"""Test fixtures — a fresh, empty PostgreSQL database per test.

Each test gets its own database created on the dev/CI Postgres (every test runs the
real engine, §6.8). The admin DSN points at the `postgres` maintenance database;
ECOMM_TEST_ADMIN_URL overrides it (CI sets it to the service container).
"""
from __future__ import annotations

import os
import uuid

import psycopg
import pytest

ADMIN_URL = os.environ.get(
    "ECOMM_TEST_ADMIN_URL", "postgresql://ecomm:ecomm@localhost:5432/postgres"
)


def _swap_dbname(dsn: str, dbname: str) -> str:
    # ADMIN_URL ends in `/postgres`; point the same credentials at `dbname`.
    base, _, _old = dsn.rpartition("/")
    return f"{base}/{dbname}"


@pytest.fixture()
def fresh_db_url():
    """Create a uniquely-named empty database; drop it after the test."""
    dbname = f"ecomm_test_{uuid.uuid4().hex}"
    admin = psycopg.connect(ADMIN_URL, autocommit=True)
    try:
        admin.execute(f'CREATE DATABASE "{dbname}"')
    finally:
        admin.close()
    try:
        yield _swap_dbname(ADMIN_URL, dbname)
    finally:
        admin = psycopg.connect(ADMIN_URL, autocommit=True)
        try:
            admin.execute(
                "SELECT pg_terminate_backend(pid) FROM pg_stat_activity "
                "WHERE datname = %s AND pid <> pg_backend_pid()",
                (dbname,),
            )
            admin.execute(f'DROP DATABASE IF EXISTS "{dbname}"')
        finally:
            admin.close()