new performant way to calculate the last modified date #824

Author: oscarotero

core/utils/date.ts

@@ -44,3 +44,31 @@ export function getZonedDateTime(
     return Temporal.PlainDateTime.from(date).toZonedDateTime(timezone);
   }
 }
+
+/**
+ * Thanks to https://meiert.com/blog/eleventy-git-last-modified/
+ */
+export function getGitLastModified(path = "."): Map<string, string> {
+  const dates = new Map<string, string>();
+  const args = ["log", "-1", "--format=%at", "--", path];
+  const { stdout, success } = new Deno.Command("git", { args }).outputSync();
+  if (!success) {
+    return dates;
+  }
+  let currentDate: string | undefined;
+  const str = new TextDecoder().decode(stdout);
+  for (const line of str.split("\n")) {
+    const text = line.trim();
+
+    if (text.startsWith("DATE:")) {
+      currentDate = text.slice(5).trim();
+    } else if (text && currentDate) {
+      // First commits, last modification
+      if (!dates.has(text)) {
+        dates.set(text, currentDate);
+      }
+    }
+  }
+
+  return dates;
+}