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Diffstat (limited to 'lib/Emails.Transactional.Plugin/src/Mta/ResendMta.cs')
| -rw-r--r-- | lib/Emails.Transactional.Plugin/src/Mta/ResendMta.cs | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/lib/Emails.Transactional.Plugin/src/Mta/ResendMta.cs b/lib/Emails.Transactional.Plugin/src/Mta/ResendMta.cs new file mode 100644 index 0000000..3f20aba --- /dev/null +++ b/lib/Emails.Transactional.Plugin/src/Mta/ResendMta.cs @@ -0,0 +1,224 @@ +/* +* Copyright (c) 2023 Vaughn Nugent +* +* Library: VNLib +* Package: Emails.Transactional +* File: ResendMta.cs +* +* ResendMta.cs is part of Emails.Transactional which is part of the larger +* VNLib collection of libraries and utilities. +* +* Emails.Transactional is free software: you can redistribute it and/or modify +* it under the terms of the GNU General Public License as published +* by the Free Software Foundation, either version 2 of the License, +* or (at your option) any later version. +* +* Emails.Transactional is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +* General Public License for more details. +* +* You should have received a copy of the GNU General Public License +* along with Emails.Transactional. If not, see http://www.gnu.org/licenses/. +*/ + +using System; +using System.Net; +using System.Linq; +using System.Text; +using System.Threading; +using System.Threading.Tasks; +using System.Text.Json.Serialization; + +using RestSharp; + +using VNLib.Net.Http; +using VNLib.Utils.Logging; +using VNLib.Utils.Extensions; +using VNLib.Net.Rest.Client.Construction; +using VNLib.Net.Rest.Client; +using VNLib.Plugins; +using VNLib.Plugins.Extensions.Loading; +using VNLib.Plugins.Extensions.Loading.Events; + +using ContentType = VNLib.Net.Http.ContentType; + +namespace Emails.Transactional.Mta +{ + [ConfigurationName("resend")] + internal sealed class ResendMta : IMailTransferAgent + { + const int ResendMaxPerSecond = 10; + + /* + * Resend has a rate limit of 10 request per second, + * this timer resets the request counter every second + */ + private int _remainingRequests; + + Task ResetRateLimitAsync(ILogProvider log, CancellationToken pluginExitToken) + { + //Reset the request counter + _remainingRequests = ResendMaxPerSecond; + return Task.CompletedTask; + } + + private readonly ResendSiteAdapter _resendAdapter; + private readonly TimeSpan _rateLimitDelay; + private readonly int _rateLimitRetry; + + public ResendMta(PluginBase plugin, IConfigScope config) + { + int timeoutMs = config.GetRequiredProperty("timeout_ms", e => e.GetInt32()); + int maxClients = config.GetRequiredProperty("max_clients", e => e.GetInt32()); + string? userAgent = config.GetProperty("user_agent", e => e.GetString()); + _rateLimitDelay = config["rate_limit_delay_ms"].GetTimeSpan(TimeParseType.Milliseconds); + _rateLimitRetry = config["rate_limit_retry"].GetInt32(); + + //Create the resend adapter + _resendAdapter = new ResendSiteAdapter(timeoutMs, maxClients, userAgent); + + //Retrieve the access token + IAsyncLazy<string> authToken = plugin.GetSecretAsync("resend_token").ToLazy(p => p.Result.ToString()); + + //Define the send endpoint + //https://resend.com/docs/api-reference/emails/send-email + _resendAdapter.DefineSingleEndpoint() + .WithEndpoint<ResendEmail>() + .WithMethod(Method.Post) + .WithUrl("/emails") + .WithHeader("Accept", "application/json") + .WithHeader("Content-Type", HttpHelpers.GetContentTypeString(ContentType.Json)) + //Add authorization header on requests + .WithHeader("Authorization", e => $"Bearer {authToken.Value}") + //Add message body + .WithModifier(static (re, r) => r.AddJsonBody(re)); + + //Schedule timer to reset the rate limit + plugin.ScheduleInterval(ResetRateLimitAsync, TimeSpan.FromSeconds(1)); + } + + ///<inheritdoc/> + public async Task<MtaResult> SendEmailAsync(EmailTransaction transaction, IEmailMessageData message, CancellationToken cancellation = default) + { + int retryCount = 0; + + while (retryCount < _rateLimitRetry) + { + //Increment the request counter + int newCount = Interlocked.Increment(ref _remainingRequests); + + //if rate limit hasn't been reached, break + if (newCount >= 0) + { + break; + } + + retryCount++; + + //Wait for the rate limit delay + await Task.Delay(_rateLimitDelay, cancellation); + } + + //Create the resend email object + ResendEmail email = new(transaction) + { + Html = message.GetHtml(), + }; + + //Execute the request + RestResponse<ResendResponse> response = await _resendAdapter.ExecuteAsync<ResendEmail, ResendResponse>(email, cancellation); + + if(response.IsSuccessful) + { + //Store the raw response content data + transaction.Result = response.Content; + return new MtaResult(true, response.Data?.Id); + } + else + { + switch (response.StatusCode) + { + case HttpStatusCode.UnprocessableEntity: + return new MtaResult(false, response.Data?.StatusText); + default: + return new MtaResult(false, response.Content); + } + } + } + + private sealed record class ResendEmail(EmailTransaction Transaction) + { + [JsonPropertyName("from")] + public string From => $"{Transaction.FromName} <{Transaction.From}>"; + + [JsonPropertyName("subject")] + public string? Subject => Transaction.Subject; + + [JsonPropertyName("to")] + public string[]? To => Transaction.ToAddresses?.Select(static t => $"{t.Value} <{t.Key}>").ToArray(); + + [JsonPropertyName("bcc")] + public string[]? Bcc => Transaction.BccAddresses?.Select(static t => $"{t.Value} <{t.Key}>").ToArray(); + + [JsonPropertyName("cc")] + public string[]? Cc => Transaction.CcAddresses?.Select(static t => $"{t.Value} <{t.Key}>").ToArray(); + + [JsonPropertyName("reply_to")] + public string? ReplyTo => Transaction.ReplyTo == null ? null : $"{Transaction.ReplyToName} <{Transaction.ReplyTo}>"; + + [JsonPropertyName("html")] + public string Html { get; init; } = ""; + } + + private sealed class ResendResponse + { + [JsonPropertyName("id")] + public string Id { get; set; } = null!; + + [JsonPropertyName("name")] + public string? Name { get; set; } + + [JsonPropertyName("statusCode")] + public int StatusCpde { get; set; } + + [JsonPropertyName("message")] + public string? StatusText { get; set; } + } + + private sealed class ResendSiteAdapter : RestSiteAdapterBase + { + //Fixed resend api url + private const string BaseUrl = "https://api.resend.com"; + + ///<inheritdoc/> + protected override RestClientPool Pool { get; } + + public ResendSiteAdapter(int maxTimeoutMs, int maxClients, string? userAgent) + { + RestClientOptions options = new(BaseUrl) + { + AutomaticDecompression = DecompressionMethods.All, + Encoding = Encoding.UTF8, + FollowRedirects = false, + MaxTimeout = maxTimeoutMs, + UserAgent = userAgent, + }; + + //Create client pool + Pool = new RestClientPool(maxClients, options); + } + + ///<inheritdoc/> + public override void OnResponse(RestResponse response) + { } + + ///<inheritdoc/> + public override Task WaitAsync(CancellationToken cancellation = default) + { + //TODO implement rate limit wait + return Task.CompletedTask; + } + } + } +} |