4 files changed, 231 insertions, 1 deletions
diff --git a/apps/files/src/actions/convertAction.ts b/apps/files/src/actions/convertAction.ts
new file mode 100644
index 00000000000..a8b4d537eb2
--- /dev/null
+++ b/apps/files/src/actions/convertAction.ts
@@ -0,0 +1,81 @@
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+import type { Node, View } from '@nextcloud/files'
+
+import { FileAction, registerFileAction } from '@nextcloud/files'
+import { generateUrl } from '@nextcloud/router'
+import { getCapabilities } from '@nextcloud/capabilities'
+import { t } from '@nextcloud/l10n'
+
+import AutoRenewSvg from '@mdi/svg/svg/autorenew.svg?raw'
+
+import { convertFile, convertFiles, getParentFolder } from './convertUtils'
+
+type ConversionsProvider = {
+	from: string,
+	to: string,
+	displayName: string,
+}
+
+export const ACTION_CONVERT = 'convert'
+export const registerConvertActions = () => {
+	// Generate sub actions
+	const convertProviders = getCapabilities()?.files?.file_conversions as ConversionsProvider[] ?? []
+	const actions = convertProviders.map(({ to, from, displayName }) => {
+		return new FileAction({
+			id: `convert-${from}-${to}`,
+			displayName: () => t('files', 'Save as {displayName}', { displayName }),
+			iconSvgInline: () => generateIconSvg(to),
+			enabled: (nodes: Node[]) => {
+				// Check that all nodes have the same mime type
+				return nodes.every(node => from === node.mime)
+			},
+
+			async exec(node: Node, view: View, dir: string) {
+				// If we're here, we know that the node has a fileid
+				convertFile(node.fileid as number, to, getParentFolder(view, dir))
+
+				// Silently terminate, we'll handle the UI in the background
+				return null
+			},
+
+			async execBatch(nodes: Node[], view: View, dir: string) {
+				const fileIds = nodes.map(node => node.fileid).filter(Boolean) as number[]
+				convertFiles(fileIds, to, getParentFolder(view, dir))
+
+				// Silently terminate, we'll handle the UI in the background
+				return Array(nodes.length).fill(null)
+			},
+
+			parent: ACTION_CONVERT,
+		})
+	})
+
+	// Register main action
+	registerFileAction(new FileAction({
+		id: ACTION_CONVERT,
+		displayName: () => t('files', 'Save as …'),
+		iconSvgInline: () => AutoRenewSvg,
+		enabled: (nodes: Node[], view: View) => {
+			return actions.some(action => action.enabled!(nodes, view))
+		},
+		async exec() {
+			return null
+		},
+		order: 25,
+	}))
+
+	// Register sub actions
+	actions.forEach(registerFileAction)
+}
+
+export const generateIconSvg = (mime: string) => {
+	// Generate icon based on mime type
+	const url = generateUrl('/core/mimeicon?mime=' + encodeURIComponent(mime))
+	return `<svg width="32" height="32" viewBox="0 0 32 32"
+		xmlns="http://www.w3.org/2000/svg">
+		<image href="${url}" height="32" width="32" />
+	</svg>`
+}
diff --git a/apps/files/src/actions/convertUtils.ts b/apps/files/src/actions/convertUtils.ts
new file mode 100644
index 00000000000..f32dbed0cd1
--- /dev/null
+++ b/apps/files/src/actions/convertUtils.ts
@@ -0,0 +1,147 @@
+/**
+ * SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+import type { AxiosResponse } from '@nextcloud/axios'
+import type { Folder, View } from '@nextcloud/files'
+
+import { emit } from '@nextcloud/event-bus'
+import { generateOcsUrl } from '@nextcloud/router'
+import { showError, showLoading, showSuccess } from '@nextcloud/dialogs'
+import { t } from '@nextcloud/l10n'
+import axios from '@nextcloud/axios'
+import PQueue from 'p-queue'
+
+import logger from '../logger'
+import { useFilesStore } from '../store/files'
+import { getPinia } from '../store'
+import { usePathsStore } from '../store/paths'
+
+const queue = new PQueue({ concurrency: 5 })
+
+const requestConversion = function(fileId: number, targetMimeType: string): Promise<AxiosResponse> {
+	return axios.post(generateOcsUrl('/apps/files/api/v1/convert'), {
+		fileId,
+		targetMimeType,
+	})
+}
+
+export const convertFiles = async function(fileIds: number[], targetMimeType: string, parentFolder: Folder | null) {
+	const conversions = fileIds.map(fileId => queue.add(() => requestConversion(fileId, targetMimeType)))
+
+	// Start conversion
+	const toast = showLoading(t('files', 'Converting files…'))
+
+	// Handle results
+	try {
+		const results = await Promise.allSettled(conversions)
+		const failed = results.filter(result => result.status === 'rejected')
+		if (failed.length > 0) {
+			const messages = failed.map(result => result.reason?.response?.data?.ocs?.meta?.message) as string[]
+			logger.error('Failed to convert files', { fileIds, targetMimeType, messages })
+
+			// If all failed files have the same error message, show it
+			if (new Set(messages).size === 1) {
+				showError(t('files', 'Failed to convert files: {message}', { message: messages[0] }))
+				return
+			}
+
+			if (failed.length === fileIds.length) {
+				showError(t('files', 'All files failed to be converted'))
+				return
+			}
+
+			// A single file failed
+			if (failed.length === 1) {
+				// If we have a message for the failed file, show it
+				if (messages[0]) {
+					showError(t('files', 'One file could not be converted: {message}', { message: messages[0] }))
+					return
+				}
+
+				// Otherwise, show a generic error
+				showError(t('files', 'One file could not be converted'))
+				return
+			}
+
+			// We already check above when all files failed
+			// if we're here, we have a mix of failed and successful files
+			showError(t('files', '{count} files could not be converted', { count: failed.length }))
+			showSuccess(t('files', '{count} files successfully converted', { count: fileIds.length - failed.length }))
+			return
+		}
+
+		// All files converted
+		showSuccess(t('files', 'Files successfully converted'))
+
+		// Trigger a reload of the file list
+		if (parentFolder) {
+			emit('files:node:updated', parentFolder)
+		}
+
+		// Switch to the new files
+		const firstSuccess = results[0] as PromiseFulfilledResult<AxiosResponse>
+		const newFileId = firstSuccess.value.data.ocs.data.fileId
+		window.OCP.Files.Router.goToRoute(null, { ...window.OCP.Files.Router.params, fileid: newFileId }, window.OCP.Files.Router.query)
+	} catch (error) {
+		// Should not happen as we use allSettled and handle errors above
+		showError(t('files', 'Failed to convert files'))
+		logger.error('Failed to convert files', { fileIds, targetMimeType, error })
+	} finally {
+		// Hide loading toast
+		toast.hideToast()
+	}
+}
+
+export const convertFile = async function(fileId: number, targetMimeType: string, parentFolder: Folder | null) {
+	const toast = showLoading(t('files', 'Converting file…'))
+
+	try {
+		const result = await queue.add(() => requestConversion(fileId, targetMimeType)) as AxiosResponse
+		showSuccess(t('files', 'File successfully converted'))
+
+		// Trigger a reload of the file list
+		if (parentFolder) {
+			emit('files:node:updated', parentFolder)
+		}
+
+		// Switch to the new file
+		const newFileId = result.data.ocs.data.fileId
+		window.OCP.Files.Router.goToRoute(null, { ...window.OCP.Files.Router.params, fileid: newFileId }, window.OCP.Files.Router.query)
+	} catch (error) {
+		// If the server returned an error message, show it
+		if (error.response?.data?.ocs?.meta?.message) {
+			showError(t('files', 'Failed to convert file: {message}', { message: error.response.data.ocs.meta.message }))
+			return
+		}
+
+		logger.error('Failed to convert file', { fileId, targetMimeType, error })
+		showError(t('files', 'Failed to convert file'))
+	} finally {
+		// Hide loading toast
+		toast.hideToast()
+	}
+}
+
+/**
+ * Get the parent folder of a path
+ *
+ * TODO: replace by the parent node straight away when we
+ * update the Files actions api accordingly.
+ *
+ * @param view The current view
+ * @param path The path to the file
+ * @returns The parent folder
+ */
+export const getParentFolder = function(view: View, path: string): Folder | null {
+	const filesStore = useFilesStore(getPinia())
+	const pathsStore = usePathsStore(getPinia())
+
+	const parentSource = pathsStore.getPath(view.id, path)
+	if (!parentSource) {
+		return null
+	}
+
+	const parentFolder = filesStore.getNode(parentSource) as Folder | undefined
+	return parentFolder ?? null
+}
diff --git a/apps/files/src/init.ts b/apps/files/src/init.ts
index 7080fe09bb3..fd6533c6c23 100644
--- a/apps/files/src/init.ts
+++ b/apps/files/src/init.ts
@@ -32,8 +32,10 @@ import registerPreviewServiceWorker from './services/ServiceWorker.js'
 
 import { initLivePhotos } from './services/LivePhotos'
 import { isPublicShare } from '@nextcloud/sharing/public'
+import { registerConvertActions } from './actions/convertAction.ts'
 
 // Register file actions
+registerConvertActions()
 registerFileAction(deleteAction)
 registerFileAction(downloadAction)
 registerFileAction(editLocallyAction)
diff --git a/apps/files/src/store/files.ts b/apps/files/src/store/files.ts
index 08b5d0757d3..a2413b5a1ba 100644
--- a/apps/files/src/store/files.ts
+++ b/apps/files/src/store/files.ts
@@ -54,7 +54,7 @@ export const useFilesStore = function(...args) {
 
 		actions: {
 			/**
-			 * Get cached nodes within a given path
+			 * Get cached child nodes within a given path
 			 *
 			 * @param service The service (files view)
 			 * @param path The path relative within the service