add feature interface and implementation to get child from directory

.github/workflows/test.yaml

@@ -13,7 +13,7 @@ jobs:
 
     strategy:
       matrix:
-        php-version: [ '8.3' ]
+        php-version: [ '8.3', '8.4' ]
 
     name: Run tests on PHP v${{ matrix.php-version }}
 

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2024 Aternos GmbH
+Copyright (c) 2024-2025 Aternos GmbH
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

src/Interfaces/Features/GetChildInterface.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace Aternos\IO\Interfaces\Features;
+
+use Aternos\IO\Exception\IOException;
+use Aternos\IO\Interfaces\IOElementInterface;
+
+interface GetChildInterface extends IOElementInterface
+{
+    /**
+     * Get a child element that has the given features
+     *
+     * The child element does not have to exist (yet)
+     * The child element might support additional features
+     *
+     * @param string $name
+     * @param class-string<IOElementInterface>[] $features
+     * @return IOElementInterface
+     * @throws IOException
+     */
+    public function getChild(string $name, string ...$features): IOElementInterface;
+}

src/Interfaces/Types/DirectoryInterface.php

@@ -2,6 +2,7 @@
 
 namespace Aternos\IO\Interfaces\Types;
 
+use Aternos\IO\Interfaces\Features\GetChildInterface;
 use Aternos\IO\Interfaces\Features\CreateInterface;
 use Aternos\IO\Interfaces\Features\DeleteInterface;
 use Aternos\IO\Interfaces\Features\ExistsInterface;
@@ -17,6 +18,7 @@
 interface DirectoryInterface extends
     DeleteInterface,
     GetChildrenInterface,
+    GetChildInterface,
     CreateInterface,
     ExistsInterface
 {

src/System/Directory/Directory.php

@@ -10,11 +10,16 @@
 use Aternos\IO\Interfaces\Features\GetChildrenInterface;
 use Aternos\IO\Interfaces\Features\GetPathInterface;
 use Aternos\IO\Interfaces\Features\GetTargetInterface;
+use Aternos\IO\Interfaces\IOElementInterface;
 use Aternos\IO\Interfaces\Types\DirectoryInterface;
+use Aternos\IO\System\File\File;
 use Aternos\IO\System\FilesystemElement;
+use Aternos\IO\System\Link\DirectoryLink;
+use Aternos\IO\System\Link\FileLink;
 use Aternos\IO\System\Link\Link;
 use DirectoryIterator;
 use Generator;
+use InvalidArgumentException;
 
 /**
  * Class Directory
@@ -55,6 +60,64 @@ public function getChildren(bool $allowOutsideLinks = false): Generator
         }
     }
 
+    /**
+     * @inheritDoc
+     * @return FilesystemElement
+     */
+    public function getChild(string $name, string ...$features): FilesystemElement
+    {
+        /** @var class-string<FilesystemElement>[] $supportedChildClasses */
+        $supportedChildClasses = [
+            static::class,
+            DirectoryLink::class,
+            File::class,
+            FileLink::class,
+            Link::class
+        ];
+
+        /** @var class-string<FilesystemElement> $childClass */
+        $childClass = $this->findInstanceOfAll($supportedChildClasses, $features);
+        if (!$childClass) {
+            throw new InvalidArgumentException("No supported child class found for features: " . implode(", ", $features));
+        }
+        return new $childClass($this->getPath() . DIRECTORY_SEPARATOR . $name);
+    }
+
+    /**
+     * Find a class that is an instance of all required classes
+     *
+     * @param class-string[] $availableClasses
+     * @param class-string[] $requiredClasses
+     * @return string|null
+     */
+    protected function findInstanceOfAll(array $availableClasses, array $requiredClasses): ?string
+    {
+        foreach ($availableClasses as $availableClass) {
+            if ($this->isInstanceOfAll($availableClass, $requiredClasses)) {
+                return $availableClass;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Check if a class is an instance of all required classes
+     *
+     * @param class-string $class
+     * @param class-string[] $requiredClasses
+     * @return bool
+     */
+    protected function isInstanceOfAll(string $class, array $requiredClasses): bool
+    {
+        foreach ($requiredClasses as $requiredClass) {
+            if (!is_a($class, $requiredClass, true)) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+
     /**
      * @inheritDoc
      * @throws GetTargetException

src/System/Link/DirectoryLink.php

@@ -6,6 +6,7 @@
 use Aternos\IO\Exception\GetTargetException;
 use Aternos\IO\Exception\SetTargetException;
 use Aternos\IO\Interfaces\Features\GetPathInterface;
+use Aternos\IO\Interfaces\IOElementInterface;
 use Aternos\IO\Interfaces\Types\DirectoryInterface;
 use Aternos\IO\Interfaces\Types\Link\DirectoryLinkInterface;
 use Aternos\IO\System\Directory\Directory;
@@ -83,4 +84,12 @@ public function getChildrenRecursive(bool $allowOutsideLinks = false, bool $foll
     {
         yield from $this->getTarget()->getChildrenRecursive($allowOutsideLinks, $followLinks, $currentDepth);
     }
+
+    /**
+     * @inheritDoc
+     */
+    public function getChild(string $name, string ...$features): IOElementInterface
+    {
+        return $this->getTarget()->getChild($name, ...$features);
+    }
 }

test/Unit/System/Directory/DirectoryTest.php

@@ -7,16 +7,23 @@
 use Aternos\IO\Exception\GetTargetException;
 use Aternos\IO\Exception\IOException;
 use Aternos\IO\Exception\MissingPermissionsException;
+use Aternos\IO\Interfaces\Features\GetChildrenInterface;
+use Aternos\IO\Interfaces\Features\ReadInterface;
+use Aternos\IO\Interfaces\Features\WriteInterface;
 use Aternos\IO\Interfaces\IOElementInterface;
 use Aternos\IO\Interfaces\Types\DirectoryInterface;
 use Aternos\IO\Interfaces\Types\FileInterface;
 use Aternos\IO\Interfaces\Types\Link\LinkInterface;
 use Aternos\IO\System\Directory\Directory;
+use Aternos\IO\System\File\File;
+use Aternos\IO\System\FilesystemElement;
 use Aternos\IO\System\Link\DirectoryLink;
 use Aternos\IO\System\Link\FileLink;
 use Aternos\IO\System\Link\Link;
 use Aternos\IO\Test\Unit\System\FilesystemTestCase;
 use Generator;
+use InvalidArgumentException;
+use PHPUnit\Framework\Attributes\TestWith;
 
 class DirectoryTest extends FilesystemTestCase
 {
@@ -120,6 +127,52 @@ public function testThrowsExceptionOnGetChildrenRecursiveWithMissingPermissions(
         chmod($path, 0777);
     }
 
+    /**
+     * @param class-string[] $features
+     * @param class-string $expected
+     * @return void
+     * @throws IOException
+     */
+    #[TestWith([FileInterface::class])]
+    #[TestWith([File::class])]
+    #[TestWith([DirectoryInterface::class])]
+    #[TestWith([Directory::class])]
+    #[TestWith([LinkInterface::class])]
+    #[TestWith([FileLink::class])]
+    #[TestWith([DirectoryLink::class])]
+    #[TestWith([Link::class])]
+    #[TestWith([[WriteInterface::class, ReadInterface::class], File::class])]
+    #[TestWith([[GetChildrenInterface::class], Directory::class])]
+    public function testGetChild(array|string $features, ?string $expected = null): void
+    {
+        if (is_string($features)) {
+            $features = [$features];
+        }
+
+        if ($expected === null) {
+            $expected = $features[0];
+        }
+
+        $path = $this->getTmpPath();
+        $element = $this->createElement($path);
+
+        $child = $element->getChild("test", ...$features);
+        $this->assertInstanceOf($expected, $child);
+        $this->assertEquals($path . "/test", $child->getPath());
+    }
+
+    /**
+     * @return void
+     * @throws IOException
+     */
+    public function testGetChildThrowsExceptionOnInvalidFeatureCombination(): void
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage("No supported child class found for features: Aternos\IO\Interfaces\Features\WriteInterface, Aternos\IO\Interfaces\Features\GetChildrenInterface");
+        $element = $this->createElement($this->getTmpPath());
+        $element->getChild("test", WriteInterface::class, GetChildrenInterface::class);
+    }
+
     /**
      * @throws GetTargetException
      * @throws MissingPermissionsException

test/Unit/System/Link/DirectoryLinkTest.php

@@ -261,4 +261,19 @@ public function testGetChildrenRecursive(): void
         $this->assertPathHasTypeInArray($path . "/file1", FileInterface::class, $children);
         $this->assertPathHasTypeInArray($path . "/file2", FileInterface::class, $children);
     }
+
+    /**
+     * @return void
+     * @throws DeleteException
+     * @throws IOException
+     * @throws SetTargetException
+     */
+    public function testGetChild(): void
+    {
+        mkdir($this->getTmpPath() . "/test-target");
+        $element = $this->createElement($this->getTmpPath() . "/test");
+        $element->setTarget(new Directory($this->getTmpPath() . "/test-target"));
+
+        $this->assertInstanceOf(File::class, $element->getChild("test", FileInterface::class));
+    }
 }