feat(tia): adds poc

src/Plugins/Tia/ChangedFiles.php

@@ -0,0 +1,219 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Pest\Plugins\Tia;
+
+use Symfony\Component\Process\Process;
+
+/**
+ * Detects files that changed between the last recorded TIA run and the
+ * current working tree.
+ *
+ * Strategy:
+ *   1. If we have a `recordedAtSha`, `git diff <sha>..HEAD` captures committed
+ *      changes on top of the recording point.
+ *   2. `git status --short` captures unstaged + staged + untracked changes on
+ *      top of that.
+ *
+ * We return relative paths to the project root. Deletions are included so the
+ * caller can decide whether to invalidate: a deleted source file may still
+ * appear in the graph and should mark its dependents as affected.
+ *
+ * @internal
+ */
+final readonly class ChangedFiles
+{
+    public function __construct(private string $projectRoot) {}
+
+    /**
+     * @return array<int, string>|null `null` when git is unavailable, or when
+     *                                  the recorded SHA is no longer reachable
+     *                                  from HEAD (rebase / force-push) — in
+     *                                  that case the graph should be rebuilt.
+     */
+    public function since(?string $sha): ?array
+    {
+        if (! $this->gitAvailable()) {
+            return null;
+        }
+
+        $files = [];
+
+        if ($sha !== null && $sha !== '') {
+            if (! $this->shaIsReachable($sha)) {
+                return null;
+            }
+
+            $files = array_merge($files, $this->diffSinceSha($sha));
+        }
+
+        $files = array_merge($files, $this->workingTreeChanges());
+
+        // Normalise + dedupe, filtering out paths that can never belong to the
+        // graph: vendor (caught by the fingerprint instead), cache dirs, and
+        // anything starting with a dot we don't care about.
+        $unique = [];
+
+        foreach ($files as $file) {
+            if ($file === '') {
+                continue;
+            }
+            if ($this->shouldIgnore($file)) {
+                continue;
+            }
+            $unique[$file] = true;
+        }
+
+        return array_keys($unique);
+    }
+
+    private function shouldIgnore(string $path): bool
+    {
+        static $prefixes = [
+            '.pest/',
+            '.phpunit.cache/',
+            '.phpunit.result.cache',
+            'vendor/',
+            'node_modules/',
+        ];
+
+        foreach ($prefixes as $prefix) {
+            if (str_starts_with($path, (string) $prefix)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public function gitAvailable(): bool
+    {
+        $process = new Process(['git', 'rev-parse', '--git-dir'], $this->projectRoot);
+        $process->run();
+
+        return $process->isSuccessful();
+    }
+
+    private function shaIsReachable(string $sha): bool
+    {
+        $process = new Process(
+            ['git', 'merge-base', '--is-ancestor', $sha, 'HEAD'],
+            $this->projectRoot,
+        );
+        $process->run();
+
+        // Exit 0 → ancestor; 1 → not ancestor; anything else → git error
+        // (e.g. unknown commit after a rebase/gc). Treat non-zero as
+        // "unreachable" and force a rebuild.
+        return $process->getExitCode() === 0;
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function diffSinceSha(string $sha): array
+    {
+        $process = new Process(
+            ['git', 'diff', '--name-only', $sha.'..HEAD'],
+            $this->projectRoot,
+        );
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return [];
+        }
+
+        return $this->splitLines($process->getOutput());
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function workingTreeChanges(): array
+    {
+        // `-z` produces NUL-terminated records with no path quoting, so paths
+        // that contain spaces, tabs, unicode or other special characters
+        // are passed through verbatim. Without `-z`, git wraps such paths in
+        // quotes with backslash escapes, which would corrupt our lookup keys.
+        //
+        // Record format: `XY <SP> <path> <NUL>` for most entries, and
+        // `R  <new> <NUL> <orig> <NUL>` for renames/copies (two NUL-separated
+        // fields).
+        $process = new Process(
+            ['git', 'status', '--porcelain', '-z', '--untracked-files=all'],
+            $this->projectRoot,
+        );
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return [];
+        }
+
+        $output = $process->getOutput();
+
+        if ($output === '') {
+            return [];
+        }
+
+        $records = explode("\x00", rtrim($output, "\x00"));
+        $files = [];
+        $count = count($records);
+
+        for ($i = 0; $i < $count; $i++) {
+            $record = $records[$i];
+
+            if (strlen($record) < 4) {
+                continue;
+            }
+
+            $status = substr($record, 0, 2);
+            $path = substr($record, 3);
+
+            // Renames/copies emit two records: the new path first, then the
+            // original. Consume both.
+            if ($status[0] === 'R' || $status[0] === 'C') {
+                $files[] = $path;
+
+                if (isset($records[$i + 1]) && $records[$i + 1] !== '') {
+                    $files[] = $records[$i + 1];
+                    $i++;
+                }
+
+                continue;
+            }
+
+            $files[] = $path;
+        }
+
+        return $files;
+    }
+
+    public function currentSha(): ?string
+    {
+        if (! $this->gitAvailable()) {
+            return null;
+        }
+
+        $process = new Process(['git', 'rev-parse', 'HEAD'], $this->projectRoot);
+        $process->run();
+
+        if (! $process->isSuccessful()) {
+            return null;
+        }
+
+        $sha = trim($process->getOutput());
+
+        return $sha === '' ? null : $sha;
+    }
+
+    /**
+     * @return array<int, string>
+     */
+    private function splitLines(string $output): array
+    {
+        $lines = preg_split('/\R+/', trim($output), flags: PREG_SPLIT_NO_EMPTY);
+
+        return $lines === false ? [] : $lines;
+    }
+}