"""audit_log: append-only admin/scheduler audit trail (who/what/when/before->after)

Revision ID: 0054_audit_log
Revises: 0053_user_session_epoch
Create Date: 2026-07-12
"""
from typing import Sequence, Union

from alembic import op
import sqlalchemy as sa

revision: str = "0054_audit_log"
down_revision: Union[str, None] = "0053_user_session_epoch"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    op.create_table(
        "audit_log",
        sa.Column("id", sa.Integer(), primary_key=True),
        # SET NULL on user delete: keep the trail (it just becomes system-attributed).
        sa.Column(
            "actor_id",
            sa.Integer(),
            sa.ForeignKey("users.id", ondelete="SET NULL"),
            nullable=True,
        ),
        sa.Column("action", sa.String(length=48), nullable=False),
        sa.Column("target_type", sa.String(length=32), nullable=True),
        sa.Column("target_id", sa.String(length=128), nullable=True),
        sa.Column("summary", sa.String(length=255), nullable=True),
        sa.Column("before", sa.JSON(), nullable=True),
        sa.Column("after", sa.JSON(), nullable=True),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            server_default=sa.func.now(),
            nullable=False,
        ),
    )
    op.create_index("ix_audit_log_actor_id", "audit_log", ["actor_id"])
    op.create_index("ix_audit_log_action", "audit_log", ["action"])
    op.create_index("ix_audit_log_created_at", "audit_log", ["created_at"])


def downgrade() -> None:
    op.drop_index("ix_audit_log_created_at", table_name="audit_log")
    op.drop_index("ix_audit_log_action", table_name="audit_log")
    op.drop_index("ix_audit_log_actor_id", table_name="audit_log")
    op.drop_table("audit_log")
