# app/db/repositories/home_featured.py
from typing import List, Sequence

from asyncpg import Connection

from app.db.repositories.base import BaseRepository


class HomeFeaturedRepository(BaseRepository):
    """
    维护首页推送文章的排序列表（最多 10 条）。
    仅存 slug + sort_order，真正返回文章数据时再通过 ArticlesRepository 拉取。
    """

    def __init__(self, conn: Connection) -> None:
        super().__init__(conn)

    async def _ensure_table(self) -> None:
        await self.connection.execute(
            """
            CREATE TABLE IF NOT EXISTS home_featured_articles (
              slug TEXT PRIMARY KEY,
              sort_order INT NOT NULL DEFAULT 0,
              created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
              updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
            );
            """,
        )

    async def list_slugs(self, *, limit: int = 10) -> List[str]:
        await self._ensure_table()
        rows = await self.connection.fetch(
            """
            SELECT slug
              FROM home_featured_articles
             ORDER BY sort_order ASC, updated_at DESC, created_at DESC
             LIMIT $1;
            """,
            limit,
        )
        return [row["slug"] for row in rows]

    async def save_slugs(self, *, slugs: Sequence[str], limit: int = 10) -> List[str]:
        """
        保存首页推送顺序，自动去重并截断到 limit。
        返回最终生效的 slug 顺序。
        """
        await self._ensure_table()
        clean_slugs: List[str] = []
        for slug in slugs:
            normalized = str(slug).strip()
            if not normalized:
                continue
            if normalized not in clean_slugs:
                clean_slugs.append(normalized)
        clean_slugs = clean_slugs[:limit]

        async with self.connection.transaction():
            if clean_slugs:
                await self.connection.execute(
                    """
                    DELETE FROM home_featured_articles
                     WHERE slug <> ALL($1::text[]);
                    """,
                    clean_slugs,
                )
                for idx, slug in enumerate(clean_slugs):
                    await self.connection.execute(
                        """
                        INSERT INTO home_featured_articles (slug, sort_order)
                        VALUES ($1, $2)
                        ON CONFLICT (slug) DO UPDATE
                          SET sort_order = EXCLUDED.sort_order,
                              updated_at = NOW();
                        """,
                        slug,
                        idx,
                    )
            else:
                await self.connection.execute("DELETE FROM home_featured_articles;")

        return clean_slugs