<?php

declare(strict_types=1);

/**
 * @copyright 2018, Roeland Jago Douma <roeland@famdouma.nl>
 *
 * @author Robin Appelman <robin@icewind.nl>
 * @author Roeland Jago Douma <roeland@famdouma.nl>
 *
 * @license GNU AGPL version 3 or any later version
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 *
 */
namespace OCA\Files_Versions\Sabre;

use OCA\Files_Versions\Versions\IVersion;
use OCA\Files_Versions\Versions\IVersionManager;
use OCP\Files\NotFoundException;
use Sabre\DAV\Exception\Forbidden;
use Sabre\DAV\Exception\NotFound;
use Sabre\DAV\IFile;

class VersionFile implements IFile {
	/** @var IVersion */
	private $version;

	/** @var IVersionManager */
	private $versionManager;

	public function __construct(IVersion $version, IVersionManager $versionManager) {
		$this->version = $version;
		$this->versionManager = $versionManager;
	}

	public function put($data) {
		throw new Forbidden();
	}

	public function get() {
		try {
			return $this->versionManager->read($this->version);
		} catch (NotFoundException $e) {
			throw new NotFound();
		}
	}

	public function getContentType(): string {
		return $this->version->getMimeType();
	}

	public function getETag(): string {
		return (string)$this->version->getRevisionId();
	}

	public function getSize(): int {
		return $this->version->getSize();
	}

	public function delete() {
		throw new Forbidden();
	}

	public function getName(): string {
		return (string)$this->version->getRevisionId();
	}

	public function setName($name) {
		throw new Forbidden();
	}

	public function getLastModified(): int {
		return $this->version->getTimestamp();
	}

	public function rollBack() {
		$this->versionManager->rollback($this->version);
	}

	public function getVersion(): IVersion {
		return $this->version;
	}
}
alue='changelog-8.27.6'>changelog-8.27.6</option>
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<option value='dependabot/maven/org.eclipse.jetty-jetty-webapp-9.4.44.v20210927'>dependabot/maven/org.eclipse.jetty-jetty-webapp-9.4.44.v20210927</option>
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<option value='dependabot/maven/org.eclipse.jgit-org.eclipse.jgit-7.2.1.202505142326-r'>dependabot/maven/org.eclipse.jgit-org.eclipse.jgit-7.2.1.202505142326-r</option>
<option value='dependabot/maven/org.hsqldb-hsqldb-2.7.1'>dependabot/maven/org.hsqldb-hsqldb-2.7.1</option>
<option value='documentation'>documentation</option>
<option value='documentation-7.6'>documentation-7.6</option>
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<option value='exclude-element-screenshot'>exclude-element-screenshot</option>
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<option value='feature/elements'>feature/elements</option>
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<option value='feature/karaf-feature-file'>feature/karaf-feature-file</option>
<option value='feature/nullrepresentation'>feature/nullrepresentation</option>
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<option value='feature/vaadin8-sass-valo-only'>feature/vaadin8-sass-valo-only</option>
<option value='fileToFilesReplacement'>fileToFilesReplacement</option>
<option value='fix11576'>fix11576</option>
<option value='fix_event_router_prototype'>fix_event_router_prototype</option>
<option value='grid'>grid</option>
<option value='grid_dnd_autoscroller'>grid_dnd_autoscroller</option>
<option value='grid_dragger'>grid_dragger</option>
<option value='issue/8307_select_using_collection'>issue/8307_select_using_collection</option>
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<option value='vaadin-icons-3.0.1'>vaadin-icons-3.0.1</option>
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.highlight .il { color: #0000DD; font-weight: bold } /* Literal.Number.Integer.Long */</style><div class="highlight"><pre><span></span>---
title: Creating A Component Extension
order: 72
layout: page
---

[[creating-a-component-extension]]
Creating a component extension
------------------------------

In this tutorial we create a simple extension that can be attached to a
`PasswordField`, displaying a floating notification if the user&#39;s Caps
Lock seems to be enabled. We assume the reader is already familiar with
the link:CreatingAUIExtension.asciidoc[Creating a UI extension]
tutorial.

This extension has almost no server-side functionality; the whole Extension
class is as follows:

[source,java]
....
public class CapsLockWarning extends AbstractExtension {
  protected CapsLockWarning(PasswordField field) {
    // Non-public constructor to discourage direct instantiation
    extend(field);
  }

  public static CapsLockWarning warnFor(PasswordField field) {
    return new CapsLockWarning(field);
  }
}
....

When there&#39;s nothing to configure for the extension, users just want to
enable it for some component and be done with it. By defining a static
factory method, the user only needs to do something like
`CapsLockWarning.warnFor(myPasswordField);` to make `myPasswordField`
get the new functionality.

The client side is not overly complicated, either. We override the
`extend` method, called by the framework when the client-side extension
connector is attached to its target the client-side counterpart of the
connector to which the server-side extension instance is attached in
this case, `PasswordFieldConnector`.

We add a key press handler to the password widget, checking if the input
looks like Caps Lock might be enabled. The Caps Lock state cannot be
directly queried in GWT/JavaScript, so we use a trick: check if either

* the shift key was not held but the entered character was uppercase, or
* the shift key _was_ held but the entered character was lowercase.

If this is the case, we show a warning in the form of a floating widget
(`VOverlay`). This demonstrates how an extension may make use of UI
elements even though it is not a part of the layout hierarchy. A
frequent use case for extensions is showing different types of floating
overlay elements that are temporary in character.

[source,java]
....

@Connect(CapsLockWarning.class)
public class CapsLockWarningConnector extends AbstractExtensionConnector {
  @Override
  protected void extend(ServerConnector target) {
    final Widget passwordWidget = ((ComponentConnector) target).getWidget();

    final VOverlay warning = new VOverlay();
    warning.setOwner(passwordWidget);
    warning.add(new HTML(&quot;Caps Lock is enabled!&quot;));

    passwordWidget.addDomHandler(new KeyPressHandler() {
      @Override
      public void onKeyPress(KeyPressEvent event) {
        if (isEnabled() &amp;&amp; isCapsLockOn(event)) {
          warning.showRelativeTo(passwordWidget);
        } else {
          warning.hide();
        }
      }
    }, KeyPressEvent.getType());
  }

  private boolean isCapsLockOn(KeyPressEvent e) {
    return e.isShiftKeyDown() ^ Character.isUpperCase(e.getCharCode());
  }
}
....

To use the Caps Lock warning, compile your widgetset and extend a
PasswordField with something like this

[source,java]
....
PasswordField field = new PasswordField(&quot;Enter your password&quot;);
CapsLockWarning.warnFor(field);
addComponent(field);
....
</pre></div>
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