import datetime
from typing import Type, Union

from sqlalchemy import select
from sqlalchemy.orm import joinedload, selectinload

from models import User, Deal
from models.deal import *
from schemas.client import ClientDetailsSchema
from schemas.deal import *
from services.base import BaseService
from services.client import ClientService


class DealService(BaseService):

    async def _get_deal_by_id(self, deal_id) -> Union[Deal, None]:
        return await self.session.get(Deal, deal_id)

    async def change_status(self, deal: Deal,
                            status: DealStatus,
                            user: User,
                            deadline: datetime.datetime = None) -> DealStatusHistory:
        deadline = deadline
        status_change = DealStatusHistory(
            deal_id=deal.id,
            user_id=user.id,
            changed_at=datetime.datetime.now(),
            from_status=deal.current_status,
            to_status=status,
            next_status_deadline=deadline
        )
        self.session.add(status_change)
        await self.session.flush()
        return status_change

    async def create(self, request: DealCreateRequest, user: User) -> DealCreateResponse:
        deal = Deal(
            name=request.name,
            created_at=datetime.datetime.now(),
            current_status=DealStatus.CREATED
        )
        self.session.add(deal)
        await self.session.flush()

        # Append status history
        await self.change_status(deal, DealStatus.AWAITING_ACCEPTANCE, user)

        await self.session.commit()
        return DealCreateResponse(ok=True)

    async def quick_create(self, request: DealQuickCreateRequest, user: User) -> DealQuickCreateResponse:
        client_service = ClientService(self.session)
        client = await client_service.get_by_name(request.client_name)
        if not client:
            client = await client_service.create_client_raw(
                user,
                request.client_name,
                ClientDetailsSchema(address=request.client_address))
        await client_service.update_details(user, client, ClientDetailsSchema(address=request.client_address))
        deal = Deal(
            name=request.name,
            created_at=datetime.datetime.now(),
            client_id=client.id,
            current_status=DealStatus.CREATED
        )
        self.session.add(deal)
        await self.session.flush()
        await self.change_status(deal, DealStatus.AWAITING_ACCEPTANCE, user, deadline=request.acceptance_date)
        await self.session.commit()
        return DealQuickCreateResponse(deal_id=deal.id)

    async def change_status_manual(self, request: DealChangeStatusRequest, user: User) -> DealChangeStatusResponse:
        # Changing current status
        deal = await self._get_deal_by_id(request.deal_id)
        if not deal:
            return DealChangeStatusResponse(ok=False)
        await self.change_status(deal, DealStatus(request.new_status), user)
        await self.session.commit()
        return DealChangeStatusResponse(ok=True)

    async def get_summary(self) -> DealSummaryResponse:
        deals_query = await self.session.scalars(select(Deal)
                                                 .options(selectinload(Deal.status_history),
                                                          joinedload(Deal.client))
                                                 .where(Deal.is_deleted == False,
                                                        Deal.is_completed == False))
        summaries = []
        for deal in deals_query.all():
            deal: Deal
            last_status: DealStatusHistory = max(deal.status_history, key=lambda status: status.changed_at)
            summaries.append(
                DealSummary(
                    id=deal.id,
                    client_name=deal.client.name,
                    name=deal.name,
                    changed_at=last_status.changed_at,
                    status=last_status.to_status
                )
            )
        return DealSummaryResponse(summaries=summaries)