ReC/src/ReC.Application/RecActions/Commands/InvokeRecActionViewCommand.cs

using MediatR;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;
using ReC.Application.Common.Constants;
using ReC.Application.Common.Dto;
using ReC.Application.Common.Exceptions;
using ReC.Application.Common.Options;
using ReC.Application.Results.Commands;
using ReC.Domain.Constants;
using System.Net;
using System.Net.Http.Headers;
using System.Text;
using System.Text.Json;

namespace ReC.Application.RecActions.Commands;

public record InvokeRecActionViewCommand : IRequest
{
    public RecActionViewDto Action { get; set; } = null!;
}

public class InvokeRecActionViewCommandHandler(
    IOptions<RecActionOptions> options,
    ISender sender,
    IHttpClientFactory clientFactory,
    IConfiguration? config = null
    ) : IRequestHandler<InvokeRecActionViewCommand>
{
    private readonly RecActionOptions _options = options.Value;

    public async Task Handle(InvokeRecActionViewCommand request, CancellationToken cancel)
    {
        var action = request.Action;
        HttpClient? ntlmClient = null;

        try
        {
            if (action.RestType is not RestType restType)
                throw new DataIntegrityException(
                    $"Rec action could not be invoked because the RestType value is null. " +
                    $"ProfileId: {action.ProfileId}, " +
                    $"Id: {action.Id}"
                );

            using var httpReq = CreateHttpRequestMessage(restType, action.EndpointUri);

            if (action.Body is not null)
                httpReq.Content = new StringContent(action.Body);

            if (action.Headers is not null)
                foreach (var header in action.Headers)
                    httpReq.Headers.Add(header.Key, header.Value);

            switch (action.EndpointAuthType)
            {
                case EndpointAuthType.NoAuth:
                    break;

                case EndpointAuthType.ApiKey:
                    if (action.EndpointAuthApiKey is string apiKey && action.EndpointAuthApiValue is string apiValue)
                    {
                        switch (action.EndpointAuthApiKeyAddTo)
                        {
                            case ApiKeyLocation.Header:
                                httpReq.Headers.Add(apiKey, apiValue);
                                break;                        
                            case ApiKeyLocation.Query:                        
                                var uriBuilder = new UriBuilder(httpReq.RequestUri!);
                                var query = System.Web.HttpUtility.ParseQueryString(uriBuilder.Query);
                                query[apiKey] = apiValue;
                                uriBuilder.Query = query.ToString();
                                httpReq.RequestUri = uriBuilder.Uri;
                                break;
                            default:
                                throw new DataIntegrityException(
                                    $"The API key location '{action.EndpointAuthApiKeyAddTo}' is not supported. " +
                                    $"ProfileId: {action.ProfileId}, " +
                                    $"Id: {action.Id}"
                                );
                        }
                    }
                    break;

                case EndpointAuthType.BearerToken:
                case EndpointAuthType.JwtBearer:
                case EndpointAuthType.OAuth2:
                    if (action.EndpointAuthToken is string authToken)
                        httpReq.Headers.Authorization = new AuthenticationHeaderValue("Bearer", authToken);
                    break;

                case EndpointAuthType.BasicAuth:
                    if (action.EndpointAuthUsername is string authUsername && action.EndpointAuthPassword is string authPassword)
                    {
                        var basicAuth = Convert.ToBase64String(Encoding.UTF8.GetBytes($"{authUsername}:{authPassword}"));
                        httpReq.Headers.Authorization = new AuthenticationHeaderValue("Basic", basicAuth);
                    }
                    break;

                case EndpointAuthType.NtlmAuth:
                    if (!string.IsNullOrWhiteSpace(action.EndpointAuthUsername))
                    {
                        if (_options.UseHttp1ForNtlm)
                        {
                            httpReq.Version = HttpVersion.Version11;
                            httpReq.VersionPolicy = HttpVersionPolicy.RequestVersionExact;
                        }
                        var endpointAuthPassword = action.EndpointAuthPassword
#if DEBUG
                            ?.Replace("%NTLM_PW%", config?.GetValue<string>("%NTLM_PW%"))
#endif
                            ;
                        var credentials = new NetworkCredential(
                            action.EndpointAuthUsername,
                            endpointAuthPassword,
                            action.EndpointAuthDomain);
                        var credentialCache = new CredentialCache { { httpReq.RequestUri!, "NTLM", credentials } };
                        var ntlmHandler = new HttpClientHandler
                        {
                            Credentials = credentialCache,
                            UseDefaultCredentials = false
                        };
                        ntlmClient = new HttpClient(ntlmHandler, disposeHandler: true);
                    }
                    break;

                case EndpointAuthType.DigestAuth:
                case EndpointAuthType.OAuth1:
                case EndpointAuthType.AwsSignature:
                // These authentication methods require more complex implementations,
                // often involving multi-step handshakes or specialized libraries.
                // They are left as placeholders for future implementation.
                default:
                    throw new NotImplementedException(
                        $"The authentication type '{action.EndpointAuthType}' is not supported yet. " +
                        $"ProfileId: {action.ProfileId}, " +
                        $"Id: {action.Id}"
                    );
            }

            var http = ntlmClient ?? clientFactory.CreateClient(Http.ClientName);
            using var response = await http.SendAsync(httpReq, cancel);
            var resBody = await response.Content.ReadAsStringAsync(cancel);
            var resHeaders = response.Headers.ToDictionary();

            var statusCode = (short)response.StatusCode;

            await sender.Send(new InsertResultCommand()
            {
                StatusId = statusCode,
                ActionId = action.Id,
                Header = JsonSerializer.Serialize(resHeaders, options: new() { WriteIndented = false }),
                Body = resBody
            }, cancel);
        }
        catch(Exception ex)
        {
            await sender.Send(new InsertResultCommand()
            {
                ActionId = action.Id,
                Error = ex.ToString()
            }, cancel);

            if (action.ErrorAction == ErrorAction.Stop)
                throw new RecActionException(action.Id, action.ProfileId, ex);
        }
        finally
        {
            ntlmClient?.Dispose();
        }
    }

    private static HttpRequestMessage CreateHttpRequestMessage(RestType restType, string? endpointUri)
    {
        var method = restType switch
        {
            RestType.Get => HttpMethod.Get,
            RestType.Post => HttpMethod.Post,
            RestType.Put => HttpMethod.Put,
            RestType.Delete => HttpMethod.Delete,
            RestType.Patch => HttpMethod.Patch,
            RestType.Head => HttpMethod.Head,
            RestType.Options => HttpMethod.Options,
            RestType.Trace => HttpMethod.Trace,
            RestType.Connect => HttpMethod.Connect,
            RestType.None => throw new ArgumentOutOfRangeException(nameof(restType), $"The RestType value '{restType}' is not valid."),
            _ => new HttpMethod(restType.ToString().ToUpperInvariant())
        };

        return new HttpRequestMessage(method, endpointUri);
    }
}