using DocumentService.Application.Common.DTOs;
using DocumentService.Application.SignPdf;
using DocumentService.Domain.Common.Exceptions;
using MediatR;
using Microsoft.AspNetCore.Mvc;

namespace DocumentService.API.Controllers;

/// <summary>
/// Controller for PDF digital signing (PKCS#11 / company certificate).
/// </summary>
[ApiController]
[Route("api/pdf/signature")]
public class PdfSignatureController(IMediator mediator) : ControllerBase
{
    /// <summary>
    /// Digitally signs a PDF using the configured PKCS#11 signing infrastructure.
    /// </summary>
    /// <param name="request">Base64-encoded PDF, optional signature image, and signing options</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>Signed PDF</returns>
    /// <response code="200">PDF signed successfully - returns signed PDF</response>
    /// <response code="400">Invalid input (Base64 format error, invalid appearance)</response>
    /// <response code="500">Internal server error during signing</response>
    [HttpPost("sign")]
    [Consumes("application/json")]
    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
    public async Task<IActionResult> Sign([FromBody] SignPdfRequest request, CancellationToken cancellationToken)
    {
        byte[] signedPdf;
        try
        {
            signedPdf = await mediator.Send(new SignPdfCommand
            {
                InputPdf = new MemoryStream(Convert.FromBase64String(request.Base64Pdf)),
                Options = request.Options,
                SignatureImage = string.IsNullOrWhiteSpace(request.Base64SignatureImage)
                    ? null
                    : new MemoryStream(Convert.FromBase64String(request.Base64SignatureImage))
            }, cancellationToken);
        }
        catch (FormatException ex)
        {
            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
        }

        return File(signedPdf, "application/pdf", "signed.pdf");
    }
}

/// <summary>
/// Request DTO for PDF signing via JSON payload.
/// </summary>
public sealed class SignPdfRequest
{
    /// <summary>
    /// Base64-encoded PDF to sign.
    /// </summary>
    public required string Base64Pdf { get; init; }

    /// <summary>
    /// Optional Base64-encoded signature image (PNG/JPEG).
    /// </summary>
    public string? Base64SignatureImage { get; init; }

    /// <summary>
    /// Signing options (metadata + appearance).
    /// </summary>
    public required PdfSignOptionsDto Options { get; init; }
}