using DevExpress.Drawing;
using DevExpress.Pdf;
using EnvelopeGenerator.Application.Common.Dto;
using EnvelopeGenerator.Application.Common.Interfaces.Doc;

namespace EnvelopeGenerator.Infrastructure.Doc;

public class PdfPageImageRenderer : IPdfPageImageRenderer
{
    private const float RenderDpi = 110f;

    public Task<IReadOnlyList<PdfPageImageDto>> RenderPagesAsImagesAsync(byte[] pdfBytes, CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(pdfBytes);

        if (pdfBytes.Length == 0)
            return Task.FromResult<IReadOnlyList<PdfPageImageDto>>(Array.Empty<PdfPageImageDto>());

        using var stream = new MemoryStream(pdfBytes, writable: false);
        using var processor = new PdfDocumentProcessor();
        processor.LoadDocument(stream);

        var pages = processor.Document.Pages;
        if (pages.Count == 0)
            return Task.FromResult<IReadOnlyList<PdfPageImageDto>>(Array.Empty<PdfPageImageDto>());

        var renderOptions = PdfPageRenderingParameters.CreateWithResolution(RenderDpi);
        var results = new List<PdfPageImageDto>(pages.Count);

        for (var i = 0; i < pages.Count; i++)
        {
            cancellationToken.ThrowIfCancellationRequested();

            var pageNumber = i + 1;
            var page = pages[i];
            var cropBox = page.CropBox;

            using DXBitmap bitmap = processor.CreateDXBitmap(pageNumber, renderOptions);
            using var imageStream = new MemoryStream();
            bitmap.Save(imageStream, DXImageFormat.Png);

            var dataUrl = $"data:image/png;base64,{Convert.ToBase64String(imageStream.ToArray())}";

            results.Add(new PdfPageImageDto
            {
                PageNumber = pageNumber,
                WidthPt = cropBox.Width,
                HeightPt = cropBox.Height,
                WidthPx = bitmap.Width,
                HeightPx = bitmap.Height,
                ImageDataUrl = dataUrl
            });
        }

        return Task.FromResult<IReadOnlyList<PdfPageImageDto>>(results);
    }
}