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using System.Text;
using System.Text.Json;
using RestSharp;
using Emails.Transactional.Client;
using VNLib.Utils.Logging;
using VNLib.Utils.Extensions;
using VNLib.Net.Rest.Client;
using VNLib.Net.Rest.Client.OAuth2;
using VNLib.Plugins.Extensions.Loading;
namespace VNLib.Plugins.Extentions.TransactionalEmail
{
/// <summary>
/// Contains extension methods for implementing templated
/// transactional emails
/// </summary>
public static class TransactionalEmailExtensions
{
public const string EMAIL_CONFIG_KEY = "emails";
public const string REQUIRED_EMAIL_TEMPALTE_CONFIG_KEY = "required_email_templates";
public const uint DEFAULT_MAX_CLIENTS = 5;
public const uint DEFAULT_CLIENT_TIMEOUT_MS = 10000;
/// <summary>
/// Gets (or loads) the ambient <see cref="TransactionalEmailConfig"/> configuration object
/// to send transactional emails against
/// </summary>
/// <param name="pbase"></param>
/// <returns>The <see cref="TransactionalEmailConfig"/> from the current plugins config</returns>
public static TransactionalEmailConfig GetEmailConfig(this PluginBase pbase) => LoadingExtensions.GetOrCreateSingleton(pbase, LoadConfig);
/// <summary>
/// Sends an <see cref="EmailTransactionRequest"/> on the current configuration resource pool
/// </summary>
/// <param name="config"></param>
/// <param name="request">The <see cref="EmailTransactionRequest"/> request to send to the server</param>
/// <returns>A task the resolves the <see cref="TransactionResult"/> of the request</returns>
public static async Task<TransactionResult> SendEmailAsync(this TransactionalEmailConfig config, EmailTransactionRequest request)
{
//Get a new client contract from the configuration's pool assuming its a EmailSystemConfig class
using ClientContract client = ((EmailSystemConfig)config).RestClientPool.Lease();
//Send the email and await the result before releasing the client
return await client.Resource.SendEmailAsync(request);
}
private static TransactionalEmailConfig LoadConfig(PluginBase pbase)
{
//Get the required email config
IReadOnlyDictionary<string, JsonElement> conf = pbase.GetConfig(EMAIL_CONFIG_KEY);
string emailFromName = conf["from_name"].GetString() ?? throw new KeyNotFoundException("Missing required configuration key 'from_name'");
string emailFromAddress = conf["from_address"].GetString() ?? throw new KeyNotFoundException("Missing required configuration key 'from_address'");
Uri baseServerPath = new(conf["base_url"].GetString()!, UriKind.RelativeOrAbsolute);
//Get the token server url or use the base path if no set
Uri tokenServerBase = conf.TryGetValue("token_server_url", out JsonElement tksEl) && tksEl.GetString() != null ?
new(tksEl.GetString()!, UriKind.RelativeOrAbsolute)
: baseServerPath;
//Get the transaction endpoint path, should be a realative path
Uri transactionEndpoint = new(conf["transaction_path"].GetString()!, UriKind.Relative);
//Load credentials
string authEndpoint = conf["token_path"].GetString() ?? throw new KeyNotFoundException("Missing required configuration key 'token_path'");
//Optional user-agent
string? userAgent = conf.GetPropString("user_agent");
//Get optional timeout ms
int timeoutMs = (int)(conf.TryGetValue("request_timeout_ms", out JsonElement timeoutEl) ? timeoutEl.GetUInt32() : DEFAULT_CLIENT_TIMEOUT_MS);
//Get maximum client limit
int maxClients = (int)(conf.TryGetValue("max_clients", out JsonElement mxcEl) ? mxcEl.GetUInt32() : DEFAULT_MAX_CLIENTS);
//Load all templates from the plugin config
Dictionary<string, string> templates = pbase.PluginConfig.GetProperty(REQUIRED_EMAIL_TEMPALTE_CONFIG_KEY)
.EnumerateObject()
.ToDictionary(static jp => jp.Name, static jp => jp.Value.GetString()!);
pbase.Log.Verbose("Required email templates {t}", templates);
//Load oauth secrets from vault
Task<SecretResult?> oauth2ClientID = pbase.TryGetSecretAsync("email_client_id");
Task<SecretResult?> oauth2Password = pbase.TryGetSecretAsync("email_client_secret");
//Lazy cred loaded, tasks should be loaded before this method will ever get called
Credential lazyCredentialGet()
{
//Load the results
SecretResult cliendId = oauth2ClientID.GetAwaiter().GetResult() ?? throw new KeyNotFoundException("Missing required oauth2 client id");
SecretResult password = oauth2Password.GetAwaiter().GetResult() ?? throw new KeyNotFoundException("Missing required oauth2 client secret");
//Creat credential
return Credential.Create(cliendId.Result, password.Result);
}
//Init client creation options
RestClientOptions poolOptions = new(baseServerPath)
{
AllowMultipleDefaultParametersWithSameName = true,
AutomaticDecompression = System.Net.DecompressionMethods.All,
PreAuthenticate = true,
Encoding = Encoding.UTF8,
MaxTimeout = timeoutMs,
UserAgent = userAgent,
//Server should not redirect
FollowRedirects = false,
};
//Options for auth token endpoint
RestClientOptions oAuth2ClientOptions = new(tokenServerBase)
{
AllowMultipleDefaultParametersWithSameName = true,
//Server supports compression
AutomaticDecompression = System.Net.DecompressionMethods.All,
PreAuthenticate = false,
Encoding = Encoding.UTF8,
MaxTimeout = timeoutMs,
UserAgent = userAgent,
//Server should not redirect
FollowRedirects = false
};
//Init Oauth authenticator
OAuth2Authenticator authenticator = new(oAuth2ClientOptions, lazyCredentialGet, authEndpoint);
//Create client pool
RestClientPool pool = new(maxClients, poolOptions, authenticator: authenticator);
void Cleanup()
{
authenticator.Dispose();
pool.Dispose();
oauth2ClientID.Dispose();
oauth2Password.Dispose();
}
//register password cleanup
_ = pbase.RegisterForUnload(Cleanup);
//Create config
EmailSystemConfig config = new ()
{
EmailFromName = emailFromName,
EmailFromAddress = emailFromAddress,
RestClientPool = pool,
};
//Store templates and set service url
config.WithTemplates(templates)
.WithUrl(transactionEndpoint);
return config;
}
}
}
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