feat(settings): implement group settings handlers for welcome messages

- Added handlers for setting, resetting, and retrieving custom welcome messages in group chats.
- Included admin verification to restrict command usage to administrators only.
- Enhanced user feedback with localized messages for command usage and current settings.

Author: MattiaFailla

src/python_italy_bot/handlers/settings.py

@@ -0,0 +1,151 @@
+"""Group settings handlers: setwelcome, etc."""
+
+import logging
+
+from telegram import Update
+from telegram.constants import ChatMemberStatus
+from telegram.ext import CommandHandler, ContextTypes
+
+from ..services.captcha import CaptchaService
+
+logger = logging.getLogger(__name__)
+
+
+async def _is_admin(
+    context: ContextTypes.DEFAULT_TYPE, chat_id: int, user_id: int
+) -> bool:
+    """Check if user is admin in the chat."""
+    try:
+        member = await context.bot.get_chat_member(chat_id, user_id)
+        return member.status in (
+            ChatMemberStatus.ADMINISTRATOR,
+            ChatMemberStatus.OWNER,
+        )
+    except Exception:
+        return False
+
+
+def create_settings_handlers() -> list:
+    """Create group settings handlers."""
+    return [
+        CommandHandler("setwelcome", _handle_setwelcome),
+        CommandHandler("resetwelcome", _handle_resetwelcome),
+        CommandHandler("getwelcome", _handle_getwelcome),
+    ]
+
+
+async def _handle_setwelcome(
+    update: Update, context: ContextTypes.DEFAULT_TYPE
+) -> None:
+    """Set custom welcome message for the group.
+    
+    Usage: /setwelcome <message>
+    
+    Supports placeholders:
+      - {username}: @username or full name
+      - {chatname}: group name
+    
+    Supports button syntax:
+      - [Button Text](buttonurl://URL)
+    """
+    captcha_service: CaptchaService = context.bot_data["captcha_service"]
+    message = update.message
+    if message is None or message.from_user is None:
+        return
+
+    chat = update.effective_chat
+    if chat is None or chat.type == "private":
+        await message.reply_text("Questo comando funziona solo nei gruppi.")
+        return
+
+    if not await _is_admin(context, chat.id, message.from_user.id):
+        await message.reply_text(
+            "Solo gli amministratori possono usare questo comando."
+        )
+        return
+
+    if message.text is None:
+        return
+
+    parts = message.text.split(maxsplit=1)
+    if len(parts) < 2:
+        await message.reply_text(
+            "Uso: /setwelcome <messaggio>\n\n"
+            "Placeholder disponibili:\n"
+            "  {username} - @username o nome completo\n"
+            "  {chatname} - nome del gruppo\n\n"
+            "Sintassi bottoni:\n"
+            "  [Testo](buttonurl://URL)"
+        )
+        return
+
+    welcome_message = parts[1]
+    await captcha_service.set_welcome_message(chat.id, welcome_message)
+    await message.reply_text("Messaggio di benvenuto impostato!")
+    logger.info(
+        "Welcome message set for chat %s by admin %s",
+        chat.id,
+        message.from_user.id,
+    )
+
+
+async def _handle_resetwelcome(
+    update: Update, context: ContextTypes.DEFAULT_TYPE
+) -> None:
+    """Reset welcome message to default."""
+    captcha_service: CaptchaService = context.bot_data["captcha_service"]
+    message = update.message
+    if message is None or message.from_user is None:
+        return
+
+    chat = update.effective_chat
+    if chat is None or chat.type == "private":
+        await message.reply_text("Questo comando funziona solo nei gruppi.")
+        return
+
+    if not await _is_admin(context, chat.id, message.from_user.id):
+        await message.reply_text(
+            "Solo gli amministratori possono usare questo comando."
+        )
+        return
+
+    await captcha_service.set_welcome_message(chat.id, None)
+    await message.reply_text("Messaggio di benvenuto ripristinato al default.")
+    logger.info(
+        "Welcome message reset for chat %s by admin %s",
+        chat.id,
+        message.from_user.id,
+    )
+
+
+async def _handle_getwelcome(
+    update: Update, context: ContextTypes.DEFAULT_TYPE
+) -> None:
+    """Show current welcome message."""
+    captcha_service: CaptchaService = context.bot_data["captcha_service"]
+    message = update.message
+    if message is None or message.from_user is None:
+        return
+
+    chat = update.effective_chat
+    if chat is None or chat.type == "private":
+        await message.reply_text("Questo comando funziona solo nei gruppi.")
+        return
+
+    if not await _is_admin(context, chat.id, message.from_user.id):
+        await message.reply_text(
+            "Solo gli amministratori possono usare questo comando."
+        )
+        return
+
+    custom_message = await captcha_service.get_welcome_message(chat.id)
+    if custom_message:
+        await message.reply_text(
+            f"Messaggio di benvenuto attuale:\n\n{custom_message}"
+        )
+    else:
+        bot_username = (await context.bot.get_me()).username or "bot"
+        default = captcha_service.get_default_welcome_template(bot_username)
+        await message.reply_text(
+            f"Nessun messaggio personalizzato. Default:\n\n{default}"
+        )