Introduce standalone DirDiff util class

src/SPC/store/DirDiff.php

@@ -0,0 +1,95 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SPC\store;
+
+/**
+ * A util class to diff directory file increments.
+ */
+class DirDiff
+{
+    protected array $before = [];
+
+    protected array $before_file_hashes = [];
+
+    public function __construct(protected string $dir, protected bool $track_content_changes = false)
+    {
+        $this->reset();
+    }
+
+    /**
+     * Reset the baseline to current state.
+     */
+    public function reset(): void
+    {
+        $this->before = FileSystem::scanDirFiles($this->dir, relative: true) ?: [];
+
+        if ($this->track_content_changes) {
+            $this->before_file_hashes = [];
+            foreach ($this->before as $file) {
+                $this->before_file_hashes[$file] = md5_file($this->dir . DIRECTORY_SEPARATOR . $file);
+            }
+        }
+    }
+
+    /**
+     * Get the list of incremented files.
+     *
+     * @param  bool          $relative Return relative paths or absolute paths
+     * @return array<string> List of incremented files
+     */
+    public function getIncrementFiles(bool $relative = false): array
+    {
+        $after = FileSystem::scanDirFiles($this->dir, relative: true) ?: [];
+        $diff = array_diff($after, $this->before);
+        if ($relative) {
+            return $diff;
+        }
+        return array_map(fn ($f) => $this->dir . DIRECTORY_SEPARATOR . $f, $diff);
+    }
+
+    /**
+     * Get the list of changed files (including new files).
+     *
+     * @param  bool          $relative          Return relative paths or absolute paths
+     * @param  bool          $include_new_files Include new files as changed files
+     * @return array<string> List of changed files
+     */
+    public function getChangedFiles(bool $relative = false, bool $include_new_files = true): array
+    {
+        $after = FileSystem::scanDirFiles($this->dir, relative: true) ?: [];
+        $changed = [];
+        foreach ($after as $file) {
+            if (isset($this->before_file_hashes[$file])) {
+                $after_hash = md5_file($this->dir . DIRECTORY_SEPARATOR . $file);
+                if ($after_hash !== $this->before_file_hashes[$file]) {
+                    $changed[] = $file;
+                }
+            } elseif ($include_new_files) {
+                // New file, consider as changed
+                $changed[] = $file;
+            }
+        }
+        if ($relative) {
+            return $changed;
+        }
+        return array_map(fn ($f) => $this->dir . DIRECTORY_SEPARATOR . $f, $changed);
+    }
+
+    /**
+     * Get the list of removed files.
+     *
+     * @param  bool          $relative Return relative paths or absolute paths
+     * @return array<string> List of removed files
+     */
+    public function getRemovedFiles(bool $relative = false): array
+    {
+        $after = FileSystem::scanDirFiles($this->dir, relative: true) ?: [];
+        $removed = array_diff($this->before, $after);
+        if ($relative) {
+            return $removed;
+        }
+        return array_map(fn ($f) => $this->dir . DIRECTORY_SEPARATOR . $f, $removed);
+    }
+}