"""Promote nonce_hex to PK on musehub_auth_challenges; drop challenge_id.

The nonce_hex column IS the natural identity of a challenge row — it was
already UNIQUE and was the lookup key in all service code. challenge_id was a
redundant UUID surrogate that provided no additional information.

Revision ID: 0022
Revises: 0021
"""
from __future__ import annotations

from alembic import op
import sqlalchemy as sa

revision = "0022"
down_revision = "0021"
branch_labels = None
depends_on = None


def upgrade() -> None:
    from sqlalchemy import inspect as sa_inspect
    conn = op.get_bind()
    insp = sa_inspect(conn)

    if not insp.has_table("musehub_auth_challenges"):
        # Table was never created on this instance — create it with the final
        # schema (nonce_hex as PK, no challenge_id surrogate).
        op.create_table(
            "musehub_auth_challenges",
            sa.Column("nonce_hex", sa.String(64), primary_key=True),
            sa.Column("public_key", sa.Text, nullable=False),
            sa.Column("expires_at", sa.DateTime(timezone=True), nullable=False),
        )
        op.create_index(
            "ix_musehub_auth_challenges_expires_at",
            "musehub_auth_challenges",
            ["expires_at"],
        )
        return

    # Drop the old UUID primary key
    op.drop_constraint("musehub_auth_challenges_pkey", "musehub_auth_challenges", type_="primary")
    op.drop_column("musehub_auth_challenges", "challenge_id")

    # Drop the now-redundant unique constraint on nonce_hex (PK implies uniqueness)
    op.drop_constraint(
        "uq_musehub_auth_challenges_nonce_hex", "musehub_auth_challenges", type_="unique"
    )

    # Make nonce_hex the primary key
    op.create_primary_key("musehub_auth_challenges_pkey", "musehub_auth_challenges", ["nonce_hex"])


def downgrade() -> None:
    from sqlalchemy import inspect as sa_inspect
    conn = op.get_bind()
    insp = sa_inspect(conn)

    if not insp.has_table("musehub_auth_challenges"):
        return  # nothing to undo

    cols = {c["name"] for c in insp.get_columns("musehub_auth_challenges")}
    if "challenge_id" not in cols:
        # Table was created fresh by upgrade (the if-not-exists branch) — drop it entirely.
        op.drop_table("musehub_auth_challenges")
        return

    # Restore the surrogate PK (new UUIDs — existing rows get new random IDs)
    op.drop_constraint("musehub_auth_challenges_pkey", "musehub_auth_challenges", type_="primary")

    op.add_column(
        "musehub_auth_challenges",
        sa.Column(
            "challenge_id",
            sa.String(36),
            nullable=False,
            server_default=sa.text("gen_random_uuid()::text"),
        ),
    )
    op.create_primary_key("musehub_auth_challenges_pkey", "musehub_auth_challenges", ["challenge_id"])
    op.create_unique_constraint(
        "uq_musehub_auth_challenges_nonce_hex", "musehub_auth_challenges", ["nonce_hex"]
    )