Prompt before overwriting config.ini

GH: closes #86

sbws/core/init.py

 from sbws.globals import (is_initted, fail_hard, touch_file)
 from sbws.util.config import get_user_example_config
+from sbws.util.userquery import query_yes_no
 from argparse import ArgumentDefaultsHelpFormatter
 import os
 import logging
@@ -23,10 +24,18 @@ def main(args, conf):
         log.info('Creating %s', args.directory)
         os.makedirs(args.directory, exist_ok=False)
 
+    # Create config.log.ini ####
     touch_file(os.path.join(args.directory, 'config.log.ini'))
-    config_fname = os.path.join(args.directory, 'config.ini')
+
+    # Create config.ini ####
+    fname = os.path.join(args.directory, 'config.ini')
+    if os.path.exists(fname) and not os.path.isfile(fname):
+        fail_hard('Don\'t know how to handle %s existing as a non-file', fname)
+    if os.path.isfile(fname) and not query_yes_no(
+            'Is it okay to overwrite {}?'.format(fname), default=None):
+        fail_hard('Cannot continue')
     c = get_user_example_config()
     c['paths']['sbws_home'] = args.directory
-    log.info('Creating %s based on example config', config_fname)
-    with open(config_fname, 'wt') as fd:
+    log.info('Creating %s based on example config', fname)
+    with open(fname, 'wt') as fd:
         c.write(fd)

sbws/globals.py

@@ -29,7 +29,7 @@ def is_initted(d):
     conf_fnames = [os.path.join(d, 'config.ini'),
                    os.path.join(d, 'config.log.ini')]
     for fname in conf_fnames:
-        if not os.path.exists(fname):
+        if not os.path.isfile(fname):
             return False
     return True
 

sbws/util/userquery.py

+# Based on https://stackoverflow.com/a/3041990
+def query_yes_no(question, default='yes'):
+    '''
+    Ask a yes/no question via input() and return the user's answer.
+
+    :param str question: Prompt given to the user.
+    :param str default: The assumed answer if th user just hits **Enter**. It
+        must be ``'yes'`` (the default if no default is given), ``'no'``, or
+        ``None`` (meaning an answer is required from the user).
+    :returns: ``True`` if we ended up with a 'yes' answer, otherwise
+        ``False``.
+    '''
+    valid = {'yes': True, 'y': True, 'ye': True, 'no': False, 'n': False}
+    if default is None:
+        prompt = ' [y/n] '
+    elif default == 'yes':
+        prompt = ' [Y/n] '
+    elif default == 'no':
+        prompt = ' [y/N] '
+    else:
+        raise ValueError('invalid default answer: "%s"' % default)
+    while True:
+        print(question + prompt, end='')
+        choice = input().lower()
+        if default is not None and choice == '':
+            return valid[default]
+        elif choice in valid:
+            return valid[choice]
+        else:
+            print('Please respond with "yes" or "no" (or "y" or "n").\n')