"""A file remembers where it came from

Revision ID: 0105_job_source_key
Revises: 0104_job_ready_at
Create Date: 2026-10-12

`download_jobs.source_key` is the origin a file came from — the source folder it may go back to —
recorded when it is placed. An edit used to work its origin out through its parent each time, and
once the parent was deleted or expired it fell back to "upload": moved into an own folder, it could
no longer go back to its folder, and deleting that folder sent it to Uploads to stay forever.

A file in a source folder takes that folder's key. One already in an own folder is left NULL and
keeps being worked out (`folders.source_key_for`), as before.
"""

import sqlalchemy as sa
from alembic import op

revision: str = "0105_job_source_key"
down_revision: str | None = "0104_job_ready_at"
branch_labels: str | None = None
depends_on: str | None = None


def upgrade() -> None:
    op.add_column("download_jobs", sa.Column("source_key", sa.String(260)))
    op.execute(
        """
        UPDATE download_jobs j SET source_key = f.source_key
          FROM file_folders f
         WHERE f.id = j.folder_id AND f.kind = 'source'
        """
    )


def downgrade() -> None:
    op.drop_column("download_jobs", "source_key")