feat: Modularize handlers

Signed-off-by: Frost Ming <me@frostming.com>

handlers/__init__.py

@@ -0,0 +1,79 @@
+from __future__ import annotations
+
+import importlib
+import re
+import traceback
+from functools import update_wrapper
+from pathlib import Path
+from typing import Any, Callable, TypeVar
+
+from telebot import TeleBot
+from telebot.types import BotCommand, Message
+
+T = TypeVar("T", bound=Callable)
+
+
+def extract_prompt(message: str, bot_name: str) -> str:
+    """
+    This function filters messages for prompts.
+
+    Returns:
+      str: If it is not a prompt, return None. Otherwise, return the trimmed prefix of the actual prompt.
+    """
+    # remove '@bot_name' as it is considered part of the command when in a group chat.
+    message = re.sub(re.escape(f"@{bot_name}"), "", message).strip()
+    # add a whitespace after the first colon to make sure it is separated from the prompt.
+    message = re.sub(":", ": ", message, count=1).strip()
+    try:
+        left, message = message.split(maxsplit=1)
+    except ValueError:
+        return ""
+    if ":" not in left:
+        # restore the added space
+        message = message.replace(": ", ":", 1)
+    return message.strip()
+
+
+def wrap_handler(handler: T, bot: TeleBot) -> T:
+    def wrapper(message: Message, *args: Any, **kwargs: Any) -> None:
+        try:
+            m = ""
+            if message.text is not None:
+                m = message.text = extract_prompt(message.text, bot.get_me().username)
+            elif message.caption is not None:
+                m = message.caption = extract_prompt(
+                    message.caption, bot.get_me().username
+                )
+            if not m:
+                bot.reply_to(message, "Please provide info after start words.")
+                return
+            return handler(m, *args, **kwargs)
+        except Exception:
+            traceback.print_exc()
+            bot.reply_to(message, "Something wrong, please check the log")
+
+    return update_wrapper(wrapper, handler)
+
+
+def load_handlers(bot: TeleBot) -> None:
+    # import all submodules
+    this_path = Path(__file__).parent
+    for child in this_path.iterdir():
+        if child.name.startswith("_"):
+            continue
+        module = importlib.import_module(f".{child.stem}", __package__)
+        if hasattr(module, "register"):
+            print(f"Loading {child.stem} handlers.")
+            module.register(bot)
+    print("Loading handlers done.")
+
+    all_commands: list[BotCommand] = []
+    for handler in bot.message_handlers:
+        help_text = getattr(handler["function"], "__doc__", "")
+        handler["function"] = wrap_handler(handler["function"], bot)
+        for command in handler["filters"].get("commands", []):
+            all_commands.append(BotCommand(command, help_text))
+
+    if all_commands:
+        bot.set_my_commands(all_commands)
+        print("Setting commands done.")