from abc import ABC, abstractmethod
from typing import Tuple

from sqlalchemy import case, func, nulls_last, select, update
from sqlalchemy.ext.asyncio import AsyncSession

from common.database.db_session_manager import DB_SESSION_MNG
from common.database.model.models import items, quotations, sessions
from common.enums import ErrorType, SessionStatus
from common.logger import LOG


# 협상 세션 CRUD. 목록은 세션(negotiation) ⨝ 상품(partner) ⨝ 견적(quotation) 조인으로 만든다.
# 마감일(qt_end_time)은 견적(quotation.end_time)이 진실값이다(session.end_time 은 협상 종료 시점 기록용).
class ISessionCRUD(ABC):
    @abstractmethod
    async def list_by_supplier(self, cdb: AsyncSession, supplier_id, status, qt_type, order, offset, limit) -> Tuple[ErrorType, list]:
        pass

    @abstractmethod
    async def count_by_supplier(self, cdb: AsyncSession, supplier_id, status, qt_type) -> Tuple[ErrorType, int]:
        pass

    @abstractmethod
    async def get_session_by_id(self, cdb: AsyncSession, session_id) -> Tuple[ErrorType, sessions]:
        pass

    @abstractmethod
    async def get_quotation_by_id(self, cdb: AsyncSession, quotation_id) -> Tuple[ErrorType, quotations]:
        pass

    @abstractmethod
    async def update_session_status(self, cdb: AsyncSession, session_id, status: int) -> ErrorType:
        pass

    @abstractmethod
    async def update_quotation_status(self, cdb: AsyncSession, quotation_id, status: int) -> ErrorType:
        pass

    @abstractmethod
    async def update_session_reject(self, cdb: AsyncSession, session_id, status: int, reject_reason: str) -> ErrorType:
        pass

    @abstractmethod
    async def update_session_custom(self, cdb: AsyncSession, session_id, supplier_id, custom: dict) -> ErrorType:
        pass


class SessionCRUD(ISessionCRUD):
    @staticmethod
    def __filters(supplier_id, status, qt_type):
        conds = [sessions.supplier_id == supplier_id, sessions.deleted == False]  # noqa: E712
        if status is not None:
            conds.append(sessions.status == status)
        if qt_type is not None:
            conds.append(sessions.qt_type == qt_type)
        return conds

    async def list_by_supplier(self, cdb: AsyncSession, supplier_id, status, qt_type, order, offset, limit) -> Tuple[ErrorType, list]:
        try:
            conds = self.__filters(supplier_id, status, qt_type)

            # 정렬 규칙:
            #  - order 를 명시(asc/desc)하면 그룹 구분 없이 전체를 마감 기준 한 줄로 정렬(전체 정렬).
            #  - order 가 없으면(기본) UX 그룹 정렬:
            #      (1) '할 일'(협상생성·협상중)을 위로, 종료(완료·미참여·거부)는 아래로 그룹핑
            #      (2) 액션 그룹은 마감 임박순, (3) 종료 그룹은 최근 마감순(desc)
            #  - 어느 경우든 동일 마감은 session_id 로 tie-break → 페이지네이션 안정화.
            #    end_time 이 실제 NULL 인 견적은 nulls_last 로 맨 뒤로 민다.
            if order in ("asc", "desc"):
                flat = quotations.end_time.desc() if order == "desc" else quotations.end_time.asc()
                order_cols = (nulls_last(flat), sessions.session_id.asc())
            else:
                # 그룹별로 정렬 방향이 달라, case 로 '자기 그룹 행만 end_time' 을 갖는 키를 만들고
                # 반대 그룹은 NULL 로 눌러 간섭을 없앤다. status_rank 가 1차 키라 그룹 경계는 항상 유지.
                actionable = sessions.status.in_((SessionStatus.CREATED.value, SessionStatus.IN_PROGRESS.value))
                status_rank = case((actionable, 0), else_=1)
                action_order = case((actionable, quotations.end_time), else_=None).asc()
                done_order = case((~actionable, quotations.end_time), else_=None).desc()
                order_cols = (status_rank.asc(), nulls_last(action_order), nulls_last(done_order), sessions.session_id.asc())

            query = (
                select(
                    sessions.session_id,
                    sessions.status,
                    sessions.qt_type,
                    sessions.qt_number,
                    quotations.end_time,  # qt_end_time = 견적 마감 시각
                    items.code,
                    items.name,
                    items.model_name,
                    items.manufacturer,
                    sessions.custom,
                )
                .join(items, items.item_id == sessions.item_id)
                .join(quotations, quotations.qt_id == sessions.quotation_id)
                .where(*conds, items.deleted == False, quotations.deleted == False)  # noqa: E712
                .order_by(*order_cols)
                .offset(offset)
                .limit(limit)
            )
            err_type, rows = await DB_SESSION_MNG.execute(cdb, query, "list_by_supplier failed.")
            if err_type != ErrorType.SUCCESS:
                return err_type, []
            return ErrorType.SUCCESS, rows
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED, []

    async def count_by_supplier(self, cdb: AsyncSession, supplier_id, status, qt_type) -> Tuple[ErrorType, int]:
        try:
            conds = self.__filters(supplier_id, status, qt_type)
            query = (
                select(func.count())
                .select_from(sessions)
                .join(items, items.item_id == sessions.item_id)
                .join(quotations, quotations.qt_id == sessions.quotation_id)
                .where(*conds, items.deleted == False, quotations.deleted == False)  # noqa: E712
            )
            err_type, rows = await DB_SESSION_MNG.execute(cdb, query, "count_by_supplier failed.")
            if err_type != ErrorType.SUCCESS:
                return err_type, 0
            return ErrorType.SUCCESS, (rows[0] if rows else 0)
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED, 0

    async def get_session_by_id(self, cdb: AsyncSession, session_id) -> Tuple[ErrorType, sessions]:
        try:
            query = select(sessions).where(sessions.session_id == session_id, sessions.deleted == False).limit(1)  # noqa: E712
            err_type, row_list = await DB_SESSION_MNG.execute(cdb, query, f"get_session_by_id({session_id}) failed.")
            if err_type != ErrorType.SUCCESS:
                return err_type, None
            if len(row_list) != 1:
                return ErrorType.DB_INVALID_KEY, None
            return ErrorType.SUCCESS, row_list[0]
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED, None

    async def get_quotation_by_id(self, cdb: AsyncSession, quotation_id) -> Tuple[ErrorType, quotations]:
        try:
            query = select(quotations).where(quotations.qt_id == quotation_id, quotations.deleted == False).limit(1)  # noqa: E712
            err_type, row_list = await DB_SESSION_MNG.execute(cdb, query, f"get_quotation_by_id({quotation_id}) failed.")
            if err_type != ErrorType.SUCCESS:
                return err_type, None
            if len(row_list) != 1:
                return ErrorType.DB_INVALID_KEY, None
            return ErrorType.SUCCESS, row_list[0]
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED, None

    async def update_session_status(self, cdb: AsyncSession, session_id, status: int) -> ErrorType:
        try:
            query = update(sessions).where(sessions.session_id == session_id).values(status=status)
            return await DB_SESSION_MNG.add(cdb, query)
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED

    async def update_quotation_status(self, cdb: AsyncSession, quotation_id, status: int) -> ErrorType:
        try:
            query = update(quotations).where(quotations.qt_id == quotation_id).values(status=status)
            return await DB_SESSION_MNG.add(cdb, query)
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED

    async def update_session_reject(self, cdb: AsyncSession, session_id, status: int, reject_reason: str) -> ErrorType:
        try:
            query = (
                update(sessions)
                .where(sessions.session_id == session_id)
                .values(status=status, reject_reason=reject_reason)
            )
            return await DB_SESSION_MNG.add(cdb, query)
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED

    async def update_session_custom(self, cdb: AsyncSession, session_id, supplier_id, custom: dict) -> ErrorType:
        # 협상완료 부가정보(sessions.custom) 저장. 본인 공급사 세션만(supplier_id 가드).
        try:
            query = (
                update(sessions)
                .where(sessions.session_id == session_id, sessions.supplier_id == supplier_id)
                .values(custom=custom)
            )
            return await DB_SESSION_MNG.add(cdb, query)
        except Exception as ex:
            LOG.e_no_callstack(ex)
            return ErrorType.DB_RUN_FAILED