from __future__ import annotations

import importlib.util
from pathlib import Path

import sqlalchemy as sa
from alembic.migration import MigrationContext
from alembic.operations import Operations


def _load_migration_module():
    path = (
        Path(__file__).resolve().parents[1]
        / "alembic"
        / "versions"
        / "20260327_add_external_qa_followup_state.py"
    )
    spec = importlib.util.spec_from_file_location("external_qa_followup_state_migration", path)
    module = importlib.util.module_from_spec(spec)
    assert spec is not None
    assert spec.loader is not None
    spec.loader.exec_module(module)
    return module


def _create_qa_tables(metadata: sa.MetaData) -> None:
    sa.Table(
        "qa_sessions",
        metadata,
        sa.Column("id", sa.Integer(), primary_key=True, autoincrement=True),
        sa.Column("tenant_id", sa.BigInteger(), nullable=False),
        sa.Column("created_at", sa.TIMESTAMP(), nullable=False),
        sa.Column("updated_at", sa.TIMESTAMP(), nullable=False),
        sa.Column("user_id", sa.BigInteger(), nullable=True),
        sa.Column("title", sa.String(length=120), nullable=False),
        sa.Column("project_id", sa.BigInteger(), nullable=True),
        sa.Column("started_at", sa.TIMESTAMP(), nullable=True),
        sa.Column("last_message_at", sa.TIMESTAMP(), nullable=True),
        sa.Column("message_count", sa.Integer(), nullable=False),
    )
    sa.Table(
        "qa_session_states",
        metadata,
        sa.Column("id", sa.Integer(), primary_key=True, autoincrement=True),
        sa.Column("tenant_id", sa.BigInteger(), nullable=False),
        sa.Column("created_at", sa.TIMESTAMP(), nullable=False),
        sa.Column("updated_at", sa.TIMESTAMP(), nullable=False),
        sa.Column("session_id", sa.Integer(), nullable=False),
        sa.Column("last_subject", sa.String(length=255), nullable=True),
        sa.Column("last_entity_ids", sa.JSON(), nullable=True),
        sa.Column("last_intent", sa.String(length=20), nullable=True),
        sa.Column("ambiguity", sa.String(length=20), nullable=True),
        sa.Column("rewrite_history", sa.JSON(), nullable=True),
    )


def test_external_qa_followup_migration_adds_and_removes_columns_and_indexes() -> None:
    migration = _load_migration_module()
    engine = sa.create_engine("sqlite:///:memory:")
    metadata = sa.MetaData()
    _create_qa_tables(metadata)
    metadata.create_all(engine)

    with engine.begin() as conn:
        context = MigrationContext.configure(conn)
        migration.op = Operations(context)
        migration.upgrade()

        inspector = sa.inspect(conn)
        session_columns = {column["name"] for column in inspector.get_columns("qa_sessions")}
        state_columns = {column["name"] for column in inspector.get_columns("qa_session_states")}
        session_indexes = {index["name"]: index for index in inspector.get_indexes("qa_sessions")}
        state_indexes = {index["name"]: index for index in inspector.get_indexes("qa_session_states")}

        assert "external_conversation_key" in session_columns
        assert "pending_clarification" in state_columns
        assert "pending_clarification_expires_at" in state_columns
        assert "ix_qa_sessions_external_conversation_key" in session_indexes
        assert "uq_qa_sessions_tenant_external_conversation_key" in session_indexes
        assert bool(session_indexes["uq_qa_sessions_tenant_external_conversation_key"]["unique"]) is True
        assert "ix_qa_session_states_pending_clarification_expires_at" in state_indexes

        migration.downgrade()

        inspector = sa.inspect(conn)
        session_columns = {column["name"] for column in inspector.get_columns("qa_sessions")}
        state_columns = {column["name"] for column in inspector.get_columns("qa_session_states")}
        session_indexes = {index["name"] for index in inspector.get_indexes("qa_sessions")}
        state_indexes = {index["name"] for index in inspector.get_indexes("qa_session_states")}

        assert "external_conversation_key" not in session_columns
        assert "pending_clarification" not in state_columns
        assert "pending_clarification_expires_at" not in state_columns
        assert "ix_qa_sessions_external_conversation_key" not in session_indexes
        assert "uq_qa_sessions_tenant_external_conversation_key" not in session_indexes
        assert "ix_qa_session_states_pending_clarification_expires_at" not in state_indexes