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

// ──── 前向声明 ────
static void presentQRScannerWithName(NSString *goName);

@interface QRScannerViewController : UIViewController <AVCaptureMetadataOutputObjectsDelegate>
@property (nonatomic, strong) AVCaptureSession *session;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;
@property (nonatomic, copy) NSString *gameObjectName;
@property (nonatomic, assign) BOOL hasScanned;
@end

@implementation QRScannerViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor blackColor];

    self.session = [[AVCaptureSession alloc] init];

    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if (!device) {
        [self sendResultToUnity:@"ERROR:NO_CAMERA"];
        return;
    }

    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) {
        [self sendResultToUnity:[NSString stringWithFormat:@"ERROR:CAMERA_INPUT:%@", error.localizedDescription]];
        return;
    }

    [self.session addInput:input];

    AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];
    [self.session addOutput:output];
    [output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    output.metadataObjectTypes = @[AVMetadataObjectTypeQRCode];

    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
    self.previewLayer.frame = self.view.bounds;
    self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer:self.previewLayer];

    // 半透明遮罩 + 扫描框
    CGFloat boxSize = self.view.bounds.size.width * 0.65;
    CGRect boxRect = CGRectMake(
        (self.view.bounds.size.width - boxSize) / 2,
        (self.view.bounds.size.height - boxSize) / 2 - 60,
        boxSize, boxSize
    );

    CAShapeLayer *mask = [CAShapeLayer layer];
    UIBezierPath *fullPath = [UIBezierPath bezierPathWithRect:self.view.bounds];
    [fullPath appendPath:[[UIBezierPath bezierPathWithRoundedRect:boxRect cornerRadius:4] bezierPathByReversingPath]];
    mask.path = fullPath.CGPath;
    mask.fillColor = [UIColor colorWithWhite:0 alpha:0.5].CGColor;
    [self.view.layer addSublayer:mask];

    CAShapeLayer *border = [CAShapeLayer layer];
    border.path = [UIBezierPath bezierPathWithRoundedRect:boxRect cornerRadius:4].CGPath;
    border.strokeColor = [UIColor greenColor].CGColor;
    border.lineWidth = 2;
    border.fillColor = UIColor.clearColor.CGColor;
    [self.view.layer addSublayer:border];

    UILabel *hint = [[UILabel alloc] init];
    hint.text = @"将二维码放入框内，即可自动扫描";
    hint.textColor = UIColor.whiteColor;
    hint.font = [UIFont systemFontOfSize:14];
    hint.textAlignment = NSTextAlignmentCenter;
    hint.frame = CGRectMake(20, boxRect.origin.y + boxRect.size.height + 20,
                            self.view.bounds.size.width - 40, 30);
    [self.view addSubview:hint];

    UIButton *cancel = [UIButton buttonWithType:UIButtonTypeSystem];
    [cancel setTitle:@"关闭" forState:UIControlStateNormal];
    [cancel setTitleColor:UIColor.whiteColor forState:UIControlStateNormal];
    cancel.titleLabel.font = [UIFont systemFontOfSize:17];
    cancel.frame = CGRectMake(0, self.view.bounds.size.height - 100,
                              self.view.bounds.size.width, 50);
    [cancel addTarget:self action:@selector(onCancel) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:cancel];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        [self.session startRunning];
    });
}

- (void)onCancel {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        [self.session stopRunning];
    });
    [self dismissViewControllerAnimated:YES completion:^{
        [self sendResultToUnity:@"CANCEL"];
    }];
}

- (void)sendResultToUnity:(NSString *)result {
    const char *go = [self.gameObjectName UTF8String];
    const char *msg = [result UTF8String];
    UnitySendMessage((char *)go, "OnScanResult", (char *)msg);
}

#pragma mark - AVCaptureMetadataOutputObjectsDelegate

- (void)captureOutput:(AVCaptureOutput *)output
didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects
          fromConnection:(AVCaptureConnection *)connection {

    if (self.hasScanned) return;
    if (metadataObjects.count == 0) return;

    AVMetadataMachineReadableCodeObject *code = metadataObjects.firstObject;
    if (![code isKindOfClass:[AVMetadataMachineReadableCodeObject class]]) return;

    self.hasScanned = YES;

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        [self.session stopRunning];
    });

    [self dismissViewControllerAnimated:YES completion:^{
        [self sendResultToUnity:code.stringValue ?: @"ERROR:EMPTY_RESULT"];
    }];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        [self.session stopRunning];
    });
}

@end

// ──── C 函数实现 ────

static void presentQRScannerWithName(NSString *goName) {
    dispatch_async(dispatch_get_main_queue(), ^{
        UIViewController *rootVC = UnityGetGLViewController();
        if (!rootVC) {
            UnitySendMessage((char *)[goName UTF8String],
                             "OnScanResult",
                             "ERROR:NO_ROOT_VC");
            return;
        }

        QRScannerViewController *scanner = [[QRScannerViewController alloc] init];
        scanner.gameObjectName = goName;
        scanner.modalPresentationStyle = UIModalPresentationFullScreen;
        [rootVC presentViewController:scanner animated:YES completion:nil];
    });
}

extern "C" {

    void _StartScanIOS(const char *gameObjectName)
    {
        NSString *goName = [NSString stringWithUTF8String:gameObjectName];

        dispatch_async(dispatch_get_main_queue(), ^{
            AVAuthorizationStatus status = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];

            if (status == AVAuthorizationStatusNotDetermined) {
                [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
                    if (granted) {
                        presentQRScannerWithName(goName);
                    } else {
                        UnitySendMessage((char *)[goName UTF8String],
                                         "OnScanResult",
                                         "ERROR:PERMISSION_DENIED");
                    }
                }];
                return;
            }

            if (status == AVAuthorizationStatusAuthorized) {
                presentQRScannerWithName(goName);
            } else {
                UnitySendMessage((char *)[goName UTF8String],
                                 "OnScanResult",
                                 "ERROR:PERMISSION_DENIED");
            }
        });
    }

}