Implement guest avatar endpoint

Signed-off-by: Michael Weimann <mail@michael-weimann.eu>

4 files changed, 906 insertions, 0 deletions

diff --git a/lib/private/Avatar/Avatar.php b/lib/private/Avatar/Avatar.php
new file mode 100644
index 00000000000..4468af82053
--- /dev/null
+++ b/lib/private/Avatar/Avatar.php
@@ -0,0 +1,318 @@
+<?php
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ * @copyright 2018 John Molakvoæ <skjnldsv@protonmail.com>
+ *
+ * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
+ * @author Christopher Schäpers <kondou@ts.unde.re>
+ * @author Lukas Reschke <lukas@statuscode.ch>
+ * @author Morris Jobke <hey@morrisjobke.de>
+ * @author Olivier Mehani <shtrom@ssji.net>
+ * @author Robin Appelman <robin@icewind.nl>
+ * @author Roeland Jago Douma <roeland@famdouma.nl>
+ * @author Thomas Müller <thomas.mueller@tmit.eu>
+ * @author John Molakvoæ <skjnldsv@protonmail.com>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\Avatar;
+
+use OC\Color;
+use OCP\Files\NotFoundException;
+use OCP\IAvatar;
+use OCP\ILogger;
+use OC_Image;
+use Imagick;
+
+/**
+ * This class gets and sets users avatars.
+ */
+abstract class Avatar implements IAvatar {
+
+	/** @var ILogger  */
+	protected $logger;
+
+	/**
+	 * https://github.com/sebdesign/cap-height -- for 500px height
+	 * Automated check: https://codepen.io/skjnldsv/pen/PydLBK/
+	 * Nunito cap-height is 0.716 and we want a 200px caps height size
+	 * (0.4 letter-to-total-height ratio, 500*0.4=200), so: 200/0.716 = 279px.
+	 * Since we start from the baseline (text-anchor) we need to
+	 * shift the y axis by 100px (half the caps height): 500/2+100=350
+	 *
+	 * @var string
+	 */
+	private $svgTemplate = '<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+		<svg width="{size}" height="{size}" version="1.1" viewBox="0 0 500 500" xmlns="http://www.w3.org/2000/svg">
+			<rect width="100%" height="100%" fill="#{fill}"></rect>
+			<text x="50%" y="350" style="font-weight:normal;font-size:279px;font-family:\'Nunito\';text-anchor:middle;fill:#fff">{letter}</text>
+		</svg>';
+
+	/**
+	 * The base avatar constructor.
+	 *
+	 * @param ILogger $logger The logger
+	 */
+	public function __construct(ILogger $logger) {
+		$this->logger = $logger;
+	}
+
+	/**
+	 * Returns the user display name.
+	 *
+	 * @return string
+	 */
+	abstract public function getDisplayName(): string;
+
+	/**
+	 * Returns the first letter of the display name, or "?" if no name given.
+	 *
+	 * @return string
+	 */
+	private function getAvatarLetter(): string {
+		$displayName = $this->getDisplayName();
+		if (empty($displayName) === true) {
+			return '?';
+		} else {
+			return mb_strtoupper(mb_substr($displayName, 0, 1), 'UTF-8');
+		}
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	public function get($size = 64) {
+		$size = (int) $size;
+
+		try {
+			$file = $this->getFile($size);
+		} catch (NotFoundException $e) {
+			return false;
+		}
+
+		$avatar = new OC_Image();
+		$avatar->loadFromData($file->getContent());
+		return $avatar;
+	}
+
+	/**
+	 * {size} = 500
+	 * {fill} = hex color to fill
+	 * {letter} = Letter to display
+	 *
+	 * Generate SVG avatar
+	 *
+	 * @param int $size The requested image size in pixel
+	 * @return string
+	 *
+	 */
+	protected function getAvatarVector(int $size): string {
+		$userDisplayName = $this->getDisplayName();
+		$bgRGB = $this->avatarBackgroundColor($userDisplayName);
+		$bgHEX = sprintf("%02x%02x%02x", $bgRGB->r, $bgRGB->g, $bgRGB->b);
+		$letter = $this->getAvatarLetter();
+		$toReplace = ['{size}', '{fill}', '{letter}'];
+		return str_replace($toReplace, [$size, $bgHEX, $letter], $this->svgTemplate);
+	}
+
+	/**
+	 * Generate png avatar from svg with Imagick
+	 *
+	 * @param int $size
+	 * @return string|boolean
+	 */
+	protected function generateAvatarFromSvg(int $size) {
+		if (!extension_loaded('imagick')) {
+			return false;
+		}
+		try {
+			$font = __DIR__ . '/../../core/fonts/Nunito-Regular.ttf';
+			$svg = $this->getAvatarVector($size);
+			$avatar = new Imagick();
+			$avatar->setFont($font);
+			$avatar->readImageBlob($svg);
+			$avatar->setImageFormat('png');
+			$image = new OC_Image();
+			$image->loadFromData($avatar);
+			return $image->data();
+		} catch (\Exception $e) {
+			return false;
+		}
+	}
+
+	/**
+	 * Generate png avatar with GD
+	 *
+	 * @param string $userDisplayName
+	 * @param int $size
+	 * @return string
+	 */
+	protected function generateAvatar($userDisplayName, $size) {
+		$letter = $this->getAvatarLetter();
+		$backgroundColor = $this->avatarBackgroundColor($userDisplayName);
+
+		$im = imagecreatetruecolor($size, $size);
+		$background = imagecolorallocate(
+			$im,
+			$backgroundColor->r,
+			$backgroundColor->g,
+			$backgroundColor->b
+		);
+		$white = imagecolorallocate($im, 255, 255, 255);
+		imagefilledrectangle($im, 0, 0, $size, $size, $background);
+
+		$font = __DIR__ . '/../../../core/fonts/Nunito-Regular.ttf';
+
+		$fontSize = $size * 0.4;
+		list($x, $y) = $this->imageTTFCenter(
+			$im, $letter, $font, (int)$fontSize
+		);
+
+		imagettftext($im, $fontSize, 0, $x, $y, $white, $font, $letter);
+
+		ob_start();
+		imagepng($im);
+		$data = ob_get_contents();
+		ob_end_clean();
+
+		return $data;
+	}
+
+	/**
+	 * Calculate real image ttf center
+	 *
+	 * @param resource $image
+	 * @param string $text text string
+	 * @param string $font font path
+	 * @param int $size font size
+	 * @param int $angle
+	 * @return array
+	 */
+	protected function imageTTFCenter(
+		$image,
+		string $text,
+		string $font,
+		int $size,
+		$angle = 0
+	): array {
+		// Image width & height
+		$xi = imagesx($image);
+		$yi = imagesy($image);
+
+		// bounding box
+		$box = imagettfbbox($size, $angle, $font, $text);
+
+		// imagettfbbox can return negative int
+		$xr = abs(max($box[2], $box[4]));
+		$yr = abs(max($box[5], $box[7]));
+
+		// calculate bottom left placement
+		$x = intval(($xi - $xr) / 2);
+		$y = intval(($yi + $yr) / 2);
+
+		return array($x, $y);
+	}
+
+	/**
+	 * Calculate steps between two Colors
+	 * @param object Color $steps start color
+	 * @param object Color $ends end color
+	 * @return array [r,g,b] steps for each color to go from $steps to $ends
+	 */
+	private function stepCalc($steps, $ends) {
+		$step = array();
+		$step[0] = ($ends[1]->r - $ends[0]->r) / $steps;
+		$step[1] = ($ends[1]->g - $ends[0]->g) / $steps;
+		$step[2] = ($ends[1]->b - $ends[0]->b) / $steps;
+		return $step;
+	}
+
+	/**
+	 * Convert a string to an integer evenly
+	 * @param string $hash the text to parse
+	 * @param int $maximum the maximum range
+	 * @return int[] between 0 and $maximum
+	 */
+	private function mixPalette($steps, $color1, $color2) {
+		$palette = array($color1);
+		$step = $this->stepCalc($steps, [$color1, $color2]);
+		for ($i = 1; $i < $steps; $i++) {
+			$r = intval($color1->r + ($step[0] * $i));
+			$g = intval($color1->g + ($step[1] * $i));
+			$b = intval($color1->b + ($step[2] * $i));
+			$palette[] = new Color($r, $g, $b);
+		}
+		return $palette;
+	}
+
+	/**
+	 * Convert a string to an integer evenly
+	 * @param string $hash the text to parse
+	 * @param int $maximum the maximum range
+	 * @return int between 0 and $maximum
+	 */
+	private function hashToInt($hash, $maximum) {
+		$final = 0;
+		$result = array();
+
+		// Splitting evenly the string
+		for ($i = 0; $i < strlen($hash); $i++) {
+			// chars in md5 goes up to f, hex:16
+			$result[] = intval(substr($hash, $i, 1), 16) % 16;
+		}
+		// Adds up all results
+		foreach ($result as $value) {
+			$final += $value;
+		}
+		// chars in md5 goes up to f, hex:16
+		return intval($final % $maximum);
+	}
+
+	/**
+	 * @param string $hash
+	 * @return Color Object containting r g b int in the range [0, 255]
+	 */
+	public function avatarBackgroundColor(string $hash) {
+		// Normalize hash
+		$hash = strtolower($hash);
+
+		// Already a md5 hash?
+		if( preg_match('/^([0-9a-f]{4}-?){8}$/', $hash, $matches) !== 1 ) {
+			$hash = md5($hash);
+		}
+
+		// Remove unwanted char
+		$hash = preg_replace('/[^0-9a-f]+/', '', $hash);
+
+		$red = new Color(182, 70, 157);
+		$yellow = new Color(221, 203, 85);
+		$blue = new Color(0, 130, 201); // Nextcloud blue
+
+		// Number of steps to go from a color to another
+		// 3 colors * 6 will result in 18 generated colors
+		$steps = 6;
+
+		$palette1 = $this->mixPalette($steps, $red, $yellow);
+		$palette2 = $this->mixPalette($steps, $yellow, $blue);
+		$palette3 = $this->mixPalette($steps, $blue, $red);
+
+		$finalPalette = array_merge($palette1, $palette2, $palette3);
+
+		return $finalPalette[$this->hashToInt($hash, $steps * 3)];
+	}
+}
diff --git a/lib/private/Avatar/AvatarManager.php b/lib/private/Avatar/AvatarManager.php
new file mode 100644
index 00000000000..567ed3aec1e
--- /dev/null
+++ b/lib/private/Avatar/AvatarManager.php
@@ -0,0 +1,133 @@
+<?php
+declare(strict_types=1);
+/**
+ * @copyright Copyright (c) 2016, ownCloud, Inc.
+ *
+ * @author Arthur Schiwon <blizzz@arthur-schiwon.de>
+ * @author Lukas Reschke <lukas@statuscode.ch>
+ * @author Morris Jobke <hey@morrisjobke.de>
+ * @author Robin Appelman <robin@icewind.nl>
+ * @author Roeland Jago Douma <roeland@famdouma.nl>
+ * @author Thomas Müller <thomas.mueller@tmit.eu>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OC\Avatar;
+
+use OC\User\Manager;
+use OCP\Files\IAppData;
+use OCP\Files\NotFoundException;
+use OCP\IAvatar;
+use OCP\IAvatarManager;
+use OCP\IConfig;
+use OCP\ILogger;
+use OCP\IL10N;
+
+/**
+ * This class implements methods to access Avatar functionality
+ */
+class AvatarManager implements IAvatarManager {
+
+	/** @var Manager */
+	private $userManager;
+
+	/** @var IAppData */
+	private $appData;
+
+	/** @var IL10N */
+	private $l;
+
+	/** @var ILogger  */
+	private $logger;
+
+	/** @var IConfig */
+	private $config;
+
+	/**
+	 * AvatarManager constructor.
+	 *
+	 * @param Manager $userManager
+	 * @param IAppData $appData
+	 * @param IL10N $l
+	 * @param ILogger $logger
+	 * @param IConfig $config
+	 */
+	public function __construct(
+			Manager $userManager,
+			IAppData $appData,
+			IL10N $l,
+			ILogger $logger,
+			IConfig $config) {
+		$this->userManager = $userManager;
+		$this->appData = $appData;
+		$this->l = $l;
+		$this->logger = $logger;
+		$this->config = $config;
+	}
+
+	/**
+	 * return a user specific instance of \OCP\IAvatar
+	 * @see \OCP\IAvatar
+	 * @param string $userId the ownCloud user id
+	 * @return \OCP\IAvatar
+	 * @throws \Exception In case the username is potentially dangerous
+	 * @throws NotFoundException In case there is no user folder yet
+	 */
+	public function getAvatar(string $userId) : IAvatar {
+		$user = $this->userManager->get($userId);
+		if ($user === null) {
+			throw new \Exception('user does not exist');
+		}
+
+		// sanitize userID - fixes casing issue (needed for the filesystem stuff that is done below)
+		$userId = $user->getUID();
+
+		try {
+			$folder = $this->appData->getFolder($userId);
+		} catch (NotFoundException $e) {
+			$folder = $this->appData->newFolder($userId);
+		}
+
+		return new UserAvatar($folder, $this->l, $user, $this->logger, $this->config);
+	}
+
+	/**
+	 * Clear generated avatars
+	 */
+	public function clearCachedAvatars() {
+		$users = $this->config->getUsersForUserValue('avatar', 'generated', 'true');
+		foreach($users as $userId) {
+			try {
+				$folder = $this->appData->getFolder($userId);
+				$folder->delete();
+			} catch (NotFoundException $e) {
+				$this->logger->debug("No cache for the user $userId. Ignoring...");
+			}
+			$this->config->setUserValue($userId, 'avatar', 'generated', 'false');
+		}
+	}
+
+	/**
+	 * Returns a GuestAvatar.
+	 *
+	 * @param string $name The guest name, e.g. "Albert".
+	 * @return IAvatar
+	 */
+	public function getGuestAvatar(string $name): IAvatar {
+		return new GuestAvatar($name, $this->logger);
+	}
+}
diff --git a/lib/private/Avatar/GuestAvatar.php b/lib/private/Avatar/GuestAvatar.php
new file mode 100644
index 00000000000..e0eefa47b6b
--- /dev/null
+++ b/lib/private/Avatar/GuestAvatar.php
@@ -0,0 +1,119 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2018, Michael Weimann <mail@michael-weimann.eu>
+ *
+ * @author Michael Weimann <mail@michael-weimann.eu>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+namespace OC\Avatar;
+
+use OCP\Files\SimpleFS\InMemoryFile;
+use OCP\ILogger;
+
+/**
+ * This class represents a guest user's avatar.
+ */
+class GuestAvatar extends Avatar {
+	/**
+	 * Holds the guest user display name.
+	 *
+	 * @var string
+	 */
+	private $userDisplayName;
+
+	/**
+	 * GuestAvatar constructor.
+	 *
+	 * @param string $userDisplayName The guest user display name
+	 * @param ILogger $logger The logger
+	 */
+	public function __construct(string $userDisplayName, ILogger $logger) {
+		parent::__construct($logger);
+		$this->userDisplayName = $userDisplayName;
+	}
+
+	/**
+	 * Tests if the user has an avatar.
+	 *
+	 * @return true Guests always have an avatar.
+	 */
+	public function exists() {
+		return true;
+	}
+
+	/**
+	 * Returns the guest user display name.
+	 *
+	 * @return string
+	 */
+	public function getDisplayName(): string {
+		return $this->userDisplayName;
+	}
+
+	/**
+	 * Setting avatars isn't implemented for guests.
+	 *
+	 * @param \OCP\IImage|resource|string $data
+	 * @return void
+	 */
+	public function set($data) {
+		// unimplemented for guest user avatars
+	}
+
+	/**
+	 * Removing avatars isn't implemented for guests.
+	 */
+	public function remove() {
+		// unimplemented for guest user avatars
+	}
+
+	/**
+	 * Generates an avatar for the guest.
+	 *
+	 * @param int $size The desired image size.
+	 * @return InMemoryFile
+	 */
+	public function getFile($size) {
+		$avatar = $this->getAvatarVector($size);
+		return new InMemoryFile('avatar.svg', $avatar);
+	}
+
+	/**
+	 * Updates the display name if changed.
+	 *
+	 * @param string $feature The changed feature
+	 * @param mixed $oldValue The previous value
+	 * @param mixed $newValue The new value
+	 * @return void
+	 */
+	public function userChanged($feature, $oldValue, $newValue) {
+		if ($feature === 'displayName') {
+			$this->userDisplayName = $newValue;
+		}
+	}
+
+	/**
+	 * Guests don't have custom avatars.
+	 *
+	 * @return bool
+	 */
+	public function isCustomAvatar(): bool {
+		return false;
+	}
+}
diff --git a/lib/private/Avatar/UserAvatar.php b/lib/private/Avatar/UserAvatar.php
new file mode 100644
index 00000000000..db5e041d66c
--- /dev/null
+++ b/lib/private/Avatar/UserAvatar.php
@@ -0,0 +1,336 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * @copyright Copyright (c) 2018, Michael Weimann <mail@michael-weimann.eu>
+ *
+ * @author Michael Weimann <mail@michael-weimann.eu>
+ *
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * 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, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+namespace OC\Avatar;
+
+use OC\NotSquareException;
+use OC\User\User;
+use OC_Image;
+use OCP\Files\NotFoundException;
+use OCP\Files\NotPermittedException;
+use OCP\Files\SimpleFS\ISimpleFile;
+use OCP\Files\SimpleFS\ISimpleFolder;
+use OCP\IConfig;
+use OCP\IImage;
+use OCP\IL10N;
+use OCP\ILogger;
+
+/**
+ * This class represents a registered user's avatar.
+ */
+class UserAvatar extends Avatar {
+	/** @var IConfig */
+	private $config;
+
+	/** @var ISimpleFolder */
+	private $folder;
+
+	/** @var IL10N */
+	private $l;
+
+	/** @var User */
+	private $user;
+
+	/**
+	 * UserAvatar constructor.
+	 *
+	 * @param IConfig $config The configuration
+	 * @param ISimpleFolder $folder The avatar files folder
+	 * @param IL10N $l The localization helper
+	 * @param User $user The user this class manages the avatar for
+	 * @param ILogger $logger The logger
+	 */
+	public function __construct(
+		ISimpleFolder $folder,
+		IL10N $l,
+		$user,
+		ILogger $logger,
+		IConfig $config) {
+		parent::__construct($logger);
+		$this->folder = $folder;
+		$this->l = $l;
+		$this->user = $user;
+		$this->config = $config;
+	}
+
+	/**
+	 * Check if an avatar exists for the user
+	 *
+	 * @return bool
+	 */
+	public function exists() {
+		return $this->folder->fileExists('avatar.jpg') || $this->folder->fileExists('avatar.png');
+	}
+
+	/**
+	 * Sets the users avatar.
+	 *
+	 * @param IImage|resource|string $data An image object, imagedata or path to set a new avatar
+	 * @throws \Exception if the provided file is not a jpg or png image
+	 * @throws \Exception if the provided image is not valid
+	 * @throws NotSquareException if the image is not square
+	 * @return void
+	 */
+	public function set($data) {
+		$img = $this->getAvatarImage($data);
+		$data = $img->data();
+
+		$this->validateAvatar($img);
+
+		$this->remove();
+		$type = $this->getAvatarImageType($img);
+		$file = $this->folder->newFile('avatar.' . $type);
+		$file->putContent($data);
+
+		try {
+			$generated = $this->folder->getFile('generated');
+			$this->config->setUserValue($this->user->getUID(), 'avatar', 'generated', 'false');
+			$generated->delete();
+		} catch (NotFoundException $e) {
+			//
+		}
+
+		$this->user->triggerChange('avatar', $file);
+	}
+
+	/**
+	 * Returns an image from several sources.
+	 *
+	 * @param IImage|resource|string $data An image object, imagedata or path to the avatar
+	 * @return IImage
+	 */
+	private function getAvatarImage($data) {
+		if ($data instanceof IImage) {
+			return $data;
+		}
+
+		$img = new OC_Image();
+		if (is_resource($data) && get_resource_type($data) === 'gd') {
+			$img->setResource($data);
+		} elseif (is_resource($data)) {
+			$img->loadFromFileHandle($data);
+		} else {
+			try {
+				// detect if it is a path or maybe the images as string
+				$result = @realpath($data);
+				if ($result === false || $result === null) {
+					$img->loadFromData($data);
+				} else {
+					$img->loadFromFile($data);
+				}
+			} catch (\Error $e) {
+				$img->loadFromData($data);
+			}
+		}
+
+		return $img;
+	}
+
+	/**
+	 * Returns the avatar image type.
+	 *
+	 * @param IImage $avatar
+	 * @return string
+	 */
+	private function getAvatarImageType(IImage $avatar) {
+		$type = substr($avatar->mimeType(), -3);
+		if ($type === 'peg') {
+			$type = 'jpg';
+		}
+		return $type;
+	}
+
+	/**
+	 * Validates an avatar image:
+	 * - must be "png" or "jpg"
+	 * - must be "valid"
+	 * - must be in square format
+	 *
+	 * @param IImage $avatar The avatar to validate
+	 * @throws \Exception if the provided file is not a jpg or png image
+	 * @throws \Exception if the provided image is not valid
+	 * @throws NotSquareException if the image is not square
+	 */
+	private function validateAvatar(IImage $avatar) {
+		$type = $this->getAvatarImageType($avatar);
+
+		if ($type !== 'jpg' && $type !== 'png') {
+			throw new \Exception($this->l->t('Unknown filetype'));
+		}
+
+		if (!$avatar->valid()) {
+			throw new \Exception($this->l->t('Invalid image'));
+		}
+
+		if (!($avatar->height() === $avatar->width())) {
+			throw new NotSquareException($this->l->t('Avatar image is not square'));
+		}
+	}
+
+	/**
+	 * Removes the users avatar.
+	 * @return void
+	 * @throws \OCP\Files\NotPermittedException
+	 * @throws \OCP\PreConditionNotMetException
+	 */
+	public function remove() {
+		$avatars = $this->folder->getDirectoryListing();
+
+		$this->config->setUserValue($this->user->getUID(), 'avatar', 'version',
+			(int) $this->config->getUserValue($this->user->getUID(), 'avatar', 'version', 0) + 1);
+
+		foreach ($avatars as $avatar) {
+			$avatar->delete();
+		}
+		$this->config->setUserValue($this->user->getUID(), 'avatar', 'generated', 'true');
+		$this->user->triggerChange('avatar', '');
+	}
+
+	/**
+	 * Get the extension of the avatar. If there is no avatar throw Exception
+	 *
+	 * @return string
+	 * @throws NotFoundException
+	 */
+	private function getExtension() {
+		if ($this->folder->fileExists('avatar.jpg')) {
+			return 'jpg';
+		} elseif ($this->folder->fileExists('avatar.png')) {
+			return 'png';
+		}
+		throw new NotFoundException;
+	}
+
+	/**
+	 * Returns the avatar for an user.
+	 *
+	 * If there is no avatar file yet, one is generated.
+	 *
+	 * @param int $size
+	 * @return ISimpleFile
+	 * @throws NotFoundException
+	 * @throws \OCP\Files\NotPermittedException
+	 * @throws \OCP\PreConditionNotMetException
+	 */
+	public function getFile($size) {
+		$size = (int) $size;
+
+		try {
+			$ext = $this->getExtension();
+		} catch (NotFoundException $e) {
+			if (!$data = $this->generateAvatarFromSvg(1024)) {
+				$data = $this->generateAvatar($this->getDisplayName(), 1024);
+			}
+			$avatar = $this->folder->newFile('avatar.png');
+			$avatar->putContent($data);
+			$ext = 'png';
+
+			$this->folder->newFile('generated');
+			$this->config->setUserValue($this->user->getUID(), 'avatar', 'generated', 'true');
+		}
+
+		if ($size === -1) {
+			$path = 'avatar.' . $ext;
+		} else {
+			$path = 'avatar.' . $size . '.' . $ext;
+		}
+
+		try {
+			$file = $this->folder->getFile($path);
+		} catch (NotFoundException $e) {
+			if ($size <= 0) {
+				throw new NotFoundException;
+			}
+
+			if ($this->folder->fileExists('generated')) {
+				if (!$data = $this->generateAvatarFromSvg($size)) {
+					$data = $this->generateAvatar($this->getDisplayName(), $size);
+				}
+
+			} else {
+				$avatar = new OC_Image();
+				$file = $this->folder->getFile('avatar.' . $ext);
+				$avatar->loadFromData($file->getContent());
+				$avatar->resize($size);
+				$data = $avatar->data();
+			}
+
+			try {
+				$file = $this->folder->newFile($path);
+				$file->putContent($data);
+			} catch (NotPermittedException $e) {
+				$this->logger->error('Failed to save avatar for ' . $this->user->getUID());
+				throw new NotFoundException();
+			}
+
+		}
+
+		if ($this->config->getUserValue($this->user->getUID(), 'avatar', 'generated', null) === null) {
+			$generated = $this->folder->fileExists('generated') ? 'true' : 'false';
+			$this->config->setUserValue($this->user->getUID(), 'avatar', 'generated', $generated);
+		}
+
+		return $file;
+	}
+
+	/**
+	 * Returns the user display name.
+	 *
+	 * @return string
+	 */
+	public function getDisplayName(): string {
+		return $this->user->getDisplayName();
+	}
+
+	/**
+	 * Handles user changes.
+	 *
+	 * @param string $feature The changed feature
+	 * @param mixed $oldValue The previous value
+	 * @param mixed $newValue The new value
+	 * @throws NotPermittedException
+	 * @throws \OCP\PreConditionNotMetException
+	 */
+	public function userChanged($feature, $oldValue, $newValue) {
+		// We only change the avatar on display name changes
+		if ($feature !== 'displayName') {
+			return;
+		}
+
+		// If the avatar is not generated (so an uploaded image) we skip this
+		if (!$this->folder->fileExists('generated')) {
+			return;
+		}
+
+		$this->remove();
+	}
+
+	/**
+	 * Check if the avatar of a user is a custom uploaded one
+	 *
+	 * @return bool
+	 */
+	public function isCustomAvatar(): bool {
+		return $this->config->getUserValue($this->user->getUID(), 'avatar', 'generated', 'false') !== 'true';
+	}
+}