"""Track first-message idempotency and bounded, recoverable agent progress.

Revision ID: 0004
Revises: 0003
"""
from alembic import op
import sqlalchemy as sa

revision = "0004"
down_revision = "0003"
branch_labels = None
depends_on = None


def upgrade():
    inspector = sa.inspect(op.get_bind())
    if "first_request_id" not in {c["name"] for c in inspector.get_columns("conversations")}:
        op.add_column("conversations", sa.Column("first_request_id", sa.String(36), nullable=True))
    if not any(item["column_names"] == ["first_request_id"] for item in
               sa.inspect(op.get_bind()).get_unique_constraints("conversations")):
        op.create_unique_constraint("uq_conversations_first_request_id", "conversations", ["first_request_id"])
    columns = {c["name"] for c in inspector.get_columns("agent_runs")}
    if "tool_calls" not in columns:
        op.add_column("agent_runs", sa.Column("tool_calls", sa.JSON(), nullable=False, server_default="[]"))
    if "events" not in columns:
        op.add_column("agent_runs", sa.Column("events", sa.JSON(), nullable=False, server_default="[]"))


def downgrade():
    op.drop_column("agent_runs", "events")
    op.drop_column("agent_runs", "tool_calls")
    unique = next((item["name"] for item in sa.inspect(op.get_bind()).get_unique_constraints("conversations")
                   if item["column_names"] == ["first_request_id"]), None)
    if unique:
        op.drop_constraint(unique, "conversations", type_="unique")
    op.drop_column("conversations", "first_request_id")