from __future__ import annotations

from datetime import UTC, datetime
from uuid import uuid4

from sqlalchemy import select

from app.core.database import session_scope
from app.modules.content.models import ContentPage

ALLOWED_PAGE_STATUSES = {"draft", "published"}


def _detach(db, instance):
    db.refresh(instance)
    db.expunge(instance)
    return instance


def list_published_pages() -> list[ContentPage]:
    with session_scope() as db:
        pages = list(
            db.scalars(select(ContentPage).where(ContentPage.status == "published").order_by(ContentPage.slug))
        )
        return [_detach(db, page) for page in pages]


def list_all_pages() -> list[ContentPage]:
    with session_scope() as db:
        pages = list(db.scalars(select(ContentPage).order_by(ContentPage.slug)))
        return [_detach(db, page) for page in pages]


def get_page_by_slug(slug: str, include_draft: bool = False) -> ContentPage | None:
    with session_scope() as db:
        page = db.scalar(select(ContentPage).where(ContentPage.slug == slug))
        if not page:
            return None
        if include_draft or page.status == "published":
            return _detach(db, page)
        return None


def get_page_by_id(page_id: str) -> ContentPage | None:
    with session_scope() as db:
        page = db.get(ContentPage, page_id)
        if not page:
            return None
        return _detach(db, page)


def create_page(
    slug: str,
    title: str,
    body: str,
    status: str,
    author_id: str,
) -> ContentPage:
    if status not in ALLOWED_PAGE_STATUSES:
        raise ValueError("INVALID_STATUS")
    with session_scope() as db:
        page = ContentPage(
            id=str(uuid4()),
            slug=slug,
            title=title,
            body=body,
            status=status,
            author_id=author_id,
            published_at=datetime.now(UTC) if status == "published" else None,
        )
        db.add(page)
        db.flush()
        return _detach(db, page)


def update_page(
    page_id: str,
    title: str | None,
    body: str | None,
    status: str | None,
) -> ContentPage:
    with session_scope() as db:
        page = db.get(ContentPage, page_id)
        if not page:
            raise KeyError(page_id)
        if title:
            page.title = title
        if body:
            page.body = body
        if status:
            if status not in ALLOWED_PAGE_STATUSES:
                raise ValueError("INVALID_STATUS")
            page.status = status
            if status == "published" and page.published_at is None:
                page.published_at = datetime.now(UTC)
        page.updated_at = datetime.now(UTC)
        db.flush()
        return _detach(db, page)


def delete_page(page_id: str) -> None:
    with session_scope() as db:
        page = db.get(ContentPage, page_id)
        if page:
            db.delete(page)