DocumentService/DocumentOperator.API/Controllers/ZugferdController.cs

using DocumentOperator.Application.Common.DTOs;
using DocumentOperator.Application.ExtractZugferd;
using DocumentOperator.Application.HasZugferd.Queries;
using DocumentOperator.Domain.Common.Exceptions;
using MediatR;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

namespace DocumentOperator.API.Controllers;

/// <summary>
/// Controller for ZUGFeRD operations (detection, extraction)
/// </summary>
[ApiController]
[Route("api/pdf/zugferd")]
[Produces("application/json")]
public class ZugferdController(IMediator mediator) : ControllerBase
{
    /// <summary>
    /// Checks if a PDF contains ZUGFeRD XML attachment.
    /// Supports multipart/form-data file upload.
    /// </summary>
    /// <param name="file">The PDF file to check for ZUGFeRD</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>ZUGFeRD check result with metadata</returns>
    /// <response code="200">PDF successfully checked - returns ZUGFeRD status</response>
    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
    /// <response code="500">Internal server error during PDF processing</response>
    [HttpPost("has-zugferd")]
    [Consumes("multipart/form-data")]
    [ProducesResponseType(typeof(ZugferdCheckResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> HasZugferdFromFile(
        IFormFile file,
        CancellationToken cancellationToken)
    {
        // Use IFormFile stream directly (no intermediate byte[] conversion)
        using var pdfStream = file.OpenReadStream();

        // Send query to MediatR (ValidationBehavior runs automatically)
        var query = new HasZugferdQuery { PdfStream = pdfStream };
        var result = await mediator.Send(query, cancellationToken);

        return Ok(result);
    }

    /// <summary>
    /// Checks if a PDF contains ZUGFeRD XML attachment.
    /// Supports Base64-encoded PDF via JSON payload.
    /// </summary>
    /// <param name="request">Request containing Base64-encoded PDF</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>ZUGFeRD check result with metadata</returns>
    /// <response code="200">PDF successfully checked - returns ZUGFeRD status</response>
    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
    /// <response code="500">Internal server error during PDF processing</response>
    [HttpPost("has-zugferd")]
    [Consumes("application/json")]
    [ProducesResponseType(typeof(ZugferdCheckResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> HasZugferdFromBase64(
        [FromBody] HasZugferdRequest request,
        CancellationToken cancellationToken)
    {
        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
        byte[] pdfBytes;
        try
        {
            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
        }
        catch (FormatException ex)
        {
            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
        }
        
        using var pdfStream = new MemoryStream(pdfBytes);
        
        // Send query to MediatR (ValidationBehavior runs automatically)
        var query = new HasZugferdQuery { PdfStream = pdfStream };
        var result = await mediator.Send(query, cancellationToken);

        return Ok(result);
    }

    /// <summary>
    /// Extracts ZUGFeRD XML from a PDF document.
    /// Supports multipart/form-data file upload.
    /// </summary>
    /// <param name="file">The PDF file to extract ZUGFeRD from</param>
    /// <param name="asFile">if true, 'file' (returns XML file directly); otherwise output format: 'json' (default, returns metadata + XML content)</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>ZUGFeRD XML content and metadata (JSON) or XML file (application/xml)</returns>
    /// <response code="200">ZUGFeRD XML extracted successfully</response>
    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
    /// <response code="404">PDF contains no ZUGFeRD XML</response>
    /// <response code="500">Internal server error during PDF processing</response>
    [HttpPost("extract")]
    [Consumes("multipart/form-data")]
    [ProducesResponseType(typeof(ZugferdExtractionResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> ExtractZugferdFromFile(
        IFormFile file,
        [FromQuery] bool asFile = true,
        CancellationToken cancellationToken = default)
    {
        // Use IFormFile stream directly (no intermediate byte[] conversion)
        using var pdfStream = file.OpenReadStream();

        // Send command to MediatR
        var command = new ExtractZugferdCommand { PdfStream = pdfStream };
        var result = await mediator.Send(command, cancellationToken);

        // Return as file or JSON based on format parameter
        if (asFile)
        {
            byte[] xmlBytes = System.Text.Encoding.UTF8.GetBytes(result.XmlContent);
            return File(xmlBytes, "application/xml", result.FileName);
        }

        return Ok(result);
    }

    /// <summary>
    /// Extracts ZUGFeRD XML from a PDF document.
    /// Supports Base64-encoded PDF via JSON payload.
    /// </summary>
    /// <param name="request">Request containing Base64-encoded PDF</param>
    /// <param name="format">Output format: 'json' (default, returns metadata + XML content) or 'file' (returns XML file directly)</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>ZUGFeRD XML content and metadata (JSON) or XML file (application/xml)</returns>
    /// <response code="200">ZUGFeRD XML extracted successfully</response>
    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
    /// <response code="404">PDF contains no ZUGFeRD XML</response>
    /// <response code="500">Internal server error during PDF processing</response>
    [HttpPost("extract")]
    [Consumes("application/json")]
    [ProducesResponseType(typeof(ZugferdExtractionResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> ExtractZugferdFromBase64(
        [FromBody] ExtractZugferdRequest request,
        [FromQuery] string format = "json",
        CancellationToken cancellationToken = default)
    {
        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
        byte[] pdfBytes;
        try
        {
            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
        }
        catch (FormatException ex)
        {
            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
        }
        
        using var pdfStream = new MemoryStream(pdfBytes);

        // Send command to MediatR
        var command = new ExtractZugferdCommand { PdfStream = pdfStream };
        var result = await mediator.Send(command, cancellationToken);

        // Return as file or JSON based on format parameter
        if (format.Equals("file", StringComparison.OrdinalIgnoreCase))
        {
            byte[] xmlBytes = System.Text.Encoding.UTF8.GetBytes(result.XmlContent);
            return File(xmlBytes, "application/xml", result.FileName);
        }

        return Ok(result);
    }
}

/// <summary>
/// Request DTO for Base64-encoded PDF ZUGFeRD check
/// </summary>
public record HasZugferdRequest
{
    /// <summary>
    /// PDF document encoded as Base64 string
    /// </summary>
    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
    public string Base64Pdf { get; init; } = string.Empty;
}

/// <summary>
/// Request DTO for Base64-encoded PDF ZUGFeRD extraction
/// </summary>
public record ExtractZugferdRequest
{
    /// <summary>
    /// PDF document encoded as Base64 string
    /// </summary>
    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
    public required string Base64Pdf { get; init; }
}