Add very basic support for finding and rendering templates

express/util.ts

@@ -0,0 +1,36 @@
+import { readFile } from "node:fs/promises";
+import nunjucks from "nunjucks";
+import { contentTypes } from "./content-types";
+import { executionContext } from "./execution-context";
+import { httpCodes } from "./http-codes";
+import type { Result } from "./types";
+
+// FIXME: Handle the error here
+const loadFile = async (path: string): Promise<string> => {
+    // Specifying 'utf8' returns a string; otherwise, it returns a Buffer
+    const data = await readFile(path, "utf8");
+
+    return data;
+};
+
+const render = async (path: string, ctx: object): Promise<string> => {
+    const fullPath = `${executionContext.diachron_root}/templates/${path}.html.njk`;
+
+    const template = await loadFile(fullPath);
+
+    const retval = nunjucks.renderString(template, ctx);
+
+    return retval;
+};
+
+const html = (payload: string): Result => {
+      const retval: Result = {
+        code: httpCodes.success.OK,
+        result: payload,
+        contentType: contentTypes.text.html,
+    };
+
+    return retval;
+};
+
+export { render, html };