using AutoMapper;
using DocumentOperator.Application.Common.DTOs;
using DocumentOperator.Application.Common.Interfaces;
using MediatR;

namespace DocumentOperator.Application.ValidatePdfA.Queries;

/// <summary>
/// Query for PDF/A validation (supports both byte array and Base64 input)
/// </summary>
public record ValidatePdfAQuery : IRequest<PdfAValidationResult>
{
    /// <summary>
    /// PDF as byte array (direct upload)
    /// </summary>
    public byte[]? PdfBytes { get; init; }

    /// <summary>
    /// PDF as Base64 string (API clients)
    /// </summary>
    public string? Base64Pdf { get; init; }
}

/// <summary>
/// Handler for ValidatePdfAQuery
/// Orchestrates PDF/A validation using IPdfProcessor and AutoMapper
/// </summary>
public class ValidatePdfAQueryHandler(IPdfProcessor PdfProcessor, IMapper Mapper) 
    : IRequestHandler<ValidatePdfAQuery, PdfAValidationResult>
{
    /// <summary>
    /// Validates PDF/A and returns metadata with conformance level
    /// </summary>
    public async Task<PdfAValidationResult> Handle(ValidatePdfAQuery request, CancellationToken cancellationToken)
    {
        // Use byte[] if available, otherwise convert Base64
        byte[] pdfBytes = request.PdfBytes ?? Convert.FromBase64String(request.Base64Pdf!);

        // Convert to stream for IPdfProcessor
        using var pdfStream = new MemoryStream(pdfBytes);

        // Call DevExpress service (exceptions propagate naturally)
        var metadata = await PdfProcessor.ValidatePdfAAsync(pdfStream);

        // Map DTO to response DTO using AutoMapper
        return Mapper.Map<PdfAValidationResult>(metadata);
    }
}