using DocumentOperator.Application.Common.Interfaces;
using FluentValidation;
using MediatR;

namespace DocumentOperator.Application.ExtractPdfAttachments;

/// <summary>
/// Command to extract all embedded files from a PDF document and return as ZIP archive.
/// </summary>
public record ExtractPdfAttachmentsCommand : IRequest<byte[]>
{
    /// <summary>
    /// PDF document stream. Must be positioned at the beginning (Position = 0).
    /// </summary>
    public required Stream PdfStream { get; init; }
}

/// <summary>
/// Handler for ExtractPdfAttachmentsCommand.
/// Extracts all embedded files from PDF and returns as ZIP archive.
/// </summary>
public class ExtractPdfAttachmentsCommandHandler(IPdfProcessor pdfProcessor) 
    : IRequestHandler<ExtractPdfAttachmentsCommand, byte[]>
{
    public async Task<byte[]> Handle(ExtractPdfAttachmentsCommand request, CancellationToken cancellationToken)
    {
        // Delegate to infrastructure layer
        return await pdfProcessor.ExtractAttachmentsAsync(request.PdfStream);
    }
}

/// <summary>
/// Validator for ExtractPdfAttachmentsCommand.
/// </summary>
public class ExtractPdfAttachmentsCommandValidator : AbstractValidator<ExtractPdfAttachmentsCommand>
{
    public ExtractPdfAttachmentsCommandValidator()
    {
        RuleFor(x => x.PdfStream)
            .NotNull()
            .WithMessage("PDF stream is required");
    }
}
