Improve Handlebars implementation

- now first compiles handlebars and then markdown, instead of the other way around
- that improves markdown rendering, e.g. proper paragraphs instead of double line breaks and handlebars "~" working properly
- has markdown escaping now

src/lib/mail.ts

@@ -3,9 +3,8 @@ import Gender from "$lib/genders";
 import { locales, type Locale } from "$lib/i18n/i18n";
 import type { Tutor } from "$lib/server/database/entities/Tutor.entity";
 import markdownit from "markdown-it";
-import type { Localized } from "$lib/utils";
+import { mapLocalized, type Localized } from "$lib/utils";
 import type { Config } from "$lib/server/config";
-import type { DateTimeFormatOptions } from "intl";
 import Handlebars from "handlebars";
 
 const md = markdownit({
@@ -238,13 +237,50 @@ export const conditions: Record<TemplateType, Condition[]> = {
 const bodyFormatter = ({ de, en }: Localized) => `-------- english version below --------\n\n${de}\n\n-------- english version --------\n\n${en}`;
 const subjectFormatter = ({ de, en }: Localized) => [de, en].filter(s=>s).join(" / ");
 
+const originalEscapeExpression = Handlebars.Utils.escapeExpression;
+const handlebars = {} as Localized<typeof Handlebars>;
+for(const locale of locales){
+	handlebars[locale] = Handlebars.create();
+	handlebars[locale].registerHelper("date", (date, ...options)=>{
+		const formatOptions: Intl.DateTimeFormatOptions = {};
+		// last argument in options is from Handlebars, not provided by user
+		if(options.length > 1) formatOptions.year = options[0];
+		if(options.length > 2) formatOptions.month = options[1];
+		if(options.length > 3) formatOptions.day = options[2];
+		if(options.length > 4) formatOptions.hour = options[3];
+		if(options.length > 5) formatOptions.minute = options[4];
+		const formatter = new Intl.DateTimeFormat(locale, formatOptions);
+		return formatter.format(new Date(date));
+	});
+}
+
 export function compileTemplate(template: MailTemplate){
-	const subjectTemplate = Handlebars.compile(subjectFormatter(template.subject));
-	const textTemplate = Handlebars.compile(bodyFormatter(template.text));
-	const htmlTemplate = Handlebars.compile(md.render(bodyFormatter(template.text)));
+	const compiledSubject = {} as Localized<HandlebarsTemplateDelegate>;
+	const compiledText = {} as Localized<HandlebarsTemplateDelegate>;
+	const compiledHtml = {} as Localized<HandlebarsTemplateDelegate>;
+	for(const locale of locales){
+		compiledSubject[locale] = handlebars[locale].compile(template.subject[locale]);
+		compiledText[locale] = handlebars[locale].compile(template.text[locale]);
+		compiledHtml[locale] = handlebars[locale].compile(template.text[locale]);
+	}
 	return {
-		subject: subjectTemplate,
-		text: textTemplate,
-		html: htmlTemplate,
+		subject: (context: any, options?: Handlebars.RuntimeOptions) => {
+			Handlebars.Utils.escapeExpression = str => String(str);
+			const subject = subjectFormatter(mapLocalized(compiledSubject, (template) => template(context, options)));
+			Handlebars.Utils.escapeExpression = originalEscapeExpression;
+			return subject;
+		},
+		text: (context: any, options?: Handlebars.RuntimeOptions) => {
+			Handlebars.Utils.escapeExpression = originalEscapeExpression;
+			return bodyFormatter(mapLocalized(compiledText, (template) => template(context, options)));
+		},
+		html: (context: any, options?: Handlebars.RuntimeOptions) => {
+			Handlebars.Utils.escapeExpression = str=>{
+				return originalEscapeExpression(String(str).replace(/([*#/()[\]_`\\-])/g, "\\$1")); // < and > dont need to be escaped, already happends by Handlebars
+			}
+			const html = md.render(bodyFormatter(mapLocalized(compiledHtml, (template) => template(context, options))));
+			Handlebars.Utils.escapeExpression = originalEscapeExpression;
+			return html;
+		},
 	};
 }

src/lib/utils.ts

@@ -112,3 +112,20 @@ export function pick<T extends object, K extends keyof T>(obj: T, keys: K[]): Pi
 	}
 	return result;
 }
+
+export function shuffle<T>(array: T[]): T[]{
+	const shuffled = array.slice();
+	for(let i = shuffled.length - 1; i > 0; i--){
+		const j = Math.floor(Math.random() * (i + 1));
+		const temp = shuffled[i];
+		shuffled[i] = shuffled[j];
+		shuffled[j] = temp;
+	}
+	return shuffled;
+}
+
+export function mapLocalized<T, U>(obj: Localized<T>, fn: (value: T)=>U): Localized<U> {
+	return Object.fromEntries(
+		Object.entries(obj).map(([key, value])=>[key, fn(value)])
+	) as Localized<U>;
+}