"""Handlers for group events."""
import telebot
from typing import Optional
from telebot import types
from sqlalchemy.orm import Session
from database import get_db_session, User, Chat, UserChat


def register_group_handlers(bot: telebot.TeleBot) -> None:
    """Register all group event handlers."""
    
    @bot.message_handler(content_types=['new_chat_members'])
    def handle_new_member(message: telebot.types.Message) -> None:
        """Handle bot being added to a chat."""
        # Check if bot was added
        bot_me = bot.get_me()
        if not bot_me:
            return
        
        for member in message.new_chat_members:
            if member.id == bot_me.id:
                chat_id = message.chat.id
                chat_title: str = message.chat.title or "Unknown"
                
                db = get_db_session()
                try:
                    # Check if chat exists
                    chat = db.query(Chat).filter(Chat.chat_id == chat_id).first()
                    if not chat:
                        chat = Chat(chat_id=chat_id, chat_title=chat_title, bot_is_admin=False)
                        db.add(chat)
                        db.commit()
                    
                    # Check if bot is admin
                    try:
                        bot_me = bot.get_me()
                        if not bot_me:
                            return
                        bot_member = bot.get_chat_member(chat_id, bot_me.id)
                        is_admin = bot_member.status in ['administrator', 'creator']
                        chat.bot_is_admin = is_admin
                        db.commit()
                        
                        if not is_admin:
                            # Request admin rights
                            bot.reply_to(
                                message,
                                "Привет! Мне нужны права администратора, чтобы видеть список участников чата. "
                                "Пожалуйста, выдайте мне права администратора."
                            )
                        else:
                            # Sync users and show statistics
                            sync_chat_users(bot, db, chat_id)
                            show_statistics(bot, message.chat)
                    except Exception:
                        # Bot might not have permission to check
                        chat.bot_is_admin = False
                        db.commit()
                        bot.reply_to(
                            message,
                            "Привет! Мне нужны права администратора, чтобы видеть список участников чата. "
                            "Пожалуйста, выдайте мне права администратора."
                        )
                finally:
                    db.close()
                break
    
    # NOTE:
    # Updates about the bot itself (когда бота повышают до админа / понижают)
    # приходят в поле `my_chat_member`, а не `chat_member`.
    # Для их обработки в pyTelegramBotAPI нужно использовать my_chat_member_handler.
    @bot.my_chat_member_handler()
    def handle_chat_member_update(message: telebot.types.ChatMemberUpdated) -> None:
        """Handle my_chat_member updates (bot role changes, e.g. becoming admin)."""
        bot_me = bot.get_me()
        if not bot_me:
            return
        
        if message.new_chat_member.user.id == bot_me.id:
            # Bot's status changed
            chat_id = message.chat.id
            chat_title: str = message.chat.title or "Unknown"
            
            db = get_db_session()
            try:
                chat = db.query(Chat).filter(Chat.chat_id == chat_id).first()
                if not chat:
                    chat = Chat(chat_id=chat_id, chat_title=chat_title, bot_is_admin=False)
                    db.add(chat)
                
                # Check if bot became admin
                is_admin = message.new_chat_member.status in ['administrator', 'creator']
                was_admin = chat.bot_is_admin if chat else False
                if chat:
                    chat.bot_is_admin = is_admin
                    chat.chat_title = chat_title
                    db.commit()
                
                if is_admin and not was_admin:
                    # Bot just became admin - sync users and show statistics
                    sync_chat_users(bot, db, chat_id)
                    show_statistics(bot, message.chat)
            finally:
                db.close()


def sync_chat_users(bot: telebot.TeleBot, db: Session, chat_id: int) -> None:
    """Sync users from chat with database."""
    try:
        # Get all chat members (this requires admin rights)
        # Note: This is a simplified approach - in production you might want to
        # use get_chat_administrators or iterate through members differently
        # For now, we'll sync users as they interact with the bot
        
        # Get all users who already shared birthday
        existing_users = db.query(User).all()
        
        # Try to check if they're in this chat and add relationships
        for user in existing_users:
            try:
                member = bot.get_chat_member(chat_id, user.user_id)
                if member.status not in ['left', 'kicked']:
                    # User is in chat - ensure relationship exists
                    user_chat = db.query(UserChat).filter(
                        UserChat.user_id == user.user_id,
                        UserChat.chat_id == chat_id
                    ).first()
                    
                    if not user_chat:
                        user_chat = UserChat(user_id=user.user_id, chat_id=chat_id)
                        db.add(user_chat)
            except Exception:
                # User might have blocked bot or is not in chat
                pass
        
        db.commit()
    except Exception:
        # If sync fails, continue anyway
        pass


def show_statistics(bot: telebot.TeleBot, chat: telebot.types.Chat) -> None:
    """Show statistics about users who shared their birthday."""
    db = get_db_session()
    try:
        chat_id = chat.id
        
        # Get all chat members
        try:
            members_count = bot.get_chat_member_count(chat_id)
        except Exception:
            members_count = 0
        
        # Get users from this chat who shared birthday
        users_with_birthday = db.query(User).join(UserChat).filter(
            UserChat.chat_id == chat_id
        ).distinct().count()
        
        # Create message
        if members_count > 0:
            percentage = (users_with_birthday / members_count) * 100
            message_text = (
                f"Отлично! Теперь я админ этого чата.\n\n"
                f"📊 Статистика:\n"
                f"• Поделились днем рождения: {users_with_birthday} из {members_count} участников\n"
                f"• Процент: {percentage:.1f}%"
            )
        else:
            message_text = (
                f"Отлично! Теперь я админ этого чата.\n\n"
                f"📊 Поделились днем рождения: {users_with_birthday} участников"
            )
        
        # Create inline keyboard with button to start private chat
        bot_me = bot.get_me()
        if not bot_me or not bot_me.username:
            bot.send_message(chat_id, message_text)
            return
        
        keyboard = types.InlineKeyboardMarkup()
        start_button = types.InlineKeyboardButton(
            text="Поделиться днем рождения",
            url=f"https://t.me/{bot_me.username}?start=share_birthday"
        )
        keyboard.add(start_button)
        
        bot.send_message(chat_id, message_text, reply_markup=keyboard)
    finally:
        db.close()