"""IP-адрес уникален в пределах VRF и хранится в самом узком префиксе

Revision ID: 0007
Revises: 0006
"""
from alembic import op
import sqlalchemy as sa

revision = "0007"
down_revision = "0006"
branch_labels = None
depends_on = None


def upgrade() -> None:
    bind = op.get_bind()
    dup = bind.execute(sa.text(
        "SELECT p.vrf_id, host(a.address) AS ip, array_agg(p.prefix::text ORDER BY p.id) AS prefixes "
        "FROM addresses a JOIN prefixes p ON p.id = a.prefix_id GROUP BY p.vrf_id, host(a.address) HAVING count(*) > 1")).all()
    if dup:
        lines = "; ".join(f"VRF {r.vrf_id}: {r.ip} в {', '.join(r.prefixes)}" for r in dup[:20])
        raise RuntimeError(f"Один IP записан несколько раз в одном VRF ({len(dup)} шт.): {lines}. Разберите дубли (scripts/find_duplicate_addresses.py) и повторите миграцию")

    op.create_unique_constraint("uq_prefixes_id_vrf_id", "prefixes", ["id", "vrf_id"])
    op.add_column("addresses", sa.Column("vrf_id", sa.Integer(), nullable=True))
    bind.execute(sa.text("UPDATE addresses a SET vrf_id = p.vrf_id FROM prefixes p WHERE p.id = a.prefix_id"))
    op.alter_column("addresses", "vrf_id", nullable=False)
    # адрес — в самом узком префиксе своего VRF (раньше он мог остаться в родителе)
    bind.execute(sa.text(
        "UPDATE addresses a SET prefix_id = t.best FROM ("
        "  SELECT a2.id AS aid, (SELECT p.id FROM prefixes p WHERE p.vrf_id = a2.vrf_id AND p.prefix >>= a2.address "
        "                        ORDER BY masklen(p.prefix) DESC LIMIT 1) AS best FROM addresses a2) t "
        "WHERE a.id = t.aid AND t.best IS NOT NULL AND t.best <> a.prefix_id"))
    # предупреждение (изменение 024, находка №2): перенос мог сделать адрес адресом сети/broadcast его нового префикса
    # (правило появилось позже, в изменении 015); миграцию не останавливаем, только сообщаем — найти такие поможет find_unusable_addresses.py
    bad = bind.execute(sa.text(
        "SELECT host(a.address) AS ip, p.prefix::text AS cidr FROM addresses a JOIN prefixes p ON p.id = a.prefix_id "
        "WHERE family(p.prefix) = 4 AND masklen(p.prefix) <= 30 "
        "AND (host(a.address) = host(network(p.prefix)) OR host(a.address) = host(broadcast(p.prefix)))")).all()
    if bad:
        lines = "; ".join(f"{r.ip} в {r.cidr}" for r in bad[:20])
        print(f"ВНИМАНИЕ: после переноса в самый узкий префикс {len(bad)} адрес(ов) стали адресом сети/broadcast: {lines}"
              + (" …" if len(bad) > 20 else ""))
    op.drop_constraint("addresses_prefix_id_fkey", "addresses", type_="foreignkey")
    op.create_foreign_key("fk_addresses_prefix_vrf", "addresses", "prefixes", ["prefix_id", "vrf_id"], ["id", "vrf_id"], ondelete="CASCADE", onupdate="CASCADE")
    op.create_unique_constraint("uq_addresses_vrf_address", "addresses", ["vrf_id", "address"])


def downgrade() -> None:
    op.drop_constraint("uq_addresses_vrf_address", "addresses", type_="unique")
    op.drop_constraint("fk_addresses_prefix_vrf", "addresses", type_="foreignkey")
    op.create_foreign_key("addresses_prefix_id_fkey", "addresses", "prefixes", ["prefix_id"], ["id"], ondelete="CASCADE")
    op.drop_column("addresses", "vrf_id")
    op.drop_constraint("uq_prefixes_id_vrf_id", "prefixes", type_="unique")