#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 AVCaptureDevice，找到后置摄像头
    // 注意：Unity WebCamTexture 内部的 AVCaptureSession 不会暴露给原生代码，
    // 但 AVCaptureDevice 本身可以独立 lockForConfiguration 设置对焦模式，
    // 不需要成为当前 session 的输入设备。
    if (@available(iOS 10.0, *)) {
        AVCaptureDeviceDiscoverySession *session = [AVCaptureDeviceDiscoverySession
            discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera,
                                              AVCaptureDeviceTypeBuiltInTelephotoCamera,
                                              AVCaptureDeviceTypeBuiltInDualCamera,
                                              AVCaptureDeviceTypeBuiltInDualWideCamera,
                                              AVCaptureDeviceTypeBuiltInTripleCamera]
                                  mediaType:AVMediaTypeVideo
                                   position:AVCaptureDevicePositionBack];
        for (AVCaptureDevice *d in session.devices) {
            return d; // 拿到任意后置摄像头即可
        }
    }
    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();
            });
        }
    }

    /// 周期性重新触发对焦（与 Android softTrigger 思路一致）
    /// 通过"点对焦 → 1.5s 后恢复连续对焦"的方式让镜头做一次完整对焦循环，无黑屏
    void _TriggerContinuousRefocus(void)
    {
        _TriggerAutoFocus(0.5f, 0.5f);
    }

}