Draft: E-Mail templates

Wave/Program.cs

@@ -128,6 +128,7 @@
 	logMessages.Add("No Email provider configured.");
 }
 
+builder.Services.AddSingleton<EmailTemplateService>();
 builder.Services.AddHostedService<EmailBackgroundWorker>();
 
 #endregion

Wave/Services/EmailBackgroundWorker.cs

@@ -9,12 +9,13 @@
 
 namespace Wave.Services;
 
-public class EmailBackgroundWorker(ILogger<EmailBackgroundWorker> logger, IDbContextFactory<ApplicationDbContext> contextFactory, IOptions<SmtpConfiguration> config, IOptions<Customization> customizations, IOptions<Features> features) : IHostedService, IDisposable {
+public class EmailBackgroundWorker(ILogger<EmailBackgroundWorker> logger, IDbContextFactory<ApplicationDbContext> contextFactory, IOptions<SmtpConfiguration> config, IOptions<Customization> customizations, IOptions<Features> features, EmailTemplateService templateService) : IHostedService, IDisposable {
 	private ILogger<EmailBackgroundWorker> Logger { get; } = logger;
 	private IDbContextFactory<ApplicationDbContext> ContextFactory { get; } = contextFactory;
 	private SmtpConfiguration Configuration { get; } = config.Value;
 	private Customization Customizations { get; } = customizations.Value;
 	private Features Features { get; } = features.Value;
+	private EmailTemplateService TemplateService { get; } = templateService;
 
 	private Timer? Timer { get; set; }
 
@@ -84,22 +85,19 @@ public class EmailBackgroundWorker(ILogger<EmailBackgroundWorker> logger, IDbCon
 				string articleLink = ArticleUtilities.GenerateArticleLink(
 					newsletter.Article, new Uri(Customizations.AppUrl, UriKind.Absolute));
 				string unsubscribeLink = new Uri(new Uri(Customizations.AppUrl, UriKind.Absolute), "/unsubscribe").AbsoluteUri;
-				string template = $"""
+				string template = TemplateService.Process("newsletter", new Dictionary<EmailTemplateService.Constants, object?>{
-					<mjml><mj-body><mj-section><mj-column>
+					{EmailTemplateService.Constants.BrowserLink, articleLink},
-					<mj-text align="center"><a href="{articleLink}">Read in Browser</a></mj-text>
+					{EmailTemplateService.Constants.ContentLogo, "https://blog.winter-software.com/img/logo.png"},
-					<mj-image width="200px" src="https://blog.winter-software.com/img/logo.png"></mj-image>
+					{EmailTemplateService.Constants.ContentTitle, newsletter.Article.Title},
-					<mj-divider border-width="1px"></mj-divider>
+					{EmailTemplateService.Constants.ContentBody, newsletter.Article.BodyHtml},
-					<mj-text>{newsletter.Article.BodyHtml}</mj-text>
+					{EmailTemplateService.Constants.EmailUnsubscribeLink, unsubscribeLink}
-					<mj-divider border-width="1px"></mj-divider>
+				});
-					<mj-text align="center"><a href="{unsubscribeLink}">Unsubscribe</a></mj-text>
+
-					</mj-column></mj-section></mj-body></mjml>
-					""";
 				var message = new MimeMessage {
 					From = { sender },
-					To = {  },
 					Subject = newsletter.Article.Title
 				};
-				var builder = new BodyBuilder() {
+				var builder = new BodyBuilder {
 					HtmlBody = mjmlRenderer.Render(template, options).Html
 				};
 				message.Body = builder.ToMessageBody();

Wave/Services/EmailTemplateService.cs

@@ -0,0 +1,96 @@
+using System.Text.RegularExpressions;
+using Mjml.Net;
+
+namespace Wave.Services;
+
+public partial class EmailTemplateService(ILogger<EmailTemplateService> logger) {
+	public enum Constants {
+		BrowserLink, HomeLink, ContentLogo, ContentTitle, ContentBody, EmailUnsubscribeLink
+	}
+
+	private ILogger<EmailTemplateService> Logger { get; } = logger;
+	private IMjmlRenderer Renderer { get; } = new MjmlRenderer();
+	
+	private Regex TokenMatcher { get; } = MyRegex();
+
+	public string Default(string url, string logoLink, string title, string body) {
+		return Process("default", new Dictionary<Constants, object?> {
+			{Constants.HomeLink, url},
+			{Constants.ContentLogo, logoLink},
+			{Constants.ContentTitle, title},
+			{Constants.ContentBody, body}
+		});
+	}
+
+	public string Process(string templateName, Dictionary<Constants, object?> data) {
+		var options = new MjmlOptions {
+			Beautify = false
+		};
+
+		string template = $"""
+		                    <mjml>
+		                      <mj-head>
+		                        <mj-preview/>
+		                      </mj-head>
+		                      <mj-body>
+		                        <mj-section>
+		                        	<mj-column>
+		                          	<mj-text align="center" font-size="13px" font-family="Ubuntu,Verdana">
+		                              <a href="[[{Constants.BrowserLink}]]">Read in Browser</a></mj-text>
+		                          </mj-column>
+		                        </mj-section>
+		                        <mj-section direction="rtl" padding-bottom="15px" padding-left="0px" padding-right="0px" padding-top="15px" padding="15px 0px 15px 0px">
+		                          <mj-column vertical-align="middle" width="33%">
+		                            <mj-image align="center" alt="" border-radius="0" border="none" container-background-color="transparent" height="auto" padding-bottom="5px" padding-left="5px" padding-right="5px" padding-top="5px" padding="5px 5px 5px 5px" href="[[{Constants.HomeLink}]]" src="[[{Constants.ContentLogo}]]"></mj-image>
+		                          </mj-column>
+		                          <mj-column vertical-align="middle" width="67%">
+		                            <mj-text font-size="13px" font-family="Ubuntu,Verdana">
+		                              <h1>[[{Constants.ContentTitle}]]</h1>
+		                            </mj-text>
+		                          </mj-column>
+		                        </mj-section>
+		                        <mj-section>
+		                        	<mj-column>
+		                          	<mj-divider border-width="1px"></mj-divider>
+		                          </mj-column>
+		                        </mj-section>
+		                        <mj-section>
+		                          <mj-column>
+		                            <mj-text color="#55575d" font-size="13px" font-family="Ubuntu,Verdana">[[{Constants.ContentBody}]]</mj-text>
+		                          </mj-column>
+		                        </mj-section>
+		                        <mj-section>
+		                        	<mj-column>
+		                          	<mj-divider border-width="1px"></mj-divider>
+		                          </mj-column>
+		                        </mj-section>
+		                        <mj-section>
+		                        	<mj-column>
+		                            <mj-text align="center" font-size="13px" font-family="Ubuntu,Verdana">
+		                              <a href="[[{Constants.EmailUnsubscribeLink}]]">Unsubscribe</a>
+		                            </mj-text>
+		                          </mj-column>
+		                        </mj-section>
+		                      </mj-body>
+		                    </mjml>
+		                    """;
+
+		template = TokenMatcher.Replace(template, t => 
+			data.TryGetValue(Enum.Parse<Constants>(t.Value[2..^2], true), out object? v) ? 
+				v?.ToString() ?? "" : 
+				"");
+		
+		(string html, var errors) = Renderer.Render(template, options);
+
+		foreach (var error in errors) {
+			Logger.LogWarning("Validation error in template {template}: [{position}] [{type}] {error}", 
+				templateName, error.Position, error.Type, error.Error);
+		}
+
+		return html;
+	}
+
+	[GeneratedRegex(@"(\[\[.*?\]\])", 
+		RegexOptions.IgnoreCase | RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.CultureInvariant)]
+	private static partial Regex MyRegex();
+}