"""Add compliance metadata columns to ai_providers table (B-AIPROV-COMP).

Adds region, hosting_type, dpa_status, retention_policy,
training_on_customer_data, transfer_notice, allowed_data_classes
to support AI provider compliance checks.

Revision ID: 0119
Revises: 0118
"""

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects.postgresql import JSONB

revision = "0119"
down_revision = "0118"
branch_labels = None
depends_on = None


def _table_exists(conn, table_name: str) -> bool:
    """True when the table exists (dual-path convergence, Gate B).

    On a fresh install the ai_assistant plugin SQL migration has not run
    yet when Alembic reaches this revision — skip instead of failing.
    The plugin-side migration adds the same columns idempotently.
    """
    row = conn.execute(
        sa.text("SELECT to_regclass(:tname) IS NOT NULL"),
        {"tname": f"public.{table_name}"},
    ).scalar()
    return bool(row)


def upgrade() -> None:
    conn = op.get_bind()
    if not _table_exists(conn, "ai_providers"):
        # Fresh-install path: table arrives with the ai_assistant plugin
        # migration, which includes these columns.
        return
    op.add_column("ai_providers", sa.Column("region", sa.String(20), nullable=False, server_default="unknown"))
    op.add_column("ai_providers", sa.Column("hosting_type", sa.String(30), nullable=False, server_default="cloud"))
    op.add_column("ai_providers", sa.Column("dpa_status", sa.String(20), nullable=False, server_default="none"))
    op.add_column("ai_providers", sa.Column("retention_policy", sa.Text(), nullable=False, server_default=""))
    op.add_column("ai_providers", sa.Column("training_on_customer_data", sa.Boolean(), nullable=False, server_default=sa.text("false")))
    op.add_column("ai_providers", sa.Column("transfer_notice", sa.Text(), nullable=False, server_default=""))
    op.add_column("ai_providers", sa.Column("allowed_data_classes", JSONB, nullable=False, server_default=sa.text("'[]'::jsonb")))


def downgrade() -> None:
    conn = op.get_bind()
    if not _table_exists(conn, "ai_providers"):
        return
    op.drop_column("ai_providers", "allowed_data_classes")
    op.drop_column("ai_providers", "transfer_notice")
    op.drop_column("ai_providers", "training_on_customer_data")
    op.drop_column("ai_providers", "retention_policy")
    op.drop_column("ai_providers", "dpa_status")
    op.drop_column("ai_providers", "hosting_type")
    op.drop_column("ai_providers", "region")