import pytest
from app.config import Settings

def test_settings_defaults():
    """Test that default settings are correctly loaded."""
    # We instantiate a new Settings object to test the class directly, 
    # rather than using the already-initialized 'settings' instance in app.config.
    s = Settings(_env_file=None)
    assert s.DATABASE_URL == "sqlite+aiosqlite:///./data/sleep.db"
    assert s.CORS_ORIGINS == "http://localhost:5173"
    assert s.LOG_LEVEL == "info"

def test_settings_env_overrides(monkeypatch):
    """Test that environment variables correctly override defaults."""
    # Set environment variables using monkeypatch
    monkeypatch.setenv("DATABASE_URL", "postgresql+asyncpg://testuser:testpass@localhost/testdb")
    monkeypatch.setenv("CORS_ORIGINS", "http://example.com")
    monkeypatch.setenv("LOG_LEVEL", "debug")

    # Re-instantiate Settings to pick up the new environment variables
    s = Settings(_env_file=None)

    assert s.DATABASE_URL == "postgresql+asyncpg://testuser:testpass@localhost/testdb"
    assert s.CORS_ORIGINS == "http://example.com"
    assert s.LOG_LEVEL == "debug"

def test_settings_partial_override(monkeypatch):
    """Test that overriding only some environment variables works correctly."""
    monkeypatch.setenv("LOG_LEVEL", "warning")

    s = Settings(_env_file=None)

    # Overridden value
    assert s.LOG_LEVEL == "warning"
    # Default values should remain
    assert s.DATABASE_URL == "sqlite+aiosqlite:///./data/sleep.db"
    assert s.CORS_ORIGINS == "http://localhost:5173"