"""文章已读记录(per-user)

- article_reads.user_id       BIGINT  FK users.id    ON DELETE CASCADE
- article_reads.article_id    BIGINT  FK articles.id ON DELETE CASCADE
- article_reads.read_at       TIMESTAMPTZ  DEFAULT now()
- 复合主键 (user_id, article_id) — 天然幂等

Revision ID: 0007
Revises: 0006
Create Date: 2026-06-13
"""
from __future__ import annotations

from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op

revision: str = "0007"
down_revision: Union[str, None] = "0006"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_table(
        "article_reads",
        sa.Column("user_id", sa.Integer, nullable=False),  # users.id 是 Integer
        sa.Column("article_id", sa.BigInteger, nullable=False),  # articles.id 是 BigInteger
        sa.Column("read_at", sa.DateTime(timezone=True), nullable=False, server_default=sa.text("now()")),
        sa.PrimaryKeyConstraint("user_id", "article_id", name="pk_article_reads"),
        sa.ForeignKeyConstraint(
            "user_id", ["users.id"], ondelete="CASCADE",
        ),
        sa.ForeignKeyConstraint(
            "article_id", ["articles.id"], ondelete="CASCADE",
        ),
    )
    op.create_index(
        "ix_article_reads_user_read_at",
        "article_reads",
        ["user_id", "read_at"],
    )
    op.create_index(
        "ix_article_reads_article",
        "article_reads",
        ["article_id"],
    )


def downgrade() -> None:
    op.drop_index("ix_article_reads_article", table_name="article_reads")
    op.drop_index("ix_article_reads_user_read_at", table_name="article_reads")
    op.drop_table("article_reads")