import importlib.util
from pathlib import Path
import unittest

spec = importlib.util.spec_from_file_location("usb_qmp", Path(__file__).parents[1] / "usb-device-qmp.py")
usb = importlib.util.module_from_spec(spec)
spec.loader.exec_module(usb)


class FakeQmp:
    def __init__(self, occupied=False, fail_add=False):
        self.calls = []
        self.occupied = occupied
        self.fail_add = fail_add

    def call(self, name, args=None):
        self.calls.append((name, args))
        if name == "query-chardev":
            return [{"label": "vdi_usb_box_100"}] if self.occupied else []
        if name == "qom-list":
            return [{"name": "tablet"}, {"name": "hostpci0"}]
        if name == "device_add" and self.fail_add:
            raise RuntimeError("bad USB bus")
        return {}


class UsbQmpTests(unittest.TestCase):
    def test_only_loopback_tunnel_and_approved_storage_are_attached(self):
        q = FakeQmp()
        usb.attach(q, 100, 40001, "ehci-2.0", "0951", "1666")
        channel = next(a for n, a in q.calls if n == "chardev-add")
        self.assertEqual(channel["backend"]["data"]["addr"]["data"]["host"], "127.0.0.1")
        device = next(a for n, a in q.calls if n == "device_add")
        self.assertEqual(device["filter"], "0x08:0x0951:0x1666:-1:1|-1:-1:-1:-1:0")

    def test_any_storage_filter_keeps_hid_and_hub_out(self):
        q = FakeQmp()
        usb.attach(q, 100, 40001, "ehci-2.0")
        device = next(a for n, a in q.calls if n == "device_add")
        self.assertEqual(device["filter"], "0x08:-1:-1:-1:1|-1:-1:-1:-1:0")

    def test_busy_endpoint_is_never_replaced(self):
        q = FakeQmp(occupied=True)
        with self.assertRaisesRegex(RuntimeError, "already exists"):
            usb.attach(q, 100, 40001, "ehci-2.0", "0951", "1666")
        self.assertFalse(any(n in ("chardev-add", "chardev-remove", "device_del") for n, _ in q.calls))

    def test_failed_device_add_rolls_back_only_its_new_channel(self):
        q = FakeQmp(fail_add=True)
        with self.assertRaisesRegex(RuntimeError, "bad USB bus"):
            usb.attach(q, 100, 40001, "ehci-2.0", "0951", "1666")
        self.assertEqual(q.calls[-1], ("chardev-remove", {"id": "vdi_usb_box_100"}))


if __name__ == "__main__":
    unittest.main()