feat(api): File conversion API

Signed-off-by: Elizabeth Danzberger <lizzy7128@tutanota.de>

21 files changed, 732 insertions, 2 deletions

diff --git a/apps/files/composer/composer/autoload_classmap.php b/apps/files/composer/composer/autoload_classmap.php
index 7975c6f3d83..5922560f521 100644
--- a/apps/files/composer/composer/autoload_classmap.php
+++ b/apps/files/composer/composer/autoload_classmap.php
@@ -42,6 +42,7 @@ return array(
     'OCA\\Files\\Command\\ScanAppData' => $baseDir . '/../lib/Command/ScanAppData.php',
     'OCA\\Files\\Command\\TransferOwnership' => $baseDir . '/../lib/Command/TransferOwnership.php',
     'OCA\\Files\\Controller\\ApiController' => $baseDir . '/../lib/Controller/ApiController.php',
+    'OCA\\Files\\Controller\\ConversionApiController' => $baseDir . '/../lib/Controller/ConversionApiController.php',
     'OCA\\Files\\Controller\\DirectEditingController' => $baseDir . '/../lib/Controller/DirectEditingController.php',
     'OCA\\Files\\Controller\\DirectEditingViewController' => $baseDir . '/../lib/Controller/DirectEditingViewController.php',
     'OCA\\Files\\Controller\\OpenLocalEditorController' => $baseDir . '/../lib/Controller/OpenLocalEditorController.php',
diff --git a/apps/files/composer/composer/autoload_static.php b/apps/files/composer/composer/autoload_static.php
index f2cb858f313..bf489b037f7 100644
--- a/apps/files/composer/composer/autoload_static.php
+++ b/apps/files/composer/composer/autoload_static.php
@@ -57,6 +57,7 @@ class ComposerStaticInitFiles
         'OCA\\Files\\Command\\ScanAppData' => __DIR__ . '/..' . '/../lib/Command/ScanAppData.php',
         'OCA\\Files\\Command\\TransferOwnership' => __DIR__ . '/..' . '/../lib/Command/TransferOwnership.php',
         'OCA\\Files\\Controller\\ApiController' => __DIR__ . '/..' . '/../lib/Controller/ApiController.php',
+        'OCA\\Files\\Controller\\ConversionApiController' => __DIR__ . '/..' . '/../lib/Controller/ConversionApiController.php',
         'OCA\\Files\\Controller\\DirectEditingController' => __DIR__ . '/..' . '/../lib/Controller/DirectEditingController.php',
         'OCA\\Files\\Controller\\DirectEditingViewController' => __DIR__ . '/..' . '/../lib/Controller/DirectEditingViewController.php',
         'OCA\\Files\\Controller\\OpenLocalEditorController' => __DIR__ . '/..' . '/../lib/Controller/OpenLocalEditorController.php',
diff --git a/apps/files/lib/Capabilities.php b/apps/files/lib/Capabilities.php
index 16ea42eae22..88efb4fcaf0 100644
--- a/apps/files/lib/Capabilities.php
+++ b/apps/files/lib/Capabilities.php
@@ -10,18 +10,21 @@ namespace OCA\Files;
 use OC\Files\FilenameValidator;
 use OCA\Files\Service\ChunkedUploadConfig;
 use OCP\Capabilities\ICapability;
+use OCP\Files\Conversion\ConversionMimeTuple;
+use OCP\Files\Conversion\IConversionManager;
 
 class Capabilities implements ICapability {
 
 	public function __construct(
 		protected FilenameValidator $filenameValidator,
+		protected IConversionManager $fileConversionManager,
 	) {
 	}
 
 	/**
 	 * Return this classes capabilities
 	 *
-	 * @return array{files: array{'$comment': ?string, bigfilechunking: bool, blacklisted_files: list<mixed>, forbidden_filenames: list<string>, forbidden_filename_basenames: list<string>, forbidden_filename_characters: list<string>, forbidden_filename_extensions: list<string>, chunked_upload: array{max_size: int, max_parallel_count: int}}}
+	 * @return array{files: array{'$comment': ?string, bigfilechunking: bool, blacklisted_files: list<mixed>, forbidden_filenames: list<string>, forbidden_filename_basenames: list<string>, forbidden_filename_characters: list<string>, forbidden_filename_extensions: list<string>, chunked_upload: array{max_size: int, max_parallel_count: int}, file_conversions: list<array{from: string, to: list<array{mime: string, name: string}>}>}}
 	 */
 	public function getCapabilities(): array {
 		return [
@@ -38,6 +41,10 @@ class Capabilities implements ICapability {
 					'max_size' => ChunkedUploadConfig::getMaxChunkSize(),
 					'max_parallel_count' => ChunkedUploadConfig::getMaxParallelCount(),
 				],
+
+				'file_conversions' => array_map(function (ConversionMimeTuple $mimeTuple) {
+					return $mimeTuple->jsonSerialize();
+				}, $this->fileConversionManager->getMimeTypes()),
 			],
 		];
 	}
diff --git a/apps/files/lib/Controller/ConversionApiController.php b/apps/files/lib/Controller/ConversionApiController.php
new file mode 100644
index 00000000000..1a1b7da1787
--- /dev/null
+++ b/apps/files/lib/Controller/ConversionApiController.php
@@ -0,0 +1,95 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Files\Controller;
+
+use OC\Files\Utils\PathHelper;
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Attribute\ApiRoute;
+use OCP\AppFramework\Http\Attribute\NoAdminRequired;
+use OCP\AppFramework\Http\Attribute\UserRateLimit;
+use OCP\AppFramework\Http\DataResponse;
+use OCP\AppFramework\OCS\OCSException;
+use OCP\AppFramework\OCS\OCSForbiddenException;
+use OCP\AppFramework\OCS\OCSNotFoundException;
+use OCP\AppFramework\OCSController;
+use OCP\Files\Conversion\IConversionManager;
+use OCP\Files\File;
+use OCP\Files\IRootFolder;
+use OCP\IL10N;
+use OCP\IRequest;
+
+class ConversionApiController extends OCSController {
+	public function __construct(
+		string $appName,
+		IRequest $request,
+		private IConversionManager $fileConversionManager,
+		private IRootFolder $rootFolder,
+		private IL10N $l10n,
+		private ?string $userId,
+	) {
+		parent::__construct($appName, $request);
+	}
+
+	/**
+	 * Converts a file from one MIME type to another
+	 *
+	 * @param int $fileId ID of the file to be converted
+	 * @param string $targetMimeType The MIME type to which you want to convert the file
+	 * @param string|null $destination The target path of the converted file. Written to a temporary file if left empty
+	 *
+	 * @return DataResponse<Http::STATUS_CREATED, array{path: string}, array{}>
+	 *
+	 * 201: File was converted and written to the destination or temporary file
+	 *
+	 * @throws OCSException The file was unable to be converted
+	 * @throws OCSNotFoundException The file to be converted was not found
+	 */
+	#[NoAdminRequired]
+	#[UserRateLimit(limit: 25, period: 120)]
+	#[ApiRoute(verb: 'POST', url: '/api/v1/convert')]
+	public function convert(int $fileId, string $targetMimeType, ?string $destination = null): DataResponse {
+		$userFolder = $this->rootFolder->getUserFolder($this->userId);
+		$file = $userFolder->getFirstNodeById($fileId);
+
+		if (!($file instanceof File)) {
+			throw new OCSNotFoundException($this->l10n->t('The file cannot be found'));
+		}
+
+		if ($destination !== null) {
+			$destination = PathHelper::normalizePath($destination);
+			$parentDir = dirname($destination);
+
+			if (!$userFolder->nodeExists($parentDir)) {
+				throw new OCSNotFoundException($this->l10n->t('The destination path does not exist: %1$s', [$parentDir]));
+			}
+
+			if (!$userFolder->get($parentDir)->isCreatable()) {
+				throw new OCSForbiddenException();
+			}
+
+			$destination = $userFolder->getFullPath($destination);
+		}
+
+		try {
+			$convertedFile = $this->fileConversionManager->convert($file, $targetMimeType, $destination);
+		} catch (\Exception $e) {
+			throw new OCSException($e->getMessage());
+		}
+
+		$convertedFileRelativePath = $userFolder->getRelativePath($convertedFile);
+		if ($convertedFileRelativePath === null) {
+			throw new OCSNotFoundException($this->l10n->t('Could not get relative path to converted file'));
+		}
+
+		return new DataResponse([
+			'path' => $convertedFileRelativePath,
+		], Http::STATUS_CREATED);
+	}
+}
diff --git a/apps/files/openapi.json b/apps/files/openapi.json
index 2c33097438f..c196353cdd1 100644
--- a/apps/files/openapi.json
+++ b/apps/files/openapi.json
@@ -37,6 +37,7 @@
                             "forbidden_filename_characters",
                             "forbidden_filename_extensions",
                             "chunked_upload",
+                            "file_conversions",
                             "directEditing"
                         ],
                         "properties": {
@@ -94,6 +95,27 @@
                                     }
                                 }
                             },
+                            "file_conversions": {
+                                "type": "array",
+                                "items": {
+                                    "type": "object",
+                                    "required": [
+                                        "from",
+                                        "to"
+                                    ],
+                                    "properties": {
+                                        "from": {
+                                            "type": "string"
+                                        },
+                                        "to": {
+                                            "type": "object",
+                                            "additionalProperties": {
+                                                "type": "string"
+                                            }
+                                        }
+                                    }
+                                }
+                            },
                             "directEditing": {
                                 "type": "object",
                                 "required": [
@@ -2221,6 +2243,133 @@
                     }
                 }
             }
+        },
+        "/ocs/v2.php/apps/files/api/v1/convert": {
+            "post": {
+                "operationId": "conversion_api-convert",
+                "summary": "Converts a file from one MIME type to another",
+                "tags": [
+                    "conversion_api"
+                ],
+                "security": [
+                    {
+                        "bearer_auth": []
+                    },
+                    {
+                        "basic_auth": []
+                    }
+                ],
+                "requestBody": {
+                    "required": true,
+                    "content": {
+                        "application/json": {
+                            "schema": {
+                                "type": "object",
+                                "required": [
+                                    "fileId",
+                                    "targetMimeType"
+                                ],
+                                "properties": {
+                                    "fileId": {
+                                        "type": "integer",
+                                        "format": "int64",
+                                        "description": "ID of the file to be converted"
+                                    },
+                                    "targetMimeType": {
+                                        "type": "string",
+                                        "description": "The MIME type to which you want to convert the file"
+                                    },
+                                    "destination": {
+                                        "type": "string",
+                                        "nullable": true,
+                                        "description": "The target path of the converted file. Written to a temporary file if left empty"
+                                    }
+                                }
+                            }
+                        }
+                    }
+                },
+                "parameters": [
+                    {
+                        "name": "OCS-APIRequest",
+                        "in": "header",
+                        "description": "Required to be true for the API request to pass",
+                        "required": true,
+                        "schema": {
+                            "type": "boolean",
+                            "default": true
+                        }
+                    }
+                ],
+                "responses": {
+                    "201": {
+                        "description": "File was converted and written to the destination or temporary file",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "type": "object",
+                                    "required": [
+                                        "ocs"
+                                    ],
+                                    "properties": {
+                                        "ocs": {
+                                            "type": "object",
+                                            "required": [
+                                                "meta",
+                                                "data"
+                                            ],
+                                            "properties": {
+                                                "meta": {
+                                                    "$ref": "#/components/schemas/OCSMeta"
+                                                },
+                                                "data": {
+                                                    "type": "object",
+                                                    "required": [
+                                                        "path"
+                                                    ],
+                                                    "properties": {
+                                                        "path": {
+                                                            "type": "string"
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    },
+                    "404": {
+                        "description": "The file to be converted was not found",
+                        "content": {
+                            "application/json": {
+                                "schema": {
+                                    "type": "object",
+                                    "required": [
+                                        "ocs"
+                                    ],
+                                    "properties": {
+                                        "ocs": {
+                                            "type": "object",
+                                            "required": [
+                                                "meta",
+                                                "data"
+                                            ],
+                                            "properties": {
+                                                "meta": {
+                                                    "$ref": "#/components/schemas/OCSMeta"
+                                                },
+                                                "data": {}
+                                            }
+                                        }
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
         }
     },
     "tags": []
diff --git a/apps/files/tests/Controller/ConversionApiControllerTest.php b/apps/files/tests/Controller/ConversionApiControllerTest.php
new file mode 100644
index 00000000000..d2e68a8a32c
--- /dev/null
+++ b/apps/files/tests/Controller/ConversionApiControllerTest.php
@@ -0,0 +1,91 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Files\Controller;
+
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\DataResponse;
+use OCP\AppFramework\OCS\OCSException;
+use OCP\AppFramework\OCS\OCSNotFoundException;
+use OCP\Files\Conversion\IConversionManager;
+use OCP\Files\File;
+use OCP\Files\Folder;
+use OCP\Files\IRootFolder;
+use OCP\IL10N;
+use OCP\IRequest;
+use PHPUnit\Framework\MockObject\MockObject;
+use Test\TestCase;
+
+/**
+ * Class ConversionApiController
+ *
+ * @package OCA\Files\Controller
+ */
+class ConversionApiControllerTest extends TestCase {
+	private string $appName = 'files';
+	private ConversionApiController $conversionApiController;
+	private IRequest&MockObject $request;
+	private IConversionManager&MockObject $fileConversionManager;
+	private IRootFolder&MockObject $rootFolder;
+	private File&MockObject $file;
+	private Folder&MockObject $userFolder;
+	private IL10N&MockObject $l10n;
+	private string $user;
+
+	protected function setUp(): void {
+		parent::setUp();
+
+		$this->request = $this->createMock(IRequest::class);
+		$this->fileConversionManager = $this->createMock(IConversionManager::class);
+		$this->file = $this->createMock(File::class);
+		$this->l10n = $this->createMock(IL10N::class);
+		$this->user = 'userid';
+
+		$this->userFolder = $this->createMock(Folder::class);
+
+		$this->rootFolder = $this->createMock(IRootFolder::class);
+		$this->rootFolder->method('getUserFolder')->with($this->user)->willReturn($this->userFolder);
+
+		$this->conversionApiController = new ConversionApiController(
+			$this->appName,
+			$this->request,
+			$this->fileConversionManager,
+			$this->rootFolder,
+			$this->l10n,
+			$this->user,
+		);
+	}
+
+	public function testThrowsNotFoundException() {
+		$this->expectException(OCSNotFoundException::class);
+		$this->conversionApiController->convert(42, 'image/png');
+	}
+
+	public function testThrowsOcsException() {
+		$this->userFolder->method('getFirstNodeById')->with(42)->willReturn($this->file);
+		$this->fileConversionManager->method('convert')->willThrowException(new \Exception());
+
+		$this->expectException(OCSException::class);
+		$this->conversionApiController->convert(42, 'image/png');
+	}
+
+	public function testConvert() {
+		$convertedFileAbsolutePath = $this->user . '/files/test.png';
+
+		$this->userFolder->method('getFirstNodeById')->with(42)->willReturn($this->file);
+		$this->userFolder->method('getRelativePath')->with($convertedFileAbsolutePath)->willReturn('/test.png');
+
+		$this->fileConversionManager->method('convert')->with($this->file, 'image/png', null)->willReturn($convertedFileAbsolutePath);
+
+		$actual = $this->conversionApiController->convert(42, 'image/png', null);
+		$expected = new DataResponse([
+			'path' => '/test.png',
+		], Http::STATUS_CREATED);
+
+		$this->assertEquals($expected, $actual);
+	}
+}
diff --git a/apps/testing/composer/composer/autoload_classmap.php b/apps/testing/composer/composer/autoload_classmap.php
index 83d1fc771fc..e7f1ce74466 100644
--- a/apps/testing/composer/composer/autoload_classmap.php
+++ b/apps/testing/composer/composer/autoload_classmap.php
@@ -12,6 +12,7 @@ return array(
     'OCA\\Testing\\Controller\\ConfigController' => $baseDir . '/../lib/Controller/ConfigController.php',
     'OCA\\Testing\\Controller\\LockingController' => $baseDir . '/../lib/Controller/LockingController.php',
     'OCA\\Testing\\Controller\\RateLimitTestController' => $baseDir . '/../lib/Controller/RateLimitTestController.php',
+    'OCA\\Testing\\Conversion\\ConversionProvider' => $baseDir . '/../lib/Conversion/ConversionProvider.php',
     'OCA\\Testing\\Listener\\GetDeclarativeSettingsValueListener' => $baseDir . '/../lib/Listener/GetDeclarativeSettingsValueListener.php',
     'OCA\\Testing\\Listener\\RegisterDeclarativeSettingsListener' => $baseDir . '/../lib/Listener/RegisterDeclarativeSettingsListener.php',
     'OCA\\Testing\\Listener\\SetDeclarativeSettingsValueListener' => $baseDir . '/../lib/Listener/SetDeclarativeSettingsValueListener.php',
diff --git a/apps/testing/composer/composer/autoload_static.php b/apps/testing/composer/composer/autoload_static.php
index 3dc4bfe2fd6..f87a822aaf2 100644
--- a/apps/testing/composer/composer/autoload_static.php
+++ b/apps/testing/composer/composer/autoload_static.php
@@ -27,6 +27,7 @@ class ComposerStaticInitTesting
         'OCA\\Testing\\Controller\\ConfigController' => __DIR__ . '/..' . '/../lib/Controller/ConfigController.php',
         'OCA\\Testing\\Controller\\LockingController' => __DIR__ . '/..' . '/../lib/Controller/LockingController.php',
         'OCA\\Testing\\Controller\\RateLimitTestController' => __DIR__ . '/..' . '/../lib/Controller/RateLimitTestController.php',
+        'OCA\\Testing\\Conversion\\ConversionProvider' => __DIR__ . '/..' . '/../lib/Conversion/ConversionProvider.php',
         'OCA\\Testing\\Listener\\GetDeclarativeSettingsValueListener' => __DIR__ . '/..' . '/../lib/Listener/GetDeclarativeSettingsValueListener.php',
         'OCA\\Testing\\Listener\\RegisterDeclarativeSettingsListener' => __DIR__ . '/..' . '/../lib/Listener/RegisterDeclarativeSettingsListener.php',
         'OCA\\Testing\\Listener\\SetDeclarativeSettingsValueListener' => __DIR__ . '/..' . '/../lib/Listener/SetDeclarativeSettingsValueListener.php',
diff --git a/apps/testing/lib/AppInfo/Application.php b/apps/testing/lib/AppInfo/Application.php
index 3502b78402e..bbd9e288cc1 100644
--- a/apps/testing/lib/AppInfo/Application.php
+++ b/apps/testing/lib/AppInfo/Application.php
@@ -7,6 +7,7 @@
 namespace OCA\Testing\AppInfo;
 
 use OCA\Testing\AlternativeHomeUserBackend;
+use OCA\Testing\Conversion\ConversionProvider;
 use OCA\Testing\Listener\GetDeclarativeSettingsValueListener;
 use OCA\Testing\Listener\RegisterDeclarativeSettingsListener;
 use OCA\Testing\Listener\SetDeclarativeSettingsValueListener;
@@ -49,6 +50,8 @@ class Application extends App implements IBootstrap {
 		$context->registerTaskProcessingProvider(FakeTranscribeProvider::class);
 		$context->registerTaskProcessingProvider(FakeContextWriteProvider::class);
 
+		$context->registerFileConversionProvider(ConversionProvider::class);
+
 		$context->registerDeclarativeSettings(DeclarativeSettingsForm::class);
 		$context->registerEventListener(DeclarativeSettingsRegisterFormEvent::class, RegisterDeclarativeSettingsListener::class);
 		$context->registerEventListener(DeclarativeSettingsGetValueEvent::class, GetDeclarativeSettingsValueListener::class);
diff --git a/apps/testing/lib/Conversion/ConversionProvider.php b/apps/testing/lib/Conversion/ConversionProvider.php
new file mode 100644
index 00000000000..15e468b0756
--- /dev/null
+++ b/apps/testing/lib/Conversion/ConversionProvider.php
@@ -0,0 +1,40 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Testing\Conversion;
+
+use OCP\Files\Conversion\ConversionMimeTuple;
+use OCP\Files\Conversion\IConversionProvider;
+use OCP\Files\File;
+use OCP\IL10N;
+
+class ConversionProvider implements IConversionProvider {
+	public function __construct(
+		private IL10N $l10n,
+	) {
+	}
+
+	public function getSupportedMimeTypes(): array {
+		return [
+			new ConversionMimeTuple('image/jpeg', [
+				['mime' => 'image/png', 'name' => $this->l10n->t('Image (.png)')],
+			])
+		];
+	}
+
+	public function convertFile(File $file, string $targetMimeType): mixed {
+		$image = imagecreatefromstring($file->getContent());
+
+		imagepalettetotruecolor($image);
+
+		ob_start();
+		imagepng($image);
+		return ob_get_clean();
+	}
+}
diff --git a/config/config.sample.php b/config/config.sample.php
index ebc8427558f..b0b0f21853b 100644
--- a/config/config.sample.php
+++ b/config/config.sample.php
@@ -1429,6 +1429,14 @@ $CONFIG = [
 'metadata_max_filesize' => 256,
 
 /**
+ * Maximum file size for file conversion.
+ * If a file exceeds this size, the file will not be converted.
+ *
+ * Default: 100 MiB
+ */
+'max_file_conversion_filesize' => 100,
+
+/**
  * LDAP
  *
  * Global settings used by LDAP User and Group Backend
diff --git a/lib/composer/composer/autoload_classmap.php b/lib/composer/composer/autoload_classmap.php
index 9809ea53508..d6a8ac73c5f 100644
--- a/lib/composer/composer/autoload_classmap.php
+++ b/lib/composer/composer/autoload_classmap.php
@@ -377,6 +377,9 @@ return array(
     'OCP\\Files\\Config\\IRootMountProvider' => $baseDir . '/lib/public/Files/Config/IRootMountProvider.php',
     'OCP\\Files\\Config\\IUserMountCache' => $baseDir . '/lib/public/Files/Config/IUserMountCache.php',
     'OCP\\Files\\ConnectionLostException' => $baseDir . '/lib/public/Files/ConnectionLostException.php',
+    'OCP\\Files\\Conversion\\ConversionMimeTuple' => $baseDir . '/lib/public/Files/Conversion/ConversionMimeTuple.php',
+    'OCP\\Files\\Conversion\\IConversionManager' => $baseDir . '/lib/public/Files/Conversion/IConversionManager.php',
+    'OCP\\Files\\Conversion\\IConversionProvider' => $baseDir . '/lib/public/Files/Conversion/IConversionProvider.php',
     'OCP\\Files\\DavUtil' => $baseDir . '/lib/public/Files/DavUtil.php',
     'OCP\\Files\\EmptyFileNameException' => $baseDir . '/lib/public/Files/EmptyFileNameException.php',
     'OCP\\Files\\EntityTooLargeException' => $baseDir . '/lib/public/Files/EntityTooLargeException.php',
@@ -1575,6 +1578,7 @@ return array(
     'OC\\Files\\Config\\MountProviderCollection' => $baseDir . '/lib/private/Files/Config/MountProviderCollection.php',
     'OC\\Files\\Config\\UserMountCache' => $baseDir . '/lib/private/Files/Config/UserMountCache.php',
     'OC\\Files\\Config\\UserMountCacheListener' => $baseDir . '/lib/private/Files/Config/UserMountCacheListener.php',
+    'OC\\Files\\Conversion\\ConversionManager' => $baseDir . '/lib/private/Files/Conversion/ConversionManager.php',
     'OC\\Files\\FileInfo' => $baseDir . '/lib/private/Files/FileInfo.php',
     'OC\\Files\\FilenameValidator' => $baseDir . '/lib/private/Files/FilenameValidator.php',
     'OC\\Files\\Filesystem' => $baseDir . '/lib/private/Files/Filesystem.php',
diff --git a/lib/composer/composer/autoload_static.php b/lib/composer/composer/autoload_static.php
index f612e0d5fc6..0fba81fd3cd 100644
--- a/lib/composer/composer/autoload_static.php
+++ b/lib/composer/composer/autoload_static.php
@@ -418,6 +418,9 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OCP\\Files\\Config\\IRootMountProvider' => __DIR__ . '/../../..' . '/lib/public/Files/Config/IRootMountProvider.php',
         'OCP\\Files\\Config\\IUserMountCache' => __DIR__ . '/../../..' . '/lib/public/Files/Config/IUserMountCache.php',
         'OCP\\Files\\ConnectionLostException' => __DIR__ . '/../../..' . '/lib/public/Files/ConnectionLostException.php',
+        'OCP\\Files\\Conversion\\ConversionMimeTuple' => __DIR__ . '/../../..' . '/lib/public/Files/Conversion/ConversionMimeTuple.php',
+        'OCP\\Files\\Conversion\\IConversionManager' => __DIR__ . '/../../..' . '/lib/public/Files/Conversion/IConversionManager.php',
+        'OCP\\Files\\Conversion\\IConversionProvider' => __DIR__ . '/../../..' . '/lib/public/Files/Conversion/IConversionProvider.php',
         'OCP\\Files\\DavUtil' => __DIR__ . '/../../..' . '/lib/public/Files/DavUtil.php',
         'OCP\\Files\\EmptyFileNameException' => __DIR__ . '/../../..' . '/lib/public/Files/EmptyFileNameException.php',
         'OCP\\Files\\EntityTooLargeException' => __DIR__ . '/../../..' . '/lib/public/Files/EntityTooLargeException.php',
@@ -1616,6 +1619,7 @@ class ComposerStaticInit749170dad3f5e7f9ca158f5a9f04f6a2
         'OC\\Files\\Config\\MountProviderCollection' => __DIR__ . '/../../..' . '/lib/private/Files/Config/MountProviderCollection.php',
         'OC\\Files\\Config\\UserMountCache' => __DIR__ . '/../../..' . '/lib/private/Files/Config/UserMountCache.php',
         'OC\\Files\\Config\\UserMountCacheListener' => __DIR__ . '/../../..' . '/lib/private/Files/Config/UserMountCacheListener.php',
+        'OC\\Files\\Conversion\\ConversionManager' => __DIR__ . '/../../..' . '/lib/private/Files/Conversion/ConversionManager.php',
         'OC\\Files\\FileInfo' => __DIR__ . '/../../..' . '/lib/private/Files/FileInfo.php',
         'OC\\Files\\FilenameValidator' => __DIR__ . '/../../..' . '/lib/private/Files/FilenameValidator.php',
         'OC\\Files\\Filesystem' => __DIR__ . '/../../..' . '/lib/private/Files/Filesystem.php',
diff --git a/lib/private/AppFramework/Bootstrap/RegistrationContext.php b/lib/private/AppFramework/Bootstrap/RegistrationContext.php
index 77cc58c6468..c3b829825c2 100644
--- a/lib/private/AppFramework/Bootstrap/RegistrationContext.php
+++ b/lib/private/AppFramework/Bootstrap/RegistrationContext.php
@@ -154,6 +154,9 @@ class RegistrationContext {
 
 	/** @var ServiceRegistration<\OCP\TaskProcessing\ITaskType>[] */
 	private array $taskProcessingTaskTypes = [];
+
+	/** @var ServiceRegistration<\OCP\Files\Conversion\IConversionProvider>[] */
+	private array $fileConversionProviders = [];
 	
 	/** @var ServiceRegistration<IMailProvider>[] */
 	private $mailProviders = [];
@@ -421,6 +424,13 @@ class RegistrationContext {
 				);
 			}
 
+			public function registerFileConversionProvider(string $class): void {
+				$this->context->registerFileConversionProvider(
+					$this->appId,
+					$class
+				);
+			}
+
 			public function registerMailProvider(string $class): void {
 				$this->context->registerMailProvider(
 					$this->appId,
@@ -626,6 +636,14 @@ class RegistrationContext {
 	public function registerTaskProcessingTaskType(string $appId, string $taskProcessingTaskTypeClass) {
 		$this->taskProcessingTaskTypes[] = new ServiceRegistration($appId, $taskProcessingTaskTypeClass);
 	}
+
+	/**
+	 * @psalm-param class-string<\OCP\Files\Conversion\IConversionProvider> $class
+	 */
+	public function registerFileConversionProvider(string $appId, string $class): void {
+		$this->fileConversionProviders[] = new ServiceRegistration($appId, $class);
+	}
+
 	/**
 	 * @psalm-param class-string<IMailProvider> $migratorClass
 	 */
@@ -986,6 +1004,13 @@ class RegistrationContext {
 	}
 
 	/**
+	 * @return ServiceRegistration<\OCP\Files\Conversion\IConversionProvider>[]
+	 */
+	public function getFileConversionProviders(): array {
+		return $this->fileConversionProviders;
+	}
+
+	/**
 	 * @return ServiceRegistration<IMailProvider>[]
 	 */
 	public function getMailProviders(): array {
diff --git a/lib/private/CapabilitiesManager.php b/lib/private/CapabilitiesManager.php
index d7bf25f078a..07076d9aacd 100644
--- a/lib/private/CapabilitiesManager.php
+++ b/lib/private/CapabilitiesManager.php
@@ -32,7 +32,7 @@ class CapabilitiesManager {
 	}
 
 	/**
-	 * Get an array of al the capabilities that are registered at this manager
+	 * Get an array of all the capabilities that are registered at this manager
 	 *
 	 * @param bool $public get public capabilities only
 	 * @throws \InvalidArgumentException
diff --git a/lib/private/Files/Conversion/ConversionManager.php b/lib/private/Files/Conversion/ConversionManager.php
new file mode 100644
index 00000000000..37fc9a6c754
--- /dev/null
+++ b/lib/private/Files/Conversion/ConversionManager.php
@@ -0,0 +1,152 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OC\Files\Conversion;
+
+use OC\AppFramework\Bootstrap\Coordinator;
+use OC\SystemConfig;
+use OCP\Files\Conversion\ConversionMimeTuple;
+use OCP\Files\Conversion\IConversionManager;
+use OCP\Files\Conversion\IConversionProvider;
+use OCP\Files\File;
+use OCP\Files\GenericFileException;
+use OCP\Files\IRootFolder;
+use OCP\ITempManager;
+use OCP\PreConditionNotMetException;
+use Psr\Container\ContainerExceptionInterface;
+use Psr\Container\ContainerInterface;
+use Psr\Container\NotFoundExceptionInterface;
+use Psr\Log\LoggerInterface;
+use RuntimeException;
+use Throwable;
+
+class ConversionManager implements IConversionManager {
+	/** @var string[] */
+	private array $preferredApps = [
+		'richdocuments',
+	];
+
+	/** @var IConversionProvider[] */
+	private array $preferredProviders = [];
+
+	/** @var IConversionProvider[] */
+	private array $providers = [];
+
+	public function __construct(
+		private Coordinator $coordinator,
+		private ContainerInterface $serverContainer,
+		private IRootFolder $rootFolder,
+		private ITempManager $tempManager,
+		private LoggerInterface $logger,
+		private SystemConfig $config,
+	) {
+	}
+
+	public function hasProviders(): bool {
+		$context = $this->coordinator->getRegistrationContext();
+		return !empty($context->getFileConversionProviders());
+	}
+
+	public function getMimeTypes(): array {
+		$mimeTypes = [];
+
+		foreach ($this->getProviders() as $provider) {
+			$mimeTypes[] = $provider->getSupportedMimetypes();
+		}
+
+		/** @var list<ConversionMimeTuple> */
+		$mimeTypes = array_merge(...$mimeTypes);
+		return $mimeTypes;
+	}
+
+	public function convert(File $file, string $targetMimeType, ?string $destination = null): string {
+		if (!$this->hasProviders()) {
+			throw new PreConditionNotMetException('No file conversion providers available');
+		}
+
+		// Operate in mebibytes
+		$fileSize = $file->getSize() / (1024 * 1024);
+		$threshold = $this->config->getValue('max_file_conversion_filesize', 100);
+		if ($fileSize > $threshold) {
+			throw new GenericFileException('File is too large to convert');
+		}
+
+		$fileMimeType = $file->getMimetype();
+		$validProvider = $this->getValidProvider($fileMimeType, $targetMimeType);
+
+		if ($validProvider !== null) {
+			$convertedFile = $validProvider->convertFile($file, $targetMimeType);
+
+			if ($destination !== null) {
+				$convertedFile = $this->writeToDestination($destination, $convertedFile);
+				return $convertedFile->getPath();
+			}
+
+			$tmp = $this->tempManager->getTemporaryFile();
+			file_put_contents($tmp, $convertedFile);
+
+			return $tmp;
+		}
+
+		throw new RuntimeException('Could not convert file');
+	}
+
+	public function getProviders(): array {
+		if (count($this->providers) > 0) {
+			return $this->providers;
+		}
+
+		$context = $this->coordinator->getRegistrationContext();
+		foreach ($context->getFileConversionProviders() as $providerRegistration) {
+			$class = $providerRegistration->getService();
+			$appId = $providerRegistration->getAppId();
+
+			try {
+				if (in_array($appId, $this->preferredApps)) {
+					$this->preferredProviders[$class] = $this->serverContainer->get($class);
+					continue;
+				}
+				
+				$this->providers[$class] = $this->serverContainer->get($class);
+			} catch (NotFoundExceptionInterface|ContainerExceptionInterface|Throwable $e) {
+				$this->logger->error('Failed to load file conversion provider ' . $class, [
+					'exception' => $e,
+				]);
+			}
+		}
+
+		return array_merge([], $this->preferredProviders, $this->providers);
+	}
+
+	private function writeToDestination(string $destination, mixed $content): File {
+		return $this->rootFolder->newFile($destination, $content);
+	}
+
+	private function getValidProvider(string $fileMimeType, string $targetMimeType): ?IConversionProvider {
+		$validProvider = null;
+		foreach ($this->getProviders() as $provider) {
+			$suitableMimeTypes = array_filter(
+				$provider->getSupportedMimeTypes(),
+				function (ConversionMimeTuple $mimeTuple) use ($fileMimeType, $targetMimeType) {
+					['from' => $from, 'to' => $to] = $mimeTuple->jsonSerialize();
+					
+					$supportsTargetMimeType = in_array($targetMimeType, array_column($to, 'mime'));
+					return ($from === $fileMimeType) && $supportsTargetMimeType;
+				}
+			);
+
+			if (!empty($suitableMimeTypes)) {
+				$validProvider = $provider;
+				break;
+			}
+		}
+
+		return $validProvider;
+	}
+}
diff --git a/lib/private/Server.php b/lib/private/Server.php
index a20c37732a7..f806c368eaf 100644
--- a/lib/private/Server.php
+++ b/lib/private/Server.php
@@ -45,6 +45,7 @@ use OC\Files\Cache\FileAccess;
 use OC\Files\Config\MountProviderCollection;
 use OC\Files\Config\UserMountCache;
 use OC\Files\Config\UserMountCacheListener;
+use OC\Files\Conversion\ConversionManager;
 use OC\Files\Lock\LockManager;
 use OC\Files\Mount\CacheMountProvider;
 use OC\Files\Mount\LocalHomeMountProvider;
@@ -155,6 +156,7 @@ use OCP\Federation\ICloudIdManager;
 use OCP\Files\Cache\IFileAccess;
 use OCP\Files\Config\IMountProviderCollection;
 use OCP\Files\Config\IUserMountCache;
+use OCP\Files\Conversion\IConversionManager;
 use OCP\Files\IMimeTypeDetector;
 use OCP\Files\IMimeTypeLoader;
 use OCP\Files\IRootFolder;
@@ -1258,6 +1260,8 @@ class Server extends ServerContainer implements IServerContainer {
 
 		$this->registerAlias(ITranslationManager::class, TranslationManager::class);
 
+		$this->registerAlias(IConversionManager::class, ConversionManager::class);
+
 		$this->registerAlias(ISpeechToTextManager::class, SpeechToTextManager::class);
 
 		$this->registerAlias(IEventSourceFactory::class, EventSourceFactory::class);
diff --git a/lib/public/AppFramework/Bootstrap/IRegistrationContext.php b/lib/public/AppFramework/Bootstrap/IRegistrationContext.php
index 8a18ec8ae9d..011d1520414 100644
--- a/lib/public/AppFramework/Bootstrap/IRegistrationContext.php
+++ b/lib/public/AppFramework/Bootstrap/IRegistrationContext.php
@@ -415,6 +415,19 @@ interface IRegistrationContext {
 	public function registerTaskProcessingTaskType(string $taskProcessingTaskTypeClass): void;
 
 	/**
+	 * Register an implementation of \OCP\Files\Conversion\IConversionProvider
+	 * that will handle the conversion of files from one MIME type to another
+	 *
+	 * @param string $class
+	 * @psalm-param class-string<\OCP\Files\Conversion\IConversionProvider> $class
+	 *
+	 * @return void
+	 *
+	 * @since 31.0.0
+	 */
+	public function registerFileConversionProvider(string $class): void;
+
+	/**
 	 * Register a mail provider
 	 *
 	 * @param string $class
diff --git a/lib/public/Files/Conversion/ConversionMimeTuple.php b/lib/public/Files/Conversion/ConversionMimeTuple.php
new file mode 100644
index 00000000000..0180f3311f3
--- /dev/null
+++ b/lib/public/Files/Conversion/ConversionMimeTuple.php
@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Files\Conversion;
+
+use JsonSerializable;
+
+/**
+ * A tuple-like object representing both an original and target
+ * MIME type for a file conversion
+ *
+ * @since 31.0.0
+ */
+class ConversionMimeTuple implements JsonSerializable {
+	/**
+	 * @param string $from The original MIME type of a file
+	 * @param list<array{mime: string, name: string}> $to The desired MIME type for the file mapped to its translated name
+	 *
+	 * @since 31.0.0
+	 */
+	public function __construct(
+		private string $from,
+		private array $to,
+	) {
+	}
+
+	/**
+	 * @return array{from: string, to: list<array{mime: string, name: string}>}
+	 *
+	 * @since 31.0.0
+	 */
+	public function jsonSerialize(): array {
+		return [
+			'from' => $this->from,
+			'to' => $this->to,
+		];
+	}
+}
diff --git a/lib/public/Files/Conversion/IConversionManager.php b/lib/public/Files/Conversion/IConversionManager.php
new file mode 100644
index 00000000000..59ff580fdf1
--- /dev/null
+++ b/lib/public/Files/Conversion/IConversionManager.php
@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Files\Conversion;
+
+use OCP\Files\File;
+
+/**
+ * @since 31.0.0
+ */
+interface IConversionManager {
+	/**
+	 * Determines whether or not conversion providers are available
+	 *
+	 * @since 31.0.0
+	 */
+	public function hasProviders(): bool;
+
+	/**
+	 * Gets all supported MIME type conversions
+	 *
+	 * @return list<ConversionMimeTuple>
+	 *
+	 * @since 31.0.0
+	 */
+	public function getMimeTypes(): array;
+
+	/**
+	 * Convert a file to a given MIME type
+	 *
+	 * @param File $file The file to be converted
+	 * @param string $targetMimeType The MIME type to convert the file to
+	 * @param ?string $destination The destination to save the converted file
+	 *
+	 * @return string Path to the converted file
+	 *
+	 * @since 31.0.0
+	 */
+	public function convert(File $file, string $targetMimeType, ?string $destination = null): string;
+}
diff --git a/lib/public/Files/Conversion/IConversionProvider.php b/lib/public/Files/Conversion/IConversionProvider.php
new file mode 100644
index 00000000000..b0a09fc93a4
--- /dev/null
+++ b/lib/public/Files/Conversion/IConversionProvider.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\Files\Conversion;
+
+use OCP\Files\File;
+
+/**
+ * This interface is implemented by apps that provide
+ * a file conversion provider
+ *
+ * @since 31.0.0
+ */
+interface IConversionProvider {
+	/**
+	 * Get an array of MIME type tuples this conversion provider supports
+	 *
+	 * @return list<ConversionMimeTuple>
+	 *
+	 * @since 31.0.0
+	 */
+	public function getSupportedMimeTypes(): array;
+
+	/**
+	 * Convert a file to a given MIME type
+	 *
+	 * @param File $file The file to be converted
+	 * @param string $targetMimeType The MIME type to convert the file to
+	 *
+	 * @return resource|string Resource or string content of the file
+	 *
+	 * @since 31.0.0
+	 */
+	public function convertFile(File $file, string $targetMimeType): mixed;
+}