"""
Service layer for Page CRUD operations.
All DB queries are async; HTML body is sanitized on write.
"""
import nh3
from typing import Optional
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.models.page import Page
from app.schemas.page import PageCreate, PageUpdate


def _sanitize_body(body: str) -> str:
    """Strip dangerous HTML tags/attributes using nh3."""
    return nh3.clean(body)


async def get_published_pages(db: AsyncSession) -> list[Page]:
    result = await db.execute(
        select(Page).where(Page.published == True).order_by(Page.created_at.desc())
    )
    return list(result.scalars().all())


async def get_page_by_slug(db: AsyncSession, slug: str, published_only: bool = True) -> Optional[Page]:
    stmt = select(Page).where(Page.slug == slug)
    if published_only:
        stmt = stmt.where(Page.published == True)
    result = await db.execute(stmt)
    return result.scalars().first()


async def create_page(db: AsyncSession, data: PageCreate) -> Page:
    page = Page(
        title=data.title,
        slug=data.slug,
        body=_sanitize_body(data.body),
        meta_title=data.meta_title,
        meta_description=data.meta_description,
        og_image_url=data.og_image_url,
        published=data.published,
    )
    db.add(page)
    await db.flush()
    await db.refresh(page)
    return page


async def update_page(db: AsyncSession, slug: str, data: PageUpdate) -> Optional[Page]:
    page = await get_page_by_slug(db, slug, published_only=False)
    if page is None:
        return None

    update_data = data.model_dump(exclude_unset=True)
    if "body" in update_data and update_data["body"] is not None:
        update_data["body"] = _sanitize_body(update_data["body"])

    for field, value in update_data.items():
        setattr(page, field, value)

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


async def delete_page(db: AsyncSession, slug: str) -> bool:
    page = await get_page_by_slug(db, slug, published_only=False)
    if page is None:
        return False
    await db.delete(page)
    await db.flush()
    return True