"""Durable operator configuration and revision history.

Revision ID: 20260907_0025
Revises: 20260830_0024
"""

import sqlalchemy as sa

from alembic import op

revision = "20260907_0025"
down_revision = "20260830_0024"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_table(
        "configuration_state",
        sa.Column("id", sa.Integer(), primary_key=True),
        sa.Column("revision", sa.Integer(), nullable=False),
        sa.Column("overrides", sa.JSON(), nullable=False),
        sa.CheckConstraint("id = 1"),
        sa.CheckConstraint("revision >= 0"),
    )
    op.create_table(
        "configuration_revisions",
        sa.Column("revision", sa.Integer(), primary_key=True),
        sa.Column("previous_revision", sa.Integer(), nullable=False),
        sa.Column("created_at", sa.DateTime(timezone=True), nullable=False),
        sa.Column("actor", sa.String(255), nullable=False),
        sa.Column("correlation_id", sa.String(255), nullable=False),
        sa.Column("overrides", sa.JSON(), nullable=False),
        sa.Column("preview_digest", sa.String(64), nullable=False),
    )
    if op.get_bind().dialect.name == "postgresql":
        op.execute("GRANT SELECT, INSERT, UPDATE ON configuration_state TO modelforge_runtime")
        op.execute("REVOKE UPDATE, DELETE, TRUNCATE ON configuration_revisions FROM modelforge_runtime")
        op.execute("GRANT SELECT, INSERT ON configuration_revisions TO modelforge_runtime")


def downgrade() -> None:
    if op.get_bind().execute(sa.text("SELECT count(*) FROM configuration_revisions")).scalar_one():
        raise RuntimeError("Configuration history exists; recover the pre-migration backup instead.")
    op.drop_table("configuration_revisions")
    op.drop_table("configuration_state")