Build a Barcode Scanner API in C# (Developer Guide)

Install-Package IronBarCode

using IronBarCode;

// Verify installation with a basic barcode read
public class InstallationTest
{
    public static void VerifySetup()
    {
        try
        {
            // Test with a sample barcode image
            var result = BarcodeReader.Read("test-barcode.png");

            if (result.Any())
            {
                Console.WriteLine($"Success! Detected: {result.First().Value}");
                Console.WriteLine($"Format: {result.First().BarcodeType}");
                Console.WriteLine($"Confidence: {result.First().Confidence}%");
            }
            else
            {
                Console.WriteLine("No barcode detected in test image");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Setup issue: {ex.Message}");
        }
    }
}

Imports IronBarCode

' Verify installation with a basic barcode read
Public Class InstallationTest
    Public Shared Sub VerifySetup()
        Try
            ' Test with a sample barcode image
            Dim result = BarcodeReader.Read("test-barcode.png")

            If result.Any() Then
                Console.WriteLine($"Success! Detected: {result.First().Value}")
                Console.WriteLine($"Format: {result.First().BarcodeType}")
                Console.WriteLine($"Confidence: {result.First().Confidence}%")
            Else
                Console.WriteLine("No barcode detected in test image")
            End If
        Catch ex As Exception
            Console.WriteLine($"Setup issue: {ex.Message}")
        End Try
    End Sub
End Class

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Authorization;
using IronBarCode;
using System.Drawing;
using System.ComponentModel.DataAnnotations;

namespace BarcodeScannerAPI.Controllers
{
    [ApiController]
    [Route("api/v1/[controller]")]
    [Authorize] // Require authentication for all endpoints
    public class ScannerController : ControllerBase
    {
        private readonly ILogger<ScannerController> _logger;
        private readonly IConfiguration _configuration;

        public ScannerController(ILogger<ScannerController> logger, IConfiguration configuration)
        {
            _logger = logger;
            _configuration = configuration;
        }

        // Enhanced result model with audit fields
        public class ScanResult
        {
            public bool Success { get; set; }
            public List<BarcodeData> Barcodes { get; set; } = new List<BarcodeData>();
            public string RequestId { get; set; } = Guid.NewGuid().ToString();
            public DateTime ProcessedAt { get; set; } = DateTime.UtcNow;
            public long ProcessingTimeMs { get; set; }
            public string ErrorMessage { get; set; }
            public Dictionary<string, object> Metadata { get; set; } = new Dictionary<string, object>();
        }

        public class BarcodeData
        {
            public string Value { get; set; }
            public string Format { get; set; }
            public double Confidence { get; set; }
            public Rectangle Location { get; set; }
            public int PageNumber { get; set; } // For PDF processing
        }

        // Input validation model
        public class ScanRequest
        {
            [Required]
            public IFormFile File { get; set; }

            [Range(1, 10)]
            public int MaxBarcodes { get; set; } = 5;

            public string[] ExpectedFormats { get; set; }

            public bool EnableImageCorrection { get; set; } = true;
        }

        [HttpPost("scan")]
        [RequestSizeLimit(52428800)] // 50MB limit
        public async Task<ActionResult<ScanResult>> ScanDocument([FromForm] ScanRequest request)
        {
            var stopwatch = System.Diagnostics.Stopwatch.StartNew();
            var result = new ScanResult();

            try
            {
                // Validate file type for security
                var allowedExtensions = new[] { ".pdf", ".png", ".jpg", ".jpeg", ".gif", ".tiff", ".bmp" };
                var fileExtension = Path.GetExtension(request.File.FileName).ToLowerInvariant();

                if (!allowedExtensions.Contains(fileExtension))
                {
                    _logger.LogWarning($"Rejected file type: {fileExtension}");
                    return BadRequest(new ScanResult
                    {
                        Success = false,
                        ErrorMessage = "Unsupported file type. Allowed: PDF, PNG, JPG, GIF, TIFF, BMP"
                    });
                }

                // Process the file
                using var stream = new MemoryStream();
                await request.File.CopyToAsync(stream);
                var fileBytes = stream.ToArray();

                // Log for audit trail
                _logger.LogInformation($"Processing {request.File.FileName} ({fileBytes.Length} bytes) - RequestId: {result.RequestId}");

                // Configure scanner based on requirements
                var options = ConfigureOptions(request);

                // Handle different file types
                BarcodeResults scanResults;
                if (fileExtension == ".pdf")
                {
                    var pdfOptions = new PdfBarcodeReaderOptions
                    {
                        Scale = 3,
                        DPI = 300,
                        MaxThreads = 4
                    };
                    scanResults = BarcodeReader.ReadPdf(fileBytes, pdfOptions);
                }
                else
                {
                    scanResults = BarcodeReader.Read(fileBytes, options);
                }

                // Process results
                if (scanResults.Any())
                {
                    result.Success = true;
                    foreach (var barcode in scanResults.Take(request.MaxBarcodes))
                    {
                        result.Barcodes.Add(new BarcodeData
                        {
                            Value = barcode.Value,
                            Format = barcode.BarcodeType.ToString(),
                            Confidence = barcode.Confidence,
                            Location = barcode.Bounds,
                            PageNumber = barcode.PageNumber
                        });
                    }

                    result.Metadata["TotalFound"] = scanResults.Count();
                    result.Metadata["FileSize"] = fileBytes.Length;
                    result.Metadata["FileName"] = request.File.FileName;

                    _logger.LogInformation($"Successfully scanned {scanResults.Count()} barcodes - RequestId: {result.RequestId}");
                }
                else
                {
                    result.Success = false;
                    result.ErrorMessage = "No barcodes detected in the document";
                    _logger.LogWarning($"No barcodes found - RequestId: {result.RequestId}");
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, $"Scanning error - RequestId: {result.RequestId}");
                result.Success = false;
                result.ErrorMessage = "An error occurred during processing";

                // Don't expose internal errors to clients
                if (_configuration.GetValue<bool>("DetailedErrors"))
                {
                    result.Metadata["Exception"] = ex.Message;
                }
            }
            finally
            {
                stopwatch.Stop();
                result.ProcessingTimeMs = stopwatch.ElapsedMilliseconds;
            }

            return result;
        }

        private BarcodeReaderOptions ConfigureOptions(ScanRequest request)
        {
            var options = new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Balanced,
                ExpectMultipleBarcodes = request.MaxBarcodes > 1,
                RemoveFalsePositive = true,
                Multithreaded = true,
                MaxParallelThreads = Environment.ProcessorCount
            };

            // Apply format filtering if specified
            if (request.ExpectedFormats?.Any() == true)
            {
                var formats = BarcodeEncoding.None;
                foreach (var format in request.ExpectedFormats)
                {
                    if (Enum.TryParse<BarcodeEncoding>(format, true, out var encoding))
                    {
                        formats |= encoding;
                    }
                }
                options.ExpectBarcodeTypes = formats;
            }

            // Enable image correction for damaged barcodes
            if (request.EnableImageCorrection)
            {
                options.ImageFilters = new ImageFilterCollection
                {
                    new SharpenFilter(2),
                    new ContrastFilter(1.5f),
                    new BrightnessFilter(1.1f)
                };
                options.AutoRotate = true;
            }

            return options;
        }

        // Batch processing endpoint for high-volume scenarios
        [HttpPost("scan-batch")]
        [RequestSizeLimit(524288000)] // 500MB for batch operations
        public async Task<ActionResult<List<ScanResult>>> ScanBatch(List<IFormFile> files)
        {
            if (files == null || !files.Any())
            {
                return BadRequest("No files provided");
            }

            if (files.Count > 50)
            {
                return BadRequest("Maximum 50 files per batch");
            }

            var tasks = files.Select(file => ProcessFileAsync(file));
            var results = await Task.WhenAll(tasks);

            _logger.LogInformation($"Batch processed {files.Count} files, {results.Count(r => r.Success)} successful");

            return Ok(results);
        }

        private async Task<ScanResult> ProcessFileAsync(IFormFile file)
        {
            // Reuse the scanning logic
            var request = new ScanRequest 
            { 
                File = file,
                EnableImageCorrection = true 
            };
            var actionResult = await ScanDocument(request);

            if (actionResult.Result is OkObjectResult okResult)
            {
                return okResult.Value as ScanResult;
            }
            else if (actionResult.Result is BadRequestObjectResult badResult)
            {
                return badResult.Value as ScanResult;
            }

            return new ScanResult 
            { 
                Success = false, 
                ErrorMessage = "Processing failed" 
            };
        }
    }
}

Imports Microsoft.AspNetCore.Mvc
Imports Microsoft.AspNetCore.Authorization
Imports IronBarCode
Imports System.Drawing
Imports System.ComponentModel.DataAnnotations

Namespace BarcodeScannerAPI.Controllers
    <ApiController>
    <Route("api/v1/[controller]")>
    <Authorize>
    Public Class ScannerController
        Inherits ControllerBase

        Private ReadOnly _logger As ILogger(Of ScannerController)
        Private ReadOnly _configuration As IConfiguration

        Public Sub New(logger As ILogger(Of ScannerController), configuration As IConfiguration)
            _logger = logger
            _configuration = configuration
        End Sub

        ' Enhanced result model with audit fields
        Public Class ScanResult
            Public Property Success As Boolean
            Public Property Barcodes As List(Of BarcodeData) = New List(Of BarcodeData)()
            Public Property RequestId As String = Guid.NewGuid().ToString()
            Public Property ProcessedAt As DateTime = DateTime.UtcNow
            Public Property ProcessingTimeMs As Long
            Public Property ErrorMessage As String
            Public Property Metadata As Dictionary(Of String, Object) = New Dictionary(Of String, Object)()
        End Class

        Public Class BarcodeData
            Public Property Value As String
            Public Property Format As String
            Public Property Confidence As Double
            Public Property Location As Rectangle
            Public Property PageNumber As Integer
        End Class

        ' Input validation model
        Public Class ScanRequest
            <Required>
            Public Property File As IFormFile

            <Range(1, 10)>
            Public Property MaxBarcodes As Integer = 5

            Public Property ExpectedFormats As String()

            Public Property EnableImageCorrection As Boolean = True
        End Class

        <HttpPost("scan")>
        <RequestSizeLimit(52428800)>
        Public Async Function ScanDocument(<FromForm> request As ScanRequest) As Task(Of ActionResult(Of ScanResult))
            Dim stopwatch = System.Diagnostics.Stopwatch.StartNew()
            Dim result = New ScanResult()

            Try
                ' Validate file type for security
                Dim allowedExtensions = {".pdf", ".png", ".jpg", ".jpeg", ".gif", ".tiff", ".bmp"}
                Dim fileExtension = Path.GetExtension(request.File.FileName).ToLowerInvariant()

                If Not allowedExtensions.Contains(fileExtension) Then
                    _logger.LogWarning($"Rejected file type: {fileExtension}")
                    Return BadRequest(New ScanResult With {
                        .Success = False,
                        .ErrorMessage = "Unsupported file type. Allowed: PDF, PNG, JPG, GIF, TIFF, BMP"
                    })
                End If

                ' Process the file
                Using stream = New MemoryStream()
                    Await request.File.CopyToAsync(stream)
                    Dim fileBytes = stream.ToArray()

                    ' Log for audit trail
                    _logger.LogInformation($"Processing {request.File.FileName} ({fileBytes.Length} bytes) - RequestId: {result.RequestId}")

                    ' Configure scanner based on requirements
                    Dim options = ConfigureOptions(request)

                    ' Handle different file types
                    Dim scanResults As BarcodeResults
                    If fileExtension = ".pdf" Then
                        Dim pdfOptions = New PdfBarcodeReaderOptions With {
                            .Scale = 3,
                            .DPI = 300,
                            .MaxThreads = 4
                        }
                        scanResults = BarcodeReader.ReadPdf(fileBytes, pdfOptions)
                    Else
                        scanResults = BarcodeReader.Read(fileBytes, options)
                    End If

                    ' Process results
                    If scanResults.Any() Then
                        result.Success = True
                        For Each barcode In scanResults.Take(request.MaxBarcodes)
                            result.Barcodes.Add(New BarcodeData With {
                                .Value = barcode.Value,
                                .Format = barcode.BarcodeType.ToString(),
                                .Confidence = barcode.Confidence,
                                .Location = barcode.Bounds,
                                .PageNumber = barcode.PageNumber
                            })
                        Next

                        result.Metadata("TotalFound") = scanResults.Count()
                        result.Metadata("FileSize") = fileBytes.Length
                        result.Metadata("FileName") = request.File.FileName

                        _logger.LogInformation($"Successfully scanned {scanResults.Count()} barcodes - RequestId: {result.RequestId}")
                    Else
                        result.Success = False
                        result.ErrorMessage = "No barcodes detected in the document"
                        _logger.LogWarning($"No barcodes found - RequestId: {result.RequestId}")
                    End If
                End Using
            Catch ex As Exception
                _logger.LogError(ex, $"Scanning error - RequestId: {result.RequestId}")
                result.Success = False
                result.ErrorMessage = "An error occurred during processing"

                ' Don't expose internal errors to clients
                If _configuration.GetValue(Of Boolean)("DetailedErrors") Then
                    result.Metadata("Exception") = ex.Message
                End If
            Finally
                stopwatch.Stop()
                result.ProcessingTimeMs = stopwatch.ElapsedMilliseconds
            End Try

            Return result
        End Function

        Private Function ConfigureOptions(request As ScanRequest) As BarcodeReaderOptions
            Dim options = New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Balanced,
                .ExpectMultipleBarcodes = request.MaxBarcodes > 1,
                .RemoveFalsePositive = True,
                .Multithreaded = True,
                .MaxParallelThreads = Environment.ProcessorCount
            }

            ' Apply format filtering if specified
            If request.ExpectedFormats?.Any() = True Then
                Dim formats = BarcodeEncoding.None
                For Each format In request.ExpectedFormats
                    Dim encoding As BarcodeEncoding
                    If [Enum].TryParse(format, True, encoding) Then
                        formats = formats Or encoding
                    End If
                Next
                options.ExpectBarcodeTypes = formats
            End If

            ' Enable image correction for damaged barcodes
            If request.EnableImageCorrection Then
                options.ImageFilters = New ImageFilterCollection From {
                    New SharpenFilter(2),
                    New ContrastFilter(1.5F),
                    New BrightnessFilter(1.1F)
                }
                options.AutoRotate = True
            End If

            Return options
        End Function

        ' Batch processing endpoint for high-volume scenarios
        <HttpPost("scan-batch")>
        <RequestSizeLimit(524288000)>
        Public Async Function ScanBatch(files As List(Of IFormFile)) As Task(Of ActionResult(Of List(Of ScanResult)))
            If files Is Nothing OrElse Not files.Any() Then
                Return BadRequest("No files provided")
            End If

            If files.Count > 50 Then
                Return BadRequest("Maximum 50 files per batch")
            End If

            Dim tasks = files.Select(Function(file) ProcessFileAsync(file))
            Dim results = Await Task.WhenAll(tasks)

            _logger.LogInformation($"Batch processed {files.Count} files, {results.Count(Function(r) r.Success)} successful")

            Return Ok(results)
        End Function

        Private Async Function ProcessFileAsync(file As IFormFile) As Task(Of ScanResult)
            ' Reuse the scanning logic
            Dim request = New ScanRequest With {
                .File = file,
                .EnableImageCorrection = True
            }
            Dim actionResult = Await ScanDocument(request)

            If TypeOf actionResult.Result Is OkObjectResult Then
                Return DirectCast(actionResult.Result, OkObjectResult).Value
            ElseIf TypeOf actionResult.Result Is BadRequestObjectResult Then
                Return DirectCast(actionResult.Result, BadRequestObjectResult).Value
            End If

            Return New ScanResult With {
                .Success = False,
                .ErrorMessage = "Processing failed"
            }
        End Function
    End Class
End Namespace

// Extended controller with multiple input handlers
[ApiController]
[Route("api/v1/[controller]")]
[Authorize]
public class AdvancedScannerController : ControllerBase
{
    private readonly IHttpClientFactory _httpClientFactory;
    private readonly ILogger<AdvancedScannerController> _logger;

    public AdvancedScannerController(
        IHttpClientFactory httpClientFactory, 
        ILogger<AdvancedScannerController> logger)
    {
        _httpClientFactory = httpClientFactory;
        _logger = logger;
    }

    // Handle Base64 input (common in web applications)
    [HttpPost("scan-base64")]
    public ActionResult<ScanResult> ScanBase64([FromBody] Base64Request request)
    {
        if (!ModelState.IsValid)
        {
            return BadRequest(ModelState);
        }

        try
        {
            // Validate Base64 format
            var base64Data = request.ImageData;
            if (base64Data.Contains(","))
            {
                // Handle data URL format: "data:image/png;base64,..."
                base64Data = base64Data.Substring(base64Data.IndexOf(",") + 1);
            }

            var imageBytes = Convert.FromBase64String(base64Data);

            // Implement size validation
            if (imageBytes.Length > 10 * 1024 * 1024) // 10MB limit
            {
                return BadRequest(new ScanResult
                {
                    Success = false,
                    ErrorMessage = "Image size exceeds 10MB limit"
                });
            }

            // Configure for web-uploaded images (often lower quality)
            var options = new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Detailed,
                ImageFilters = new ImageFilterCollection
                {
                    new SharpenFilter(3),
                    new ContrastFilter(2),
                    new DeNoise()
                },
                TryInvertColor = true, // Handle inverted barcodes
                AutoRotate = true
            };

            var results = BarcodeReader.Read(imageBytes, options);
            return ProcessResults(results, "base64", request.FileName);
        }
        catch (FormatException)
        {
            return BadRequest(new ScanResult
            {
                Success = false,
                ErrorMessage = "Invalid Base64 format"
            });
        }
    }

    // Handle URL input (for cloud storage integration)
    [HttpPost("scan-url")]
    public async Task<ActionResult<ScanResult>> ScanFromUrl([FromBody] UrlScanRequest request)
    {
        if (!Uri.TryCreate(request.Url, UriKind.Absolute, out var uri))
        {
            return BadRequest(new ScanResult
            {
                Success = false,
                ErrorMessage = "Invalid URL format"
            });
        }

        // Validate URL domain (security measure)
        var allowedDomains = _configuration.GetSection("AllowedDomains").Get<string[]>() 
            ?? new[] { "blob.core.windows.net", "s3.amazonaws.com" };

        if (!allowedDomains.Any(domain => uri.Host.EndsWith(domain)))
        {
            _logger.LogWarning($"Rejected URL from unauthorized domain: {uri.Host}");
            return BadRequest(new ScanResult
            {
                Success = false,
                ErrorMessage = "URL domain not authorized"
            });
        }

        try
        {
            using var httpClient = _httpClientFactory.CreateClient("BarcodeScanner");
            httpClient.Timeout = TimeSpan.FromSeconds(30);

            // Add headers to avoid being blocked
            httpClient.DefaultRequestHeaders.Add("User-Agent", "BarcodeScannerAPI/2.0");

            var response = await httpClient.GetAsync(uri);
            response.EnsureSuccessStatusCode();

            // Check content type
            var contentType = response.Content.Headers.ContentType?.MediaType;
            if (!IsValidContentType(contentType))
            {
                return BadRequest(new ScanResult
                {
                    Success = false,
                    ErrorMessage = $"Unsupported content type: {contentType}"
                });
            }

            var imageBytes = await response.Content.ReadAsByteArrayAsync();

            // Use async processing for better scalability
            var results = await BarcodeReader.ReadAsync(imageBytes);
            return ProcessResults(results, "url", uri.ToString());
        }
        catch (HttpRequestException ex)
        {
            _logger.LogError(ex, $"Failed to download from URL: {uri}");
            return BadRequest(new ScanResult
            {
                Success = false,
                ErrorMessage = "Failed to download image from URL"
            });
        }
        catch (TaskCanceledException)
        {
            return BadRequest(new ScanResult
            {
                Success = false,
                ErrorMessage = "Download timeout - file too large or slow connection"
            });
        }
    }

    // Handle multi-page PDFs with page-specific processing
    [HttpPost("scan-pdf-advanced")]
    public async Task<ActionResult<PdfScanResult>> ScanPdfAdvanced([FromForm] PdfScanRequest request)
    {
        using var stream = new MemoryStream();
        await request.File.CopyToAsync(stream);

        var pdfOptions = new PdfBarcodeReaderOptions
        {
            Scale = request.Scale ?? 3,
            DPI = request.DPI ?? 300,
            PageNumbers = request.PageNumbers,
            Password = request.Password,
            MaxThreads = Math.Min(request.MaxThreads ?? 4, Environment.ProcessorCount)
        };

        // For large PDFs, process in chunks
        if (stream.Length > 50 * 1024 * 1024) // 50MB
        {
            _logger.LogInformation($"Large PDF detected ({stream.Length / 1024 / 1024}MB), using chunked processing");
            pdfOptions.MaxThreads = 2; // Reduce memory pressure
        }

        var results = BarcodeReader.ReadPdf(stream.ToArray(), pdfOptions);

        // Group results by page
        var pageResults = results.GroupBy(r => r.PageNumber)
            .OrderBy(g => g.Key)
            .Select(g => new PageBarcodeResult
            {
                PageNumber = g.Key,
                BarcodeCount = g.Count(),
                Barcodes = g.Select(b => new BarcodeData
                {
                    Value = b.Value,
                    Format = b.BarcodeType.ToString(),
                    Confidence = b.Confidence,
                    Location = b.Bounds
                }).ToList()
            }).ToList();

        return Ok(new PdfScanResult
        {
            Success = true,
            TotalPages = pageResults.Count,
            TotalBarcodes = results.Count(),
            PageResults = pageResults,
            RequestId = Guid.NewGuid().ToString()
        });
    }

    // Handle damaged or low-quality barcodes
    [HttpPost("scan-damaged")]
    public async Task<ActionResult<ScanResult>> ScanDamagedBarcode([FromForm] IFormFile file)
    {
        using var stream = new MemoryStream();
        await file.CopyToAsync(stream);

        // Aggressive image correction for damaged barcodes
        var options = new BarcodeReaderOptions
        {
            Speed = ReadingSpeed.ExtremeDetail,
            ImageFilters = new ImageFilterCollection
            {
                new SharpenFilter(4),
                new ContrastFilter(3),
                new BrightnessFilter(1.5f),
                new BinaryThresholdFilter(128),
                new DeNoise(3)
            },
            TryInvertColor = true,
            AutoRotate = true,
            UseCode39ExtendedMode = true,
            RemoveFalsePositive = false, // Accept lower confidence
            Confidence = ConfidenceLevel.Low
        };

        var results = BarcodeReader.Read(stream.ToArray(), options);

        // If still no results, try with different threshold
        if (!results.Any())
        {
            options.ImageFilters = new ImageFilterCollection
            {
                new AdaptiveThresholdFilter(9),
                new MedianFilter(3),
                new Dilate(1)
            };

            results = BarcodeReader.Read(stream.ToArray(), options);
        }

        return ProcessResults(results, "damaged", file.FileName);
    }

    private bool IsValidContentType(string contentType)
    {
        var validTypes = new[]
        {
            "image/jpeg", "image/jpg", "image/png", "image/gif",
            "image/tiff", "image/bmp", "application/pdf"
        };
        return validTypes.Contains(contentType?.ToLower());
    }

    private ActionResult<ScanResult> ProcessResults(BarcodeResults results, string source, string identifier)
    {
        var scanResult = new ScanResult
        {
            Metadata = new Dictionary<string, object>
            {
                ["Source"] = source,
                ["Identifier"] = identifier,
                ["ProcessedAt"] = DateTime.UtcNow
            }
        };

        if (results.Any())
        {
            scanResult.Success = true;
            scanResult.Barcodes = results.Select(r => new BarcodeData
            {
                Value = r.Value,
                Format = r.BarcodeType.ToString(),
                Confidence = r.Confidence,
                Location = r.Bounds
            }).ToList();

            // Log low confidence results for quality monitoring
            var lowConfidence = results.Where(r => r.Confidence < 70).ToList();
            if (lowConfidence.Any())
            {
                _logger.LogWarning($"Low confidence barcodes detected: {lowConfidence.Count} of {results.Count()} from {identifier}");
            }
        }
        else
        {
            scanResult.Success = false;
            scanResult.ErrorMessage = "No barcodes detected";
        }

        return Ok(scanResult);
    }
}

// Request models
public class Base64Request
{
    [Required]
    public string ImageData { get; set; }
    public string FileName { get; set; }
}

public class UrlScanRequest
{
    [Required]
    [Url]
    public string Url { get; set; }
}

public class PdfScanRequest
{
    [Required]
    public IFormFile File { get; set; }
    public int? Scale { get; set; }
    public int? DPI { get; set; }
    public int[] PageNumbers { get; set; }
    public string Password { get; set; }
    public int? MaxThreads { get; set; }
}

// Response models
public class PdfScanResult : ScanResult
{
    public int TotalPages { get; set; }
    public int TotalBarcodes { get; set; }
    public List<PageBarcodeResult> PageResults { get; set; }
}

public class PageBarcodeResult
{
    public int PageNumber { get; set; }
    public int BarcodeCount { get; set; }
    public List<BarcodeData> Barcodes { get; set; }
}

Imports System
Imports System.Collections.Generic
Imports System.IO
Imports System.Linq
Imports System.Net.Http
Imports System.Threading.Tasks
Imports Microsoft.AspNetCore.Authorization
Imports Microsoft.AspNetCore.Http
Imports Microsoft.AspNetCore.Mvc
Imports Microsoft.Extensions.Configuration
Imports Microsoft.Extensions.Logging

<ApiController>
<Route("api/v1/[controller]")>
<Authorize>
Public Class AdvancedScannerController
    Inherits ControllerBase

    Private ReadOnly _httpClientFactory As IHttpClientFactory
    Private ReadOnly _logger As ILogger(Of AdvancedScannerController)
    Private ReadOnly _configuration As IConfiguration

    Public Sub New(httpClientFactory As IHttpClientFactory, logger As ILogger(Of AdvancedScannerController), configuration As IConfiguration)
        _httpClientFactory = httpClientFactory
        _logger = logger
        _configuration = configuration
    End Sub

    ' Handle Base64 input (common in web applications)
    <HttpPost("scan-base64")>
    Public Function ScanBase64(<FromBody> request As Base64Request) As ActionResult(Of ScanResult)
        If Not ModelState.IsValid Then
            Return BadRequest(ModelState)
        End If

        Try
            ' Validate Base64 format
            Dim base64Data = request.ImageData
            If base64Data.Contains(",") Then
                ' Handle data URL format: "data:image/png;base64,..."
                base64Data = base64Data.Substring(base64Data.IndexOf(",") + 1)
            End If

            Dim imageBytes = Convert.FromBase64String(base64Data)

            ' Implement size validation
            If imageBytes.Length > 10 * 1024 * 1024 Then ' 10MB limit
                Return BadRequest(New ScanResult With {
                    .Success = False,
                    .ErrorMessage = "Image size exceeds 10MB limit"
                })
            End If

            ' Configure for web-uploaded images (often lower quality)
            Dim options = New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Detailed,
                .ImageFilters = New ImageFilterCollection From {
                    New SharpenFilter(3),
                    New ContrastFilter(2),
                    New DeNoise()
                },
                .TryInvertColor = True, ' Handle inverted barcodes
                .AutoRotate = True
            }

            Dim results = BarcodeReader.Read(imageBytes, options)
            Return ProcessResults(results, "base64", request.FileName)
        Catch ex As FormatException
            Return BadRequest(New ScanResult With {
                .Success = False,
                .ErrorMessage = "Invalid Base64 format"
            })
        End Try
    End Function

    ' Handle URL input (for cloud storage integration)
    <HttpPost("scan-url")>
    Public Async Function ScanFromUrl(<FromBody> request As UrlScanRequest) As Task(Of ActionResult(Of ScanResult))
        Dim uri As Uri = Nothing
        If Not Uri.TryCreate(request.Url, UriKind.Absolute, uri) Then
            Return BadRequest(New ScanResult With {
                .Success = False,
                .ErrorMessage = "Invalid URL format"
            })
        End If

        ' Validate URL domain (security measure)
        Dim allowedDomains = _configuration.GetSection("AllowedDomains").Get(Of String())() _
            ?? New String() {"blob.core.windows.net", "s3.amazonaws.com"}

        If Not allowedDomains.Any(Function(domain) uri.Host.EndsWith(domain)) Then
            _logger.LogWarning($"Rejected URL from unauthorized domain: {uri.Host}")
            Return BadRequest(New ScanResult With {
                .Success = False,
                .ErrorMessage = "URL domain not authorized"
            })
        End If

        Try
            Using httpClient = _httpClientFactory.CreateClient("BarcodeScanner")
                httpClient.Timeout = TimeSpan.FromSeconds(30)

                ' Add headers to avoid being blocked
                httpClient.DefaultRequestHeaders.Add("User-Agent", "BarcodeScannerAPI/2.0")

                Dim response = Await httpClient.GetAsync(uri)
                response.EnsureSuccessStatusCode()

                ' Check content type
                Dim contentType = response.Content.Headers.ContentType?.MediaType
                If Not IsValidContentType(contentType) Then
                    Return BadRequest(New ScanResult With {
                        .Success = False,
                        .ErrorMessage = $"Unsupported content type: {contentType}"
                    })
                End If

                Dim imageBytes = Await response.Content.ReadAsByteArrayAsync()

                ' Use async processing for better scalability
                Dim results = Await BarcodeReader.ReadAsync(imageBytes)
                Return ProcessResults(results, "url", uri.ToString())
            End Using
        Catch ex As HttpRequestException
            _logger.LogError(ex, $"Failed to download from URL: {uri}")
            Return BadRequest(New ScanResult With {
                .Success = False,
                .ErrorMessage = "Failed to download image from URL"
            })
        Catch ex As TaskCanceledException
            Return BadRequest(New ScanResult With {
                .Success = False,
                .ErrorMessage = "Download timeout - file too large or slow connection"
            })
        End Try
    End Function

    ' Handle multi-page PDFs with page-specific processing
    <HttpPost("scan-pdf-advanced")>
    Public Async Function ScanPdfAdvanced(<FromForm> request As PdfScanRequest) As Task(Of ActionResult(Of PdfScanResult))
        Using stream = New MemoryStream()
            Await request.File.CopyToAsync(stream)

            Dim pdfOptions = New PdfBarcodeReaderOptions With {
                .Scale = If(request.Scale, 3),
                .DPI = If(request.DPI, 300),
                .PageNumbers = request.PageNumbers,
                .Password = request.Password,
                .MaxThreads = Math.Min(If(request.MaxThreads, 4), Environment.ProcessorCount)
            }

            ' For large PDFs, process in chunks
            If stream.Length > 50 * 1024 * 1024 Then ' 50MB
                _logger.LogInformation($"Large PDF detected ({stream.Length / 1024 / 1024}MB), using chunked processing")
                pdfOptions.MaxThreads = 2 ' Reduce memory pressure
            End If

            Dim results = BarcodeReader.ReadPdf(stream.ToArray(), pdfOptions)

            ' Group results by page
            Dim pageResults = results.GroupBy(Function(r) r.PageNumber) _
                .OrderBy(Function(g) g.Key) _
                .Select(Function(g) New PageBarcodeResult With {
                    .PageNumber = g.Key,
                    .BarcodeCount = g.Count(),
                    .Barcodes = g.Select(Function(b) New BarcodeData With {
                        .Value = b.Value,
                        .Format = b.BarcodeType.ToString(),
                        .Confidence = b.Confidence,
                        .Location = b.Bounds
                    }).ToList()
                }).ToList()

            Return Ok(New PdfScanResult With {
                .Success = True,
                .TotalPages = pageResults.Count,
                .TotalBarcodes = results.Count(),
                .PageResults = pageResults,
                .RequestId = Guid.NewGuid().ToString()
            })
        End Using
    End Function

    ' Handle damaged or low-quality barcodes
    <HttpPost("scan-damaged")>
    Public Async Function ScanDamagedBarcode(<FromForm> file As IFormFile) As Task(Of ActionResult(Of ScanResult))
        Using stream = New MemoryStream()
            Await file.CopyToAsync(stream)

            ' Aggressive image correction for damaged barcodes
            Dim options = New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.ExtremeDetail,
                .ImageFilters = New ImageFilterCollection From {
                    New SharpenFilter(4),
                    New ContrastFilter(3),
                    New BrightnessFilter(1.5F),
                    New BinaryThresholdFilter(128),
                    New DeNoise(3)
                },
                .TryInvertColor = True,
                .AutoRotate = True,
                .UseCode39ExtendedMode = True,
                .RemoveFalsePositive = False, ' Accept lower confidence
                .Confidence = ConfidenceLevel.Low
            }

            Dim results = BarcodeReader.Read(stream.ToArray(), options)

            ' If still no results, try with different threshold
            If Not results.Any() Then
                options.ImageFilters = New ImageFilterCollection From {
                    New AdaptiveThresholdFilter(9),
                    New MedianFilter(3),
                    New Dilate(1)
                }

                results = BarcodeReader.Read(stream.ToArray(), options)
            End If

            Return ProcessResults(results, "damaged", file.FileName)
        End Using
    End Function

    Private Function IsValidContentType(contentType As String) As Boolean
        Dim validTypes = New String() {
            "image/jpeg", "image/jpg", "image/png", "image/gif",
            "image/tiff", "image/bmp", "application/pdf"
        }
        Return validTypes.Contains(contentType?.ToLower())
    End Function

    Private Function ProcessResults(results As BarcodeResults, source As String, identifier As String) As ActionResult(Of ScanResult)
        Dim scanResult = New ScanResult With {
            .Metadata = New Dictionary(Of String, Object) From {
                {"Source", source},
                {"Identifier", identifier},
                {"ProcessedAt", DateTime.UtcNow}
            }
        }

        If results.Any() Then
            scanResult.Success = True
            scanResult.Barcodes = results.Select(Function(r) New BarcodeData With {
                .Value = r.Value,
                .Format = r.BarcodeType.ToString(),
                .Confidence = r.Confidence,
                .Location = r.Bounds
            }).ToList()

            ' Log low confidence results for quality monitoring
            Dim lowConfidence = results.Where(Function(r) r.Confidence < 70).ToList()
            If lowConfidence.Any() Then
                _logger.LogWarning($"Low confidence barcodes detected: {lowConfidence.Count} of {results.Count()} from {identifier}")
            End If
        Else
            scanResult.Success = False
            scanResult.ErrorMessage = "No barcodes detected"
        End If

        Return Ok(scanResult)
    End Function
End Class

' Request models
Public Class Base64Request
    <Required>
    Public Property ImageData As String
    Public Property FileName As String
End Class

Public Class UrlScanRequest
    <Required>
    <Url>
    Public Property Url As String
End Class

Public Class PdfScanRequest
    <Required>
    Public Property File As IFormFile
    Public Property Scale As Integer?
    Public Property DPI As Integer?
    Public Property PageNumbers As Integer()
    Public Property Password As String
    Public Property MaxThreads As Integer?
End Class

' Response models
Public Class PdfScanResult
    Inherits ScanResult

    Public Property TotalPages As Integer
    Public Property TotalBarcodes As Integer
    Public Property PageResults As List(Of PageBarcodeResult)
End Class

Public Class PageBarcodeResult
    Public Property PageNumber As Integer
    Public Property BarcodeCount As Integer
    Public Property Barcodes As List(Of BarcodeData)
End Class

public class OptimizedScannerService
{
    private readonly ILogger<OptimizedScannerService> _logger;
    private readonly IMemoryCache _cache;

    public OptimizedScannerService(ILogger<OptimizedScannerService> logger, IMemoryCache cache)
    {
        _logger = logger;
        _cache = cache;
    }

    // Performance-optimized scanning with caching
    public async Task<ScanResult> ScanWithOptimizationsAsync(byte[] imageData, string cacheKey = null)
    {
        // Check cache for repeat scans
        if (!string.IsNullOrEmpty(cacheKey))
        {
            if (_cache.TryGetValue(cacheKey, out ScanResult cachedResult))
            {
                _logger.LogInformation($"Cache hit for {cacheKey}");
                cachedResult.Metadata["CacheHit"] = true;
                return cachedResult;
            }
        }

        // Determine optimal settings based on image characteristics
        var settings = await DetermineOptimalSettingsAsync(imageData);

        // Apply region-specific scanning if applicable
        if (settings.UseRegionScanning)
        {
            return await ScanWithRegionsAsync(imageData, settings);
        }

        // Standard optimized scanning
        var results = await BarcodeReader.ReadAsync(imageData, settings.Options);
        var scanResult = BuildScanResult(results);

        // Cache successful results
        if (!string.IsNullOrEmpty(cacheKey) && scanResult.Success)
        {
            _cache.Set(cacheKey, scanResult, TimeSpan.FromMinutes(5));
        }

        return scanResult;
    }

    // Intelligent settings determination
    private async Task<ScanSettings> DetermineOptimalSettingsAsync(byte[] imageData)
    {
        var settings = new ScanSettings();

        // Quick analysis of image properties
        using var ms = new MemoryStream(imageData);
        using var image = Image.FromStream(ms);

        var width = image.Width;
        var height = image.Height;
        var aspectRatio = (double)width / height;

        _logger.LogInformation($"Image analysis: {width}x{height}, ratio: {aspectRatio:F2}");

        // High-resolution images can use faster scanning
        if (width > 2000 && height > 2000)
        {
            settings.Options.Speed = ReadingSpeed.Faster;
            settings.Options.ExpectBarcodeTypes = BarcodeEncoding.QRCode | BarcodeEncoding.Code128;
        }
        // Low-resolution needs more processing
        else if (width < 800 || height < 800)
        {
            settings.Options.Speed = ReadingSpeed.ExtremeDetail;
            settings.Options.ImageFilters = new ImageFilterCollection
            {
                new SharpenFilter(3),
                new ContrastFilter(2)
            };
        }
        else
        {
            settings.Options.Speed = ReadingSpeed.Balanced;
        }

        // Detect if image might contain multiple barcodes based on aspect ratio
        if (aspectRatio > 2 || aspectRatio < 0.5)
        {
            settings.Options.ExpectMultipleBarcodes = true;
            settings.UseRegionScanning = true;
        }

        // Enable rotation correction for potentially skewed images
        settings.Options.AutoRotate = true;

        return settings;
    }

    // Region-based scanning for large images
    private async Task<ScanResult> ScanWithRegionsAsync(byte[] imageData, ScanSettings settings)
    {
        var allResults = new List<BarcodeResult>();
        using var ms = new MemoryStream(imageData);
        using var image = Image.FromStream(ms);

        // Define scanning regions for common document layouts
        var regions = new[]
        {
            new Rectangle(0, 0, image.Width / 2, image.Height / 2), // Top-left
            new Rectangle(image.Width / 2, 0, image.Width / 2, image.Height / 2), // Top-right
            new Rectangle(0, image.Height / 2, image.Width / 2, image.Height / 2), // Bottom-left
            new Rectangle(image.Width / 2, image.Height / 2, image.Width / 2, image.Height / 2), // Bottom-right
            new Rectangle(image.Width / 4, image.Height / 4, image.Width / 2, image.Height / 2) // Center
        };

        var tasks = regions.Select(async region =>
        {
            var regionOptions = new BarcodeReaderOptions
            {
                CropArea = region,
                Speed = ReadingSpeed.Faster,
                ExpectMultipleBarcodes = false
            };

            try
            {
                return await BarcodeReader.ReadAsync(imageData, regionOptions);
            }
            catch (Exception ex)
            {
                _logger.LogWarning($"Region scan failed: {ex.Message}");
                return new BarcodeResult[0];
            }
        });

        var regionResults = await Task.WhenAll(tasks);

        // Combine and deduplicate results
        var uniqueResults = regionResults
            .SelectMany(r => r)
            .GroupBy(r => r.Value)
            .Select(g => g.OrderByDescending(r => r.Confidence).First())
            .ToList();

        return BuildScanResult(uniqueResults);
    }

    // Adaptive quality enhancement
    public async Task<ScanResult> ScanWithAdaptiveEnhancementAsync(byte[] imageData)
    {
        var attempts = new List<Func<Task<BarcodeResults>>>
        {
            // Attempt 1: Fast scan
            async () => await BarcodeReader.ReadAsync(imageData, new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Faster,
                RemoveFalsePositive = true
            }),

            // Attempt 2: Standard scan with basic filters
            async () => await BarcodeReader.ReadAsync(imageData, new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Balanced,
                ImageFilters = new ImageFilterCollection
                {
                    new ContrastFilter(1.5f),
                    new SharpenFilter(1)
                },
                TryInvertColor = true
            }),

            // Attempt 3: Detailed scan with aggressive filtering
            async () => await BarcodeReader.ReadAsync(imageData, new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Detailed,
                ImageFilters = new ImageFilterCollection
                {
                    new AdaptiveThresholdFilter(11),
                    new DeNoise(2),
                    new MedianFilter(3)
                },
                AutoRotate = true,
                Confidence = ConfidenceLevel.Low
            }),

            // Attempt 4: Extreme processing for damaged barcodes
            async () => await BarcodeReader.ReadAsync(imageData, new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.ExtremeDetail,
                ImageFilters = new ImageFilterCollection
                {
                    new BinaryThresholdFilter(100),
                    new Erode(1),
                    new Dilate(2),
                    new SharpenFilter(4)
                },
                RemoveFalsePositive = false,
                UseCode39ExtendedMode = true,
                TryInvertColor = true
            })
        };

        foreach (var (attempt, index) in attempts.Select((a, i) => (a, i)))
        {
            var stopwatch = Stopwatch.StartNew();
            var results = await attempt();
            stopwatch.Stop();

            _logger.LogInformation($"Attempt {index + 1} took {stopwatch.ElapsedMilliseconds}ms, found {results.Count()} barcodes");

            if (results.Any())
            {
                var scanResult = BuildScanResult(results);
                scanResult.Metadata["AttemptNumber"] = index + 1;
                scanResult.Metadata["ProcessingStrategy"] = GetStrategyName(index);
                return scanResult;
            }
        }

        return new ScanResult
        {
            Success = false,
            ErrorMessage = "No barcodes found after all enhancement attempts"
        };
    }

    // Machine learning confidence optimization
    public class MLOptimizedScanner
    {
        private readonly Dictionary<string, double> _formatConfidenceThresholds = new()
        {
            { "QRCode", 85.0 },
            { "Code128", 90.0 },
            { "Code39", 88.0 },
            { "DataMatrix", 87.0 },
            { "EAN13", 92.0 },
            { "PDF417", 86.0 }
        };

        public async Task<ScanResult> ScanWithMLConfidenceAsync(byte[] imageData, string expectedFormat = null)
        {
            var options = new BarcodeReaderOptions
            {
                Speed = ReadingSpeed.Balanced,
                Confidence = ConfidenceLevel.Optional
            };

            // If we know the expected format, improve for it
            if (!string.IsNullOrEmpty(expectedFormat) && 
                Enum.TryParse<BarcodeEncoding>(expectedFormat, out var encoding))
            {
                options.ExpectBarcodeTypes = encoding;
            }

            var results = await BarcodeReader.ReadAsync(imageData, options);

            // Apply ML confidence filtering
            var confidenceThreshold = expectedFormat != null && 
                _formatConfidenceThresholds.ContainsKey(expectedFormat)
                ? _formatConfidenceThresholds[expectedFormat]
                : 80.0;

            var highConfidenceResults = results
                .Where(r => r.Confidence >= confidenceThreshold)
                .ToList();

            if (highConfidenceResults.Any())
            {
                return BuildScanResult(highConfidenceResults);
            }

            // If no high-confidence results, include lower confidence with warnings
            var lowConfidenceResults = results
                .Where(r => r.Confidence < confidenceThreshold)
                .ToList();

            if (lowConfidenceResults.Any())
            {
                var result = BuildScanResult(lowConfidenceResults);
                result.Metadata["Warning"] = "Low confidence results - manual verification recommended";
                result.Metadata["MinConfidence"] = lowConfidenceResults.Min(r => r.Confidence);
                return result;
            }

            return new ScanResult
            {
                Success = false,
                ErrorMessage = "No barcodes met confidence threshold"
            };
        }
    }

    private ScanResult BuildScanResult(IEnumerable<BarcodeResult> results)
    {
        var resultList = results.ToList();
        return new ScanResult
        {
            Success = true,
            Barcodes = resultList.Select(r => new BarcodeData
            {
                Value = r.Value,
                Format = r.BarcodeType.ToString(),
                Confidence = r.Confidence,
                Location = r.Bounds
            }).ToList(),
            Metadata = new Dictionary<string, object>
            {
                ["TotalFound"] = resultList.Count,
                ["AverageConfidence"] = resultList.Average(r => r.Confidence),
                ["Formats"] = resultList.Select(r => r.BarcodeType.ToString()).Distinct().ToArray()
            }
        };
    }

    private string GetStrategyName(int attemptIndex)
    {
        return attemptIndex switch
        {
            0 => "FastScan",
            1 => "StandardEnhanced",
            2 => "DetailedFiltering",
            3 => "ExtremeDamageRecovery",
            _ => "Unknown"
        };
    }
}

// Supporting classes
public class ScanSettings
{
    public BarcodeReaderOptions Options { get; set; } = new BarcodeReaderOptions();
    public bool UseRegionScanning { get; set; }
    public List<Rectangle> CustomRegions { get; set; }
}

// Benchmark service for performance testing
public class BenchmarkService
{
    private readonly ILogger<BenchmarkService> _logger;

    public async Task<BenchmarkResult> BenchmarkSettingsAsync(byte[] testImage, int iterations = 10)
    {
        var results = new Dictionary<string, BenchmarkData>();

        var testConfigurations = new Dictionary<string, BarcodeReaderOptions>
        {
            ["Fastest"] = new() { Speed = ReadingSpeed.Faster },
            ["Balanced"] = new() { Speed = ReadingSpeed.Balanced },
            ["Detailed"] = new() { Speed = ReadingSpeed.Detailed },
            ["Parallel"] = new() { Speed = ReadingSpeed.Balanced, Multithreaded = true, MaxParallelThreads = 4 },
            ["Filtered"] = new() 
            { 
                Speed = ReadingSpeed.Balanced, 
                ImageFilters = new ImageFilterCollection { new SharpenFilter(2), new ContrastFilter(1.5f) } 
            }
        };

        foreach (var config in testConfigurations)
        {
            var times = new List<long>();
            var successCount = 0;

            for (int i = 0; i < iterations; i++)
            {
                var sw = Stopwatch.StartNew();
                var scanResults = await BarcodeReader.ReadAsync(testImage, config.Value);
                sw.Stop();

                times.Add(sw.ElapsedMilliseconds);
                if (scanResults.Any()) successCount++;

                // Small delay between tests
                await Task.Delay(100);
            }

            results[config.Key] = new BenchmarkData
            {
                AverageMs = times.Average(),
                MinMs = times.Min(),
                MaxMs = times.Max(),
                SuccessRate = (double)successCount / iterations * 100
            };
        }

        return new BenchmarkResult { Results = results };
    }
}

public class BenchmarkData
{
    public double AverageMs { get; set; }
    public long MinMs { get; set; }
    public long MaxMs { get; set; }
    public double SuccessRate { get; set; }
}

public class BenchmarkResult
{
    public Dictionary<string, BenchmarkData> Results { get; set; }
}

Imports System
Imports System.Collections.Generic
Imports System.Drawing
Imports System.IO
Imports System.Linq
Imports System.Threading.Tasks

Public Class OptimizedScannerService
    Private ReadOnly _logger As ILogger(Of OptimizedScannerService)
    Private ReadOnly _cache As IMemoryCache

    Public Sub New(logger As ILogger(Of OptimizedScannerService), cache As IMemoryCache)
        _logger = logger
        _cache = cache
    End Sub

    ' Performance-optimized scanning with caching
    Public Async Function ScanWithOptimizationsAsync(imageData As Byte(), Optional cacheKey As String = Nothing) As Task(Of ScanResult)
        ' Check cache for repeat scans
        If Not String.IsNullOrEmpty(cacheKey) Then
            Dim cachedResult As ScanResult = Nothing
            If _cache.TryGetValue(cacheKey, cachedResult) Then
                _logger.LogInformation($"Cache hit for {cacheKey}")
                cachedResult.Metadata("CacheHit") = True
                Return cachedResult
            End If
        End If

        ' Determine optimal settings based on image characteristics
        Dim settings = Await DetermineOptimalSettingsAsync(imageData)

        ' Apply region-specific scanning if applicable
        If settings.UseRegionScanning Then
            Return Await ScanWithRegionsAsync(imageData, settings)
        End If

        ' Standard optimized scanning
        Dim results = Await BarcodeReader.ReadAsync(imageData, settings.Options)
        Dim scanResult = BuildScanResult(results)

        ' Cache successful results
        If Not String.IsNullOrEmpty(cacheKey) AndAlso scanResult.Success Then
            _cache.Set(cacheKey, scanResult, TimeSpan.FromMinutes(5))
        End If

        Return scanResult
    End Function

    ' Intelligent settings determination
    Private Async Function DetermineOptimalSettingsAsync(imageData As Byte()) As Task(Of ScanSettings)
        Dim settings As New ScanSettings()

        ' Quick analysis of image properties
        Using ms As New MemoryStream(imageData)
            Using image As Image = Image.FromStream(ms)
                Dim width = image.Width
                Dim height = image.Height
                Dim aspectRatio = CDbl(width) / height

                _logger.LogInformation($"Image analysis: {width}x{height}, ratio: {aspectRatio:F2}")

                ' High-resolution images can use faster scanning
                If width > 2000 AndAlso height > 2000 Then
                    settings.Options.Speed = ReadingSpeed.Faster
                    settings.Options.ExpectBarcodeTypes = BarcodeEncoding.QRCode Or BarcodeEncoding.Code128
                ElseIf width < 800 OrElse height < 800 Then
                    ' Low-resolution needs more processing
                    settings.Options.Speed = ReadingSpeed.ExtremeDetail
                    settings.Options.ImageFilters = New ImageFilterCollection From {
                        New SharpenFilter(3),
                        New ContrastFilter(2)
                    }
                Else
                    settings.Options.Speed = ReadingSpeed.Balanced
                End If

                ' Detect if image might contain multiple barcodes based on aspect ratio
                If aspectRatio > 2 OrElse aspectRatio < 0.5 Then
                    settings.Options.ExpectMultipleBarcodes = True
                    settings.UseRegionScanning = True
                End If

                ' Enable rotation correction for potentially skewed images
                settings.Options.AutoRotate = True
            End Using
        End Using

        Return settings
    End Function

    ' Region-based scanning for large images
    Private Async Function ScanWithRegionsAsync(imageData As Byte(), settings As ScanSettings) As Task(Of ScanResult)
        Dim allResults As New List(Of BarcodeResult)()
        Using ms As New MemoryStream(imageData)
            Using image As Image = Image.FromStream(ms)
                ' Define scanning regions for common document layouts
                Dim regions = {
                    New Rectangle(0, 0, image.Width \ 2, image.Height \ 2), ' Top-left
                    New Rectangle(image.Width \ 2, 0, image.Width \ 2, image.Height \ 2), ' Top-right
                    New Rectangle(0, image.Height \ 2, image.Width \ 2, image.Height \ 2), ' Bottom-left
                    New Rectangle(image.Width \ 2, image.Height \ 2, image.Width \ 2, image.Height \ 2), ' Bottom-right
                    New Rectangle(image.Width \ 4, image.Height \ 4, image.Width \ 2, image.Height \ 2) ' Center
                }

                Dim tasks = regions.Select(Async Function(region)
                                               Dim regionOptions As New BarcodeReaderOptions With {
                                                   .CropArea = region,
                                                   .Speed = ReadingSpeed.Faster,
                                                   .ExpectMultipleBarcodes = False
                                               }

                                               Try
                                                   Return Await BarcodeReader.ReadAsync(imageData, regionOptions)
                                               Catch ex As Exception
                                                   _logger.LogWarning($"Region scan failed: {ex.Message}")
                                                   Return New BarcodeResult() {}
                                               End Try
                                           End Function)

                Dim regionResults = Await Task.WhenAll(tasks)

                ' Combine and deduplicate results
                Dim uniqueResults = regionResults.
                    SelectMany(Function(r) r).
                    GroupBy(Function(r) r.Value).
                    Select(Function(g) g.OrderByDescending(Function(r) r.Confidence).First()).
                    ToList()

                Return BuildScanResult(uniqueResults)
            End Using
        End Using
    End Function

    ' Adaptive quality enhancement
    Public Async Function ScanWithAdaptiveEnhancementAsync(imageData As Byte()) As Task(Of ScanResult)
        Dim attempts = New List(Of Func(Of Task(Of BarcodeResults))) From {
            ' Attempt 1: Fast scan
            Async Function() Await BarcodeReader.ReadAsync(imageData, New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Faster,
                .RemoveFalsePositive = True
            }),

            ' Attempt 2: Standard scan with basic filters
            Async Function() Await BarcodeReader.ReadAsync(imageData, New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Balanced,
                .ImageFilters = New ImageFilterCollection From {
                    New ContrastFilter(1.5F),
                    New SharpenFilter(1)
                },
                .TryInvertColor = True
            }),

            ' Attempt 3: Detailed scan with aggressive filtering
            Async Function() Await BarcodeReader.ReadAsync(imageData, New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Detailed,
                .ImageFilters = New ImageFilterCollection From {
                    New AdaptiveThresholdFilter(11),
                    New DeNoise(2),
                    New MedianFilter(3)
                },
                .AutoRotate = True,
                .Confidence = ConfidenceLevel.Low
            }),

            ' Attempt 4: Extreme processing for damaged barcodes
            Async Function() Await BarcodeReader.ReadAsync(imageData, New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.ExtremeDetail,
                .ImageFilters = New ImageFilterCollection From {
                    New BinaryThresholdFilter(100),
                    New Erode(1),
                    New Dilate(2),
                    New SharpenFilter(4)
                },
                .RemoveFalsePositive = False,
                .UseCode39ExtendedMode = True,
                .TryInvertColor = True
            })
        }

        For Each attempt In attempts.Select(Function(a, i) (a, i))
            Dim stopwatch = Stopwatch.StartNew()
            Dim results = Await attempt.a()
            stopwatch.Stop()

            _logger.LogInformation($"Attempt {attempt.i + 1} took {stopwatch.ElapsedMilliseconds}ms, found {results.Count()} barcodes")

            If results.Any() Then
                Dim scanResult = BuildScanResult(results)
                scanResult.Metadata("AttemptNumber") = attempt.i + 1
                scanResult.Metadata("ProcessingStrategy") = GetStrategyName(attempt.i)
                Return scanResult
            End If
        Next

        Return New ScanResult With {
            .Success = False,
            .ErrorMessage = "No barcodes found after all enhancement attempts"
        }
    End Function

    ' Machine learning confidence optimization
    Public Class MLOptimizedScanner
        Private ReadOnly _formatConfidenceThresholds As New Dictionary(Of String, Double) From {
            {"QRCode", 85.0},
            {"Code128", 90.0},
            {"Code39", 88.0},
            {"DataMatrix", 87.0},
            {"EAN13", 92.0},
            {"PDF417", 86.0}
        }

        Public Async Function ScanWithMLConfidenceAsync(imageData As Byte(), Optional expectedFormat As String = Nothing) As Task(Of ScanResult)
            Dim options As New BarcodeReaderOptions With {
                .Speed = ReadingSpeed.Balanced,
                .Confidence = ConfidenceLevel.Optional
            }

            ' If we know the expected format, improve for it
            If Not String.IsNullOrEmpty(expectedFormat) AndAlso
                [Enum].TryParse(Of BarcodeEncoding)(expectedFormat, encoding) Then
                options.ExpectBarcodeTypes = encoding
            End If

            Dim results = Await BarcodeReader.ReadAsync(imageData, options)

            ' Apply ML confidence filtering
            Dim confidenceThreshold = If(expectedFormat IsNot Nothing AndAlso
                _formatConfidenceThresholds.ContainsKey(expectedFormat),
                _formatConfidenceThresholds(expectedFormat),
                80.0)

            Dim highConfidenceResults = results.
                Where(Function(r) r.Confidence >= confidenceThreshold).
                ToList()

            If highConfidenceResults.Any() Then
                Return BuildScanResult(highConfidenceResults)
            End If

            ' If no high-confidence results, include lower confidence with warnings
            Dim lowConfidenceResults = results.
                Where(Function(r) r.Confidence < confidenceThreshold).
                ToList()

            If lowConfidenceResults.Any() Then
                Dim result = BuildScanResult(lowConfidenceResults)
                result.Metadata("Warning") = "Low confidence results - manual verification recommended"
                result.Metadata("MinConfidence") = lowConfidenceResults.Min(Function(r) r.Confidence)
                Return result
            End If

            Return New ScanResult With {
                .Success = False,
                .ErrorMessage = "No barcodes met confidence threshold"
            }
        End Function
    End Class

    Private Function BuildScanResult(results As IEnumerable(Of BarcodeResult)) As ScanResult
        Dim resultList = results.ToList()
        Return New ScanResult With {
            .Success = True,
            .Barcodes = resultList.Select(Function(r) New BarcodeData With {
                .Value = r.Value,
                .Format = r.BarcodeType.ToString(),
                .Confidence = r.Confidence,
                .Location = r.Bounds
            }).ToList(),
            .Metadata = New Dictionary(Of String, Object) From {
                {"TotalFound", resultList.Count},
                {"AverageConfidence", resultList.Average(Function(r) r.Confidence)},
                {"Formats", resultList.Select(Function(r) r.BarcodeType.ToString()).Distinct().ToArray()}
            }
        }
    End Function

    Private Function GetStrategyName(attemptIndex As Integer) As String
        Return attemptIndex Select Case {
            0 : "FastScan",
            1 : "StandardEnhanced",
            2 : "DetailedFiltering",
            3 : "ExtremeDamageRecovery",
            Else : "Unknown"
        }
    End Function
End Class

' Supporting classes
Public Class ScanSettings
    Public Property Options As BarcodeReaderOptions = New BarcodeReaderOptions()
    Public Property UseRegionScanning As Boolean
    Public Property CustomRegions As List(Of Rectangle)
End Class

' Benchmark service for performance testing
Public Class BenchmarkService
    Private ReadOnly _logger As ILogger(Of BenchmarkService)

    Public Async Function BenchmarkSettingsAsync(testImage As Byte(), Optional iterations As Integer = 10) As Task(Of BenchmarkResult)
        Dim results As New Dictionary(Of String, BenchmarkData)()

        Dim testConfigurations = New Dictionary(Of String, BarcodeReaderOptions) From {
            {"Fastest", New BarcodeReaderOptions With {.Speed = ReadingSpeed.Faster}},
            {"Balanced", New BarcodeReaderOptions With {.Speed = ReadingSpeed.Balanced}},
            {"Detailed", New BarcodeReaderOptions With {.Speed = ReadingSpeed.Detailed}},
            {"Parallel", New BarcodeReaderOptions With {.Speed = ReadingSpeed.Balanced, .Multithreaded = True, .MaxParallelThreads = 4}},
            {"Filtered", New BarcodeReaderOptions With {.Speed = ReadingSpeed.Balanced, .ImageFilters = New ImageFilterCollection From {New SharpenFilter(2), New ContrastFilter(1.5F)}}}
        }

        For Each config In testConfigurations
            Dim times As New List(Of Long)()
            Dim successCount = 0

            For i = 0 To iterations - 1
                Dim sw = Stopwatch.StartNew()
                Dim scanResults = Await BarcodeReader.ReadAsync(testImage, config.Value)
                sw.Stop()

                times.Add(sw.ElapsedMilliseconds)
                If scanResults.Any() Then successCount += 1

                ' Small delay between tests
                Await Task.Delay(100)
            Next

            results(config.Key) = New BenchmarkData With {
                .AverageMs = times.Average(),
                .MinMs = times.Min(),
                .MaxMs = times.Max(),
                .SuccessRate = CDbl(successCount) / iterations * 100
            }
        Next

        Return New BenchmarkResult With {.Results = results}
    End Function
End Class

Public Class BenchmarkData
    Public Property AverageMs As Double
    Public Property MinMs As Long
    Public Property MaxMs As Long
    Public Property SuccessRate As Double
End Class

Public Class BenchmarkResult
    Public Property Results As Dictionary(Of String, BenchmarkData)
End Class

public class BarcodeGenerationService
{
    private readonly ILogger<BarcodeGenerationService> _logger;

    // Generate QR codes for asset tracking
    public byte[] GenerateAssetQRCode(AssetInfo asset)
    {
        // Create JSON payload with asset information
        var assetData = JsonSerializer.Serialize(new
        {
            Id = asset.AssetId,
            Type = asset.AssetType,
            Location = asset.CurrentLocation,
            LastMaintenance = asset.LastMaintenanceDate,
            Url = "___PROTECTED_URL_45___"
        });

        // Generate QR code with high error correction for durability
        var qrCode = QRCodeWriter.CreateQrCode(assetData, 500, QRCodeWriter.QrErrorCorrectionLevel.High);

        // Add company branding
        qrCode.AddAnnotationTextAboveBarcode($"ASSET: {asset.AssetId}");
        qrCode.AddAnnotationTextBelowBarcode(asset.AssetType);
        qrCode.SetMargins(10);

        // Style for printing on asset labels
        qrCode.ChangeBarCodeColor(Color.Black);
        qrCode.ChangeBackgroundColor(Color.White);

        return qrCode.ToStream().ToArray();
    }

    // Generate visitor badges with QR codes
    public GeneratedBarcode CreateVisitorBadgeQR(VisitorInfo visitor)
    {
        // Encode visitor information with expiration
        var visitorData = new
        {
            Name = visitor.Name,
            Company = visitor.Company,
            Host = visitor.HostEmployee,
            ValidFrom = visitor.CheckInTime,
            ValidUntil = visitor.CheckInTime.AddHours(8),
            AccessLevel = visitor.AccessLevel,
            BadgeId = Guid.NewGuid().ToString()
        };

        var qrCode = QRCodeWriter.CreateQrCode(
            JsonSerializer.Serialize(visitorData), 
            400, 
            QRCodeWriter.QrErrorCorrectionLevel.Medium
        );

        // Add company logo for professional appearance
        if (File.Exists("company-logo.png"))
        {
            qrCode.AddLogo("company-logo.png");
        }

        // Style for badge printing
        qrCode.SetMargins(15);
        qrCode.ChangeBarCodeColor(Color.FromArgb(0, 48, 135)); // Company blue

        // Add visible text for security personnel
        qrCode.AddAnnotationTextAboveBarcode($"VISITOR: {visitor.Name}");
        qrCode.AddAnnotationTextBelowBarcode($"Expires: {visitor.CheckInTime.AddHours(8):HH:mm}");

        _logger.LogInformation($"Generated visitor badge for {visitor.Name}, BadgeId: {visitorData.BadgeId}");

        return qrCode;
    }

    // Generate shipping labels with multiple barcodes
    public byte[] GenerateShippingLabel(ShippingInfo shipping)
    {
        // Create a PDF with multiple barcodes
        var pdf = new IronPdf.ChromePdfRenderer();

        // Generate tracking barcode (Code 128 for USPS/UPS compatibility)
        var trackingBarcode = BarcodeWriter.CreateBarcode(
            shipping.TrackingNumber, 
            BarcodeEncoding.Code128
        );
        trackingBarcode.ResizeTo(300, 75);
        trackingBarcode.SetMargins(5);

        // Generate postal code barcode
        var postalBarcode = BarcodeWriter.CreateBarcode(
            shipping.PostalCode,
            BarcodeEncoding.Code128
        );
        postalBarcode.ResizeTo(200, 50);

        // Generate QR code with complete shipping data
        var shippingData = JsonSerializer.Serialize(shipping);
        var qrCode = QRCodeWriter.CreateQrCode(shippingData, 200);

        // Combine into shipping label HTML
        var labelHtml = $@
        <html>
        <body style='font-family: Arial, sans-serif;'>
            <div style='border: 2px solid black; padding: 20px; width: 4in; height: 6in;'>
                <h2>SHIPPING LABEL</h2>
                <hr/>
                <p><strong>From:</strong><br/>{shipping.SenderAddress}</p>
                <p><strong>To:</strong><br/>{shipping.RecipientAddress}</p>
                <hr/>
                <div style='text-align: center;'>
                    <img src='{trackingBarcode.ToDataUrl()}' alt='Tracking barcode'/>
                    <p>Tracking: {shipping.TrackingNumber}</p>
                </div>
                <div style='margin-top: 20px;'>
                    <img src='{postalBarcode.ToDataUrl()}' alt='Postal barcode' style='float: left;'/>
                    <img src='{qrCode.ToDataUrl()}' alt='Shipping QR code' style='float: right; width: 100px;'/>
                </div>
                <div style='clear: both; margin-top: 20px; font-size: 10px;'>
                    <p>Service: {shipping.ServiceType} | Weight: {shipping.Weight}lbs</p>
                </div>
            </div>
        </body>
        </html>";

        return pdf.RenderHtmlAsPdf(labelHtml).BinaryData;
    }

    // Generate secure document QR codes with encryption
    public class SecureDocumentQR
    {
        private readonly byte[] _encryptionKey;

        public SecureDocumentQR(byte[] encryptionKey)
        {
            _encryptionKey = encryptionKey;
        }

        public GeneratedBarcode GenerateSecureDocumentQR(DocumentInfo document)
        {
            // Create document reference with security features
            var documentRef = new
            {
                DocumentId = document.Id,
                Type = document.DocumentType,
                CreatedDate = document.CreatedDate,
                Hash = ComputeDocumentHash(document),
                AccessUrl = "___PROTECTED_URL_46___",
                ValidUntil = DateTime.UtcNow.AddDays(30)
            };

            // Encrypt sensitive data
            var jsonData = JsonSerializer.Serialize(documentRef);
            var encryptedData = EncryptData(jsonData);

            // Generate QR with encrypted payload
            var qrCode = QRCodeWriter.CreateQrCode(
                Convert.ToBase64String(encryptedData),
                500,
                QRCodeWriter.QrErrorCorrectionLevel.High
            );

            // Add visual security indicators
            qrCode.ChangeBarCodeColor(Color.DarkGreen);
            qrCode.AddAnnotationTextAboveBarcode("SECURE DOCUMENT");
            qrCode.AddAnnotationTextBelowBarcode($"Expires: {documentRef.ValidUntil:yyyy-MM-dd}");

            return qrCode;
        }

        private string ComputeDocumentHash(DocumentInfo document)
        {
            using var sha256 = SHA256.Create();
            var hash = sha256.ComputeHash(Encoding.UTF8.GetBytes(document.Content ?? document.Id));
            return BitConverter.ToString(hash).Replace("-", "");
        }

        private byte[] EncryptData(string data)
        {
            // Simplified encryption - use proper encryption in production
            using var aes = Aes.Create();
            aes.Key = _encryptionKey;
            aes.GenerateIV();

            using var encryptor = aes.CreateEncryptor();
            var dataBytes = Encoding.UTF8.GetBytes(data);
            var encrypted = encryptor.TransformFinalBlock(dataBytes, 0, dataBytes.Length);

            // Prepend IV for decryption
            return aes.IV.Concat(encrypted).ToArray();
        }
    }

    // Batch generation for high-volume scenarios
    public async Task<List<GeneratedBarcode>> GenerateBatchQRCodesAsync(List<string> data, QRCodeOptions options)
    {
        var tasks = data.Select(item => Task.Run(() =>
        {
            var qr = QRCodeWriter.CreateQrCode(
                item, 
                options.Size, 
                options.ErrorCorrection
            );

            if (options.IncludeMargins)
                qr.SetMargins(options.MarginSize);

            if (options.CustomColor.HasValue)
                qr.ChangeBarCodeColor(options.CustomColor.Value);

            return qr;
        }));

        return (await Task.WhenAll(tasks)).ToList();
    }
}

// Supporting models
public class AssetInfo
{
    public string AssetId { get; set; }
    public string AssetType { get; set; }
    public string CurrentLocation { get; set; }
    public DateTime LastMaintenanceDate { get; set; }
}

public class VisitorInfo
{
    public string Name { get; set; }
    public string Company { get; set; }
    public string HostEmployee { get; set; }
    public DateTime CheckInTime { get; set; }
    public string AccessLevel { get; set; }
}

public class ShippingInfo
{
    public string TrackingNumber { get; set; }
    public string SenderAddress { get; set; }
    public string RecipientAddress { get; set; }
    public string PostalCode { get; set; }
    public string ServiceType { get; set; }
    public decimal Weight { get; set; }
}

public class DocumentInfo
{
    public string Id { get; set; }
    public string DocumentType { get; set; }
    public DateTime CreatedDate { get; set; }
    public string Content { get; set; }
}

public class QRCodeOptions
{
    public int Size { get; set; } = 400;
    public QRCodeWriter.QrErrorCorrectionLevel ErrorCorrection { get; set; } = QRCodeWriter.QrErrorCorrectionLevel.Medium;
    public bool IncludeMargins { get; set; } = true;
    public int MarginSize { get; set; } = 10;
    public Color? CustomColor { get; set; }
}

Imports System
Imports System.Collections.Generic
Imports System.IO
Imports System.Linq
Imports System.Security.Cryptography
Imports System.Text
Imports System.Text.Json
Imports System.Threading.Tasks

Public Class BarcodeGenerationService
    Private ReadOnly _logger As ILogger(Of BarcodeGenerationService)

    ' Generate QR codes for asset tracking
    Public Function GenerateAssetQRCode(asset As AssetInfo) As Byte()
        ' Create JSON payload with asset information
        Dim assetData = JsonSerializer.Serialize(New With {
            .Id = asset.AssetId,
            .Type = asset.AssetType,
            .Location = asset.CurrentLocation,
            .LastMaintenance = asset.LastMaintenanceDate,
            .Url = "___PROTECTED_URL_45___"
        })

        ' Generate QR code with high error correction for durability
        Dim qrCode = QRCodeWriter.CreateQrCode(assetData, 500, QRCodeWriter.QrErrorCorrectionLevel.High)

        ' Add company branding
        qrCode.AddAnnotationTextAboveBarcode($"ASSET: {asset.AssetId}")
        qrCode.AddAnnotationTextBelowBarcode(asset.AssetType)
        qrCode.SetMargins(10)

        ' Style for printing on asset labels
        qrCode.ChangeBarCodeColor(Color.Black)
        qrCode.ChangeBackgroundColor(Color.White)

        Return qrCode.ToStream().ToArray()
    End Function

    ' Generate visitor badges with QR codes
    Public Function CreateVisitorBadgeQR(visitor As VisitorInfo) As GeneratedBarcode
        ' Encode visitor information with expiration
        Dim visitorData = New With {
            .Name = visitor.Name,
            .Company = visitor.Company,
            .Host = visitor.HostEmployee,
            .ValidFrom = visitor.CheckInTime,
            .ValidUntil = visitor.CheckInTime.AddHours(8),
            .AccessLevel = visitor.AccessLevel,
            .BadgeId = Guid.NewGuid().ToString()
        }

        Dim qrCode = QRCodeWriter.CreateQrCode(
            JsonSerializer.Serialize(visitorData),
            400,
            QRCodeWriter.QrErrorCorrectionLevel.Medium
        )

        ' Add company logo for professional appearance
        If File.Exists("company-logo.png") Then
            qrCode.AddLogo("company-logo.png")
        End If

        ' Style for badge printing
        qrCode.SetMargins(15)
        qrCode.ChangeBarCodeColor(Color.FromArgb(0, 48, 135)) ' Company blue

        ' Add visible text for security personnel
        qrCode.AddAnnotationTextAboveBarcode($"VISITOR: {visitor.Name}")
        qrCode.AddAnnotationTextBelowBarcode($"Expires: {visitor.CheckInTime.AddHours(8):HH:mm}")

        _logger.LogInformation($"Generated visitor badge for {visitor.Name}, BadgeId: {visitorData.BadgeId}")

        Return qrCode
    End Function

    ' Generate shipping labels with multiple barcodes
    Public Function GenerateShippingLabel(shipping As ShippingInfo) As Byte()
        ' Create a PDF with multiple barcodes
        Dim pdf = New IronPdf.ChromePdfRenderer()

        ' Generate tracking barcode (Code 128 for USPS/UPS compatibility)
        Dim trackingBarcode = BarcodeWriter.CreateBarcode(
            shipping.TrackingNumber,
            BarcodeEncoding.Code128
        )
        trackingBarcode.ResizeTo(300, 75)
        trackingBarcode.SetMargins(5)

        ' Generate postal code barcode
        Dim postalBarcode = BarcodeWriter.CreateBarcode(
            shipping.PostalCode,
            BarcodeEncoding.Code128
        )
        postalBarcode.ResizeTo(200, 50)

        ' Generate QR code with complete shipping data
        Dim shippingData = JsonSerializer.Serialize(shipping)
        Dim qrCode = QRCodeWriter.CreateQrCode(shippingData, 200)

        ' Combine into shipping label HTML
        Dim labelHtml = $"
        <html>
        <body style='font-family: Arial, sans-serif;'>
            <div style='border: 2px solid black; padding: 20px; width: 4in; height: 6in;'>
                <h2>SHIPPING LABEL</h2>
                <hr/>
                <p><strong>From:</strong><br/>{shipping.SenderAddress}</p>
                <p><strong>To:</strong><br/>{shipping.RecipientAddress}</p>
                <hr/>
                <div style='text-align: center;'>
                    <img src='{trackingBarcode.ToDataUrl()}' alt='Tracking barcode'/>
                    <p>Tracking: {shipping.TrackingNumber}</p>
                </div>
                <div style='margin-top: 20px;'>
                    <img src='{postalBarcode.ToDataUrl()}' alt='Postal barcode' style='float: left;'/>
                    <img src='{qrCode.ToDataUrl()}' alt='Shipping QR code' style='float: right; width: 100px;'/>
                </div>
                <div style='clear: both; margin-top: 20px; font-size: 10px;'>
                    <p>Service: {shipping.ServiceType} | Weight: {shipping.Weight}lbs</p>
                </div>
            </div>
        </body>
        </html>"

        Return pdf.RenderHtmlAsPdf(labelHtml).BinaryData
    End Function

    ' Generate secure document QR codes with encryption
    Public Class SecureDocumentQR
        Private ReadOnly _encryptionKey As Byte()

        Public Sub New(encryptionKey As Byte())
            _encryptionKey = encryptionKey
        End Sub

        Public Function GenerateSecureDocumentQR(document As DocumentInfo) As GeneratedBarcode
            ' Create document reference with security features
            Dim documentRef = New With {
                .DocumentId = document.Id,
                .Type = document.DocumentType,
                .CreatedDate = document.CreatedDate,
                .Hash = ComputeDocumentHash(document),
                .AccessUrl = "___PROTECTED_URL_46___",
                .ValidUntil = DateTime.UtcNow.AddDays(30)
            }

            ' Encrypt sensitive data
            Dim jsonData = JsonSerializer.Serialize(documentRef)
            Dim encryptedData = EncryptData(jsonData)

            ' Generate QR with encrypted payload
            Dim qrCode = QRCodeWriter.CreateQrCode(
                Convert.ToBase64String(encryptedData),
                500,
                QRCodeWriter.QrErrorCorrectionLevel.High
            )

            ' Add visual security indicators
            qrCode.ChangeBarCodeColor(Color.DarkGreen)
            qrCode.AddAnnotationTextAboveBarcode("SECURE DOCUMENT")
            qrCode.AddAnnotationTextBelowBarcode($"Expires: {documentRef.ValidUntil:yyyy-MM-dd}")

            Return qrCode
        End Function

        Private Function ComputeDocumentHash(document As DocumentInfo) As String
            Using sha256 = SHA256.Create()
                Dim hash = sha256.ComputeHash(Encoding.UTF8.GetBytes(If(document.Content, document.Id)))
                Return BitConverter.ToString(hash).Replace("-", "")
            End Using
        End Function

        Private Function EncryptData(data As String) As Byte()
            ' Simplified encryption - use proper encryption in production
            Using aes = Aes.Create()
                aes.Key = _encryptionKey
                aes.GenerateIV()

                Using encryptor = aes.CreateEncryptor()
                    Dim dataBytes = Encoding.UTF8.GetBytes(data)
                    Dim encrypted = encryptor.TransformFinalBlock(dataBytes, 0, dataBytes.Length)

                    ' Prepend IV for decryption
                    Return aes.IV.Concat(encrypted).ToArray()
                End Using
            End Using
        End Function
    End Class

    ' Batch generation for high-volume scenarios
    Public Async Function GenerateBatchQRCodesAsync(data As List(Of String), options As QRCodeOptions) As Task(Of List(Of GeneratedBarcode))
        Dim tasks = data.Select(Function(item) Task.Run(Function()
                                                             Dim qr = QRCodeWriter.CreateQrCode(
                                                                 item,
                                                                 options.Size,
                                                                 options.ErrorCorrection
                                                             )

                                                             If options.IncludeMargins Then
                                                                 qr.SetMargins(options.MarginSize)
                                                             End If

                                                             If options.CustomColor.HasValue Then
                                                                 qr.ChangeBarCodeColor(options.CustomColor.Value)
                                                             End If

                                                             Return qr
                                                         End Function))

        Return (Await Task.WhenAll(tasks)).ToList()
    End Function
End Class

' Supporting models
Public Class AssetInfo
    Public Property AssetId As String
    Public Property AssetType As String
    Public Property CurrentLocation As String
    Public Property LastMaintenanceDate As DateTime
End Class

Public Class VisitorInfo
    Public Property Name As String
    Public Property Company As String
    Public Property HostEmployee As String
    Public Property CheckInTime As DateTime
    Public Property AccessLevel As String
End Class

Public Class ShippingInfo
    Public Property TrackingNumber As String
    Public Property SenderAddress As String
    Public Property RecipientAddress As String
    Public Property PostalCode As String
    Public Property ServiceType As String
    Public Property Weight As Decimal
End Class

Public Class DocumentInfo
    Public Property Id As String
    Public Property DocumentType As String
    Public Property CreatedDate As DateTime
    Public Property Content As String
End Class

Public Class QRCodeOptions
    Public Property Size As Integer = 400
    Public Property ErrorCorrection As QRCodeWriter.QrErrorCorrectionLevel = QRCodeWriter.QrErrorCorrectionLevel.Medium
    Public Property IncludeMargins As Boolean = True
    Public Property MarginSize As Integer = 10
    Public Property CustomColor As Color?
End Class