from typing import Union, Optional

from libs.infinite_scroll_pagination import InfiniteScrollPagination
from extensions.ext_database import db
from models.account import Account
from models.model import Conversation, App, EndUser
from services.errors.conversation import ConversationNotExistsError, LastConversationNotExistsError


class ConversationService:
    @classmethod
    def pagination_by_last_id(cls, app_model: App, user: Optional[Union[Account | EndUser]],
                              last_id: Optional[str], limit: int,
                              include_ids: Optional[list] = None, exclude_ids: Optional[list] = None) -> InfiniteScrollPagination:
        if not user:
            return InfiniteScrollPagination(data=[], limit=limit, has_more=False)

        base_query = db.session.query(Conversation).filter(
            Conversation.is_deleted == False,
            Conversation.app_id == app_model.id,
            Conversation.from_source == ('api' if isinstance(user, EndUser) else 'console'),
            Conversation.from_end_user_id == (user.id if isinstance(user, EndUser) else None),
            Conversation.from_account_id == (user.id if isinstance(user, Account) else None),
        )

        if include_ids is not None:
            base_query = base_query.filter(Conversation.id.in_(include_ids))

        if exclude_ids is not None:
            base_query = base_query.filter(~Conversation.id.in_(exclude_ids))

        if last_id:
            last_conversation = base_query.filter(
                Conversation.id == last_id,
            ).first()

            if not last_conversation:
                raise LastConversationNotExistsError()

            conversations = base_query.filter(
                Conversation.created_at < last_conversation.created_at,
                Conversation.id != last_conversation.id
            ).order_by(Conversation.created_at.desc()).limit(limit).all()
        else:
            conversations = base_query.order_by(Conversation.created_at.desc()).limit(limit).all()

        has_more = False
        if len(conversations) == limit:
            current_page_first_conversation = conversations[-1]
            rest_count = base_query.filter(
                Conversation.created_at < current_page_first_conversation.created_at,
                Conversation.id != current_page_first_conversation.id
            ).count()

            if rest_count > 0:
                has_more = True

        return InfiniteScrollPagination(
            data=conversations,
            limit=limit,
            has_more=has_more
        )

    @classmethod
    def rename(cls, app_model: App, conversation_id: str,
               user: Optional[Union[Account | EndUser]], name: str):
        conversation = cls.get_conversation(app_model, conversation_id, user)

        conversation.name = name
        db.session.commit()

        return conversation

    @classmethod
    def get_conversation(cls, app_model: App, conversation_id: str, user: Optional[Union[Account | EndUser]]):
        conversation = db.session.query(Conversation) \
            .filter(
            Conversation.id == conversation_id,
            Conversation.app_id == app_model.id,
            Conversation.from_source == ('api' if isinstance(user, EndUser) else 'console'),
            Conversation.from_end_user_id == (user.id if isinstance(user, EndUser) else None),
            Conversation.from_account_id == (user.id if isinstance(user, Account) else None),
            Conversation.is_deleted == False
        ).first()

        if not conversation:
            raise ConversationNotExistsError()

        return conversation

    @classmethod
    def delete(cls, app_model: App, conversation_id: str, user: Optional[Union[Account | EndUser]]):
        conversation = cls.get_conversation(app_model, conversation_id, user)

        conversation.is_deleted = True
        db.session.commit()