"""artist_visit: per-artist last-viewed timestamp for the "+N new" badge

Revision ID: 0034
Revises: 0033
Create Date: 2026-06-03

Powers the artists-directory "+N new since last visit" badge + ArtistView
banner. Single row per artist (no user_id yet — rule #47 multi-user ACL
is aspirational; widens to (user_id, artist_id) PK when User lands).

Seed every existing artist with `last_viewed_at = NOW()` so the badge
starts at 0 across the board — no noisy "you have 5000 unseen images"
on first deploy. New artists auto-get a row via
`ArtistService.find_or_create`.
"""
from typing import Sequence, Union

import sqlalchemy as sa
from alembic import op

revision: str = "0034"
down_revision: Union[str, None] = "0033"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        "artist_visit",
        sa.Column(
            "artist_id",
            sa.Integer,
            sa.ForeignKey("artist.id", ondelete="CASCADE"),
            primary_key=True,
        ),
        sa.Column(
            "last_viewed_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.text("NOW()"),
        ),
    )
    # Seed: every existing artist starts "fully caught up". Without this,
    # every operator with N artists would see N badges (worth of every
    # image ever imported) on first deploy.
    op.execute(
        "INSERT INTO artist_visit (artist_id, last_viewed_at) "
        "SELECT id, NOW() FROM artist"
    )


def downgrade() -> None:
    op.drop_table("artist_visit")