#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
测试OpenCV VideoCapture的行为
验证当设备索引不存在时VideoCapture的表现
"""

import cv2
import time

def test_video_capture_behavior():
    """
    测试不同设备索引的VideoCapture行为
    """
    print("=== OpenCV VideoCapture 行为测试 ===")
    print(f"OpenCV版本: {cv2.__version__}")
    print()
    
    # 测试不同的设备索引
    test_indices = [0, 1, 2, 3, -1]
    backends = [cv2.CAP_DSHOW, cv2.CAP_MSMF, cv2.CAP_ANY]
    backend_names = ['CAP_DSHOW', 'CAP_MSMF', 'CAP_ANY']
    
    for device_index in test_indices:
        print(f"\n--- 测试设备索引 {device_index} ---")
        
        for backend, backend_name in zip(backends, backend_names):
            print(f"\n后端: {backend_name}")
            
            try:
                start_time = time.time()
                cap = cv2.VideoCapture(device_index, backend)
                open_time = (time.time() - start_time) * 1000
                
                print(f"  VideoCapture创建: 成功 (耗时: {open_time:.1f}ms)")
                print(f"  isOpened(): {cap.isOpened()}")
                
                if cap.isOpened():
                    # 尝试读取帧
                    start_time = time.time()
                    ret, frame = cap.read()
                    read_time = (time.time() - start_time) * 1000
                    
                    print(f"  read()返回值: ret={ret}")
                    if ret and frame is not None:
                        print(f"  帧形状: {frame.shape}")
                        print(f"  读取耗时: {read_time:.1f}ms")
                    else:
                        print(f"  读取失败 (耗时: {read_time:.1f}ms)")
                        
                    # 获取一些属性
                    try:
                        width = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
                        height = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
                        fps = cap.get(cv2.CAP_PROP_FPS)
                        print(f"  分辨率: {int(width)}x{int(height)}")
                        print(f"  帧率: {fps}")
                    except Exception as e:
                        print(f"  获取属性失败: {e}")
                else:
                    print("  相机未打开")
                    
                cap.release()
                
            except Exception as e:
                print(f"  异常: {e}")
    
    print("\n=== 测试完成 ===")

def test_specific_case():
    """
    专门测试device_index=1的情况
    """
    print("\n=== 专门测试 device_index=1 ===")
    
    try:
        # 使用DSHOW后端（Windows默认）
        cap = cv2.VideoCapture(1, cv2.CAP_DSHOW)
        print(f"VideoCapture(1, CAP_DSHOW) 创建成功")
        print(f"isOpened(): {cap.isOpened()}")
        
        if cap.isOpened():
            print("相机显示为已打开，但这可能是虚假的")
            
            # 尝试多次读取
            for i in range(3):
                print(f"\n第{i+1}次读取:")
                start_time = time.time()
                ret, frame = cap.read()
                read_time = (time.time() - start_time) * 1000
                
                print(f"  ret: {ret}")
                print(f"  frame is None: {frame is None}")
                print(f"  耗时: {read_time:.1f}ms")
                
                if ret and frame is not None:
                    print(f"  帧形状: {frame.shape}")
                    print(f"  帧数据类型: {frame.dtype}")
                    print(f"  帧数据范围: {frame.min()} - {frame.max()}")
                else:
                    print("  读取失败或帧为空")
                    break
        else:
            print("相机未打开")
            
        cap.release()
        
    except Exception as e:
        print(f"异常: {e}")

if __name__ == "__main__":
    test_video_capture_behavior()
    test_specific_case()