From b6f8da512cd71897b5a9db91717dab4bdd2a8a50 Mon Sep 17 00:00:00 2001
From: ztimson <zaktimson@gmail.com>
Date: Sat, 6 Dec 2025 15:20:51 -0500
Subject: [PATCH] Added template helper

---
 package.json    |  2 +-
 src/index.ts    |  1 +
 src/template.ts | 78 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 src/template.ts

diff --git a/package.json b/package.json
index d71e1df..704ec3a 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@ztimson/utils",
-	"version": "0.27.15",
+	"version": "0.27.16",
 	"description": "Utility library",
 	"author": "Zak Timson",
 	"license": "MIT",
diff --git a/src/index.ts b/src/index.ts
index cf20437..b1d9759 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -19,6 +19,7 @@ export * from './path-events';
 export * from './promise-progress';
 export * from './search';
 export * from './string';
+export * from './template';
 export * from './time';
 export * from './types';
 export * from 'var-persist';
diff --git a/src/template.ts b/src/template.ts
new file mode 100644
index 0000000..c8d4670
--- /dev/null
+++ b/src/template.ts
@@ -0,0 +1,78 @@
+import {BadRequestError, dotNotation, formatDate, matchAll} from '@ztimson/utils';
+
+export class TemplateError extends BadRequestError { }
+
+export async function renderTemplate(template: string, data: any, fetch?: (file: string) => Promise<string>) {
+	let content = template, found: any;
+	const now = new Date(), d = {
+		date: {
+			day: now.getDate(),
+			month: now.toLocaleString('default', { month: 'long' }),
+			year: now.getFullYear(),
+			time: now.toLocaleTimeString(),
+			format: formatDate
+		},
+		...(data || {}),
+	};
+
+	if(!fetch) fetch = (file) => {
+		throw new TemplateError(`Unable to fetch template: ${file}`);
+	}
+
+	const evaluate = (code: string, data: object, fatal = true) => {
+		try {
+			return Function('data', `Object.assign(this, data); return ${code};`)(data);
+		} catch {
+			if(fatal) throw new TemplateError(`Failed to evaluate: ${code}`);
+			else return false;
+		}
+	}
+
+	// If Statements - Optimize what we render: `{{ ? javascript }} TRUE CONTENT {{ !? }} FALSE CONTENT {{ /? }}`
+	while(!!(found = /\{\{\s*?\?\s*?(.+?)\s*?}}([\s\S]*?)(?:\{\{\s*?!\?\s*?}}([\s\S]*?))?\{\{\s*?\/\?\s*?}}/g.exec(content))) {
+		const nested = matchAll(found[0], /\{\{\s*?\?.+?}}/g).slice(-1)?.[0]?.index;
+		if(nested != 0)
+			found = /\{\{\s*?\?\s*?(.+?)\s*?}}([\s\S]*?)(?:\{\{\s*?!\?\s*?}}([\s\S]*?))?\{\{\s*?\/\?\s*?}}/g.exec(content.slice(found.index + nested))
+		content = content.replaceAll(found[0], (evaluate(found[1], d, false) ? found[2] : found[3]) || '');
+	}
+
+	// Imports - We render bottom up: `{{ < file.html }}`
+	while(!!(found = /\{\{\s*?<\s*?(.+?)\s*?}}/g.exec(content))) {
+		content = content.replaceAll(found[0], await renderTemplate(await fetch(found[1].trim()), data, fetch));
+	}
+
+	// For Loops: `{{ * (row, index) in invoice }} CONTENT {{ /* }}`
+	while(!!(found = /\{\{\s*?\*\s*?(.+?)\s+in\s+(.+?)\s*?}}([\s\S]*?)\{\{\s*?\/\*\s*?}}/g.exec(content))) {
+		const split = found[1].replaceAll(/[()\s]/g, '').split(',');
+		const element = split[0];
+		const index = split[1] || 'index';
+		const array: any[] = <any>dotNotation(data, found[2]);
+		if(!array || typeof array != 'object')
+			throw new TemplateError(`Cannot iterate: ${found[2]}`);
+
+		let compiled = [];
+		for(let i = 0; i < array.length; i++) {
+			compiled.push(renderTemplate(found[3], {
+				...d,
+				[element]: array[i],
+				[index]: i
+			}, fetch))
+		}
+		content = content.replaceAll(found[0], compiled.join('\n'));
+	}
+
+	// Evaluate whatever is left - Should come last: `{{ javascript }}`
+	while(!!(found = /\{\{\s*([^<>\*\?!/}\s][^}]*?)\s*}}/g.exec(content))) {
+		content = content.replaceAll(found[0], evaluate(found[1].trim(), d) || '');
+	}
+
+	// Extends: `{{ > file.html:property }} CONTENT {{ /> }}`
+	while(!!(found = /\{\{\s*?>\s*?(.+?):(.+?)\s*?}}([\s\S]*?)\{\{\s*?\/>\s*?}}/g.exec(content))) {
+		content = content.replace(found[0], await renderTemplate(await fetch(found[1].trim), {
+			...data,
+			[found[2].trim()]: found[3],
+		}, fetch));
+	}
+
+	return content;
+}