#import <AVFoundation/AVFoundation.h>
#import <UIKit/UIKit.h>

/// 获取当前正在使用的后置摄像头设备
static AVCaptureDevice *GetActiveRearCamera(void)
{
    // 遍历所有正在运行的 AVCaptureSession，找到后置摄像头的输入
    if (@available(iOS 10.0, *)) {
        AVCaptureDeviceDiscoverySession *session = [AVCaptureDeviceDiscoverySession
            discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera]
                                  mediaType:AVMediaTypeVideo
                                   position:AVCaptureDevicePositionBack];
        for (AVCaptureDevice *d in session.devices) {
            if (d.deviceType == AVCaptureDeviceTypeBuiltInWideAngleCamera) {
                return d;
            }
        }
    }
    return [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
}

extern "C" {

    /// 开启连续自动对焦
    void _EnableContinuousAutoFocus(void)
    {
        AVCaptureDevice *device = GetActiveRearCamera();
        if (!device) return;

        NSError *error = nil;
        if ([device lockForConfiguration:&error]) {
            if ([device isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
                device.focusMode = AVCaptureFocusModeContinuousAutoFocus;
                NSLog(@"[CameraFocusHelper] 已开启连续自动对焦");
            }
            if ([device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
                device.exposureMode = AVCaptureExposureModeContinuousAutoExposure;
            }
            [device unlockForConfiguration];
        } else {
            NSLog(@"[CameraFocusHelper] 配置失败: %@", error.localizedDescription);
        }
    }

    /// 触发单次自动对焦（点击对焦用）
    void _TriggerAutoFocus(float normalizedX, float normalizedY)
    {
        AVCaptureDevice *device = GetActiveRearCamera();
        if (!device) return;

        NSError *error = nil;
        if ([device lockForConfiguration:&error]) {
            if ([device isFocusPointOfInterestSupported]) {
                device.focusPointOfInterest = CGPointMake(normalizedX, normalizedY);
                device.focusMode = AVCaptureFocusModeAutoFocus;
            }
            if ([device isExposurePointOfInterestSupported]) {
                device.exposurePointOfInterest = CGPointMake(normalizedX, normalizedY);
                device.exposureMode = AVCaptureExposureModeAutoExpose;
            }
            [device unlockForConfiguration];

            // 1.5秒后恢复连续对焦
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1.5 * NSEC_PER_SEC)),
                           dispatch_get_main_queue(), ^{
                _EnableContinuousAutoFocus();
            });
        }
    }

}