server/extra/admin-api/Spacebar.UApi/Controllers/Messages/MessagesController.cs

using System.Text.Json.Nodes;
using System.Text.RegularExpressions;
using ArcaneLibs;
using Microsoft.AspNetCore.Mvc;
using Spacebar.Interop.Authentication.AspNetCore;
using Spacebar.Models.Db.Contexts;
using Spacebar.UApi.Services;

namespace Spacebar.UApi.Controllers.Messages;

[ApiController]
[Route("/api/v{_}/channels/{channelId}/messages")]
public partial class MessagesController(ILogger<MessagesController> logger, SpacebarDbContext db, SpacebarAspNetAuthenticationService authService, UApiConfiguration cfg) : ControllerBase {
    [Consumes("multipart/form-data")]
    [HttpPost]
    public async Task CreateMessageWithAttachments(string channelId, MultipartFormDataContent formData) {
        // Generic proxy doesnt work with multipart/form-data for some reason, so handle them specially
        JsonObject jsonPayload = null!;
        
        foreach (var content in formData)
        {
            if (content.Headers.ContentDisposition?.Name == "payload_json") {
                jsonPayload = await content.ReadFromJsonAsync<JsonObject>();
                break;
            }
            if (FileNameRegex().IsMatch(content.Headers.ContentDisposition?.Name ?? "")) {
                
                break;
            }
            throw new InvalidOperationException("Invalid multipart/form-data payload: missing payload_json or file attachments");
        }
        
        var client = new StreamingHttpClient();
        var requestMessage = new HttpRequestMessage(
            new HttpMethod(Request.Method),
            cfg.FallbackApiEndpoint + Request.Path + Request.QueryString
        ) {
            Content = new StreamContent(Request.Body)
        };
        Console.WriteLine(requestMessage.RequestUri);

        var responseMessage = await client.SendUnhandledAsync(requestMessage, CancellationToken.None);
        Response.StatusCode = (int)responseMessage.StatusCode;

        foreach (var header in responseMessage.Headers) Response.Headers[header.Key] = header.Value.ToArray();
        foreach (var header in responseMessage.Content.Headers) Response.Headers[header.Key] = header.Value.ToArray();

        await responseMessage.Content.CopyToAsync(Response.Body);
    }
    
    [GeneratedRegex(@"files\[\d+\]")]
    private static partial Regex FileNameRegex();

    private struct CloudUploadTask {
        public int index;
        public Task<string> task;
    }
}