From 0e4ccad32ae45a660d0670548e70299a416c5f78 Mon Sep 17 00:00:00 2001
From: Rapptz <rapptz@gmail.com>
Date: Wed, 26 Aug 2015 21:20:18 -0400
Subject: [PATCH] Parse permission_overwrites in every Channel instance.

---
 discord/channel.py |  7 ++++++-
 discord/client.py  | 34 +++++++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/discord/channel.py b/discord/channel.py
index 734ad64a5..a7f04ad7d 100644
--- a/discord/channel.py
+++ b/discord/channel.py
@@ -46,15 +46,20 @@ class Channel(object):
     .. attribute:: type
 
         The channel type. Usually ``'voice'`` or ``'text'``.
+    .. attribute:: changed_roles
+
+        An array of :class:`Roles` that have been overridden from their default
+        values in the :attr:`Server.roles` attribute.
     """
 
-    def __init__(self, name, server, id, position, type, **kwargs):
+    def __init__(self, name, server, id, position, type, permission_overwrites=None, **kwargs):
         self.name = name
         self.server = server
         self.id = id
         self.is_private = False
         self.position = position
         self.type = type
+        self.changed_roles = permission_overwrites if permission_overwrites is not None else []
 
 class PrivateChannel(object):
     """Represents a Discord private channel.
diff --git a/discord/client.py b/discord/client.py
index d2a1abe16..f3d12b078 100644
--- a/discord/client.py
+++ b/discord/client.py
@@ -151,9 +151,37 @@ class Client(object):
                 guild['roles'] = [Role(**role) for role in guild['roles']]
                 guild['members'] = [Member(**member) for member in guild['members']]
 
-                self.servers.append(Server(**guild))
-                channels = [Channel(server=self.servers[-1], **channel) for channel in guild['channels']]
-                self.servers[-1].channels = channels
+                server = Server(**guild)
+                for channel in guild['channels']:
+                    changed_roles = []
+                    permission_overwrites = channel['permission_overwrites']
+
+                    for overridden in permission_overwrites:
+                        # this is pretty inefficient due to the deep nested loops unfortunately
+                        role = next((role for role in guild['roles'] if role.id == overridden['id']), None)
+                        if role is None:
+                            continue
+                        denied = overridden.get('deny', 0)
+                        allowed = overridden.get('allow', 0)
+                        override = copy.deepcopy(role)
+
+                        # Basically this is what's happening here.
+                        # We have an original bit array, e.g. 1010
+                        # Then we have another bit array that is 'denied', e.g. 1111
+                        # And then we have the last one which is 'allowed', e.g. 0101
+                        # We want original OP denied to end up resulting in whatever is in denied to be set to 0.
+                        # So 1010 OP 1111 -> 0000
+                        # Then we take this value and look at the allowed values. And whatever is allowed is set to 1.
+                        # So 0000 OP2 0101 -> 0101
+                        # The OP is (base ^ denied) & ~denied.
+                        # The OP2 is base | allowed.
+                        override.permissions.value = ((override.permissions.value ^ denied) & ~denied) | allowed
+                        changed_roles.append(override)
+
+                    channel['permission_overwrites'] = changed_roles
+                channels = [Channel(server=server, **channel) for channel in guild['channels']]
+                server.channels = channels
+                self.servers.append(server)
 
             for pm in data.get('private_channels'):
                 self.private_channels.append(PrivateChannel(id=pm['id'], user=User(**pm['recipient'])))