"""文章已读记录(per-user)。

设计:
- 复合主键 (user_id, article_id) — 天然防重复,标记已读是幂等的
- read_at 默认 now(),用于排序(最近已读在前)
- 索引: (user_id, read_at DESC) — 用户查自己最近已读用
       (article_id) — 反向查"谁读过这文章"(暂不用,留扩展)

注意:
- 删文章时 ondelete=CASCADE 自动清掉已读记录
- 这是和 bookmarks 并列的"用户行为"表
- user_id 是 Integer(users.id 是 Integer),article_id 是 BigInteger(articles.id 是 BigInteger)
"""
from __future__ import annotations

from datetime import datetime

from sqlalchemy import BigInteger, DateTime, ForeignKey, Index, Integer, func
from sqlalchemy.orm import Mapped, mapped_column

from app.database import Base


class ArticleRead(Base):
    __tablename__ = "article_reads"

    user_id: Mapped[int] = mapped_column(
        Integer, ForeignKey("users.id", ondelete="CASCADE"), primary_key=True
    )
    article_id: Mapped[int] = mapped_column(
        BigInteger,
        ForeignKey("articles.id", ondelete="CASCADE"),
        primary_key=True,
    )
    read_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )

    __table_args__ = (
        Index("ix_article_reads_user_read_at", "user_id", "read_at"),
        Index("ix_article_reads_article", "article_id"),
    )

    def __repr__(self) -> str:
        return f"<ArticleRead user={self.user_id} article={self.article_id} at={self.read_at}>"