"""
Service for chat functionality.
"""

from typing import List, Dict, Any, Optional
from app.database.db import db
from app.models.chat import Chat, Message, TeamChatMember
from app.models.user import User

class ChatService:
    """Service for chat functionality."""
    
    def create_chat(self, user_id: int, title: Optional[str] = None, 
                   is_team_chat: bool = False, model_name: Optional[str] = None) -> Chat:
        """
        Create a new chat.
        
        Args:
            user_id: ID of the user creating the chat.
            title: Optional title for the chat.
            is_team_chat: Whether this is a team chat.
            model_name: Name of the model to use for this chat.
            
        Returns:
            Created chat.
        """
        from app.config.config import Config
        
        chat = Chat(
            user_id=user_id,
            title=title,
            is_team_chat=is_team_chat,
            model_name=model_name or Config().DEFAULT_MODEL
        )
        
        db.session.add(chat)
        db.session.commit()
        
        # If it's a team chat, add the creator as a member
        if is_team_chat:
            self.add_team_member(chat.id, user_id)
        
        return chat
    
    def get_chat(self, chat_id: int) -> Optional[Chat]:
        """
        Get a chat by ID.
        
        Args:
            chat_id: ID of the chat.
            
        Returns:
            Chat if found, None otherwise.
        """
        return Chat.query.get(chat_id)
    
    def get_user_chats(self, user_id: int) -> List[Chat]:
        """
        Get all chats for a user.
        
        Args:
            user_id: ID of the user.
            
        Returns:
            List of chats.
        """
        # Get private chats
        private_chats = Chat.query.filter_by(
            user_id=user_id, 
            is_team_chat=False
        ).order_by(Chat.updated_at.desc()).all()
        
        # Get team chats where user is a member
        team_chat_ids = db.session.query(TeamChatMember.chat_id).filter_by(user_id=user_id).all()
        team_chat_ids = [chat_id for (chat_id,) in team_chat_ids]
        
        team_chats = Chat.query.filter(
            Chat.id.in_(team_chat_ids)
        ).order_by(Chat.updated_at.desc()).all()
        
        # Combine and sort by updated_at
        all_chats = private_chats + team_chats
        all_chats.sort(key=lambda x: x.updated_at, reverse=True)
        
        return all_chats
    
    def add_message(self, chat_id: int, content: str, 
                   is_user_message: bool = True, user_id: Optional[int] = None) -> Message:
        """
        Add a message to a chat.
        
        Args:
            chat_id: ID of the chat.
            content: Message content.
            is_user_message: Whether this is a user message (vs. bot message).
            user_id: ID of the user sending the message (required for user messages).
            
        Returns:
            Created message.
        """
        message = Message(
            chat_id=chat_id,
            content=content,
            is_user_message=is_user_message,
            user_id=user_id if is_user_message else None
        )
        
        db.session.add(message)
        
        # Update chat's updated_at timestamp
        chat = Chat.query.get(chat_id)
        if chat:
            chat.updated_at = message.created_at
        
        db.session.commit()
        
        return message
    
    def get_chat_messages(self, chat_id: int) -> List[Message]:
        """
        Get all messages for a chat.
        
        Args:
            chat_id: ID of the chat.
            
        Returns:
            List of messages.
        """
        return Message.query.filter_by(chat_id=chat_id).order_by(Message.created_at).all()
    
    def add_team_member(self, chat_id: int, user_id: int) -> Optional[TeamChatMember]:
        """
        Add a user to a team chat.
        
        Args:
            chat_id: ID of the team chat.
            user_id: ID of the user to add.
            
        Returns:
            Created team chat member if successful, None otherwise.
        """
        chat = Chat.query.get(chat_id)
        if not chat or not chat.is_team_chat:
            return None
        
        # Check if user is already a member
        existing_member = TeamChatMember.query.filter_by(
            chat_id=chat_id, 
            user_id=user_id
        ).first()
        
        if existing_member:
            return existing_member
        
        member = TeamChatMember(
            chat_id=chat_id,
            user_id=user_id
        )
        
        db.session.add(member)
        db.session.commit()
        
        return member
    
    def get_team_members(self, chat_id: int) -> List[User]:
        """
        Get all members of a team chat.
        
        Args:
            chat_id: ID of the team chat.
            
        Returns:
            List of users.
        """
        member_ids = db.session.query(TeamChatMember.user_id).filter_by(chat_id=chat_id).all()
        member_ids = [user_id for (user_id,) in member_ids]
        
        return User.query.filter(User.id.in_(member_ids)).all()
    
    def remove_team_member(self, chat_id: int, user_id: int) -> bool:
        """
        Remove a user from a team chat.
        
        Args:
            chat_id: ID of the team chat.
            user_id: ID of the user to remove.
            
        Returns:
            True if removal was successful, False otherwise.
        """
        member = TeamChatMember.query.filter_by(
            chat_id=chat_id, 
            user_id=user_id
        ).first()
        
        if not member:
            return False
        
        db.session.delete(member)
        db.session.commit()
        
        return True
    
    def delete_chat(self, chat_id: int) -> bool:
        """
        Delete a chat and all its messages.
        
        Args:
            chat_id: ID of the chat to delete.
            
        Returns:
            True if deletion was successful, False otherwise.
        """
        chat = Chat.query.get(chat_id)
        if not chat:
            return False
        
        try:
            db.session.delete(chat)
            db.session.commit()
            return True
            
        except Exception as e:
            # Log the error
            print(f"Error deleting chat {chat_id}: {str(e)}")
            db.session.rollback()
            return False