"""
二维码识别模块 - 使用 OpenCV 识别二维码获取 serialNumber
"""
import cv2
import time
import logging
import numpy as np
from typing import Optional, Tuple

logger = logging.getLogger(__name__)

# 尝试导入二维码识别库
try:
    from pyzbar.pyzbar import decode as qr_decode
    PYZBAR_AVAILABLE = True
except ImportError:
    PYZBAR_AVAILABLE = False
    logger.warning("pyzbar 未安装，尝试用 OpenCV 内置 QRCodeDetector")


class QRScanner:
    """二维码扫描器"""

    def __init__(self, device_index: int = 0):
        self.device_index = device_index
        self._cap: Optional[cv2.VideoCapture] = None
        self._qr_detector = cv2.QRCodeDetector()  # OpenCV 内置二维码检测器

    def open(self) -> bool:
        """打开摄像头"""
        try:
            # 强制 V4L2 后端，获取标准彩色格式（与 test/server.py 一致）
            self._cap = cv2.VideoCapture(self.device_index, cv2.CAP_V4L2)
            if self._cap.isOpened():
                logger.info(f"摄像头 {self.device_index} 已打开 (V4L2)")
                return True
            else:
                # fallback: 不指定后端
                self._cap = cv2.VideoCapture(self.device_index)
                if self._cap.isOpened():
                    logger.info(f"摄像头 {self.device_index} 已打开 (默认后端)")
                    return True
                logger.error(f"无法打开摄像头 {self.device_index}")
                return False
        except Exception as e:
            logger.error(f"摄像头打开失败: {e}")
            return False

    def close(self):
        if self._cap:
            self._cap.release()
            self._cap = None

    def read_frame(self) -> Optional[np.ndarray]:
        """读取一帧"""
        if not self._cap or not self._cap.isOpened():
            return None
        ret, frame = self._cap.read()
        if not ret:
            return None
        return frame

    def detect_qr(self, frame: np.ndarray) -> Optional[str]:
        """从图像帧中检测二维码"""
        if frame is None:
            return None
        try:
            # OpenCV 内置二维码检测
            data, vertices, _ = self._qr_detector.detectAndDecode(frame)
            if data and len(data) > 0:
                return data.strip()
        except Exception as e:
            logger.debug(f"二维码检测失败: {e}")
        return None

    def scan_once(self) -> Optional[str]:
        """扫描一次（读取一帧并检测）"""
        frame = self.read_frame()
        return self.detect_qr(frame)

    def scan_with_retry(self, max_attempts: int = 5, interval: float = 0.5) -> Optional[str]:
        """多次扫描直到成功或达到最大次数"""
        for i in range(max_attempts):
            result = self.scan_once()
            if result:
                return result
            time.sleep(interval)
        return None

    def get_preview_frame(self) -> Optional[np.ndarray]:
        """获取预览帧（用于界面显示）"""
        return self.read_frame()

    def __enter__(self):
        self.open()
        return self

    def __exit__(self, *args):
        self.close()