From 8c4b7a1ac8460c0d17e2b0a4de2e31d6ab7b3e08 Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Tue, 4 Dec 2018 02:02:40 -0300
Subject: [PATCH] pubsub.lazy_guild: fix list_id for non-everyone lists

 - utils: add murmurhash3 implementation
---
 litecord/pubsub/lazy_guild.py | 29 +++++++++++++-
 litecord/utils.py             | 73 +++++++++++++++++++++++++++++++++++
 2 files changed, 101 insertions(+), 1 deletion(-)

diff --git a/litecord/pubsub/lazy_guild.py b/litecord/pubsub/lazy_guild.py
index fcbd153..cc0bf5c 100644
--- a/litecord/pubsub/lazy_guild.py
+++ b/litecord/pubsub/lazy_guild.py
@@ -13,6 +13,7 @@ from litecord.permissions import (
     Permissions, overwrite_find_mix, get_permissions, role_permissions
 )
 from litecord.utils import index_by_func
+from litecord.utils import mmh3
 
 
 log = Logger(__name__)
@@ -267,7 +268,33 @@ class GuildMemberList:
         """get the id of the member list."""
         return ('everyone'
                 if self.channel_id == self.guild_id
-                else str(self.channel_id))
+                else self._calculated_id)
+
+    @property
+    def _calculated_id(self):
+        """Calculate an id used by the client."""
+
+        if not self.list:
+            return str(self.channel_id)
+
+        # list of strings holding the hash input
+        ovs_i = []
+
+        print(self.list.overwrites)
+
+        for actor_id, overwrite in self.list.overwrites.items():
+            allow, deny = (
+                Permissions(overwrite['allow']),
+                Permissions(overwrite['deny'])
+            )
+
+            if allow.bits.read_messages:
+                ovs_i.append(f'allow:{actor_id}')
+            elif deny.bits.read_messages:
+                ovs_i.append(f'deny:{actor_id}')
+
+        hash_in = ','.join(ovs_i)
+        return str(mmh3(hash_in))
 
     def _set_empty_list(self):
         """Set the member list as being empty."""
diff --git a/litecord/utils.py b/litecord/utils.py
index 2fda9d5..26c6ba2 100644
--- a/litecord/utils.py
+++ b/litecord/utils.py
@@ -37,3 +37,76 @@ def index_by_func(function, indexable: iter) -> int:
             return index
 
     return None
+
+
+def _u(val):
+    """convert to unsigned."""
+    return val % 0x100000000
+
+
+def mmh3(key: str, seed: int = 0):
+    """MurMurHash3 implementation.
+
+    This seems to match Discord's JavaScript implementaiton.
+
+    Based off
+      https://github.com/garycourt/murmurhash-js/blob/master/murmurhash3_gc.js
+    """
+    key = [ord(c) for c in key]
+
+    remainder = len(key) & 3
+    bytecount = len(key) - remainder
+    h1 = seed
+
+    # mm3 constants
+    c1 = 0xcc9e2d51
+    c2 = 0x1b873593
+    i = 0
+
+    while i < bytecount:
+        k1 = (
+            (key[i] & 0xff) |
+            ((key[i + 1] & 0xff) << 8) |
+            ((key[i + 2] & 0xff) << 16) |
+            ((key[i + 3] & 0xff) << 24)
+        )
+
+        i += 4
+
+        k1 = ((((k1 & 0xffff) * c1) + ((((_u(k1) >> 16) * c1) & 0xffff) << 16))) & 0xffffffff
+        k1 = (k1 << 15) | (_u(k1) >> 17)
+        k1 = ((((k1 & 0xffff) * c2) + ((((_u(k1) >> 16) * c2) & 0xffff) << 16))) & 0xffffffff;
+
+        h1 ^= k1
+        h1 = (h1 << 13) | (_u(h1) >> 19);
+        h1b = ((((h1 & 0xffff) * 5) + ((((_u(h1) >> 16) * 5) & 0xffff) << 16))) & 0xffffffff;
+        h1 = (((h1b & 0xffff) + 0x6b64) + ((((_u(h1b) >> 16) + 0xe654) & 0xffff) << 16))
+
+
+    k1 = 0
+    v = None
+
+    if remainder == 3:
+        v = (key[i + 2] & 0xff) << 16
+    elif remainder == 2:
+        v = (key[i + 1] & 0xff) << 8
+    elif remainder == 1:
+        v = (key[i] & 0xff)
+
+    if v is not None:
+        k1 ^= v
+
+    k1 = (((k1 & 0xffff) * c1) + ((((_u(k1) >> 16) * c1) & 0xffff) << 16)) & 0xffffffff
+    k1 = (k1 << 15) | (_u(k1) >> 17)
+    k1 = (((k1 & 0xffff) * c2) + ((((_u(k1) >> 16) * c2) & 0xffff) << 16)) & 0xffffffff
+    h1 ^= k1
+
+    h1 ^= len(key)
+
+    h1 ^= _u(h1) >> 16
+    h1 = (((h1 & 0xffff) * 0x85ebca6b) + ((((_u(h1) >> 16) * 0x85ebca6b) & 0xffff) << 16)) & 0xffffffff
+    h1 ^= _u(h1) >> 13
+    h1 = ((((h1 & 0xffff) * 0xc2b2ae35) + ((((_u(h1) >> 16) * 0xc2b2ae35) & 0xffff) << 16))) & 0xffffffff
+    h1 ^= _u(h1) >> 16
+
+    return _u(h1) >> 0