Added external emoji replacement filter

- Added pattern `RE_EMOJI` to capture emoji markdowns
- Implemented dataclass for emoji information
- Added function `_ext_emoji_replace` to replace external undisplayable emojis with random emoticons
- Added call to said function in `_uwuify`

1 files changed, 46 insertions, 0 deletions

diff --git a/bot/exts/fun/uwu.py b/bot/exts/fun/uwu.py
index 26c5c741..053e64cd 100644
--- a/bot/exts/fun/uwu.py
+++ b/bot/exts/fun/uwu.py
@@ -1,6 +1,7 @@
 import random
 import re
 import typing as t
+from dataclasses import dataclass
 from functools import partial
 
 import discord
@@ -56,6 +57,30 @@ SUBSTITUTE_STUTTER = r"\g<1>\g<2>-\g<2>"
 REGEX_NYA = re.compile(r"n([aeou][^aeiou])")
 SUBSTITUTE_NYA = r"ny\1"
 
+RE_EMOJI = re.compile(r"<(a?)?:(\w+):(\d{18})>?")
+
+
+@dataclass(frozen=True, eq=True)
+class Emoji:
+    name: str
+    uid: int
+    animated: bool = False
+
+    def __str__(self):
+        anim_bit = "a" if self.animated else ""
+        return f"<{anim_bit}:{self.name}:{self.uid}>"
+
+    def can_display(self, bot: Bot) -> bool:
+        """Determines if a bot is in a server with the emoji."""
+        return bot.get_emoji(self.uid) is not None
+
+    @classmethod
+    def from_match(cls, match: tuple[str, str, str]) -> t.Optional['Emoji']:
+        """Creates an Emoji from a regex match tuple."""
+        if not match or len(match) != 3 or not match[2].isdigit():
+            return None
+        return cls(match[1], int(match[2]), match[0] == "a")
+
 
 class Uwu(Cog):
     """Cog for the uwu command."""
@@ -99,6 +124,26 @@ class Uwu(Cog):
             return f" {random.choice(EMOJIS)} "
         return match_string
 
+    def _ext_emoji_replace(self, input_string: str) -> str:
+        """Replaces external emojis with emoticons"""
+        groups = RE_EMOJI.findall(input_string)
+        emojis = {Emoji.from_match(match) for match in groups}
+        # Replace with random emoticon if unable to display
+        emojis_map = {
+            re.escape(str(e)): random.choice(EMOJIS)
+            for e in emojis if e and not e.can_display(self.bot)
+        }
+        if emojis_map:
+            # Pattern for all emoji markdowns to be replaced
+            emojis_re = re.compile("|".join(emojis_map.keys()))
+            # Replace matches with random emoticon
+            return emojis_re.sub(
+                lambda m: emojis_map[re.escape(m.group())],
+                input_string
+            )
+        # Return original if no replacement
+        return input_string
+
     def _uwuify(self, input_string: str, *, stutter_strength: float = 0.2, emoji_strength: float = 0.1) -> str:
         """Takes a string and returns an uwuified version of it."""
         input_string = input_string.lower()
@@ -107,6 +152,7 @@ class Uwu(Cog):
         input_string = self._char_replace(input_string)
         input_string = self._stutter(stutter_strength, input_string)
         input_string = self._emoji(emoji_strength, input_string)
+        input_string = self._ext_emoji_replace(input_string)
         return input_string
 
     @commands.command(name="uwu", aliases=("uwuwize", "uwuify",))