from fastapi import APIRouter, Depends, Query
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.credit.exceptions import ChargeRequestForbiddenError, ChargeRequestNotFoundError
from app.credit.models import ChargeRequestStatus, CreditChargeRequest, CreditTransaction
from app.credit.schemas.credit_schema import (
    ChargeRequestCreate,
    ChargeRequestListResponse,
    ChargeRequestResponse,
    CreditTransactionListResponse,
    CreditTransactionResponse,
)
from app.database.session import get_session
from app.user.dependencies.auth import get_current_user
from app.user.models import User

router = APIRouter(prefix="/credits", tags=["Credits"])


@router.post(
    "/charge-requests",
    response_model=ChargeRequestResponse,
    status_code=201,
    summary="크레딧 충전 요청 제출",
)
async def create_charge_request(
    body: ChargeRequestCreate,
    current_user: User = Depends(get_current_user),
    session: AsyncSession = Depends(get_session),
) -> ChargeRequestResponse:
    charge_request = CreditChargeRequest(
        user_uuid=current_user.user_uuid,
        requested_amount=body.requested_amount,
        message=body.message,
    )
    session.add(charge_request)
    await session.commit()
    await session.refresh(charge_request)
    return ChargeRequestResponse.model_validate(charge_request)


@router.get(
    "/charge-requests",
    response_model=ChargeRequestListResponse,
    summary="내 충전 요청 목록",
)
async def list_charge_requests(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    current_user: User = Depends(get_current_user),
    session: AsyncSession = Depends(get_session),
) -> ChargeRequestListResponse:
    offset = (page - 1) * page_size

    total_result = await session.execute(
        select(func.count()).where(CreditChargeRequest.user_uuid == current_user.user_uuid)
    )
    total = total_result.scalar_one()

    items_result = await session.execute(
        select(CreditChargeRequest)
        .where(CreditChargeRequest.user_uuid == current_user.user_uuid)
        .order_by(CreditChargeRequest.created_at.desc())
        .offset(offset)
        .limit(page_size)
    )
    items = items_result.scalars().all()

    return ChargeRequestListResponse(
        items=[ChargeRequestResponse.model_validate(i) for i in items],
        total=total,
        page=page,
        page_size=page_size,
    )


@router.get(
    "/charge-requests/{request_id}",
    response_model=ChargeRequestResponse,
    summary="내 충전 요청 상세",
)
async def get_charge_request(
    request_id: int,
    current_user: User = Depends(get_current_user),
    session: AsyncSession = Depends(get_session),
) -> ChargeRequestResponse:
    result = await session.execute(
        select(CreditChargeRequest).where(
            CreditChargeRequest.id == request_id,
            CreditChargeRequest.user_uuid == current_user.user_uuid,
        )
    )
    charge_request = result.scalar_one_or_none()

    if charge_request is None:
        raise ChargeRequestNotFoundError()

    return ChargeRequestResponse.model_validate(charge_request)


@router.delete(
    "/charge-requests/{request_id}",
    status_code=204,
    summary="충전 요청 취소 (pending 상태만)",
)
async def cancel_charge_request(
    request_id: int,
    current_user: User = Depends(get_current_user),
    session: AsyncSession = Depends(get_session),
) -> None:
    result = await session.execute(
        select(CreditChargeRequest).where(CreditChargeRequest.id == request_id)
    )
    charge_request = result.scalar_one_or_none()

    if charge_request is None:
        raise ChargeRequestNotFoundError()
    if charge_request.user_uuid != current_user.user_uuid:
        raise ChargeRequestForbiddenError()

    from app.credit.exceptions import InvalidRequestStateError
    if charge_request.status != ChargeRequestStatus.PENDING:
        raise InvalidRequestStateError("대기 중인 요청만 취소할 수 있습니다.")

    charge_request.status = ChargeRequestStatus.CANCELLED
    await session.commit()


@router.get(
    "/transactions",
    response_model=CreditTransactionListResponse,
    summary="내 크레딧 거래 이력",
)
async def list_transactions(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    current_user: User = Depends(get_current_user),
    session: AsyncSession = Depends(get_session),
) -> CreditTransactionListResponse:
    offset = (page - 1) * page_size

    total_result = await session.execute(
        select(func.count()).where(CreditTransaction.user_uuid == current_user.user_uuid)
    )
    total = total_result.scalar_one()

    items_result = await session.execute(
        select(CreditTransaction)
        .where(CreditTransaction.user_uuid == current_user.user_uuid)
        .order_by(CreditTransaction.created_at.desc())
        .offset(offset)
        .limit(page_size)
    )
    items = items_result.scalars().all()

    return CreditTransactionListResponse(
        items=[CreditTransactionResponse.model_validate(i) for i in items],
        total=total,
        page=page,
        page_size=page_size,
    )