Add support for constructing webhook from a URL

disco/types/webhook.py

@@ -1,8 +1,13 @@
+import re
+
 from disco.types.base import SlottedModel, Field, snowflake
 from disco.types.user import User
 from disco.util.functional import cached_property
 
 
+WEBHOOK_URL_RE = re.compile(r'\/api\/webhooks\/(\d+)\/(.[^/]+)')
+
+
 class Webhook(SlottedModel):
     id = Field(snowflake)
     guild_id = Field(snowflake)
@@ -12,6 +17,14 @@ class Webhook(SlottedModel):
     avatar = Field(str)
     token = Field(str)
 
+    @classmethod
+    def from_url(cls, url):
+        results = WEBHOOK_URL_RE.findall(url)
+        if len(results) != 1:
+            return Exception('Invalid Webhook URL')
+
+        return cls(id=results[0][0], token=results[0][1])
+
     @cached_property
     def guild(self):
         return self.client.state.guilds.get(self.guild_id)