#!/usr/bin/env python3

import rclpy
from rclpy.node import Node
from sensor_msgs.msg import Image
from cv_bridge import CvBridge
import cv2
from rclpy.qos import QoSProfile, QoSReliabilityPolicy, QoSHistoryPolicy
from qreader import QReader
from threading import Thread, Lock
import time
import queue


class ImageSubscriber(Node):
    def __init__(self):
        super().__init__('image_subscriber')
        # 定义 QoS 配置（匹配发布者的可靠性策略）
        qos_profile = QoSProfile(
            reliability=QoSReliabilityPolicy.BEST_EFFORT,  # 或 BEST_EFFORT，取决于发布者
            history=QoSHistoryPolicy.KEEP_LAST,
            depth=10
        )

        self.subscription = self.create_subscription(
            Image,
            '/rgb_camera/image_raw',
            self.image_callback,
            qos_profile=qos_profile
        )
        self.subscription  # 防止未使用变量警告
        self.bridge = CvBridge()
        self.cv_image = None  # Store latest image

    def image_callback(self, msg):
        try:
            # 将ROS图像消息转换为OpenCV格式
            self.cv_image = self.bridge.imgmsg_to_cv2(msg, desired_encoding='bgr8')
            
        except Exception as e:
            self.get_logger().error('Failed to convert image: %s' % str(e))


class ImageProcessor:
    def __init__(self):
        self.image_subscriber = ImageSubscriber()
        self.qreader = QReader()
        self.spin_thread = None
        self.running = True
        
        # 异步 QR 码扫描相关
        self.scan_thread = None
        self.image_queue = queue.Queue(maxsize=3)  # 限制队列大小，只保留最新的图像
        self.scan_lock = Lock()
        self.last_qr_result = None
        self.last_qr_time = 0
        self.is_scanning = False
        self.enable_async_scan = False
    
    def run(self):
        self.spin_thread = Thread(target=self._spin)
        self.spin_thread.start()
    
    def _spin(self):
        try:
            while self.running:
                rclpy.spin_once(self.image_subscriber, timeout_sec=0.1)
        except Exception as e:
            print(f"Spin thread error: {e}")
    
    def destroy(self):
        self.running = False
        self.stop_async_scan()
        if self.spin_thread:
            self.spin_thread.join()
        self.image_subscriber.destroy_node()

    def get_current_image(self):
        return self.image_subscriber.cv_image
    
    def decode_qrcode(self, img = None):
        if img is None:
            img = self.get_current_image()
        decoded_info = self.qreader.detect_and_decode(image=img)
        if decoded_info and len(decoded_info) > 0:
            return decoded_info[0]
        return None
    
    def start_async_scan(self, interval=0.3):
        """
        启动异步 QR 码扫描
        
        参数:
            interval: 扫描间隔，单位秒
        """
        if self.scan_thread is not None and self.scan_thread.is_alive():
            print("异步扫描已经在运行中")
            return
        
        self.enable_async_scan = True
        self.is_scanning = False
        self.scan_thread = Thread(target=self._async_scan_worker, args=(interval,))
        self.scan_thread.daemon = True  # 设为守护线程，主线程结束时自动结束
        self.scan_thread.start()
        print("启动异步 QR 码扫描线程")
    
    def stop_async_scan(self):
        """停止异步 QR 码扫描"""
        self.enable_async_scan = False
        if self.scan_thread and self.scan_thread.is_alive():
            self.scan_thread.join(timeout=1.0)
            print("异步 QR 码扫描线程已停止")
    
    def _async_scan_worker(self, interval):
        """异步扫描工作线程"""
        last_scan_time = 0
        
        while self.enable_async_scan and self.running:
            current_time = time.time()
            
            # 按指定间隔扫描
            if current_time - last_scan_time >= interval:
                img = self.get_current_image()
                if img is not None:
                    try:
                        self.is_scanning = True
                        qr_data = self.decode_qrcode(img)
                        self.is_scanning = False
                        
                        with self.scan_lock:
                            if qr_data:
                                self.last_qr_result = qr_data
                                self.last_qr_time = current_time
                                print(f"异步扫描到 QR 码: {qr_data}")
                    except Exception as e:
                        self.is_scanning = False
                        print(f"异步 QR 码扫描出错: {e}")
                
                last_scan_time = current_time
            
            # 短暂休眠避免占用过多 CPU
            time.sleep(0.05)
    
    def get_last_qr_result(self):
        """获取最后一次成功扫描的 QR 码结果"""
        with self.scan_lock:
            return self.last_qr_result, self.last_qr_time


""" DEBUG """

def main(args=None):
    rclpy.init(args=args)
    image_subscriber = ImageSubscriber()
    
    try:
        rclpy.spin(image_subscriber)
    except KeyboardInterrupt:
        pass
    
    # 清理
    image_subscriber.destroy_node()


if __name__ == '__main__':
    main()