add oldest and latest

src/ReferrerSources.php

@@ -91,6 +91,74 @@ public function getLast(string $source): ?ReferrerSource
         return $values[$key] ?? null;
     }
 
+    /**
+     * Oldest source based on timestamp
+     *
+     * @return null|ReferrerSource<mixed>
+     */
+    public function getOldest(): ?ReferrerSource
+    {
+        /** @var null|ReferrerSource<mixed> $oldest */
+        $oldest = null;
+
+        foreach ($this as $values) {
+            foreach ($values as $value) {
+
+                if (! $oldest) {
+                    $oldest = $value;
+                } elseif (
+                    ! $oldest->timestamp &&
+                    $value->timestamp
+                ) {
+                    $oldest = $value;
+                } elseif (
+                    $oldest->timestamp &&
+                    $value->timestamp &&
+                    $value->timestamp < $oldest->timestamp
+                ) {
+                    $oldest = $value;
+                }
+
+            }
+        }
+
+        return $oldest;
+    }
+
+    /**
+     * Most recent source based on timestamp
+     *
+     * @return null|ReferrerSource<mixed>
+     */
+    public function getLatest(): ?ReferrerSource
+    {
+        /** @var null|ReferrerSource<mixed> $latest */
+        $latest = null;
+
+        foreach ($this as $values) {
+            foreach ($values as $value) {
+
+                if (! $latest) {
+                    $latest = $value;
+                } elseif (
+                    ! $latest->timestamp &&
+                    $value->timestamp
+                ) {
+                    $latest = $value;
+                } elseif (
+                    $latest->timestamp &&
+                    $value->timestamp &&
+                    $value->timestamp >= $latest->timestamp
+                ) {
+                    $latest = $value;
+                }
+
+            }
+        }
+
+        return $latest;
+    }
+
     /**
      * @param  ReferrerSource<mixed>  $source
      * @return $this

src/Sources/ReferrerSource.php

@@ -13,6 +13,8 @@
  */
 abstract class ReferrerSource implements Arrayable, Stringable
 {
+    public ?float $timestamp = null;
+
     abstract public static function fromRequest(Request $request): static;
 
     /**