"""Unit tests for the unhandled exception handler in api/app.py."""
from unittest import mock

import pytest
from fastapi import FastAPI, HTTPException
from fastapi.responses import JSONResponse
from starlette.requests import Request
from starlette.testclient import TestClient


def _build_app() -> FastAPI:
    """Build a minimal FastAPI app with the unhandled exception handler."""
    app = FastAPI()

    @app.exception_handler(Exception)
    async def unhandled_exception_handler(request: Request, exc: Exception) -> JSONResponse:
        return JSONResponse(
            status_code=500,
            content={"detail": "Internal server error"},
        )

    @app.get("/ok")
    async def ok() -> dict[str, str]:
        return {"status": "ok"}

    @app.get("/crash")
    async def crash() -> None:
        raise RuntimeError("something unexpected")

    @app.get("/http-error")
    async def http_error() -> None:
        raise HTTPException(status_code=403, detail="forbidden")

    return app


class TestUnhandledExceptionHandler:
    """Tests for the global exception handler."""

    def test_normal_request_unaffected(self) -> None:
        client = TestClient(_build_app())
        resp = client.get("/ok")
        assert resp.status_code == 200
        assert resp.json() == {"status": "ok"}

    def test_unhandled_exception_returns_generic_500(self) -> None:
        client = TestClient(_build_app(), raise_server_exceptions=False)
        resp = client.get("/crash")
        assert resp.status_code == 500
        assert resp.json() == {"detail": "Internal server error"}

    def test_http_exception_not_caught(self) -> None:
        """HTTPException should still be handled by FastAPI's built-in handler."""
        client = TestClient(_build_app())
        resp = client.get("/http-error")
        assert resp.status_code == 403
        assert resp.json() == {"detail": "forbidden"}

    def test_error_body_does_not_leak_details(self) -> None:
        """The response must not contain the actual exception message."""
        client = TestClient(_build_app(), raise_server_exceptions=False)
        resp = client.get("/crash")
        body = resp.text
        assert "something unexpected" not in body
        assert "RuntimeError" not in body