using DocumentService.Client.Interfaces;
using DocumentService.Client.Models.Requests;
using EnvelopeGenerator.Application.Common.Dto;
using EnvelopeGenerator.Application.Common.Interfaces.Services;
using ClientCertLevel = DocumentService.Client.Models.Requests.PdfSignatureCertificationLevel;
using ClientCoordUnit = DocumentService.Client.Models.Requests.PdfSignatureCoordinateUnit;
using ClientCoordOrigin = DocumentService.Client.Models.Requests.PdfSignatureCoordinateOrigin;

namespace EnvelopeGenerator.Infrastructure.Crypt.Services;

/// <summary>
/// Proxy that forwards PDF signing to the remote DocumentService API via <see cref="IPdfSignatureClient"/>.
/// </summary>
public sealed class PdfDigitalSignatureService(IPdfSignatureClient signatureClient) : IPdfDigitalSignatureService
{
    public async Task SignPdfAsync(Stream inputPdf, Stream outputPdf, PdfSignOptionsDto? options = null, Stream? image = null, CancellationToken cancellationToken = default)
    {
        var pdfBytes = await ReadAllBytesAsync(inputPdf, cancellationToken);
        var imageBytes = image is null ? null : await ReadAllBytesAsync(image, cancellationToken);

        using var signed = await signatureClient.SignAsync(pdfBytes, Map(options), imageBytes, cancellationToken);
        await signed.CopyToAsync(outputPdf, cancellationToken);
    }

    public Task<PdfSignatureCheckResultDto> CheckPdfSignatureAsync(Stream inputPdf, CancellationToken cancellationToken = default)
        => throw new NotSupportedException("Signature checking is handled by DocumentService and is not available through this proxy.");

    private static SignPdfOptions Map(PdfSignOptionsDto? o) => new()
    {
        DocumentElementId = o?.DocumentElementId ?? 0,
        Name = o?.Name ?? string.Empty,
        Reason = o?.Reason,
        Location = o?.Location,
        Email = o?.Email,
        Phone = o?.Phone,
        ApplicationName = o?.ApplicationName,
        CertificationLevel = (ClientCertLevel)(o?.CertificationLevel ?? EnvelopeGenerator.Application.Common.Enums.PdfSignatureCertificationLevel.NoCertification),
        Appearance = o?.Appearance is null ? null : MapAppearance(o.Appearance)
    };

    private static PdfSignatureAppearance MapAppearance(PdfSignatureAppearanceDto a) => new()
    {
        PageNumber = a.PageNumber,
        Left = a.Left,
        Bottom = a.Bottom,
        Width = a.Width,
        Height = a.Height,
        ShowLabels = a.ShowLabels,
        ShowName = a.ShowName,
        ShowDate = a.ShowDate,
        ShowReason = a.ShowReason,
        ShowLocation = a.ShowLocation,
        ShowDistinguishedName = a.ShowDistinguishedName,
        DateTimeFormat = a.DateTimeFormat,
        CoordinateUnit = (ClientCoordUnit)a.CoordinateUnit,
        CoordinateOrigin = (ClientCoordOrigin)a.CoordinateOrigin,
        Font = new PdfSignatureFont
        {
            FamilyName = a.Font.FamilyName,
            Size = a.Font.Size,
            IsBold = a.Font.IsBold,
            IsItalic = a.Font.IsItalic,
            IsUnderline = a.Font.IsUnderline,
            Color = new PdfSignatureColor { R = a.Font.Color.R, G = a.Font.Color.G, B = a.Font.Color.B }
        }
    };

    private static async Task<byte[]> ReadAllBytesAsync(Stream stream, CancellationToken cancellationToken)
    {
        if (stream is MemoryStream memory && memory.TryGetBuffer(out var buffer))
            return buffer.AsSpan(0, (int)memory.Length).ToArray();

        using var copy = new MemoryStream();
        await stream.CopyToAsync(copy, cancellationToken);
        return copy.ToArray();
    }
}