From 90c90e5bbda387d82c22c72f918f1de288fc6101 Mon Sep 17 00:00:00 2001
From: jesopo <github@lolnerd.net>
Date: Fri, 21 Jun 2019 18:05:11 +0100
Subject: [PATCH] Implement dependency system for CAPs

---
 modules/line_handler/ircv3.py | 49 +++++++++++++++++++++++++++++++++--
 src/utils/irc/__init__.py     |  4 ++-
 2 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/modules/line_handler/ircv3.py b/modules/line_handler/ircv3.py
index ceda7e4b..5b3962f7 100644
--- a/modules/line_handler/ircv3.py
+++ b/modules/line_handler/ircv3.py
@@ -16,13 +16,58 @@ CAPABILITIES = [
     utils.irc.Capability(None, "draft/setname", alias="setname")
 ]
 
+def _cap_depend_sort(caps, server_caps):
+    sorted_caps = []
+
+    caps_copy = {alias: cap.copy() for alias, cap in caps.items()}
+
+    for cap in caps.values():
+        if not cap.available(server_caps):
+            del caps_copy[cap.alias]
+
+    while True:
+        remove = []
+        for alias, cap in caps_copy.items():
+            for depend_alias in cap.depends_on:
+                if not depend_alias in caps_copy:
+                    remove.append(alias)
+        if remove:
+            for alias in remove:
+                del caps_copy[alias]
+        else:
+            break
+
+    while caps_copy:
+        fulfilled = []
+        for cap in caps_copy.values():
+            remove = []
+            for depend_alias in cap.depends_on:
+                if depend_alias in sorted_caps:
+                    remove.append(depend_alias)
+            for remove_cap in remove:
+                cap.depends_on.remove(remove_cap)
+
+            if not cap.depends_on:
+                fulfilled.append(cap.alias)
+        for fulfilled_cap in fulfilled:
+            del caps_copy[fulfilled_cap]
+            sorted_caps.append(fulfilled_cap)
+    return [caps[alias] for alias in sorted_caps]
+
 def _cap_match(server, caps):
     matched_caps = {}
     blacklist = server.get_setting("blacklisted-caps", [])
+
+    cap_aliases = {}
     for cap in caps:
+        if not cap.alias in blacklist:
+            cap_aliases[cap.alias] = cap
+
+    sorted_caps = _cap_depend_sort(cap_aliases, server.server_capabilities)
+
+    for cap in sorted_caps:
         available = cap.available(server.server_capabilities)
-        if (available and not server.has_capability(cap) and
-                not available in blacklist):
+        if available and not server.has_capability(cap):
             matched_caps[available] = cap
     return matched_caps
 
diff --git a/src/utils/irc/__init__.py b/src/utils/irc/__init__.py
index c6dcbf0d..d470bdbe 100644
--- a/src/utils/irc/__init__.py
+++ b/src/utils/irc/__init__.py
@@ -291,6 +291,7 @@ class Capability(object):
             depends_on: typing.List[str]=None):
         self.alias = alias or ratified_name
         self._caps = set([ratified_name, draft_name])
+        self.depends_on = depends_on or []
         self._on_ack_callbacks = [
             ] # type: typing.List[typing.Callable[[], None]]
 
@@ -304,7 +305,8 @@ class Capability(object):
         return cap[0] if cap else None
 
     def copy(self):
-        return Capability(*self._caps)
+        return Capability(*self._caps, alias=self.alias,
+            depends_on=self.depends_on)
 
     def on_ack(self, callback: typing.Callable[[], None]):
         self._on_ack_callbacks.append(callback)