from __future__ import annotations

import importlib.util
from pathlib import Path
import sys

import pytest


MODULE_PATH = (
    Path(__file__).resolve().parents[1]
    / "tools"
    / "realsense_multi_camera_test.py"
)
SPEC = importlib.util.spec_from_file_location("realsense_multi_camera_test", MODULE_PATH)
assert SPEC is not None and SPEC.loader is not None
camera_test = importlib.util.module_from_spec(SPEC)
sys.modules[SPEC.name] = camera_test
SPEC.loader.exec_module(camera_test)


def devices() -> list[camera_test.DeviceInfo]:
    return [
        camera_test.DeviceInfo("Intel RealSense D405", "D405", "412622272532", "3.2"),
        camera_test.DeviceInfo("Intel RealSense D455", "D455", "234222303366", "3.2"),
        camera_test.DeviceInfo("Intel RealSense D405", "D405", "260322272273", "3.2"),
    ]


def test_assigns_camera_roles_with_and_without_left_serial() -> None:
    unidentified = camera_test.assign_camera_roles(devices(), None)
    assert [camera.role for camera in unidentified] == ["GLOBAL", "D405-A", "D405-B"]
    assert [camera.serial for camera in unidentified[1:]] == ["260322272273", "412622272532"]

    identified = camera_test.assign_camera_roles(devices(), "412622272532")
    assert {camera.role: camera.serial for camera in identified} == {
        "GLOBAL": "234222303366",
        "LEFT": "412622272532",
        "RIGHT": "260322272273",
    }


def test_rejects_invalid_camera_selection() -> None:
    with pytest.raises(ValueError, match="左臂序列号"):
        camera_test.assign_camera_roles(devices(), "missing")

    with pytest.raises(ValueError, match="2 台 D405 和 1 台 D455"):
        camera_test.assign_camera_roles(devices()[:-1], None)


def test_counts_frame_number_gaps() -> None:
    stats = camera_test.FrameStats(target_fps=30, start_time=0.0)
    stats.update(10, 0.0)
    stats.update(11, 1.0 / 30.0)
    stats.update(14, 2.0 / 30.0)

    assert stats.received == 3
    assert stats.dropped == 2
    assert stats.drop_rate == pytest.approx(0.4)
    assert stats.average_fps(2.0 / 30.0) == pytest.approx(30.0)


def test_snapshot_names_follow_camera_roles() -> None:
    identified = camera_test.assign_camera_roles(devices(), "412622272532")
    assert camera_test.snapshot_filenames(identified) == {
        "234222303366": "global.png",
        "412622272532": "left.png",
        "260322272273": "right.png",
    }

    unidentified = camera_test.assign_camera_roles(devices(), None)
    assert camera_test.snapshot_filenames(unidentified) == {
        "234222303366": "global.png",
        "260322272273": "d405_260322272273.png",
        "412622272532": "d405_412622272532.png",
    }