"""
Unit tests for dependency exception handling in FastAPI dependencies.

This module tests that async generator dependencies properly handle exceptions
thrown back into them, preventing the "generator didn't stop after athrow()" error.
"""
import pytest
from fastapi import FastAPI, HTTPException, Depends
from httpx import AsyncClient, ASGITransport
from typing import AsyncGenerator, Optional


@pytest.mark.asyncio
async def test_get_optional_database_session_handles_http_exception():
    """Test that get_optional_database_session properly handles HTTPException.
    
    This test verifies the fix for the "generator didn't stop after athrow()" error
    that occurred when an HTTPException was raised after yielding a database session.
    """
    from src.server.utils.dependencies import get_optional_database_session
    
    # Create a test app
    app = FastAPI()
    
    @app.post("/test")
    async def test_endpoint(
        db: Optional[object] = Depends(get_optional_database_session)
    ):
        """Test endpoint that raises HTTPException after dependency yields."""
        # Simulate validation error that raises HTTPException
        raise HTTPException(status_code=400, detail="Validation error")
    
    # Test the endpoint
    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="http://test") as client:
        response = await client.post("/test")
        
        # Should return 400, not 500 (internal server error)
        assert response.status_code == 400
        assert response.json()["detail"] == "Validation error"


@pytest.mark.asyncio
async def test_get_database_session_handles_http_exception():
    """Test that get_database_session properly handles HTTPException.
    
    This test verifies the fix for the "generator didn't stop after athrow()" error
    that occurred when an HTTPException was raised after yielding a database session.
    """
    from src.server.utils.dependencies import get_database_session
    
    # Create a test app
    app = FastAPI()
    
    @app.post("/test")
    async def test_endpoint(db: object = Depends(get_database_session)):
        """Test endpoint that raises HTTPException after dependency yields."""
        # Simulate validation error that raises HTTPException
        raise HTTPException(status_code=400, detail="Validation error")
    
    # Test the endpoint - may get 501/503 if DB not available, or 400 if it is
    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="http://test") as client:
        response = await client.post("/test")
        
        # Should return proper HTTP error, not 500 with generator error
        assert response.status_code in (400, 501, 503)
        assert "generator didn't stop" not in str(response.json())


@pytest.mark.asyncio
async def test_multiple_exceptions_in_optional_session():
    """Test that multiple different exceptions are handled correctly."""
    from src.server.utils.dependencies import get_optional_database_session
    
    app = FastAPI()
    
    @app.post("/test-400")
    async def test_400(db: Optional[object] = Depends(get_optional_database_session)):
        raise HTTPException(status_code=400, detail="Bad request")
    
    @app.post("/test-404")
    async def test_404(db: Optional[object] = Depends(get_optional_database_session)):
        raise HTTPException(status_code=404, detail="Not found")
    
    @app.post("/test-422")
    async def test_422(db: Optional[object] = Depends(get_optional_database_session)):
        raise HTTPException(status_code=422, detail="Validation error")
    
    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="http://test") as client:
        # Test 400
        response = await client.post("/test-400")
        assert response.status_code == 400
        
        # Test 404
        response = await client.post("/test-404")
        assert response.status_code == 404
        
        # Test 422
        response = await client.post("/test-422")
        assert response.status_code == 422


@pytest.mark.asyncio
async def test_successful_request_with_optional_session():
    """Test that successful requests still work properly."""
    from src.server.utils.dependencies import get_optional_database_session
    
    app = FastAPI()
    
    @app.post("/test")
    async def test_endpoint(db: Optional[object] = Depends(get_optional_database_session)):
        """Test endpoint that succeeds."""
        return {"status": "success", "db_available": db is not None}
    
    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="http://test") as client:
        response = await client.post("/test")
        
        # Should return 200 for successful request
        assert response.status_code == 200
        data = response.json()
        assert data["status"] == "success"
        assert isinstance(data["db_available"], bool)


@pytest.mark.asyncio
async def test_exception_after_using_session():
    """Test exception raised after actually using the database session."""
    from src.server.utils.dependencies import get_optional_database_session
    
    app = FastAPI()
    
    @app.post("/test")
    async def test_endpoint(db: Optional[object] = Depends(get_optional_database_session)):
        """Test endpoint that uses db then raises exception."""
        # Simulate using the database
        if db is not None:
            # In real code, would do: await db.execute(...)
            pass
        
        # Then raise an exception
        raise HTTPException(status_code=400, detail="After using db")
    
    transport = ASGITransport(app=app)
    async with AsyncClient(transport=transport, base_url="http://test") as client:
        response = await client.post("/test")
        
        # Should properly handle the exception
        assert response.status_code == 400
        assert response.json()["detail"] == "After using db"