import os
from unittest import mock

import pytest
from fastapi.testclient import TestClient
from sqlalchemy import StaticPool, create_engine, event
from sqlalchemy.orm import sessionmaker

from allmende_payment_system.api.dependencies import get_session
from allmende_payment_system.app import app
from allmende_payment_system.models import Base

engine = create_engine(
    "sqlite:///:memory:",
    connect_args={"check_same_thread": False},
    poolclass=StaticPool,
)

# Create a single connection and an outer transaction which we can rollback
# at the end of the test run. Individual tests will use nested transactions
# (SAVEPOINTs) for isolation. This ensures the TestClient (app) and the
# test fixture sessions see the same in-memory database state.
connection = engine.connect()
transaction = connection.begin()

Base.metadata.create_all(bind=connection)

# Bind sessions to the single connection so all sessions share the same DB
TestSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=connection)


def get_test_session():
    """Dependency override for get_session"""
    db = TestSessionLocal()
    try:
        yield db
    finally:
        db.close()


app.dependency_overrides[get_session] = get_test_session


@pytest.fixture(scope="session")
def client():
    os.environ["APS_username"] = "test"
    return TestClient(app)


@pytest.fixture(scope="session")
def unauthorized_client():
    os.environ.pop("APS_username", None)
    return TestClient(app)


@pytest.fixture(scope="function")
def test_db():
    """Provides a database session for direct test usage"""
    db = TestSessionLocal()

    # Start a SAVEPOINT so test changes can be rolled back without
    # closing the shared connection. Also restart the nested transaction
    # when the session issues commits internally.
    db.begin_nested()

    @event.listens_for(db, "after_transaction_end")
    def restart_savepoint(session, transaction):
        # If the nested transaction ended, re-open it for continued isolation
        if transaction.nested and not session.is_active:
            session.begin_nested()

    try:
        yield db
    finally:
        # Rollback to the SAVEPOINT and close the session to clean up
        db.rollback()
        db.close()