"""document events audit trail

An append-only history of who changed or reviewed a document, and when.
Content-bearing events (created / edited) snapshot the Markdown source of truth
so a past version can be viewed or diffed; the disposable chunks are never
snapshotted. `actor_id` is SET NULL so the trail outlives its actor's account;
events cascade with their document.

Revision ID: d5a9c1e3b7f2
Revises: c4f7a1b2e9d3
Create Date: 2026-07-22 00:00:00.000000

"""

from typing import Sequence, Union

import sqlalchemy as sa
from sqlalchemy.dialects import postgresql

from alembic import op

# revision identifiers, used by Alembic.
revision: str = "d5a9c1e3b7f2"
down_revision: Union[str, Sequence[str], None] = "c4f7a1b2e9d3"
branch_labels: Union[str, Sequence[str], None] = None
depends_on: Union[str, Sequence[str], None] = None


def upgrade() -> None:
    """Upgrade schema."""
    op.create_table(
        "document_events",
        sa.Column("document_id", sa.Uuid(), nullable=False),
        sa.Column("actor_id", sa.Uuid(), nullable=True),
        sa.Column(
            "action",
            sa.Enum(
                "created",
                "edited",
                "published",
                "archived",
                "visibility_changed",
                "review_requested",
                "review_resolved",
                name="documenteventaction",
                native_enum=False,
                length=32,
            ),
            nullable=False,
        ),
        sa.Column("content_md", sa.Text(), nullable=True),
        sa.Column("title", sa.String(length=500), nullable=True),
        sa.Column(
            "visibility",
            sa.Enum(
                "public",
                "department",
                "restricted",
                name="documentvisibility",
                native_enum=False,
                length=32,
            ),
            nullable=True,
        ),
        sa.Column("meta", postgresql.JSONB(astext_type=sa.Text()), nullable=True),
        sa.Column("id", sa.Uuid(), nullable=False),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            server_default=sa.text("now()"),
            nullable=False,
        ),
        sa.Column(
            "updated_at",
            sa.DateTime(timezone=True),
            server_default=sa.text("now()"),
            nullable=False,
        ),
        sa.ForeignKeyConstraint(["document_id"], ["documents.id"], ondelete="CASCADE"),
        sa.ForeignKeyConstraint(["actor_id"], ["users.id"], ondelete="SET NULL"),
        sa.PrimaryKeyConstraint("id"),
    )
    op.create_index(
        op.f("ix_document_events_document_id"),
        "document_events",
        ["document_id"],
        unique=False,
    )


def downgrade() -> None:
    """Downgrade schema."""
    op.drop_index(op.f("ix_document_events_document_id"), table_name="document_events")
    op.drop_table("document_events")