"""Give the existing backlog a level too. No report is 未定级 any more.

Migration 551 made *new* reports arrive at the lowest tier, and deliberately
did not touch history — the reasoning was that a level nobody chose, written
across the backlog, is indistinguishable from triage that actually happened.

That reasoning protected a distinction nobody needed at the cost of the
thing the change was for: 142 of 149 reports still showed as 未定级, the
console still displayed the wall, and the report page still nagged the
operator to go and grade something. 「默认都是低危 不要再有未定级了 不要让用户
多操作好几下」.

So the backlog gets the same treatment, and the distinction is preserved
where it actually earns its keep: ``severity_is_default`` stays TRUE on
every row this touches, which is what keeps the reply composer off the
tier's reward letter. A critical finding nobody has graded can never be
offered the $0 informational letter — a figure stated to a researcher
cannot be withdrawn. What changes is only that the console stops calling it
outstanding work.

Two things this does NOT do:

* **No money.** ``reward_amount_usd`` is untouched. The lowest tier pays $0
  and the arrival level is not a reward decision.
* **No fix deadline.** ``fix_due_date`` is untouched, because a deadline
  derived from a level nobody chose would make reports overdue on a
  judgement no human made.

Only rows with ``severity IS NULL`` are touched, so a graded report keeps
its grade and re-running changes nothing.

Revision ID: 554
Revises: 553
"""
from __future__ import annotations

import sqlalchemy as sa

from alembic import op

revision = "554"
down_revision = "553"
branch_labels = None
depends_on = None

TABLE = "bounty_reports"
TIERS = "bounty_severity_tiers"


def upgrade() -> None:
    conn = op.get_bind()
    inspector = sa.inspect(conn)
    if not inspector.has_table(TABLE) or not inspector.has_table(TIERS):
        return

    # The bottom of the ladder, by the ladder's OWN ordering rather than by
    # reward: an operator who re-prices the tiers must not silently change
    # which one is the safe default.
    lowest = conn.execute(
        sa.text(
            f"SELECT `key` FROM {TIERS} "  # noqa: S608 - constant
            "WHERE enabled = 1 ORDER BY sort_order DESC LIMIT 1",
        ),
    ).scalar()
    if not lowest:
        # No enabled tier: leave everything ungraded, which is honest.
        return

    conn.execute(
        sa.text(
            f"UPDATE {TABLE} "  # noqa: S608 - constant
            "SET severity = :lowest, severity_is_default = 1 "
            "WHERE severity IS NULL AND deleted_at IS NULL",
        ),
        {"lowest": lowest},
    )


def downgrade() -> None:
    conn = op.get_bind()
    if not sa.inspect(conn).has_table(TABLE):
        return
    # Only the rows this migration set: flagged as the arrival default. A
    # level somebody chose has the flag cleared and is left alone.
    conn.execute(
        sa.text(
            f"UPDATE {TABLE} "  # noqa: S608 - constant
            "SET severity = NULL "
            "WHERE severity_is_default = 1 AND deleted_at IS NULL",
        ),
    )