#if WINDOWS
using EnvelopeGenerator.Application.Common.Extensions;
using EnvelopeGenerator.Application.Exceptions;
using EnvelopeGenerator.Domain.Constants;
using GdPicture14;
using MediatR;

namespace EnvelopeGenerator.Application.Pdf.Behaviors;

/// <summary>
/// 
/// </summary>
public class PdfMergeBehavior : IPipelineBehavior<BurnPdfCommand, byte[]>
{
    private static readonly bool ALLOW_RASTERIZATION = true;

    private static readonly bool ALLOW_VECTORIZATION = true;

    private static readonly PdfConversionConformance PDFAConformanceLevel = PdfConversionConformance.PDF_A_1b;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="next"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    /// <exception cref="NotImplementedException"></exception>
    public async Task<byte[]> Handle(BurnPdfCommand request, RequestHandlerDelegate<byte[]> next, CancellationToken cancel)
    {
        var doc = await next(cancel);

        doc = request.Report is byte[] report
            ? MergeDocuments(doc, report)
            : throw new InvalidOperationException("The final document report could not be merged." +
            "There may be an error related to the behavior register order." +
            "Request details:\n" + request.ToJson(Format.Json.ForDiagnostics));

        string base64String = Convert.ToBase64String(doc);

        return doc;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="pDocument"></param>
    /// <param name="pReport"></param>
    /// <returns></returns>
    /// <exception cref="MergeDocumentException"></exception>
    public static byte[] MergeDocuments(byte[] pDocument, byte[] pReport)
    {
        using var oDocumentStream = new MemoryStream(pDocument);
        using var oReportStream = new MemoryStream(pReport);
        using var oFinalStream = new MemoryStream();
        using var oDocumentPDF = new GdPicturePDF();
        using var oReportPDF = new GdPicturePDF();
        GdPictureStatus oStatus = GdPictureStatus.OK;

        // Load the source file into memory
        oDocumentPDF.LoadFromStream(oDocumentStream, true);

        oStatus = oDocumentPDF.GetStat();
        if (oStatus != GdPictureStatus.OK)
            throw new MergeDocumentException($"Document could not be loaded: {oStatus}");

        // Load the report file into memory
        oReportPDF.LoadFromStream(oReportStream, true);
        oStatus = oReportPDF.GetStat();
        if (oStatus != GdPictureStatus.OK)
            throw new MergeDocumentException($"Report could not be loaded: {oStatus}");

        // Merge the documents 
        var oMergedPDF = oDocumentPDF.Merge2Documents(oDocumentPDF, oReportPDF);
        oStatus = oMergedPDF.GetStat();
        if (oStatus != GdPictureStatus.OK)
            throw new MergeDocumentException($"Documents could not be merged: {oStatus}");

        // Convert to PDF/A
        oMergedPDF.ConvertToPDFA(oFinalStream, PDFAConformanceLevel, ALLOW_VECTORIZATION, ALLOW_RASTERIZATION);
        oStatus = oDocumentPDF.GetStat();
        if (oStatus != GdPictureStatus.OK)
            throw new MergeDocumentException($"Document could not be converted to PDF/A: {oStatus}");

        return oFinalStream.ToArray();
    }
}
#endif