1 files changed, 29 insertions, 0 deletions
diff --git a/bot/utils/converters.py b/bot/utils/converters.py
index 72b64848..9e9616d8 100644
--- a/bot/utils/converters.py
+++ b/bot/utils/converters.py
@@ -85,3 +85,32 @@ class DateConverter(commands.Converter):
                 f"Can't convert `{argument}` to `datetime` in format `YYYY-MM-DD` or `int` in SOL."
             )
         return date
+
+
+class Subreddit(commands.Converter):
+    """Forces a string to begin with "r/" and checks if it's a valid subreddit."""
+
+    @staticmethod
+    async def convert(ctx: commands.Context, sub: str) -> str:
+        """
+        Force sub to begin with "r/" and check if it's a valid subreddit.
+
+        If sub is a valid subreddit, return it prepended with "r/"
+        """
+        sub = sub.lower()
+
+        if not sub.startswith("r/"):
+            sub = f"r/{sub}"
+
+        resp = await ctx.bot.http_session.get(
+            "https://www.reddit.com/subreddits/search.json",
+            params={"q": sub}
+        )
+
+        json = await resp.json()
+        if not json["data"]["children"]:
+            raise commands.BadArgument(
+                f"The subreddit `{sub}` either doesn't exist, or it has no posts."
+            )
+
+        return sub