From d0a2331d86f75eb8d596a66190ced1ccbac4a718 Mon Sep 17 00:00:00 2001
From: Markus Unterwaditzer <markus@unterwaditzer.net>
Date: Tue, 19 Aug 2014 15:54:25 +0200
Subject: [PATCH] Don't produce overlapping output or prompts.

See #96 and #101
---
 vdirsyncer/cli.py            |  3 +-
 vdirsyncer/doubleclick.py    | 55 ++++++++++++++++++++++++++++++++++++
 vdirsyncer/log.py            |  2 +-
 vdirsyncer/utils/__init__.py |  3 +-
 4 files changed, 58 insertions(+), 5 deletions(-)
 create mode 100644 vdirsyncer/doubleclick.py

diff --git a/vdirsyncer/cli.py b/vdirsyncer/cli.py
index 9e3df43..526c272 100644
--- a/vdirsyncer/cli.py
+++ b/vdirsyncer/cli.py
@@ -12,9 +12,8 @@ import json
 import os
 import sys
 
-import click
-
 from . import __version__, log
+from .doubleclick import click
 from .storage import storage_names
 from .sync import StorageEmpty, SyncConflict, sync
 from .utils import expand_path, get_class_init_args, parse_options, split_dict
diff --git a/vdirsyncer/doubleclick.py b/vdirsyncer/doubleclick.py
new file mode 100644
index 0000000..c8aed1d
--- /dev/null
+++ b/vdirsyncer/doubleclick.py
@@ -0,0 +1,55 @@
+# -*- coding: utf-8 -*-
+'''
+    vdirsyncer.utils.doubleclick
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Utilities for writing multiprocessing applications with click.
+
+    Currently the only relevant object here is the ``click`` object, which
+    provides everything importable from click.  It also wraps some UI functions
+    such that they don't produce overlapping output or prompt the user at the
+    same time.
+
+    :copyright: (c) 2014 Markus Unterwaditzer & contributors
+    :license: MIT, see LICENSE for more details.
+'''
+
+import functools
+import multiprocessing
+
+UI_FUNCTIONS = frozenset(['echo', 'echo_via_pager', 'prompt', 'clear', 'edit',
+                          'launch', 'getchar', 'pause'])
+
+
+_ui_lock = multiprocessing.Lock()
+
+
+def _ui_function(f):
+    @functools.wraps(f)
+    def inner(*a, **kw):
+        _ui_lock.acquire()
+        try:
+            return f(*a, **kw)
+        finally:
+            _ui_lock.release()
+    return inner
+
+
+class _ClickProxy(object):
+    def __init__(self, needs_wrapper, click=None):
+        if click is None:
+            import click
+        self._click = click
+        self._cache = {}
+        self._needs_wrapper = frozenset(needs_wrapper)
+
+    def __getattr__(self, name):
+        if name not in self._cache:
+            f = getattr(self._click, name)
+            if name in self._needs_wrapper:
+                f = _ui_function(f)
+            self._cache[name] = f
+
+        return self._cache[name]
+
+click = _ClickProxy(UI_FUNCTIONS)
diff --git a/vdirsyncer/log.py b/vdirsyncer/log.py
index 7ad6f7f..3c2a779 100644
--- a/vdirsyncer/log.py
+++ b/vdirsyncer/log.py
@@ -9,7 +9,7 @@
 import logging
 import sys
 
-import click
+from .doubleclick import click
 
 
 class ColorFormatter(logging.Formatter):
diff --git a/vdirsyncer/utils/__init__.py b/vdirsyncer/utils/__init__.py
index 402709a..72b3067 100644
--- a/vdirsyncer/utils/__init__.py
+++ b/vdirsyncer/utils/__init__.py
@@ -9,12 +9,11 @@
 
 import os
 
-import click
-
 import requests
 from requests.packages.urllib3.poolmanager import PoolManager
 
 from .. import exceptions, log
+from ..doubleclick import click
 from .compat import iteritems, urlparse