from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.desktopConfig import DesktopConfig
from app.schemas.admin_desktop_config import DesktopConfigCreate, DesktopConfigUpdate

DEFAULT_PAGE_SIZE = 20
MAX_PAGE_SIZE = 200


class AdminDesktopConfigError(Exception):
    def __init__(self, message: str) -> None:
        self.message = message
        super().__init__(message)


async def list_configs(
    db: AsyncSession,
    *,
    page: int = 1,
    page_size: int = DEFAULT_PAGE_SIZE,
    keyword: str | None = None,
) -> tuple[list[DesktopConfig], int]:
    page_size = min(max(page_size, 1), MAX_PAGE_SIZE)
    page = max(page, 1)
    offset = (page - 1) * page_size

    filters = []
    if keyword:
        like = f"%{keyword.strip()}%"
        filters.append(DesktopConfig.name.ilike(like))

    count_stmt = select(func.count()).select_from(DesktopConfig)
    list_stmt = select(DesktopConfig)
    for clause in filters:
        count_stmt = count_stmt.where(clause)
        list_stmt = list_stmt.where(clause)

    total = await db.scalar(count_stmt) or 0
    result = await db.scalars(
        list_stmt.order_by(DesktopConfig.name.asc()).offset(offset).limit(page_size)
    )
    return list(result.all()), total


async def create_config(db: AsyncSession, body: DesktopConfigCreate) -> DesktopConfig:
    existing = await db.scalar(
        select(DesktopConfig).where(
            DesktopConfig.name == body.name,
            DesktopConfig.oem_id == body.oem_id,
        )
    )
    if existing is not None:
        raise AdminDesktopConfigError("该 OEM 下配置键名已存在")

    row = DesktopConfig(
        name=body.name,
        value=body.value,
        mark=body.mark,
        oem_id=body.oem_id,
    )
    db.add(row)
    await db.flush()
    await db.refresh(row)
    return row


async def update_config(
    db: AsyncSession,
    config_id: int,
    body: DesktopConfigUpdate,
) -> DesktopConfig:
    row = await db.get(DesktopConfig, config_id)
    if row is None:
        raise AdminDesktopConfigError("配置不存在")

    if body.name is not None and body.name != row.name:
        taken = await db.scalar(
            select(DesktopConfig).where(
                DesktopConfig.name == body.name,
                DesktopConfig.oem_id == row.oem_id,
                DesktopConfig.id != config_id,
            )
        )
        if taken is not None:
            raise AdminDesktopConfigError("该 OEM 下配置键名已存在")
        row.name = body.name

    if body.value is not None:
        row.value = body.value

    if body.mark is not None:
        row.mark = body.mark

    await db.flush()
    await db.refresh(row)
    return row


async def delete_config(db: AsyncSession, config_id: int) -> None:
    row = await db.get(DesktopConfig, config_id)
    if row is None:
        raise AdminDesktopConfigError("配置不存在")
    await db.delete(row)