first commit

app/FileViewer.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace MingTsay\Akanyan;
+
+abstract class FileViewer
+{
+    protected abstract static function directory(): string;
+
+    protected abstract static function whitelist(): ?array;
+
+    public static function list(): array
+    {
+        $directory = static::directory();
+        $whitelist = static::whitelist();
+
+        return array_values(array_filter(
+            scandir($directory),
+            fn($file) => ($whitelist === null || in_array($file, $whitelist)) && is_file("$directory/$file")
+        ));
+    }
+
+    public static function read($file): ?string
+    {
+        $directory = static::directory();
+        $filename = "$directory/$file";
+
+        if (!in_array($file, self::list()) || !file_exists($filename) || !is_file($filename)) return null;
+
+        $extension = pathinfo($filename, PATHINFO_EXTENSION);
+        $content = file_get_contents($filename);
+        return $extension === 'gz' ? gzdecode($content) : $content;
+    }
+}