"""Re-date images whose post's date arrived after they were linked.

#4431. The native ingesters import a post's media before its record, and the
date travels in the record (`_post.json`). Every natively downloaded image was
therefore linked to an undated post and kept its download time in both gallery
date columns, while the post itself was dated correctly. The importer now
re-dates a post's images when its record lands; this repairs the images that
landed before that.

Both columns get back the rules the importer keeps:

* `effective_date` is the primary post's date (left alone when that post has
  none, as the importer does);
* `earliest_post_date` is the earliest dated post the image is linked to.

Only rows that differ are written. The downgrade does nothing: the old values
were download times that no one chose.

Revision ID: 0113
Revises: 0112
Create Date: 2026-09-25

"""
import sqlalchemy as sa
from alembic import op

revision = "0113"
down_revision = "0112"
branch_labels = None
depends_on = None


def redate_images(conn) -> None:
    """The data step, on a plain connection, so a test can run it directly."""
    conn.execute(sa.text("""
        UPDATE image_record ir SET effective_date = p.post_date
        FROM post p
        WHERE p.id = ir.primary_post_id
          AND p.post_date IS NOT NULL
          AND ir.effective_date IS DISTINCT FROM p.post_date
    """))
    conn.execute(sa.text("""
        UPDATE image_record ir SET earliest_post_date = m.earliest
        FROM (
          SELECT ip.image_record_id, MIN(p.post_date) AS earliest
          FROM image_provenance ip JOIN post p ON p.id = ip.post_id
          WHERE p.post_date IS NOT NULL
          GROUP BY ip.image_record_id
        ) m
        WHERE m.image_record_id = ir.id
          AND ir.earliest_post_date IS DISTINCT FROM m.earliest
    """))


def upgrade():
    redate_images(op.get_bind())


def downgrade():
    pass