bot: env: map known env vars to object

This just makes accessing them easier.

What could be done in the future have some kind of utility method for
debugging that prints all of them or returns all of them as a dict or
something.

Signed-off-by: Max R. Carrara <max@aequito.sh>

.gitignore

@@ -165,3 +165,5 @@ cython_debug/
 # Ruff stuff
 .ruff_cache/
 
+# Bot stuff
+token.txt

src/bot/env.py

@@ -0,0 +1,44 @@
+import functools
+import os
+import pathlib
+import re
+
+
+class Environment:
+    @classmethod
+    @functools.lru_cache(maxsize=1)
+    def bot_log_level(cls) -> str:
+        return os.environ.get("BOT_LOG_LEVEL", "INFO").strip().upper()
+
+    @classmethod
+    @functools.lru_cache(maxsize=1)
+    def bot_memory_db(cls) -> bool:
+        res = os.environ.get("BOT_MEMORY_DB", "0").strip()
+
+        return bool(int(res))
+
+    @classmethod
+    @functools.lru_cache(maxsize=1)
+    def bot_owner_id(cls) -> int | None:
+        if "BOT_OWNER_ID" in os.environ:
+            return int(os.environ["BOT_OWNER_ID"])
+        return
+
+    @classmethod
+    @functools.lru_cache(maxsize=1)
+    def bot_prefix(cls) -> str:
+        res = os.environ.get("BOT_PREFIX", "!").strip()
+
+        if re.match(r"\s", res):
+            raise ValueError(
+                f'Bot prefix may not contain any whitespace: "{res}" is invalid'
+            )
+
+        return res
+
+    @classmethod
+    @functools.lru_cache(maxsize=1)
+    def bot_token_path(cls) -> pathlib.Path:
+        res = os.environ.get("BOT_TOKEN_PATH", "./token.txt")
+
+        return pathlib.Path(res)