DocumentService/DocumentOperator.API/Controllers/PdfAttachmentController.cs

using DocumentOperator.Application.CheckPdfAttachments.Queries;
using DocumentOperator.Application.Common.DTOs;
using DocumentOperator.Application.ExtractPdfAttachments;
using DocumentOperator.Domain.Common.Exceptions;
using MediatR;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;

namespace DocumentOperator.API.Controllers;

/// <summary>
/// Controller for PDF attachment operations (detection, extraction, embedding)
/// </summary>
[ApiController]
[Route("api/pdf/attachments")]
[Produces("application/json")]
public class PdfAttachmentController(IMediator mediator) : ControllerBase
{
    /// <summary>
    /// Checks if a PDF contains embedded files (attachments) and returns their metadata.
    /// Supports multipart/form-data file upload.
    /// </summary>
    /// <param name="file">The PDF file to check for attachments</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Attachment check result with metadata for all found attachments</returns>
    /// <response code="200">PDF successfully checked - returns attachment details</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("check")]
    [Consumes("multipart/form-data")]
    [ProducesResponseType(typeof(AttachmentCheckResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> CheckAttachmentsFromFile(
        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 CheckPdfAttachmentsQuery { PdfStream = pdfStream };
        var result = await mediator.Send(query, cancellationToken);

        return Ok(result);
    }

    /// <summary>
    /// Checks if a PDF contains embedded files (attachments) and returns their metadata.
    /// Supports Base64-encoded PDF via JSON payload.
    /// </summary>
    /// <param name="request">Request containing Base64-encoded PDF</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Attachment check result with metadata for all found attachments</returns>
    /// <response code="200">PDF successfully checked - returns attachment details</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("check")]
    [Consumes("application/json")]
    [ProducesResponseType(typeof(AttachmentCheckResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> CheckAttachmentsFromBase64(
        [FromBody] CheckPdfAttachmentsRequest 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 CheckPdfAttachmentsQuery { PdfStream = pdfStream };
        var result = await mediator.Send(query, cancellationToken);

        return Ok(result);
    }

    /// <summary>
    /// Extracts all embedded files from a PDF and returns them as a ZIP archive.
    /// Supports multipart/form-data file upload.
    /// </summary>
    /// <param name="file">The PDF file to extract attachments from</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>ZIP archive containing all extracted attachments</returns>
    /// <response code="200">Attachments extracted successfully - returns ZIP file</response>
    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
    /// <response code="404">PDF contains no attachments</response>
    /// <response code="500">Internal server error during PDF processing</response>
    [HttpPost("extract")]
    [Consumes("multipart/form-data")]
    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> ExtractAttachmentsFromFile(
        IFormFile file,
        CancellationToken cancellationToken)
    {
        // Use IFormFile stream directly (no intermediate byte[] conversion)
        using var pdfStream = file.OpenReadStream();

        // Send command to MediatR
        var command = new ExtractPdfAttachmentsCommand { PdfStream = pdfStream };
        byte[] zipBytes = await mediator.Send(command, cancellationToken);

        // Return ZIP file
        return File(zipBytes, "application/zip", "attachments.zip");
    }

    /// <summary>
    /// Extracts all embedded files from a PDF and returns them as a ZIP archive.
    /// Supports Base64-encoded PDF via JSON payload.
    /// </summary>
    /// <param name="request">Request containing Base64-encoded PDF</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>ZIP archive containing all extracted attachments</returns>
    /// <response code="200">Attachments extracted successfully - returns ZIP file</response>
    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
    /// <response code="404">PDF contains no attachments</response>
    /// <response code="500">Internal server error during PDF processing</response>
    [HttpPost("extract")]
    [Consumes("application/json")]
    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> ExtractAttachmentsFromBase64(
        [FromBody] ExtractPdfAttachmentsRequest 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 command to MediatR
        var command = new ExtractPdfAttachmentsCommand { PdfStream = pdfStream };
        byte[] zipBytes = await mediator.Send(command, cancellationToken);

        // Return ZIP file
        return File(zipBytes, "application/zip", "attachments.zip");
    }
}

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