"""A file's "Added" is when it became done

Revision ID: 0104_job_ready_at
Revises: 0103_files_sha256
Create Date: 2026-10-12

`download_jobs.ready_at` is when a job became done, and the Files library sorts and dates by it: a
download that failed for days and then went through used to sit days down the list, under its
request date. Every path to done stamps it, held by `ck_download_jobs_ready_at`.

A done job from before has no record of that moment, except where its "ready to watch" notice is
still in the owner's inbox (read notices are pruned past a cap): that notice was written the moment
it finished. The rest take the request date, which is where they already sat.
"""

import sqlalchemy as sa
from alembic import op

revision: str = "0104_job_ready_at"
down_revision: str | None = "0103_files_sha256"
branch_labels: str | None = None
depends_on: str | None = None


def upgrade() -> None:
    op.add_column("download_jobs", sa.Column("ready_at", sa.DateTime(timezone=True)))
    op.execute(
        """
        UPDATE download_jobs j SET ready_at = COALESCE(
            (SELECT max(n.created_at) FROM notifications n
              WHERE n.type = 'download_done' AND n.user_id = j.user_id
                AND n.data->>'job_id' = j.id::text),
            j.created_at)
        WHERE j.status = 'done'
        """
    )
    op.create_check_constraint(
        "ck_download_jobs_ready_at", "download_jobs", "status <> 'done' OR ready_at IS NOT NULL"
    )


def downgrade() -> None:
    op.drop_constraint("ck_download_jobs_ready_at", "download_jobs", type_="check")
    op.drop_column("download_jobs", "ready_at")