"""Create automation_agent_run_steps table for ReAct loop step tracking.

Revision ID: 0121
Revises: 0120
"""

from alembic import op
import sqlalchemy as sa
from sqlalchemy.dialects.postgresql import JSONB, UUID as PGUUID

revision = "0121"
down_revision = "0120"
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 automation plugin SQL migration has not run yet
    when Alembic reaches this revision — skip instead of failing. The
    plugin-side convergence migration creates the same table.
    """
    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, "automation_agent_runs"):
        return
    op.create_table(
        "automation_agent_run_steps",
        sa.Column("id", PGUUID(as_uuid=True), primary_key=True),
        sa.Column("tenant_id", PGUUID(as_uuid=True), nullable=False, index=True),
        sa.Column(
            "agent_run_id",
            PGUUID(as_uuid=True),
            sa.ForeignKey("automation_agent_runs.id", ondelete="CASCADE"),
            nullable=False,
            index=True,
        ),
        sa.Column("step_number", sa.Integer, nullable=False),
        sa.Column("thought", sa.Text, nullable=True),
        sa.Column("action", sa.String(255), nullable=True),
        sa.Column("action_input", JSONB, nullable=True),
        sa.Column("observation", sa.Text, nullable=True),
        sa.Column("cost_usd", sa.Float, nullable=False, server_default="0.0"),
        sa.Column(
            "created_at",
            sa.DateTime(timezone=True),
            nullable=False,
            server_default=sa.func.now(),
        ),
    )
    op.create_index(
        "ix_agent_run_steps_run",
        "automation_agent_run_steps",
        ["tenant_id", "agent_run_id"],
    )


def downgrade() -> None:
    op.drop_index("ix_agent_run_steps_run", table_name="automation_agent_run_steps")
    op.drop_table("automation_agent_run_steps")