squidex/backend/extensions/Squidex.Extensions/Actions/Webhook/WebhookActionHandler.cs

// ==========================================================================
//  Squidex Headless CMS
// ==========================================================================
//  Copyright (c) Squidex UG (haftungsbeschraenkt)
//  All rights reserved. Licensed under the MIT license.
// ==========================================================================

using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using Squidex.Domain.Apps.Core.HandleRules;
using Squidex.Domain.Apps.Core.Rules.EnrichedEvents;
using Squidex.Infrastructure;

namespace Squidex.Extensions.Actions.Webhook
{
    public sealed class WebhookActionHandler : RuleActionHandler<WebhookAction, WebhookJob>
    {
        private readonly IHttpClientFactory httpClientFactory;

        public WebhookActionHandler(RuleEventFormatter formatter, IHttpClientFactory httpClientFactory)
            : base(formatter)
        {
            this.httpClientFactory = httpClientFactory;
        }

        protected override async Task<(string Description, WebhookJob Data)> CreateJobAsync(EnrichedEvent @event, WebhookAction action)
        {
            var requestUrl = await FormatAsync(action.Url, @event);
            var requestBody = string.Empty;
            var requestSignature = string.Empty;

            if (action.Method != WebhookMethod.GET)
            {
                if (!string.IsNullOrEmpty(action.Payload))
                {
                    requestBody = await FormatAsync(action.Payload, @event);
                }
                else
                {
                    requestBody = ToEnvelopeJson(@event);
                }

                requestSignature = $"{requestBody}{action.SharedSecret}".ToSha256Base64();
            }

            var ruleDescription = $"Send event to webhook '{requestUrl}'";
            var ruleJob = new WebhookJob
            {
                Method = action.Method,
                RequestUrl = await FormatAsync(action.Url.ToString(), @event),
                RequestSignature = requestSignature,
                RequestBody = requestBody,
                RequestBodyType = action.PayloadType,
                Headers = await ParseHeadersAsync(action.Headers, @event)
            };

            return (ruleDescription, ruleJob);
        }

        private async Task<Dictionary<string, string>> ParseHeadersAsync(string headers, EnrichedEvent @event)
        {
            if (string.IsNullOrWhiteSpace(headers))
            {
                return null;
            }

            var headersDictionary = new Dictionary<string, string>();

            var lines = headers.Split('\n');

            foreach (var line in lines)
            {
                var indexEqual = line.IndexOf('=', StringComparison.Ordinal);

                if (indexEqual > 0 && indexEqual < line.Length - 1)
                {
                    var headerKey = line.Substring(0, indexEqual);
                    var headerValue = line[(indexEqual + 1)..];

                    headerValue = await FormatAsync(headerValue, @event);

                    headersDictionary[headerKey] = headerValue;
                }
            }

            return headersDictionary;
        }

        protected override async Task<Result> ExecuteJobAsync(WebhookJob job,
            CancellationToken ct = default)
        {
            using (var httpClient = httpClientFactory.CreateClient())
            {
                var method = HttpMethod.Post;

                switch (job.Method)
                {
                    case WebhookMethod.PUT:
                        method = HttpMethod.Put;
                        break;
                    case WebhookMethod.GET:
                        method = HttpMethod.Get;
                        break;
                    case WebhookMethod.DELETE:
                        method = HttpMethod.Delete;
                        break;
                    case WebhookMethod.PATCH:
                        method = HttpMethod.Patch;
                        break;
                }

                var request = new HttpRequestMessage(method, job.RequestUrl);

                if (!string.IsNullOrEmpty(job.RequestBody) && job.Method != WebhookMethod.GET)
                {
                    var mediaType = job.RequestBodyType.Or("application/json");

                    request.Content = new StringContent(job.RequestBody, Encoding.UTF8, mediaType);
                }

                using (request)
                {
                    request.Headers.Add("User-Agent", "Squidex Webhook");

                    if (job.Headers != null)
                    {
                        foreach (var (key, value) in job.Headers)
                        {
                            request.Headers.TryAddWithoutValidation(key, value);
                        }
                    }

                    if (!string.IsNullOrWhiteSpace(job.RequestSignature))
                    {
                        request.Headers.Add("X-Signature", job.RequestSignature);
                    }

                    request.Headers.Add("X-Application", "Squidex Webhook");

                    return await httpClient.OneWayRequestAsync(request, job.RequestBody, ct);
                }
            }
        }
    }

    public sealed class WebhookJob
    {
        public WebhookMethod Method { get; set; }

        public string RequestUrl { get; set; }

        public string RequestSignature { get; set; }

        public string RequestBody { get; set; }

        public string RequestBodyType { get; set; }

        public Dictionary<string, string> Headers { get; set; }
    }
}