         if 'EDITOR' not in os.environ:
             print >> sys.stderr, ('In order to create/edit a cheatsheet you '
-                'must set your EDITOR environment variable to your favorite '
-                'editor\'s path.')
+                                  'must set your EDITOR environment variable '
+                                  'to your favorite editor\'s path.')
             exit(1)
         elif os.environ['EDITOR'] == "":
             print >> sys.stderr, ('Your EDITOR environment variable is set '
-                'to nothing, in order to create/edit a cheatsheet your must '
-                'set it to a valid editor\'s path.')
+                                  'to nothing, in order to create/edit a '
+                                  'cheatsheet your must set it to a valid '
+                                  'editor\'s path.')
             exit(1)
         else:
             editor = os.environ['EDITOR'].split()
         # if the cheatsheet already exists, open it for editing
         try:
-            if cheat in sheets.sheets:
+            if cheat in self.sheets:
                 subprocess.call(editor + [os.path.join(self.sheets[cheat], cheat)])
 
             # otherwise, create it
@@ -145,25 +149,50 @@ class CheatSheets(object):
         return ('\n'.join(sorted(['%s [%s]' % (key.ljust(max_command), value)
                                   for key, value in self.sheets.items()])))
 
+
 # Custom action for argparse
 class ListDirectories(argparse.Action):
     """List cheat directories and exit"""
     def __call__(self, parser, namespace, values, option_string=None):
-        print("\n".join(sheets.dirs))
+        print('\n'.join(sheets.dirs))
         parser.exit()
 
+
 class ListCheatsheets(argparse.Action):
     """List cheatsheets and exit"""
     def __call__(self, parser, namespace, values, option_string=None):
         print sheets.list()
         parser.exit()
 
+
 class EditSheet(argparse.Action):
     """If the user wants to edit a cheatsheet"""
     def __call__(self, parser, namespace, values, option_string=None):
         sheets.edit(values[0])
         parser.exit()
 
+
+def is_vim_crypted(filepath):
+    """Returns True if the canonical file path is a Vim Encrypted file."""
+    canonical_path = os.path.realpath(filepath)
+    return 'vim encrypted' in magic.from_file(canonical_path).lower()
+
+
+def vim_viewer(filepath):
+    """Use Vim to read an Vim Encrypted cheat file."""
+    canonical_path = os.path.realpath(filepath)
+    env_cmd = '/usr/bin/env'
+    if not os.path.isfile(env_cmd):
+        sys.stderr.write('No environment command {0}\n'.format(env_cmd))
+        exit(1)
+    try:
+        subprocess.call([env_cmd, 'vim', '-R', canonical_path, ])
+        return True
+    except Exception as e:
+        sys.stderr.write('Unknown exception: {0}\n'.format(unicode(e)))
+        exit(1)
+
+
 def main():
 
     global sheets
@@ -215,7 +244,9 @@ def main():
         parser.print_help()
     elif sheet in sheets.sheets:
         filename = os.path.join(sheets.sheets[sheet], sheet)
-        if USE_PYGMENTS:
+        if is_vim_crypted(filename):
+            vim_viewer(filename)
+        elif USE_PYGMENTS:
             pretty_print(filename)
         else:
             with open(filename) as istream: