"""Shared fixtures for tests that need a real PostgreSQL.

In docker compose TEST_DATABASE_URL is already set (database `<name>_test`).
Elsewhere set it to a throwaway database whose name ends with `_test`; it is
created if missing and its tables are emptied by every test that uses `session`.
Without TEST_DATABASE_URL those tests are skipped.
"""

import asyncio
import os

import pytest
from alembic import command
from alembic.config import Config
from sqlalchemy import text
from sqlalchemy.engine import make_url
from sqlalchemy.ext.asyncio import create_async_engine

from app.config import settings
from app.core.database.connection import create_engine, create_session_factory
from app.core.database.repository import TrainingRepository

TEST_DATABASE_URL = os.environ.get("TEST_DATABASE_URL")


async def ensure_test_database(url: str) -> None:
    """Create the test database if it doesn't exist yet."""
    target = make_url(url)
    name = target.database or ""
    if not name.endswith("_test"):
        pytest.fail(f"Refusing to run: database {name!r} must end with '_test'")

    admin_engine = create_async_engine(
        target.set(database="postgres"), isolation_level="AUTOCOMMIT"
    )
    try:
        async with admin_engine.connect() as conn:
            exists = await conn.scalar(
                text("SELECT 1 FROM pg_database WHERE datname = :name"), {"name": name}
            )
            if not exists:
                quoted = name.replace('"', '""')
                await conn.execute(text(f'CREATE DATABASE "{quoted}"'))
    finally:
        await admin_engine.dispose()


@pytest.fixture
async def alembic_config(monkeypatch) -> Config:
    if not TEST_DATABASE_URL:
        pytest.skip("TEST_DATABASE_URL is not set")
    await ensure_test_database(TEST_DATABASE_URL)
    # migrations/env.py takes the URL from settings
    monkeypatch.setattr(settings, "POSTGRES_DATABASE_URL", TEST_DATABASE_URL)
    return Config("alembic.ini")


@pytest.fixture
async def session(alembic_config):
    """Session on a migrated and emptied test database."""
    # env.py runs its own event loop, so alembic goes to a thread
    await asyncio.to_thread(command.upgrade, alembic_config, "head")
    engine = create_engine(TEST_DATABASE_URL)
    async with create_session_factory(engine)() as session:
        await TrainingRepository(session).delete_all()
        yield session
    await engine.dispose()