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lib/plugin-update-checker/Puc/v5p3/Vcs/Api.php

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+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+use Parsedown;
+use PucReadmeParser;
+
+if ( !class_exists(Api::class, false) ):
+
+	abstract class Api {
+		const STRATEGY_LATEST_RELEASE = 'latest_release';
+		const STRATEGY_LATEST_TAG = 'latest_tag';
+		const STRATEGY_STABLE_TAG = 'stable_tag';
+		const STRATEGY_BRANCH = 'branch';
+
+		/**
+		 * Consider all releases regardless of their version number or prerelease/upcoming
+		 * release status.
+		 */
+		const RELEASE_FILTER_ALL = 3;
+
+		/**
+		 * Exclude releases that have the "prerelease" or "upcoming release" flag.
+		 *
+		 * This does *not* look for prerelease keywords like "beta" in the version number.
+		 * It only uses the data provided by the API. For example, on GitHub, you can
+		 * manually mark a release as a prerelease.
+		 */
+		const RELEASE_FILTER_SKIP_PRERELEASE = 1;
+
+		/**
+		 * If there are no release assets or none of them match the configured filter,
+		 * fall back to the automatically generated source code archive.
+		 */
+		const PREFER_RELEASE_ASSETS = 1;
+		/**
+		 * Skip releases that don't have any matching release assets.
+		 */
+		const REQUIRE_RELEASE_ASSETS = 2;
+
+		protected $tagNameProperty = 'name';
+		protected $slug = '';
+
+		/**
+		 * @var string
+		 */
+		protected $repositoryUrl = '';
+
+		/**
+		 * @var mixed Authentication details for private repositories. Format depends on service.
+		 */
+		protected $credentials = null;
+
+		/**
+		 * @var string The filter tag that's used to filter options passed to wp_remote_get.
+		 * For example, "puc_request_info_options-slug" or "puc_request_update_options_theme-slug".
+		 */
+		protected $httpFilterName = '';
+
+		/**
+		 * @var string The filter applied to the list of update detection strategies that
+		 * are used to find the latest version.
+		 */
+		protected $strategyFilterName = '';
+
+		/**
+		 * @var string|null
+		 */
+		protected $localDirectory = null;
+
+		/**
+		 * Api constructor.
+		 *
+		 * @param string $repositoryUrl
+		 * @param array|string|null $credentials
+		 */
+		public function __construct($repositoryUrl, $credentials = null) {
+			$this->repositoryUrl = $repositoryUrl;
+			$this->setAuthentication($credentials);
+		}
+
+		/**
+		 * @return string
+		 */
+		public function getRepositoryUrl() {
+			return $this->repositoryUrl;
+		}
+
+		/**
+		 * Figure out which reference (i.e. tag or branch) contains the latest version.
+		 *
+		 * @param string $configBranch Start looking in this branch.
+		 * @return null|Reference
+		 */
+		public function chooseReference($configBranch) {
+			$strategies = $this->getUpdateDetectionStrategies($configBranch);
+
+			if ( !empty($this->strategyFilterName) ) {
+				$strategies = apply_filters(
+					$this->strategyFilterName,
+					$strategies,
+					$this->slug
+				);
+			}
+
+			foreach ($strategies as $strategy) {
+				$reference = call_user_func($strategy);
+				if ( !empty($reference) ) {
+					return $reference;
+				}
+			}
+			return null;
+		}
+
+		/**
+		 * Get an ordered list of strategies that can be used to find the latest version.
+		 *
+		 * The update checker will try each strategy in order until one of them
+		 * returns a valid reference.
+		 *
+		 * @param string $configBranch
+		 * @return array<callable> Array of callables that return Vcs_Reference objects.
+		 */
+		abstract protected function getUpdateDetectionStrategies($configBranch);
+
+		/**
+		 * Get the readme.txt file from the remote repository and parse it
+		 * according to the plugin readme standard.
+		 *
+		 * @param string $ref Tag or branch name.
+		 * @return array Parsed readme.
+		 */
+		public function getRemoteReadme($ref = 'master') {
+			$fileContents = $this->getRemoteFile($this->getLocalReadmeName(), $ref);
+			if ( empty($fileContents) ) {
+				return array();
+			}
+
+			$parser = new PucReadmeParser();
+			return $parser->parse_readme_contents($fileContents);
+		}
+
+		/**
+		 * Get the case-sensitive name of the local readme.txt file.
+		 *
+		 * In most cases it should just be called "readme.txt", but some plugins call it "README.txt",
+		 * "README.TXT", or even "Readme.txt". Most VCS are case-sensitive so we need to know the correct
+		 * capitalization.
+		 *
+		 * Defaults to "readme.txt" (all lowercase).
+		 *
+		 * @return string
+		 */
+		public function getLocalReadmeName() {
+			static $fileName = null;
+			if ( $fileName !== null ) {
+				return $fileName;
+			}
+
+			$fileName = 'readme.txt';
+			if ( isset($this->localDirectory) ) {
+				$files = scandir($this->localDirectory);
+				if ( !empty($files) ) {
+					foreach ($files as $possibleFileName) {
+						if ( strcasecmp($possibleFileName, 'readme.txt') === 0 ) {
+							$fileName = $possibleFileName;
+							break;
+						}
+					}
+				}
+			}
+			return $fileName;
+		}
+
+		/**
+		 * Get a branch.
+		 *
+		 * @param string $branchName
+		 * @return Reference|null
+		 */
+		abstract public function getBranch($branchName);
+
+		/**
+		 * Get a specific tag.
+		 *
+		 * @param string $tagName
+		 * @return Reference|null
+		 */
+		abstract public function getTag($tagName);
+
+		/**
+		 * Get the tag that looks like the highest version number.
+		 * (Implementations should skip pre-release versions if possible.)
+		 *
+		 * @return Reference|null
+		 */
+		abstract public function getLatestTag();
+
+		/**
+		 * Check if a tag name string looks like a version number.
+		 *
+		 * @param string $name
+		 * @return bool
+		 */
+		protected function looksLikeVersion($name) {
+			//Tag names may be prefixed with "v", e.g. "v1.2.3".
+			$name = ltrim($name, 'v');
+
+			//The version string must start with a number.
+			if ( !is_numeric(substr($name, 0, 1)) ) {
+				return false;
+			}
+
+			//The goal is to accept any SemVer-compatible or "PHP-standardized" version number.
+			return (preg_match('@^(\d{1,5}?)(\.\d{1,10}?){0,4}?($|[abrdp+_\-]|\s)@i', $name) === 1);
+		}
+
+		/**
+		 * Check if a tag appears to be named like a version number.
+		 *
+		 * @param \stdClass $tag
+		 * @return bool
+		 */
+		protected function isVersionTag($tag) {
+			$property = $this->tagNameProperty;
+			return isset($tag->$property) && $this->looksLikeVersion($tag->$property);
+		}
+
+		/**
+		 * Sort a list of tags as if they were version numbers.
+		 * Tags that don't look like version number will be removed.
+		 *
+		 * @param \stdClass[] $tags Array of tag objects.
+		 * @return \stdClass[] Filtered array of tags sorted in descending order.
+		 */
+		protected function sortTagsByVersion($tags) {
+			//Keep only those tags that look like version numbers.
+			$versionTags = array_filter($tags, array($this, 'isVersionTag'));
+			//Sort them in descending order.
+			usort($versionTags, array($this, 'compareTagNames'));
+
+			return $versionTags;
+		}
+
+		/**
+		 * Compare two tags as if they were version number.
+		 *
+		 * @param \stdClass $tag1 Tag object.
+		 * @param \stdClass $tag2 Another tag object.
+		 * @return int
+		 */
+		protected function compareTagNames($tag1, $tag2) {
+			$property = $this->tagNameProperty;
+			if ( !isset($tag1->$property) ) {
+				return 1;
+			}
+			if ( !isset($tag2->$property) ) {
+				return -1;
+			}
+			return -version_compare(ltrim($tag1->$property, 'v'), ltrim($tag2->$property, 'v'));
+		}
+
+		/**
+		 * Get the contents of a file from a specific branch or tag.
+		 *
+		 * @param string $path File name.
+		 * @param string $ref
+		 * @return null|string Either the contents of the file, or null if the file doesn't exist or there's an error.
+		 */
+		abstract public function getRemoteFile($path, $ref = 'master');
+
+		/**
+		 * Get the timestamp of the latest commit that changed the specified branch or tag.
+		 *
+		 * @param string $ref Reference name (e.g. branch or tag).
+		 * @return string|null
+		 */
+		abstract public function getLatestCommitTime($ref);
+
+		/**
+		 * Get the contents of the changelog file from the repository.
+		 *
+		 * @param string $ref
+		 * @param string $localDirectory Full path to the local plugin or theme directory.
+		 * @return null|string The HTML contents of the changelog.
+		 */
+		public function getRemoteChangelog($ref, $localDirectory) {
+			$filename = $this->findChangelogName($localDirectory);
+			if ( empty($filename) ) {
+				return null;
+			}
+
+			$changelog = $this->getRemoteFile($filename, $ref);
+			if ( $changelog === null ) {
+				return null;
+			}
+
+			return Parsedown::instance()->text($changelog);
+		}
+
+		/**
+		 * Guess the name of the changelog file.
+		 *
+		 * @param string $directory
+		 * @return string|null
+		 */
+		protected function findChangelogName($directory = null) {
+			if ( !isset($directory) ) {
+				$directory = $this->localDirectory;
+			}
+			if ( empty($directory) || !is_dir($directory) || ($directory === '.') ) {
+				return null;
+			}
+
+			$possibleNames = array('CHANGES.md', 'CHANGELOG.md', 'changes.md', 'changelog.md');
+			$files = scandir($directory);
+			$foundNames = array_intersect($possibleNames, $files);
+
+			if ( !empty($foundNames) ) {
+				return reset($foundNames);
+			}
+			return null;
+		}
+
+		/**
+		 * Set authentication credentials.
+		 *
+		 * @param $credentials
+		 */
+		public function setAuthentication($credentials) {
+			$this->credentials = $credentials;
+		}
+
+		public function isAuthenticationEnabled() {
+			return !empty($this->credentials);
+		}
+
+		/**
+		 * @param string $url
+		 * @return string
+		 */
+		public function signDownloadUrl($url) {
+			return $url;
+		}
+
+		/**
+		 * @param string $filterName
+		 */
+		public function setHttpFilterName($filterName) {
+			$this->httpFilterName = $filterName;
+		}
+
+		/**
+		 * @param string $filterName
+		 */
+		public function setStrategyFilterName($filterName) {
+			$this->strategyFilterName = $filterName;
+		}
+
+		/**
+		 * @param string $directory
+		 */
+		public function setLocalDirectory($directory) {
+			if ( empty($directory) || !is_dir($directory) || ($directory === '.') ) {
+				$this->localDirectory = null;
+			} else {
+				$this->localDirectory = $directory;
+			}
+		}
+
+		/**
+		 * @param string $slug
+		 */
+		public function setSlug($slug) {
+			$this->slug = $slug;
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/BaseChecker.php

@@ -0,0 +1,29 @@
+<?php
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+if ( !interface_exists(BaseChecker::class, false) ):
+
+	interface BaseChecker {
+		/**
+		 * Set the repository branch to use for updates. Defaults to 'master'.
+		 *
+		 * @param string $branch
+		 * @return $this
+		 */
+		public function setBranch($branch);
+
+		/**
+		 * Set authentication credentials.
+		 *
+		 * @param array|string $credentials
+		 * @return $this
+		 */
+		public function setAuthentication($credentials);
+
+		/**
+		 * @return Api
+		 */
+		public function getVcsApi();
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/BitBucketApi.php

@@ -0,0 +1,272 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+use YahnisElsts\PluginUpdateChecker\v5p3\OAuthSignature;
+use YahnisElsts\PluginUpdateChecker\v5p3\Utils;
+
+if ( !class_exists(BitBucketApi::class, false) ):
+
+	class BitBucketApi extends Api {
+		/**
+		 * @var OAuthSignature
+		 */
+		private $oauth = null;
+
+		/**
+		 * @var string
+		 */
+		private $username;
+
+		/**
+		 * @var string
+		 */
+		private $repository;
+
+		public function __construct($repositoryUrl, $credentials = array()) {
+			$path = wp_parse_url($repositoryUrl, PHP_URL_PATH);
+			if ( preg_match('@^/?(?P<username>[^/]+?)/(?P<repository>[^/#?&]+?)/?$@', $path, $matches) ) {
+				$this->username = $matches['username'];
+				$this->repository = $matches['repository'];
+			} else {
+				throw new \InvalidArgumentException('Invalid BitBucket repository URL: "' . $repositoryUrl . '"');
+			}
+
+			parent::__construct($repositoryUrl, $credentials);
+		}
+
+		protected function getUpdateDetectionStrategies($configBranch) {
+			$strategies = array(
+				self::STRATEGY_STABLE_TAG => function () use ($configBranch) {
+					return $this->getStableTag($configBranch);
+				},
+			);
+
+			if ( ($configBranch === 'master' || $configBranch === 'main') ) {
+				$strategies[self::STRATEGY_LATEST_TAG] = array($this, 'getLatestTag');
+			}
+
+			$strategies[self::STRATEGY_BRANCH] = function () use ($configBranch) {
+				return $this->getBranch($configBranch);
+			};
+			return $strategies;
+		}
+
+		public function getBranch($branchName) {
+			$branch = $this->api('/refs/branches/' . $branchName);
+			if ( is_wp_error($branch) || empty($branch) ) {
+				return null;
+			}
+
+			//The "/src/{stuff}/{path}" endpoint doesn't seem to handle branch names that contain slashes.
+			//If we don't encode the slash, we get a 404. If we encode it as "%2F", we get a 401.
+			//To avoid issues, if the branch name is not URL-safe, let's use the commit hash instead.
+			$ref = $branch->name;
+			if ((urlencode($ref) !== $ref) && isset($branch->target->hash)) {
+				$ref = $branch->target->hash;
+			}
+
+			return new Reference(array(
+				'name' => $ref,
+				'updated' => $branch->target->date,
+				'downloadUrl' => $this->getDownloadUrl($branch->name),
+			));
+		}
+
+		/**
+		 * Get a specific tag.
+		 *
+		 * @param string $tagName
+		 * @return Reference|null
+		 */
+		public function getTag($tagName) {
+			$tag = $this->api('/refs/tags/' . $tagName);
+			if ( is_wp_error($tag) || empty($tag) ) {
+				return null;
+			}
+
+			return new Reference(array(
+				'name' => $tag->name,
+				'version' => ltrim($tag->name, 'v'),
+				'updated' => $tag->target->date,
+				'downloadUrl' => $this->getDownloadUrl($tag->name),
+			));
+		}
+
+		/**
+		 * Get the tag that looks like the highest version number.
+		 *
+		 * @return Reference|null
+		 */
+		public function getLatestTag() {
+			$tags = $this->api('/refs/tags?sort=-target.date');
+			if ( !isset($tags, $tags->values) || !is_array($tags->values) ) {
+				return null;
+			}
+
+			//Filter and sort the list of tags.
+			$versionTags = $this->sortTagsByVersion($tags->values);
+
+			//Return the first result.
+			if ( !empty($versionTags) ) {
+				$tag = $versionTags[0];
+				return new Reference(array(
+					'name' => $tag->name,
+					'version' => ltrim($tag->name, 'v'),
+					'updated' => $tag->target->date,
+					'downloadUrl' => $this->getDownloadUrl($tag->name),
+				));
+			}
+			return null;
+		}
+
+		/**
+		 * Get the tag/ref specified by the "Stable tag" header in the readme.txt of a given branch.
+		 *
+		 * @param string $branch
+		 * @return null|Reference
+		 */
+		protected function getStableTag($branch) {
+			$remoteReadme = $this->getRemoteReadme($branch);
+			if ( !empty($remoteReadme['stable_tag']) ) {
+				$tag = $remoteReadme['stable_tag'];
+
+				//You can explicitly opt out of using tags by setting "Stable tag" to
+				//"trunk" or the name of the current branch.
+				if ( ($tag === $branch) || ($tag === 'trunk') ) {
+					return $this->getBranch($branch);
+				}
+
+				return $this->getTag($tag);
+			}
+
+			return null;
+		}
+
+		/**
+		 * @param string $ref
+		 * @return string
+		 */
+		protected function getDownloadUrl($ref) {
+			return sprintf(
+				'https://bitbucket.org/%s/%s/get/%s.zip',
+				$this->username,
+				$this->repository,
+				$ref
+			);
+		}
+
+		/**
+		 * Get the contents of a file from a specific branch or tag.
+		 *
+		 * @param string $path File name.
+		 * @param string $ref
+		 * @return null|string Either the contents of the file, or null if the file doesn't exist or there's an error.
+		 */
+		public function getRemoteFile($path, $ref = 'master') {
+			$response = $this->api('src/' . $ref . '/' . ltrim($path));
+			if ( is_wp_error($response) || !is_string($response) ) {
+				return null;
+			}
+			return $response;
+		}
+
+		/**
+		 * Get the timestamp of the latest commit that changed the specified branch or tag.
+		 *
+		 * @param string $ref Reference name (e.g. branch or tag).
+		 * @return string|null
+		 */
+		public function getLatestCommitTime($ref) {
+			$response = $this->api('commits/' . $ref);
+			if ( isset($response->values, $response->values[0], $response->values[0]->date) ) {
+				return $response->values[0]->date;
+			}
+			return null;
+		}
+
+		/**
+		 * Perform a BitBucket API 2.0 request.
+		 *
+		 * @param string $url
+		 * @param string $version
+		 * @return mixed|\WP_Error
+		 */
+		public function api($url, $version = '2.0') {
+			$url = ltrim($url, '/');
+			$isSrcResource = Utils::startsWith($url, 'src/');
+
+			$url = implode('/', array(
+				'https://api.bitbucket.org',
+				$version,
+				'repositories',
+				$this->username,
+				$this->repository,
+				$url
+			));
+			$baseUrl = $url;
+
+			if ( $this->oauth ) {
+				$url = $this->oauth->sign($url,'GET');
+			}
+
+			$options = array('timeout' => wp_doing_cron() ? 10 : 3);
+			if ( !empty($this->httpFilterName) ) {
+				$options = apply_filters($this->httpFilterName, $options);
+			}
+			$response = wp_remote_get($url, $options);
+			if ( is_wp_error($response) ) {
+				do_action('puc_api_error', $response, null, $url, $this->slug);
+				return $response;
+			}
+
+			$code = wp_remote_retrieve_response_code($response);
+			$body = wp_remote_retrieve_body($response);
+			if ( $code === 200 ) {
+				if ( $isSrcResource ) {
+					//Most responses are JSON-encoded, but src resources just
+					//return raw file contents.
+					$document = $body;
+				} else {
+					$document = json_decode($body);
+				}
+				return $document;
+			}
+
+			$error = new \WP_Error(
+				'puc-bitbucket-http-error',
+				sprintf('BitBucket API error. Base URL: "%s",  HTTP status code: %d.', $baseUrl, $code)
+			);
+			do_action('puc_api_error', $error, $response, $url, $this->slug);
+
+			return $error;
+		}
+
+		/**
+		 * @param array $credentials
+		 */
+		public function setAuthentication($credentials) {
+			parent::setAuthentication($credentials);
+
+			if ( !empty($credentials) && !empty($credentials['consumer_key']) ) {
+				$this->oauth = new OAuthSignature(
+					$credentials['consumer_key'],
+					$credentials['consumer_secret']
+				);
+			} else {
+				$this->oauth = null;
+			}
+		}
+
+		public function signDownloadUrl($url) {
+			//Add authentication data to download URLs. Since OAuth signatures incorporate
+			//timestamps, we have to do this immediately before inserting the update. Otherwise,
+			//authentication could fail due to a stale timestamp.
+			if ( $this->oauth ) {
+				$url = $this->oauth->sign($url);
+			}
+			return $url;
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/GitHubApi.php

@@ -0,0 +1,467 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+use Parsedown;
+
+if ( !class_exists(GitHubApi::class, false) ):
+
+	class GitHubApi extends Api {
+		use ReleaseAssetSupport;
+		use ReleaseFilteringFeature;
+
+		/**
+		 * @var string GitHub username.
+		 */
+		protected $userName;
+		/**
+		 * @var string GitHub repository name.
+		 */
+		protected $repositoryName;
+
+		/**
+		 * @var string Either a fully qualified repository URL, or just "user/repo-name".
+		 */
+		protected $repositoryUrl;
+
+		/**
+		 * @var string GitHub authentication token. Optional.
+		 */
+		protected $accessToken;
+
+		/**
+		 * @var bool
+		 */
+		private $downloadFilterAdded = false;
+
+		public function __construct($repositoryUrl, $accessToken = null) {
+			$path = wp_parse_url($repositoryUrl, PHP_URL_PATH);
+			if ( preg_match('@^/?(?P<username>[^/]+?)/(?P<repository>[^/#?&]+?)/?$@', $path, $matches) ) {
+				$this->userName = $matches['username'];
+				$this->repositoryName = $matches['repository'];
+			} else {
+				throw new \InvalidArgumentException('Invalid GitHub repository URL: "' . $repositoryUrl . '"');
+			}
+
+			parent::__construct($repositoryUrl, $accessToken);
+		}
+
+		/**
+		 * Get the latest release from GitHub.
+		 *
+		 * @return Reference|null
+		 */
+		public function getLatestRelease() {
+			//The "latest release" endpoint returns one release and always skips pre-releases,
+			//so we can only use it if that's compatible with the current filter settings.
+			if (
+				$this->shouldSkipPreReleases()
+				&& (
+					($this->releaseFilterMaxReleases === 1) || !$this->hasCustomReleaseFilter()
+				)
+			) {
+				//Just get the latest release.
+				$release = $this->api('/repos/:user/:repo/releases/latest');
+				if ( is_wp_error($release) || !is_object($release) || !isset($release->tag_name) ) {
+					return null;
+				}
+				$foundReleases = array($release);
+			} else {
+				//Get a list of the most recent releases.
+				$foundReleases = $this->api(
+					'/repos/:user/:repo/releases',
+					array('per_page' => $this->releaseFilterMaxReleases)
+				);
+				if ( is_wp_error($foundReleases) || !is_array($foundReleases) ) {
+					return null;
+				}
+			}
+
+			foreach ($foundReleases as $release) {
+				//Always skip drafts.
+				if ( isset($release->draft) && !empty($release->draft) ) {
+					continue;
+				}
+
+				//Skip pre-releases unless specifically included.
+				if (
+					$this->shouldSkipPreReleases()
+					&& isset($release->prerelease)
+					&& !empty($release->prerelease)
+				) {
+					continue;
+				}
+
+				$versionNumber = ltrim($release->tag_name, 'v'); //Remove the "v" prefix from "v1.2.3".
+
+				//Custom release filtering.
+				if ( !$this->matchesCustomReleaseFilter($versionNumber, $release) ) {
+					continue;
+				}
+
+				$reference = new Reference(array(
+					'name'        => $release->tag_name,
+					'version'     => $versionNumber,
+					'downloadUrl' => $release->zipball_url,
+					'updated'     => $release->created_at,
+					'apiResponse' => $release,
+				));
+
+				if ( isset($release->assets[0]) ) {
+					$reference->downloadCount = $release->assets[0]->download_count;
+				}
+
+				if ( $this->releaseAssetsEnabled ) {
+					//Use the first release asset that matches the specified regular expression.
+					if ( isset($release->assets, $release->assets[0]) ) {
+						$matchingAssets = array_values(array_filter($release->assets, array($this, 'matchesAssetFilter')));
+					} else {
+						$matchingAssets = array();
+					}
+
+					if ( !empty($matchingAssets) ) {
+						if ( $this->isAuthenticationEnabled() ) {
+							/**
+							 * Keep in mind that we'll need to add an "Accept" header to download this asset.
+							 *
+							 * @see setUpdateDownloadHeaders()
+							 */
+							$reference->downloadUrl = $matchingAssets[0]->url;
+						} else {
+							//It seems that browser_download_url only works for public repositories.
+							//Using an access_token doesn't help. Maybe OAuth would work?
+							$reference->downloadUrl = $matchingAssets[0]->browser_download_url;
+						}
+
+						$reference->downloadCount = $matchingAssets[0]->download_count;
+					} else if ( $this->releaseAssetPreference === Api::REQUIRE_RELEASE_ASSETS ) {
+						//None of the assets match the filter, and we're not allowed
+						//to fall back to the auto-generated source ZIP.
+						return null;
+					}
+				}
+
+				if ( !empty($release->body) ) {
+					$reference->changelog = Parsedown::instance()->text($release->body);
+				}
+
+				return $reference;
+			}
+
+			return null;
+		}
+
+		/**
+		 * Get the tag that looks like the highest version number.
+		 *
+		 * @return Reference|null
+		 */
+		public function getLatestTag() {
+			$tags = $this->api('/repos/:user/:repo/tags');
+
+			if ( is_wp_error($tags) || !is_array($tags) ) {
+				return null;
+			}
+
+			$versionTags = $this->sortTagsByVersion($tags);
+			if ( empty($versionTags) ) {
+				return null;
+			}
+
+			$tag = $versionTags[0];
+			return new Reference(array(
+				'name'        => $tag->name,
+				'version'     => ltrim($tag->name, 'v'),
+				'downloadUrl' => $tag->zipball_url,
+				'apiResponse' => $tag,
+			));
+		}
+
+		/**
+		 * Get a branch by name.
+		 *
+		 * @param string $branchName
+		 * @return null|Reference
+		 */
+		public function getBranch($branchName) {
+			$branch = $this->api('/repos/:user/:repo/branches/' . $branchName);
+			if ( is_wp_error($branch) || empty($branch) ) {
+				return null;
+			}
+
+			$reference = new Reference(array(
+				'name'        => $branch->name,
+				'downloadUrl' => $this->buildArchiveDownloadUrl($branch->name),
+				'apiResponse' => $branch,
+			));
+
+			if ( isset($branch->commit, $branch->commit->commit, $branch->commit->commit->author->date) ) {
+				$reference->updated = $branch->commit->commit->author->date;
+			}
+
+			return $reference;
+		}
+
+		/**
+		 * Get the latest commit that changed the specified file.
+		 *
+		 * @param string $filename
+		 * @param string $ref Reference name (e.g. branch or tag).
+		 * @return \StdClass|null
+		 */
+		public function getLatestCommit($filename, $ref = 'master') {
+			$commits = $this->api(
+				'/repos/:user/:repo/commits',
+				array(
+					'path' => $filename,
+					'sha'  => $ref,
+				)
+			);
+			if ( !is_wp_error($commits) && isset($commits[0]) ) {
+				return $commits[0];
+			}
+			return null;
+		}
+
+		/**
+		 * Get the timestamp of the latest commit that changed the specified branch or tag.
+		 *
+		 * @param string $ref Reference name (e.g. branch or tag).
+		 * @return string|null
+		 */
+		public function getLatestCommitTime($ref) {
+			$commits = $this->api('/repos/:user/:repo/commits', array('sha' => $ref));
+			if ( !is_wp_error($commits) && isset($commits[0]) ) {
+				return $commits[0]->commit->author->date;
+			}
+			return null;
+		}
+
+		/**
+		 * Perform a GitHub API request.
+		 *
+		 * @param string $url
+		 * @param array $queryParams
+		 * @return mixed|\WP_Error
+		 */
+		protected function api($url, $queryParams = array()) {
+			$baseUrl = $url;
+			$url = $this->buildApiUrl($url, $queryParams);
+
+			$options = array('timeout' => wp_doing_cron() ? 10 : 3);
+			if ( $this->isAuthenticationEnabled() ) {
+				$options['headers'] = array('Authorization' => $this->getAuthorizationHeader());
+			}
+
+			if ( !empty($this->httpFilterName) ) {
+				$options = apply_filters($this->httpFilterName, $options);
+			}
+			$response = wp_remote_get($url, $options);
+			if ( is_wp_error($response) ) {
+				do_action('puc_api_error', $response, null, $url, $this->slug);
+				return $response;
+			}
+
+			$code = wp_remote_retrieve_response_code($response);
+			$body = wp_remote_retrieve_body($response);
+			if ( $code === 200 ) {
+				$document = json_decode($body);
+				return $document;
+			}
+
+			$error = new \WP_Error(
+				'puc-github-http-error',
+				sprintf('GitHub API error. Base URL: "%s",  HTTP status code: %d.', $baseUrl, $code)
+			);
+			do_action('puc_api_error', $error, $response, $url, $this->slug);
+
+			return $error;
+		}
+
+		/**
+		 * Build a fully qualified URL for an API request.
+		 *
+		 * @param string $url
+		 * @param array $queryParams
+		 * @return string
+		 */
+		protected function buildApiUrl($url, $queryParams) {
+			$variables = array(
+				'user' => $this->userName,
+				'repo' => $this->repositoryName,
+			);
+			foreach ($variables as $name => $value) {
+				$url = str_replace('/:' . $name, '/' . urlencode($value), $url);
+			}
+			$url = 'https://api.github.com' . $url;
+
+			if ( !empty($queryParams) ) {
+				$url = add_query_arg($queryParams, $url);
+			}
+
+			return $url;
+		}
+
+		/**
+		 * Get the contents of a file from a specific branch or tag.
+		 *
+		 * @param string $path File name.
+		 * @param string $ref
+		 * @return null|string Either the contents of the file, or null if the file doesn't exist or there's an error.
+		 */
+		public function getRemoteFile($path, $ref = 'master') {
+			$apiUrl = '/repos/:user/:repo/contents/' . $path;
+			$response = $this->api($apiUrl, array('ref' => $ref));
+
+			if ( is_wp_error($response) || !isset($response->content) || ($response->encoding !== 'base64') ) {
+				return null;
+			}
+			return base64_decode($response->content);
+		}
+
+		/**
+		 * Generate a URL to download a ZIP archive of the specified branch/tag/etc.
+		 *
+		 * @param string $ref
+		 * @return string
+		 */
+		public function buildArchiveDownloadUrl($ref = 'master') {
+			$url = sprintf(
+				'https://api.github.com/repos/%1$s/%2$s/zipball/%3$s',
+				urlencode($this->userName),
+				urlencode($this->repositoryName),
+				urlencode($ref)
+			);
+			return $url;
+		}
+
+		/**
+		 * Get a specific tag.
+		 *
+		 * @param string $tagName
+		 * @return void
+		 */
+		public function getTag($tagName) {
+			//The current GitHub update checker doesn't use getTag, so I didn't bother to implement it.
+			throw new \LogicException('The ' . __METHOD__ . ' method is not implemented and should not be used.');
+		}
+
+		public function setAuthentication($credentials) {
+			parent::setAuthentication($credentials);
+			$this->accessToken = is_string($credentials) ? $credentials : null;
+
+			//Optimization: Instead of filtering all HTTP requests, let's do it only when
+			//WordPress is about to download an update.
+			add_filter('upgrader_pre_download', array($this, 'addHttpRequestFilter'), 10, 1); //WP 3.7+
+		}
+
+		protected function getUpdateDetectionStrategies($configBranch) {
+			$strategies = array();
+
+			if ( $configBranch === 'master' || $configBranch === 'main') {
+				//Use the latest release.
+				$strategies[self::STRATEGY_LATEST_RELEASE] = array($this, 'getLatestRelease');
+				//Failing that, use the tag with the highest version number.
+				$strategies[self::STRATEGY_LATEST_TAG] = array($this, 'getLatestTag');
+			}
+
+			//Alternatively, just use the branch itself.
+			$strategies[self::STRATEGY_BRANCH] = function () use ($configBranch) {
+				return $this->getBranch($configBranch);
+			};
+
+			return $strategies;
+		}
+
+		/**
+		 * Get the unchanging part of a release asset URL. Used to identify download attempts.
+		 *
+		 * @return string
+		 */
+		protected function getAssetApiBaseUrl() {
+			return sprintf(
+				'//api.github.com/repos/%1$s/%2$s/releases/assets/',
+				$this->userName,
+				$this->repositoryName
+			);
+		}
+
+		protected function getFilterableAssetName($releaseAsset) {
+			if ( isset($releaseAsset->name) ) {
+				return $releaseAsset->name;
+			}
+			return null;
+		}
+
+		/**
+		 * @param bool $result
+		 * @return bool
+		 * @internal
+		 */
+		public function addHttpRequestFilter($result) {
+			if ( !$this->downloadFilterAdded && $this->isAuthenticationEnabled() ) {
+				//phpcs:ignore WordPressVIPMinimum.Hooks.RestrictedHooks.http_request_args -- The callback doesn't change the timeout.
+				add_filter('http_request_args', array($this, 'setUpdateDownloadHeaders'), 10, 2);
+				add_action('requests-requests.before_redirect', array($this, 'removeAuthHeaderFromRedirects'), 10, 4);
+				$this->downloadFilterAdded = true;
+			}
+			return $result;
+		}
+
+		/**
+		 * Set the HTTP headers that are necessary to download updates from private repositories.
+		 *
+		 * See GitHub docs:
+		 *
+		 * @link https://developer.github.com/v3/repos/releases/#get-a-single-release-asset
+		 * @link https://developer.github.com/v3/auth/#basic-authentication
+		 *
+		 * @internal
+		 * @param array $requestArgs
+		 * @param string $url
+		 * @return array
+		 */
+		public function setUpdateDownloadHeaders($requestArgs, $url = '') {
+			//Is WordPress trying to download one of our release assets?
+			if ( $this->releaseAssetsEnabled && (strpos($url, $this->getAssetApiBaseUrl()) !== false) ) {
+				$requestArgs['headers']['Accept'] = 'application/octet-stream';
+			}
+			//Use Basic authentication, but only if the download is from our repository.
+			$repoApiBaseUrl = $this->buildApiUrl('/repos/:user/:repo/', array());
+			if ( $this->isAuthenticationEnabled() && (strpos($url, $repoApiBaseUrl)) === 0 ) {
+				$requestArgs['headers']['Authorization'] = $this->getAuthorizationHeader();
+			}
+			return $requestArgs;
+		}
+
+		/**
+		 * When following a redirect, the Requests library will automatically forward
+		 * the authorization header to other hosts. We don't want that because it breaks
+		 * AWS downloads and can leak authorization information.
+		 *
+		 * @param string $location
+		 * @param array $headers
+		 * @internal
+		 */
+		public function removeAuthHeaderFromRedirects(&$location, &$headers) {
+			$repoApiBaseUrl = $this->buildApiUrl('/repos/:user/:repo/', array());
+			if ( strpos($location, $repoApiBaseUrl) === 0 ) {
+				return; //This request is going to GitHub, so it's fine.
+			}
+			//Remove the header.
+			if ( isset($headers['Authorization']) ) {
+				unset($headers['Authorization']);
+			}
+		}
+
+		/**
+		 * Generate the value of the "Authorization" header.
+		 *
+		 * @return string
+		 */
+		protected function getAuthorizationHeader() {
+			return 'Basic ' . base64_encode($this->userName . ':' . $this->accessToken);
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/GitLabApi.php

@@ -0,0 +1,414 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+if ( !class_exists(GitLabApi::class, false) ):
+
+	class GitLabApi extends Api {
+		use ReleaseAssetSupport;
+		use ReleaseFilteringFeature;
+
+		/**
+		 * @var string GitLab username.
+		 */
+		protected $userName;
+
+		/**
+		 * @var string GitLab server host.
+		 */
+		protected $repositoryHost;
+
+		/**
+		 * @var string Protocol used by this GitLab server: "http" or "https".
+		 */
+		protected $repositoryProtocol = 'https';
+
+		/**
+		 * @var string GitLab repository name.
+		 */
+		protected $repositoryName;
+
+		/**
+		 * @var string GitLab authentication token. Optional.
+		 */
+		protected $accessToken;
+
+		/**
+		 * @deprecated
+		 * @var bool No longer used.
+		 */
+		protected $releasePackageEnabled = false;
+
+		public function __construct($repositoryUrl, $accessToken = null, $subgroup = null) {
+			//Parse the repository host to support custom hosts.
+			$port = wp_parse_url($repositoryUrl, PHP_URL_PORT);
+			if ( !empty($port) ) {
+				$port = ':' . $port;
+			}
+			$this->repositoryHost = wp_parse_url($repositoryUrl, PHP_URL_HOST) . $port;
+
+			if ( $this->repositoryHost !== 'gitlab.com' ) {
+				$this->repositoryProtocol = wp_parse_url($repositoryUrl, PHP_URL_SCHEME);
+			}
+
+			//Find the repository information
+			$path = wp_parse_url($repositoryUrl, PHP_URL_PATH);
+			if ( preg_match('@^/?(?P<username>[^/]+?)/(?P<repository>[^/#?&]+?)/?$@', $path, $matches) ) {
+				$this->userName = $matches['username'];
+				$this->repositoryName = $matches['repository'];
+			} elseif ( ($this->repositoryHost === 'gitlab.com') ) {
+				//This is probably a repository in a subgroup, e.g. "/organization/category/repo".
+				$parts = explode('/', trim($path, '/'));
+				if ( count($parts) < 3 ) {
+					throw new \InvalidArgumentException('Invalid GitLab.com repository URL: "' . $repositoryUrl . '"');
+				}
+				$lastPart = array_pop($parts);
+				$this->userName = implode('/', $parts);
+				$this->repositoryName = $lastPart;
+			} else {
+				//There could be subgroups in the URL:  gitlab.domain.com/group/subgroup/subgroup2/repository
+				if ( $subgroup !== null ) {
+					$path = str_replace(trailingslashit($subgroup), '', $path);
+				}
+
+				//This is not a traditional url, it could be gitlab is in a deeper subdirectory.
+				//Get the path segments.
+				$segments = explode('/', untrailingslashit(ltrim($path, '/')));
+
+				//We need at least /user-name/repository-name/
+				if ( count($segments) < 2 ) {
+					throw new \InvalidArgumentException('Invalid GitLab repository URL: "' . $repositoryUrl . '"');
+				}
+
+				//Get the username and repository name.
+				$usernameRepo = array_splice($segments, -2, 2);
+				$this->userName = $usernameRepo[0];
+				$this->repositoryName = $usernameRepo[1];
+
+				//Append the remaining segments to the host if there are segments left.
+				if ( count($segments) > 0 ) {
+					$this->repositoryHost = trailingslashit($this->repositoryHost) . implode('/', $segments);
+				}
+
+				//Add subgroups to username.
+				if ( $subgroup !== null ) {
+					$this->userName = $usernameRepo[0] . '/' . untrailingslashit($subgroup);
+				}
+			}
+
+			parent::__construct($repositoryUrl, $accessToken);
+		}
+
+		/**
+		 * Get the latest release from GitLab.
+		 *
+		 * @return Reference|null
+		 */
+		public function getLatestRelease() {
+			$releases = $this->api('/:id/releases', array('per_page' => $this->releaseFilterMaxReleases));
+			if ( is_wp_error($releases) || empty($releases) || !is_array($releases) ) {
+				return null;
+			}
+
+			foreach ($releases as $release) {
+				if (
+					//Skip invalid/unsupported releases.
+					!is_object($release)
+					|| !isset($release->tag_name)
+					//Skip upcoming releases.
+					|| (
+						!empty($release->upcoming_release)
+						&& $this->shouldSkipPreReleases()
+					)
+				) {
+					continue;
+				}
+
+				$versionNumber = ltrim($release->tag_name, 'v'); //Remove the "v" prefix from "v1.2.3".
+
+				//Apply custom filters.
+				if ( !$this->matchesCustomReleaseFilter($versionNumber, $release) ) {
+					continue;
+				}
+
+				$downloadUrl = $this->findReleaseDownloadUrl($release);
+				if ( empty($downloadUrl) ) {
+					//The latest release doesn't have valid download URL.
+					return null;
+				}
+
+				if ( !empty($this->accessToken) ) {
+					$downloadUrl = add_query_arg('private_token', $this->accessToken, $downloadUrl);
+				}
+
+				return new Reference(array(
+					'name'        => $release->tag_name,
+					'version'     => $versionNumber,
+					'downloadUrl' => $downloadUrl,
+					'updated'     => $release->released_at,
+					'apiResponse' => $release,
+				));
+			}
+
+			return null;
+		}
+
+		/**
+		 * @param object $release
+		 * @return string|null
+		 */
+		protected function findReleaseDownloadUrl($release) {
+			if ( $this->releaseAssetsEnabled ) {
+				if ( isset($release->assets, $release->assets->links) ) {
+					//Use the first asset link where the URL matches the filter.
+					foreach ($release->assets->links as $link) {
+						if ( $this->matchesAssetFilter($link) ) {
+							return $link->url;
+						}
+					}
+				}
+
+				if ( $this->releaseAssetPreference === Api::REQUIRE_RELEASE_ASSETS ) {
+					//Falling back to source archives is not allowed, so give up.
+					return null;
+				}
+			}
+
+			//Use the first source code archive that's in ZIP format.
+			foreach ($release->assets->sources as $source) {
+				if ( isset($source->format) && ($source->format === 'zip') ) {
+					return $source->url;
+				}
+			}
+
+			return null;
+		}
+
+		/**
+		 * Get the tag that looks like the highest version number.
+		 *
+		 * @return Reference|null
+		 */
+		public function getLatestTag() {
+			$tags = $this->api('/:id/repository/tags');
+			if ( is_wp_error($tags) || empty($tags) || !is_array($tags) ) {
+				return null;
+			}
+
+			$versionTags = $this->sortTagsByVersion($tags);
+			if ( empty($versionTags) ) {
+				return null;
+			}
+
+			$tag = $versionTags[0];
+			return new Reference(array(
+				'name'        => $tag->name,
+				'version'     => ltrim($tag->name, 'v'),
+				'downloadUrl' => $this->buildArchiveDownloadUrl($tag->name),
+				'apiResponse' => $tag,
+			));
+		}
+
+		/**
+		 * Get a branch by name.
+		 *
+		 * @param string $branchName
+		 * @return null|Reference
+		 */
+		public function getBranch($branchName) {
+			$branch = $this->api('/:id/repository/branches/' . $branchName);
+			if ( is_wp_error($branch) || empty($branch) ) {
+				return null;
+			}
+
+			$reference = new Reference(array(
+				'name'        => $branch->name,
+				'downloadUrl' => $this->buildArchiveDownloadUrl($branch->name),
+				'apiResponse' => $branch,
+			));
+
+			if ( isset($branch->commit, $branch->commit->committed_date) ) {
+				$reference->updated = $branch->commit->committed_date;
+			}
+
+			return $reference;
+		}
+
+		/**
+		 * Get the timestamp of the latest commit that changed the specified branch or tag.
+		 *
+		 * @param string $ref Reference name (e.g. branch or tag).
+		 * @return string|null
+		 */
+		public function getLatestCommitTime($ref) {
+			$commits = $this->api('/:id/repository/commits/', array('ref_name' => $ref));
+			if ( is_wp_error($commits) || !is_array($commits) || !isset($commits[0]) ) {
+				return null;
+			}
+
+			return $commits[0]->committed_date;
+		}
+
+		/**
+		 * Perform a GitLab API request.
+		 *
+		 * @param string $url
+		 * @param array $queryParams
+		 * @return mixed|\WP_Error
+		 */
+		protected function api($url, $queryParams = array()) {
+			$baseUrl = $url;
+			$url = $this->buildApiUrl($url, $queryParams);
+
+			$options = array('timeout' => wp_doing_cron() ? 10 : 3);
+			if ( !empty($this->httpFilterName) ) {
+				$options = apply_filters($this->httpFilterName, $options);
+			}
+
+			$response = wp_remote_get($url, $options);
+			if ( is_wp_error($response) ) {
+				do_action('puc_api_error', $response, null, $url, $this->slug);
+				return $response;
+			}
+
+			$code = wp_remote_retrieve_response_code($response);
+			$body = wp_remote_retrieve_body($response);
+			if ( $code === 200 ) {
+				return json_decode($body);
+			}
+
+			$error = new \WP_Error(
+				'puc-gitlab-http-error',
+				sprintf('GitLab API error. URL: "%s",  HTTP status code: %d.', $baseUrl, $code)
+			);
+			do_action('puc_api_error', $error, $response, $url, $this->slug);
+
+			return $error;
+		}
+
+		/**
+		 * Build a fully qualified URL for an API request.
+		 *
+		 * @param string $url
+		 * @param array $queryParams
+		 * @return string
+		 */
+		protected function buildApiUrl($url, $queryParams) {
+			$variables = array(
+				'user' => $this->userName,
+				'repo' => $this->repositoryName,
+				'id'   => $this->userName . '/' . $this->repositoryName,
+			);
+
+			foreach ($variables as $name => $value) {
+				$url = str_replace("/:{$name}", '/' . urlencode($value), $url);
+			}
+
+			$url = substr($url, 1);
+			$url = sprintf('%1$s://%2$s/api/v4/projects/%3$s', $this->repositoryProtocol, $this->repositoryHost, $url);
+
+			if ( !empty($this->accessToken) ) {
+				$queryParams['private_token'] = $this->accessToken;
+			}
+
+			if ( !empty($queryParams) ) {
+				$url = add_query_arg($queryParams, $url);
+			}
+
+			return $url;
+		}
+
+		/**
+		 * Get the contents of a file from a specific branch or tag.
+		 *
+		 * @param string $path File name.
+		 * @param string $ref
+		 * @return null|string Either the contents of the file, or null if the file doesn't exist or there's an error.
+		 */
+		public function getRemoteFile($path, $ref = 'master') {
+			$response = $this->api('/:id/repository/files/' . $path, array('ref' => $ref));
+			if ( is_wp_error($response) || !isset($response->content) || $response->encoding !== 'base64' ) {
+				return null;
+			}
+
+			return base64_decode($response->content);
+		}
+
+		/**
+		 * Generate a URL to download a ZIP archive of the specified branch/tag/etc.
+		 *
+		 * @param string $ref
+		 * @return string
+		 */
+		public function buildArchiveDownloadUrl($ref = 'master') {
+			$url = sprintf(
+				'%1$s://%2$s/api/v4/projects/%3$s/repository/archive.zip',
+				$this->repositoryProtocol,
+				$this->repositoryHost,
+				urlencode($this->userName . '/' . $this->repositoryName)
+			);
+			$url = add_query_arg('sha', urlencode($ref), $url);
+
+			if ( !empty($this->accessToken) ) {
+				$url = add_query_arg('private_token', $this->accessToken, $url);
+			}
+
+			return $url;
+		}
+
+		/**
+		 * Get a specific tag.
+		 *
+		 * @param string $tagName
+		 * @return void
+		 */
+		public function getTag($tagName) {
+			throw new \LogicException('The ' . __METHOD__ . ' method is not implemented and should not be used.');
+		}
+
+		protected function getUpdateDetectionStrategies($configBranch) {
+			$strategies = array();
+
+			if ( ($configBranch === 'main') || ($configBranch === 'master') ) {
+				$strategies[self::STRATEGY_LATEST_RELEASE] = array($this, 'getLatestRelease');
+				$strategies[self::STRATEGY_LATEST_TAG] = array($this, 'getLatestTag');
+			}
+
+			$strategies[self::STRATEGY_BRANCH] = function () use ($configBranch) {
+				return $this->getBranch($configBranch);
+			};
+
+			return $strategies;
+		}
+
+		public function setAuthentication($credentials) {
+			parent::setAuthentication($credentials);
+			$this->accessToken = is_string($credentials) ? $credentials : null;
+		}
+
+		/**
+		 * Use release assets that link to GitLab generic packages (e.g. .zip files)
+		 * instead of automatically generated source archives.
+		 *
+		 * This is included for backwards compatibility with older versions of PUC.
+		 *
+		 * @return void
+		 * @deprecated   Use enableReleaseAssets() instead.
+		 * @noinspection PhpUnused -- Public API
+		 */
+		public function enableReleasePackages() {
+			$this->enableReleaseAssets(
+			/** @lang RegExp */ '/\.zip($|[?&#])/i',
+				Api::REQUIRE_RELEASE_ASSETS
+			);
+		}
+
+		protected function getFilterableAssetName($releaseAsset) {
+			if ( isset($releaseAsset->url) ) {
+				return $releaseAsset->url;
+			}
+			return null;
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/PluginUpdateChecker.php

@@ -0,0 +1,275 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+use YahnisElsts\PluginUpdateChecker\v5p3\Plugin;
+
+if ( !class_exists(PluginUpdateChecker::class, false) ):
+
+	class PluginUpdateChecker extends Plugin\UpdateChecker implements BaseChecker {
+		use VcsCheckerMethods;
+
+		/**
+		 * PluginUpdateChecker constructor.
+		 *
+		 * @param Api $api
+		 * @param string $pluginFile
+		 * @param string $slug
+		 * @param int $checkPeriod
+		 * @param string $optionName
+		 * @param string $muPluginFile
+		 */
+		public function __construct($api, $pluginFile, $slug = '', $checkPeriod = 12, $optionName = '', $muPluginFile = '') {
+			$this->api = $api;
+
+			parent::__construct($api->getRepositoryUrl(), $pluginFile, $slug, $checkPeriod, $optionName, $muPluginFile);
+
+			$this->api->setHttpFilterName($this->getUniqueName('request_info_options'));
+			$this->api->setStrategyFilterName($this->getUniqueName('vcs_update_detection_strategies'));
+			$this->api->setSlug($this->slug);
+		}
+
+		public function requestInfo($unusedParameter = null) {
+			//We have to make several remote API requests to gather all the necessary info
+			//which can take a while on slow networks.
+			if ( function_exists('set_time_limit') ) {
+				@set_time_limit(60);
+			}
+
+			$api = $this->api;
+			$api->setLocalDirectory($this->package->getAbsoluteDirectoryPath());
+
+			$info = new Plugin\PluginInfo();
+			$info->filename = $this->pluginFile;
+			$info->slug = $this->slug;
+
+			$this->setInfoFromHeader($this->package->getPluginHeader(), $info);
+			$this->setIconsFromLocalAssets($info);
+			$this->setBannersFromLocalAssets($info);
+
+			//Pick a branch or tag.
+			$updateSource = $api->chooseReference($this->branch);
+			if ( $updateSource ) {
+				$ref = $updateSource->name;
+				$info->version = $updateSource->version;
+				$info->last_updated = $updateSource->updated;
+				$info->download_url = $updateSource->downloadUrl;
+
+				if ( !empty($updateSource->changelog) ) {
+					$info->sections['changelog'] = $updateSource->changelog;
+				}
+				if ( isset($updateSource->downloadCount) ) {
+					$info->downloaded = $updateSource->downloadCount;
+				}
+			} else {
+				//There's probably a network problem or an authentication error.
+				do_action(
+					'puc_api_error',
+					new \WP_Error(
+						'puc-no-update-source',
+						'Could not retrieve version information from the repository. '
+						. 'This usually means that the update checker either can\'t connect '
+						. 'to the repository or it\'s configured incorrectly.'
+					),
+					null, null, $this->slug
+				);
+				return null;
+			}
+
+			//Get headers from the main plugin file in this branch/tag. Its "Version" header and other metadata
+			//are what the WordPress install will actually see after upgrading, so they take precedence over releases/tags.
+			$mainPluginFile = basename($this->pluginFile);
+			$remotePlugin = $api->getRemoteFile($mainPluginFile, $ref);
+			if ( !empty($remotePlugin) ) {
+				$remoteHeader = $this->package->getFileHeader($remotePlugin);
+				$this->setInfoFromHeader($remoteHeader, $info);
+			}
+
+			//Sanity check: Reject updates that don't have a version number.
+			//This can happen when we're using a branch, and we either fail to retrieve the main plugin
+			//file or the file doesn't have a "Version" header.
+			if ( empty($info->version) ) {
+				do_action(
+					'puc_api_error',
+					new \WP_Error(
+						'puc-no-plugin-version',
+						'Could not find the version number in the repository.'
+					),
+					null, null, $this->slug
+				);
+				return null;
+			}
+
+			//Try parsing readme.txt. If it's formatted according to WordPress.org standards, it will contain
+			//a lot of useful information like the required/tested WP version, changelog, and so on.
+			if ( $this->readmeTxtExistsLocally() ) {
+				$this->setInfoFromRemoteReadme($ref, $info);
+			}
+
+			//The changelog might be in a separate file.
+			if ( empty($info->sections['changelog']) ) {
+				$info->sections['changelog'] = $api->getRemoteChangelog($ref, $this->package->getAbsoluteDirectoryPath());
+				if ( empty($info->sections['changelog']) ) {
+					$info->sections['changelog'] = __('There is no changelog available.', 'plugin-update-checker');
+				}
+			}
+
+			if ( empty($info->last_updated) ) {
+				//Fetch the latest commit that changed the tag or branch and use it as the "last_updated" date.
+				$latestCommitTime = $api->getLatestCommitTime($ref);
+				if ( $latestCommitTime !== null ) {
+					$info->last_updated = $latestCommitTime;
+				}
+			}
+
+			$info = apply_filters($this->getUniqueName('request_info_result'), $info, null);
+			return $info;
+		}
+
+		/**
+		 * Check if the currently installed version has a readme.txt file.
+		 *
+		 * @return bool
+		 */
+		protected function readmeTxtExistsLocally() {
+			return $this->package->fileExists($this->api->getLocalReadmeName());
+		}
+
+		/**
+		 * Copy plugin metadata from a file header to a Plugin Info object.
+		 *
+		 * @param array $fileHeader
+		 * @param Plugin\PluginInfo $pluginInfo
+		 */
+		protected function setInfoFromHeader($fileHeader, $pluginInfo) {
+			$headerToPropertyMap = array(
+				'Version' => 'version',
+				'Name' => 'name',
+				'PluginURI' => 'homepage',
+				'Author' => 'author',
+				'AuthorName' => 'author',
+				'AuthorURI' => 'author_homepage',
+
+				'Requires WP' => 'requires',
+				'Tested WP' => 'tested',
+				'Requires at least' => 'requires',
+				'Tested up to' => 'tested',
+
+				'Requires PHP' => 'requires_php',
+			);
+			foreach ($headerToPropertyMap as $headerName => $property) {
+				if ( isset($fileHeader[$headerName]) && !empty($fileHeader[$headerName]) ) {
+					$pluginInfo->$property = $fileHeader[$headerName];
+				}
+			}
+
+			if ( !empty($fileHeader['Description']) ) {
+				$pluginInfo->sections['description'] = $fileHeader['Description'];
+			}
+		}
+
+		/**
+		 * Copy plugin metadata from the remote readme.txt file.
+		 *
+		 * @param string $ref GitHub tag or branch where to look for the readme.
+		 * @param Plugin\PluginInfo $pluginInfo
+		 */
+		protected function setInfoFromRemoteReadme($ref, $pluginInfo) {
+			$readme = $this->api->getRemoteReadme($ref);
+			if ( empty($readme) ) {
+				return;
+			}
+
+			if ( isset($readme['sections']) ) {
+				$pluginInfo->sections = array_merge($pluginInfo->sections, $readme['sections']);
+			}
+			if ( !empty($readme['tested_up_to']) ) {
+				$pluginInfo->tested = $readme['tested_up_to'];
+			}
+			if ( !empty($readme['requires_at_least']) ) {
+				$pluginInfo->requires = $readme['requires_at_least'];
+			}
+			if ( !empty($readme['requires_php']) ) {
+				$pluginInfo->requires_php = $readme['requires_php'];
+			}
+
+			if ( isset($readme['upgrade_notice'], $readme['upgrade_notice'][$pluginInfo->version]) ) {
+				$pluginInfo->upgrade_notice = $readme['upgrade_notice'][$pluginInfo->version];
+			}
+		}
+
+		/**
+		 * Add icons from the currently installed version to a Plugin Info object.
+		 *
+		 * The icons should be in a subdirectory named "assets". Supported image formats
+		 * and file names are described here:
+		 * @link https://developer.wordpress.org/plugins/wordpress-org/plugin-assets/#plugin-icons
+		 *
+		 * @param Plugin\PluginInfo $pluginInfo
+		 */
+		protected function setIconsFromLocalAssets($pluginInfo) {
+			$icons = $this->getLocalAssetUrls(array(
+				'icon.svg'         => 'svg',
+				'icon-256x256.png' => '2x',
+				'icon-256x256.jpg' => '2x',
+				'icon-128x128.png' => '1x',
+				'icon-128x128.jpg' => '1x',
+			));
+
+			if ( !empty($icons) ) {
+				//The "default" key seems to be used only as last-resort fallback in WP core (5.8/5.9),
+				//but we'll set it anyway in case some code somewhere needs it.
+				reset($icons);
+				$firstKey = key($icons);
+				$icons['default'] = $icons[$firstKey];
+
+				$pluginInfo->icons = $icons;
+			}
+		}
+
+		/**
+		 * Add banners from the currently installed version to a Plugin Info object.
+		 *
+		 * The banners should be in a subdirectory named "assets". Supported image formats
+		 * and file names are described here:
+		 * @link https://developer.wordpress.org/plugins/wordpress-org/plugin-assets/#plugin-headers
+		 *
+		 * @param Plugin\PluginInfo $pluginInfo
+		 */
+		protected function setBannersFromLocalAssets($pluginInfo) {
+			$banners = $this->getLocalAssetUrls(array(
+				'banner-772x250.png' => 'high',
+				'banner-772x250.jpg' => 'high',
+				'banner-1544x500.png' => 'low',
+				'banner-1544x500.jpg' => 'low',
+			));
+
+			if ( !empty($banners) ) {
+				$pluginInfo->banners = $banners;
+			}
+		}
+
+		/**
+		 * @param array<string, string> $filesToKeys
+		 * @return array<string, string>
+		 */
+		protected function getLocalAssetUrls($filesToKeys) {
+			$assetDirectory = $this->package->getAbsoluteDirectoryPath() . DIRECTORY_SEPARATOR . 'assets';
+			if ( !is_dir($assetDirectory) ) {
+				return array();
+			}
+			$assetBaseUrl = trailingslashit(plugins_url('', $assetDirectory . '/imaginary.file'));
+
+			$foundAssets = array();
+			foreach ($filesToKeys as $fileName => $key) {
+				$fullBannerPath = $assetDirectory . DIRECTORY_SEPARATOR . $fileName;
+				if ( !isset($icons[$key]) && is_file($fullBannerPath) ) {
+					$foundAssets[$key] = $assetBaseUrl . $fileName;
+				}
+			}
+
+			return $foundAssets;
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/Reference.php

@@ -0,0 +1,51 @@
+<?php
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+if ( !class_exists(Reference::class, false) ):
+
+	/**
+	 * This class represents a VCS branch or tag. It's intended as a read only, short-lived container
+	 * that only exists to provide a limited degree of type checking.
+	 *
+	 * @property string $name
+	 * @property string|null version
+	 * @property string $downloadUrl
+	 * @property string $updated
+	 *
+	 * @property string|null $changelog
+	 * @property int|null $downloadCount
+	 */
+	class Reference {
+		private $properties = array();
+
+		public function __construct($properties = array()) {
+			$this->properties = $properties;
+		}
+
+		/**
+		 * @param string $name
+		 * @return mixed|null
+		 */
+		public function __get($name) {
+			return array_key_exists($name, $this->properties) ? $this->properties[$name] : null;
+		}
+
+		/**
+		 * @param string $name
+		 * @param mixed $value
+		 */
+		public function __set($name, $value) {
+			$this->properties[$name] = $value;
+		}
+
+		/**
+		 * @param string $name
+		 * @return bool
+		 */
+		public function __isset($name) {
+			return isset($this->properties[$name]);
+		}
+
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/ReleaseAssetSupport.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+if ( !trait_exists(ReleaseAssetSupport::class, false) ) :
+
+	trait ReleaseAssetSupport {
+		/**
+		 * @var bool Whether to download release assets instead of the auto-generated
+		 *           source code archives.
+		 */
+		protected $releaseAssetsEnabled = false;
+
+		/**
+		 * @var string|null Regular expression that's used to filter release assets
+		 *                  by file name or URL. Optional.
+		 */
+		protected $assetFilterRegex = null;
+
+		/**
+		 * How to handle releases that don't have any matching release assets.
+		 *
+		 * @var int
+		 */
+		protected $releaseAssetPreference = Api::PREFER_RELEASE_ASSETS;
+
+		/**
+		 * Enable updating via release assets.
+		 *
+		 * If the latest release contains no usable assets, the update checker
+		 * will fall back to using the automatically generated ZIP archive.
+		 *
+		 * @param string|null $nameRegex Optional. Use only those assets where
+		 *                               the file name or URL matches this regex.
+		 * @param int $preference Optional. How to handle releases that don't have
+		 *                        any matching release assets.
+		 */
+		public function enableReleaseAssets($nameRegex = null, $preference = Api::PREFER_RELEASE_ASSETS) {
+			$this->releaseAssetsEnabled = true;
+			$this->assetFilterRegex = $nameRegex;
+			$this->releaseAssetPreference = $preference;
+		}
+
+		/**
+		 * Disable release assets.
+		 *
+		 * @return void
+		 * @noinspection PhpUnused -- Public API
+		 */
+		public function disableReleaseAssets() {
+			$this->releaseAssetsEnabled = false;
+			$this->assetFilterRegex = null;
+		}
+
+		/**
+		 * Does the specified asset match the name regex?
+		 *
+		 * @param mixed $releaseAsset Data type and structure depend on the host/API.
+		 * @return bool
+		 */
+		protected function matchesAssetFilter($releaseAsset) {
+			if ( $this->assetFilterRegex === null ) {
+				//The default is to accept all assets.
+				return true;
+			}
+
+			$name = $this->getFilterableAssetName($releaseAsset);
+			if ( !is_string($name) ) {
+				return false;
+			}
+			return (bool)preg_match($this->assetFilterRegex, $releaseAsset->name);
+		}
+
+		/**
+		 * Get the part of asset data that will be checked against the filter regex.
+		 *
+		 * @param mixed $releaseAsset
+		 * @return string|null
+		 */
+		abstract protected function getFilterableAssetName($releaseAsset);
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/ReleaseFilteringFeature.php

@@ -0,0 +1,108 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+if ( !trait_exists(ReleaseFilteringFeature::class, false) ) :
+
+	trait ReleaseFilteringFeature {
+		/**
+		 * @var callable|null
+		 */
+		protected $releaseFilterCallback = null;
+		/**
+		 * @var int
+		 */
+		protected $releaseFilterMaxReleases = 1;
+		/**
+		 * @var string One of the Api::RELEASE_FILTER_* constants.
+		 */
+		protected $releaseFilterByType = Api::RELEASE_FILTER_SKIP_PRERELEASE;
+
+		/**
+		 * Set a custom release filter.
+		 *
+		 * Setting a new filter will override the old filter, if any.
+		 *
+		 * @param callable $callback A callback that accepts a version number and a release
+		 *                           object, and returns a boolean.
+		 * @param int $releaseTypes  One of the Api::RELEASE_FILTER_* constants.
+		 * @param int $maxReleases   Optional. The maximum number of recent releases to examine
+		 *                           when trying to find a release that matches the filter. 1 to 100.
+		 * @return $this
+		 */
+		public function setReleaseFilter(
+			$callback,
+			$releaseTypes = Api::RELEASE_FILTER_SKIP_PRERELEASE,
+			$maxReleases = 20
+		) {
+			if ( $maxReleases > 100 ) {
+				throw new \InvalidArgumentException(sprintf(
+					'The max number of releases is too high (%d). It must be 100 or less.',
+					$maxReleases
+				));
+			} else if ( $maxReleases < 1 ) {
+				throw new \InvalidArgumentException(sprintf(
+					'The max number of releases is too low (%d). It must be at least 1.',
+					$maxReleases
+				));
+			}
+
+			$this->releaseFilterCallback = $callback;
+			$this->releaseFilterByType = $releaseTypes;
+			$this->releaseFilterMaxReleases = $maxReleases;
+			return $this;
+		}
+
+		/**
+		 * Filter releases by their version number.
+		 *
+		 * @param string $regex A regular expression. The release version number must match this regex.
+		 * @param int $releaseTypes
+		 * @param int $maxReleasesToExamine
+		 * @return $this
+		 * @noinspection PhpUnused -- Public API
+		 */
+		public function setReleaseVersionFilter(
+			$regex,
+			$releaseTypes = Api::RELEASE_FILTER_SKIP_PRERELEASE,
+			$maxReleasesToExamine = 20
+		) {
+			return $this->setReleaseFilter(
+				function ($versionNumber) use ($regex) {
+					return (preg_match($regex, $versionNumber) === 1);
+				},
+				$releaseTypes,
+				$maxReleasesToExamine
+			);
+		}
+
+		/**
+		 * @param string $versionNumber The detected release version number.
+		 * @param object $releaseObject Varies depending on the host/API.
+		 * @return bool
+		 */
+		protected function matchesCustomReleaseFilter($versionNumber, $releaseObject) {
+			if ( !is_callable($this->releaseFilterCallback) ) {
+				return true; //No custom filter.
+			}
+			return call_user_func($this->releaseFilterCallback, $versionNumber, $releaseObject);
+		}
+
+		/**
+		 * @return bool
+		 */
+		protected function shouldSkipPreReleases() {
+			//Maybe this could be a bitfield in the future, if we need to support
+			//more release types.
+			return ($this->releaseFilterByType !== Api::RELEASE_FILTER_ALL);
+		}
+
+		/**
+		 * @return bool
+		 */
+		protected function hasCustomReleaseFilter() {
+			return isset($this->releaseFilterCallback) && is_callable($this->releaseFilterCallback);
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/ThemeUpdateChecker.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+use YahnisElsts\PluginUpdateChecker\v5p3\Theme;
+use YahnisElsts\PluginUpdateChecker\v5p3\Utils;
+
+if ( !class_exists(ThemeUpdateChecker::class, false) ):
+
+	class ThemeUpdateChecker extends Theme\UpdateChecker implements BaseChecker {
+		use VcsCheckerMethods;
+
+		/**
+		 * ThemeUpdateChecker constructor.
+		 *
+		 * @param Api $api
+		 * @param null $stylesheet
+		 * @param null $customSlug
+		 * @param int $checkPeriod
+		 * @param string $optionName
+		 */
+		public function __construct($api, $stylesheet = null, $customSlug = null, $checkPeriod = 12, $optionName = '') {
+			$this->api = $api;
+
+			parent::__construct($api->getRepositoryUrl(), $stylesheet, $customSlug, $checkPeriod, $optionName);
+
+			$this->api->setHttpFilterName($this->getUniqueName('request_update_options'));
+			$this->api->setStrategyFilterName($this->getUniqueName('vcs_update_detection_strategies'));
+			$this->api->setSlug($this->slug);
+		}
+
+		public function requestUpdate() {
+			$api = $this->api;
+			$api->setLocalDirectory($this->package->getAbsoluteDirectoryPath());
+
+			$update = new Theme\Update();
+			$update->slug = $this->slug;
+
+			//Figure out which reference (tag or branch) we'll use to get the latest version of the theme.
+			$updateSource = $api->chooseReference($this->branch);
+			if ( $updateSource ) {
+				$ref = $updateSource->name;
+				$update->download_url = $updateSource->downloadUrl;
+			} else {
+				do_action(
+					'puc_api_error',
+					new \WP_Error(
+						'puc-no-update-source',
+						'Could not retrieve version information from the repository. '
+						. 'This usually means that the update checker either can\'t connect '
+						. 'to the repository or it\'s configured incorrectly.'
+					),
+					null, null, $this->slug
+				);
+				$ref = $this->branch;
+			}
+
+			//Get headers from the main stylesheet in this branch/tag. Its "Version" header and other metadata
+			//are what the WordPress install will actually see after upgrading, so they take precedence over releases/tags.
+			$remoteHeader = $this->package->getFileHeader($api->getRemoteFile('style.css', $ref));
+			$update->version = Utils::findNotEmpty(array(
+				$remoteHeader['Version'],
+				Utils::get($updateSource, 'version'),
+			));
+
+			//The details URL defaults to the Theme URI header or the repository URL.
+			$update->details_url = Utils::findNotEmpty(array(
+				$remoteHeader['ThemeURI'],
+				$this->package->getHeaderValue('ThemeURI'),
+				$this->metadataUrl,
+			));
+
+			if ( empty($update->version) ) {
+				//It looks like we didn't find a valid update after all.
+				$update = null;
+			}
+
+			$update = $this->filterUpdateResult($update);
+			return $update;
+		}
+	}
+
+endif;

lib/plugin-update-checker/Puc/v5p3/Vcs/VcsCheckerMethods.php

@@ -0,0 +1,59 @@
+<?php
+
+namespace YahnisElsts\PluginUpdateChecker\v5p3\Vcs;
+
+if ( !trait_exists(VcsCheckerMethods::class, false) ) :
+
+	trait VcsCheckerMethods {
+		/**
+		 * @var string The branch where to look for updates. Defaults to "master".
+		 */
+		protected $branch = 'master';
+
+		/**
+		 * @var Api Repository API client.
+		 */
+		protected $api = null;
+
+		public function setBranch($branch) {
+			$this->branch = $branch;
+			return $this;
+		}
+
+		/**
+		 * Set authentication credentials.
+		 *
+		 * @param array|string $credentials
+		 * @return $this
+		 */
+		public function setAuthentication($credentials) {
+			$this->api->setAuthentication($credentials);
+			return $this;
+		}
+
+		/**
+		 * @return Api
+		 */
+		public function getVcsApi() {
+			return $this->api;
+		}
+
+		public function getUpdate() {
+			$update = parent::getUpdate();
+
+			if ( isset($update) && !empty($update->download_url) ) {
+				$update->download_url = $this->api->signDownloadUrl($update->download_url);
+			}
+
+			return $update;
+		}
+
+		public function onDisplayConfiguration($panel) {
+			parent::onDisplayConfiguration($panel);
+			$panel->row('Branch', $this->branch);
+			$panel->row('Authentication enabled', $this->api->isAuthenticationEnabled() ? 'Yes' : 'No');
+			$panel->row('API client', get_class($this->api));
+		}
+	}
+
+endif;