"""drop unused overlay tables

Revision ID: o6e7f8g9j0a1
Revises: n5d6e7f8h9i0
Create Date: 2026-04-26

Removes overlay subsystem tables that are no longer fed (wikimedia / youtube /
google_trends / feature_build / scoring were retired). Keeps:
  - overlay_headline_events
  - overlay_job_log
  - company_aliases
"""
from typing import Sequence, Union

from alembic import op

revision: str = "o6e7f8g9j0a1"
down_revision: Union[str, Sequence[str], None] = "n5d6e7f8h9i0"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


_TABLES_TO_DROP = [
    "overlay_feature_records",
    "overlay_video_events",
    "overlay_wiki_pageviews",
    "overlay_trend_observations",
    "youtube_channel_registry",
    "wiki_page_map",
    "theme_topic_map",
]


def upgrade() -> None:
    conn = op.get_bind()
    for tbl in _TABLES_TO_DROP:
        if conn.dialect.has_table(conn, tbl):
            op.drop_table(tbl)


def downgrade() -> None:
    # One-way drop; recreate would require restoring the deleted models.
    pass