"""
Pytest configuration and fixtures for integration tests.

Provides test database setup, client fixtures, and authentication helpers.
"""

import asyncio
from typing import AsyncGenerator, Generator
import pytest
from httpx import AsyncClient, ASGITransport
from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine, async_sessionmaker
from sqlalchemy.pool import NullPool

from app.main import app
from app.core.database import Base, get_db
from app.core.config import settings


# Test database URL (separate from production)
TEST_DATABASE_URL = "postgresql+asyncpg://postgres:postgres@localhost:5432/patherly_test"


@pytest.fixture(scope="session")
def event_loop() -> Generator:
    """Create an instance of the default event loop for each test case."""
    loop = asyncio.get_event_loop_policy().new_event_loop()
    yield loop
    loop.close()


@pytest.fixture
async def test_db() -> AsyncGenerator[AsyncSession, None]:
    """
    Create a fresh database for each test function.

    This fixture:
    1. Creates a test database engine
    2. Creates all tables
    3. Yields a session for the test
    4. Drops all tables after the test
    """
    # Create async engine for tests (with NullPool to avoid connection reuse issues)
    engine = create_async_engine(
        TEST_DATABASE_URL,
        poolclass=NullPool,
        echo=False
    )

    # Create all tables
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.create_all)

    # Create async session maker
    async_session_maker = async_sessionmaker(
        engine,
        class_=AsyncSession,
        expire_on_commit=False
    )

    # Provide session to test
    async with async_session_maker() as session:
        yield session

    # Drop all tables after test
    async with engine.begin() as conn:
        await conn.run_sync(Base.metadata.drop_all)

    await engine.dispose()


@pytest.fixture
async def client(test_db: AsyncSession):
    """
    Create an async HTTP client for testing API endpoints.

    Overrides the database dependency to use the test database.
    """

    async def override_get_db():
        yield test_db

    app.dependency_overrides[get_db] = override_get_db

    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="http://test") as ac:
        yield ac

    app.dependency_overrides.clear()


@pytest.fixture
async def test_user(client):
    """
    Create a test user and return their credentials.

    Returns:
        dict with email, password, and user_data
    """
    user_data = {
        "email": "test@example.com",
        "password": "TestPassword123!",
        "name": "Test User",
        "role": "engineer"
    }

    response = await client.post("/api/v1/auth/register", json=user_data)
    assert response.status_code == 200 or response.status_code == 201

    return {
        "email": user_data["email"],
        "password": user_data["password"],
        "user_data": response.json()
    }


@pytest.fixture
async def auth_headers(client, test_user):
    """
    Get authentication headers for an authenticated test user.

    Returns:
        dict with Authorization header
    """
    login_data = {
        "email": test_user["email"],
        "password": test_user["password"]
    }

    response = await client.post("/api/v1/auth/login/json", json=login_data)
    assert response.status_code == 200

    token_data = response.json()
    return {"Authorization": f"Bearer {token_data['access_token']}"}


@pytest.fixture
async def test_tree(client, auth_headers):
    """
    Create a test decision tree.

    Returns:
        dict with tree data
    """
    tree_data = {
        "name": "Test Troubleshooting Tree",
        "description": "A test tree for integration tests",
        "category": "Testing",
        "tree_structure": {
            "id": "root",
            "type": "decision",
            "question": "Is this a test?",
            "options": [
                {"id": "yes", "label": "Yes", "next_node_id": "solution1"},
                {"id": "no", "label": "No", "next_node_id": "solution2"}
            ],
            "children": [
                {
                    "id": "solution1",
                    "type": "solution",
                    "title": "Test Confirmed",
                    "description": "This is a test tree"
                },
                {
                    "id": "solution2",
                    "type": "solution",
                    "title": "Not a Test",
                    "description": "This should not happen"
                }
            ]
        }
    }

    response = await client.post(
        "/api/v1/trees",
        json=tree_data,
        headers=auth_headers
    )
    assert response.status_code == 201

    return response.json()


@pytest.fixture
async def test_admin(client):
    """
    Create a test admin user and return their credentials.

    Returns:
        dict with email, password, and user_data
    """
    admin_data = {
        "email": "admin@example.com",
        "password": "AdminPassword123!",
        "name": "Test Admin",
        "role": "admin"
    }

    response = await client.post("/api/v1/auth/register", json=admin_data)
    assert response.status_code == 200 or response.status_code == 201

    return {
        "email": admin_data["email"],
        "password": admin_data["password"],
        "user_data": response.json()
    }


@pytest.fixture
async def admin_auth_headers(client, test_admin):
    """
    Get authentication headers for an authenticated admin user.

    Returns:
        dict with Authorization header
    """
    login_data = {
        "email": test_admin["email"],
        "password": test_admin["password"]
    }

    response = await client.post("/api/v1/auth/login/json", json=login_data)
    assert response.status_code == 200

    token_data = response.json()
    return {"Authorization": f"Bearer {token_data['access_token']}"}