<?php
/**
 * @defgroup FileAbstraction File abstraction
 * @ingroup FileRepo
 *
 * Represents files in a repository.
 */

use MediaWiki\Config\ConfigException;
use MediaWiki\Context\IContextSource;
use MediaWiki\HookContainer\ProtectedHookAccessorTrait;
use MediaWiki\Language\Language;
use MediaWiki\Linker\LinkTarget;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MainConfigNames;
use MediaWiki\MediaWikiServices;
use MediaWiki\Page\PageIdentity;
use MediaWiki\Permissions\Authority;
use MediaWiki\PoolCounter\PoolCounterWorkViaCallback;
use MediaWiki\Status\Status;
use MediaWiki\Title\Title;
use MediaWiki\User\UserIdentity;
use Shellbox\Command\BoxedCommand;
use Wikimedia\FileBackend\FileBackend;
use Wikimedia\FileBackend\FSFile\FSFile;
use Wikimedia\FileBackend\FSFile\TempFSFile;
use Wikimedia\ObjectCache\WANObjectCache;

/**
 * Base code for files.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @ingroup FileAbstraction
 */

/**
 * Implements some public methods and some protected utility functions which
 * are required by multiple child classes. Contains stub functionality for
 * unimplemented public methods.
 *
 * Stub functions which should be overridden are marked with STUB. Some more
 * concrete functions are also typically overridden by child classes.
 *
 * Note that only the repo object knows what its file class is called. You should
 * never name a file class explicitly outside of the repo class. Instead use the
 * repo's factory functions to generate file objects, for example:
 *
 * RepoGroup::singleton()->getLocalRepo()->newFile( $title );
 *
 * Consider the services container below;
 *
 * $services = MediaWikiServices::getInstance();
 *
 * The convenience services $services->getRepoGroup()->getLocalRepo()->newFile()
 * and $services->getRepoGroup()->findFile() should be sufficient in most cases.
 *
 * @TODO: DI - Instead of using MediaWikiServices::getInstance(), a service should
 * ideally accept a RepoGroup in its constructor and then, use $this->repoGroup->findFile()
 * and $this->repoGroup->getLocalRepo()->newFile().
 *
 * @stable to extend
 * @ingroup FileAbstraction
 */
abstract class File implements MediaHandlerState {
	use ProtectedHookAccessorTrait;

	// Bitfield values akin to the revision deletion constants
	public const DELETED_FILE = 1;
	public const DELETED_COMMENT = 2;
	public const DELETED_USER = 4;
	public const DELETED_RESTRICTED = 8;

	/** Force rendering in the current process */
	public const RENDER_NOW = 1;
	/**
	 * Force rendering even if thumbnail already exist and using RENDER_NOW
	 * I.e. you have to pass both flags: File::RENDER_NOW | File::RENDER_FORCE
	 */
	public const RENDER_FORCE = 2;

	public const DELETE_SOURCE = 1;

	// Audience options for File::getDescription()
	public const FOR_PUBLIC = 1;
	public const FOR_THIS_USER = 2;
	public const RAW = 3;

	// Options for File::thumbName()
	public const THUMB_FULL_NAME = 1;

	/**
	 * Some member variables can be lazy-initialised using __get(). The
	 * initialisation function for these variables is always a function named
	 * like getVar(), where Var is the variable name with upper-case first
	 * letter.
	 *
	 * The following variables are initialised in this way in this base class:
	 *    name, extension, handler, path, canRender, isSafeFile,
	 *    transformScript, hashPath, pageCount, url
	 *
	 * Code within this class should generally use the accessor function
	 * directly, since __get() isn't re-entrant and therefore causes bugs that
	 * depend on initialisation order.
	 */

	/**
	 * The following member variables are not lazy-initialised
	 */

	/** @var FileRepo|LocalRepo|ForeignAPIRepo|false */
	public $repo;

	/** @var Title|string|false */
	protected $title;

	/** @var string Text of last error */
	protected $lastError;

	/** @var ?string The name that was used to access the file, before
	 *       resolving redirects. Main part of the title, with underscores
	 *       per Title::getDBkey().
	 */
	protected $redirected;

	/** @var Title */
	protected $redirectedTitle;

	/** @var FSFile|false False if undefined */
	protected $fsFile;

	/** @var MediaHandler */
	protected $handler;

	/** @var string The URL corresponding to one of the four basic zones */
	protected $url;

	/** @var string File extension */
	protected $extension;

	/** @var string|null The name of a file from its title object */
	protected $name;

	/** @var string The storage path corresponding to one of the zones */
	protected $path;

	/** @var string|null Relative path including trailing slash */
	protected $hashPath;

	/** @var int|false Number of pages of a multipage document, or false for
	 *    documents which aren't multipage documents
	 */
	protected $pageCount;

	/** @var string|false URL of transformscript (for example thumb.php) */
	protected $transformScript;

	/** @var Title */
	protected $redirectTitle;

	/** @var bool Whether the output of transform() for this file is likely to be valid. */
	protected $canRender;

	/** @var bool Whether this media file is in a format that is unlikely to
	 *    contain viruses or malicious content
	 */
	protected $isSafeFile;

	/** @var string Required Repository class type */
	protected $repoClass = FileRepo::class;

	/** @var array Cache of tmp filepaths pointing to generated bucket thumbnails, keyed by width */
	protected $tmpBucketedThumbCache = [];

	/** @var array */
	private $handlerState = [];

	/**
	 * Call this constructor from child classes.
	 *
	 * Both $title and $repo are optional, though some functions
	 * may return false or throw exceptions if they are not set.
	 * Most subclasses will want to call assertRepoDefined() here.
	 *
	 * @stable to call
	 * @param Title|string|false $title
	 * @param FileRepo|false $repo
	 */
	public function __construct( $title, $repo ) {
		// Some subclasses do not use $title, but set name/title some other way
		if ( $title !== false ) {
			$title = self::normalizeTitle( $title, 'exception' );
		}
		$this->title = $title;
		$this->repo = $repo;
	}

	/**
	 * Given a string or Title object return either a
	 * valid Title object with namespace NS_FILE or null
	 *
	 * @param PageIdentity|LinkTarget|string $title
	 * @param string|false $exception Use 'exception' to throw an error on bad titles
	 * @return Title|null
	 */
	public static function normalizeTitle( $title, $exception = false ) {
		$ret = $title;

		if ( !$ret instanceof Title ) {
			if ( $ret instanceof PageIdentity ) {
				$ret = Title::castFromPageIdentity( $ret );
			} elseif ( $ret instanceof LinkTarget ) {
				$ret = Title::castFromLinkTarget( $ret );
			}
		}

		if ( $ret instanceof Title ) {
			# Normalize NS_MEDIA -> NS_FILE
			if ( $ret->getNamespace() === NS_MEDIA ) {
				$ret = Title::makeTitleSafe( NS_FILE, $ret->getDBkey() );
			# Double check the titles namespace
			} elseif ( $ret->getNamespace() !== NS_FILE ) {
				$ret = null;
			}
		} else {
			# Convert strings to Title objects
			$ret = Title::makeTitleSafe( NS_FILE, (string)$ret );
		}
		if ( !$ret && $exception !== false ) {
			throw new RuntimeException( "`$title` is not a valid file title." );
		}

		return $ret;
	}

	public function __get( $name ) {
		$function = [ $this, 'get' . ucfirst( $name ) ];
		if ( !is_callable( $function ) ) {
			return null;
		} else {
			$this->$name = $function();

			return $this->$name;
		}
	}

	/**
	 * Normalize a file extension to the common form, making it lowercase and checking some synonyms,
	 * and ensure it's clean. Extensions with non-alphanumeric characters will be discarded.
	 * Keep in sync with mw.Title.normalizeExtension() in JS.
	 *
	 * @param string $extension File extension (without the leading dot)
	 * @return string File extension in canonical form
	 */
	public static function normalizeExtension( $extension ) {
		$lower = strtolower( $extension );
		$squish = [
			'htm' => 'html',
			'jpeg' => 'jpg',
			'mpeg' => 'mpg',
			'tiff' => 'tif',
			'ogv' => 'ogg' ];
		if ( isset( $squish[$lower] ) ) {
			return $squish[$lower];
		} elseif ( preg_match( '/^[0-9a-z]+$/', $lower ) ) {
			return $lower;
		} else {
			return '';
		}
	}

	/**
	 * Checks if file extensions are compatible
	 *
	 * @param File $old Old file
	 * @param string $new New name
	 *
	 * @return bool|null
	 */
	public static function checkExtensionCompatibility( File $old, $new ) {
		$oldMime = $old->getMimeType();
		$n = strrpos( $new, '.' );
		$newExt = self::normalizeExtension( $n ? substr( $new, $n + 1 ) : '' );
		$mimeMagic = MediaWikiServices::getInstance()->getMimeAnalyzer();

		return $mimeMagic->isMatchingExtension( $newExt, $oldMime );
	}

	/**
	 * Upgrade the database row if there is one
	 * Called by ImagePage
	 * STUB
	 *
	 * @stable to override
	 */
	public function upgradeRow() {
	}

	/**
	 * Split an internet media type into its two components; if not
	 * a two-part name, set the minor type to 'unknown'.
	 *
	 * @param ?string $mime "text/html" etc
	 * @return string[] ("text", "html") etc
	 */
	public static function splitMime( ?string $mime ) {
		if ( $mime === null ) {
			return [ 'unknown', 'unknown' ];
		} elseif ( str_contains( $mime, '/' ) ) {
			return explode( '/', $mime, 2 );
		} else {
			return [ $mime, 'unknown' ];
		}
	}

	/**
	 * Callback for usort() to do file sorts by name
	 *
	 * @param File $a
	 * @param File $b
	 * @return int Result of name comparison
	 */
	public static function compare( File $a, File $b ) {
		return strcmp( $a->getName(), $b->getName() );
	}

	/**
	 * Return the name of this file
	 *
	 * @stable to override
	 * @return string
	 */
	public function getName() {
		if ( $this->name === null ) {
			$this->assertRepoDefined();
			$this->name = $this->repo->getNameFromTitle( $this->title );
		}

		return $this->name;
	}

	/**
	 * Get the file extension, e.g. "svg"
	 *
	 * @stable to override
	 * @return string
	 */
	public function getExtension() {
		if ( !isset( $this->extension ) ) {
			$n = strrpos( $this->getName(), '.' );
			$this->extension = self::normalizeExtension(
				$n ? substr( $this->getName(), $n + 1 ) : '' );
		}

		return $this->extension;
	}

	/**
	 * Return the associated title object
	 *
	 * @return Title
	 */
	public function getTitle() {
		return $this->title;
	}

	/**
	 * Return the title used to find this file
	 *
	 * @return Title
	 */
	public function getOriginalTitle() {
		if ( $this->redirected !== null ) {
			return $this->getRedirectedTitle();
		}

		return $this->title;
	}

	/**
	 * Return the URL of the file
	 * @stable to override
	 *
	 * @return string
	 */
	public function getUrl() {
		if ( !isset( $this->url ) ) {
			$this->assertRepoDefined();
			$ext = $this->getExtension();
			$this->url = $this->repo->getZoneUrl( 'public', $ext ) . '/' . $this->getUrlRel();
		}

		return $this->url;
	}

	/**
	 * Get short description URL for a files based on the page ID
	 * @stable to override
	 *
	 * @return string|null
	 * @since 1.27
	 */
	public function getDescriptionShortUrl() {
		return null;
	}

	/**
	 * Return a fully-qualified URL to the file.
	 * Upload URL paths _may or may not_ be fully qualified, so
	 * we check. Local paths are assumed to belong on $wgServer.
	 * @stable to override
	 *
	 * @return string
	 */
	public function getFullUrl() {
		return (string)MediaWikiServices::getInstance()->getUrlUtils()
			->expand( $this->getUrl(), PROTO_RELATIVE );
	}

	/**
	 * @stable to override
	 * @return string
	 */
	public function getCanonicalUrl() {
		return (string)MediaWikiServices::getInstance()->getUrlUtils()
			->expand( $this->getUrl(), PROTO_CANONICAL );
	}

	/**
	 * @return string
	 */
	public function getViewURL() {
		if ( $this->mustRender() ) {
			if ( $this->canRender() ) {
				return $this->createThumb( $this->getWidth() );
			} else {
				wfDebug( __METHOD__ . ': supposed to render ' . $this->getName() .
					' (' . $this->getMimeType() . "), but can't!" );

				return $this->getUrl(); # hm... return NULL?
			}
		} else {
			return $this->getUrl();
		}
	}

	/**
	 * Return the storage path to the file. Note that this does
	 * not mean that a file actually exists under that location.
	 *
	 * This path depends on whether directory hashing is active or not,
	 * i.e. whether the files are all found in the same directory,
	 * or in hashed paths like /images/3/3c.
	 *
	 * Most callers don't check the return value, but ForeignAPIFile::getPath
	 * returns false.
	 *
	 * @stable to override
	 * @return string|false ForeignAPIFile::getPath can return false
	 */
	public function getPath() {
		if ( !isset( $this->path ) ) {
			$this->assertRepoDefined();
			$this->path = $this->repo->getZonePath( 'public' ) . '/' . $this->getRel();
		}

		return $this->path;
	}

	/**
	 * Get an FS copy or original of this file and return the path.
	 * Returns false on failure. Callers must not alter the file.
	 * Temporary files are cleared automatically.
	 *
	 * @return string|false False on failure
	 */
	public function getLocalRefPath() {
		$this->assertRepoDefined();
		if ( !isset( $this->fsFile ) ) {
			$timer = MediaWikiServices::getInstance()->getStatsFactory()
				->getTiming( 'media_thumbnail_generate_fetchoriginal_seconds' )
				->copyToStatsdAt( 'media.thumbnail.generate.fetchoriginal' );
			$timer->start();

			$this->fsFile = $this->repo->getLocalReference( $this->getPath() );

			$timer->stop();

			if ( !$this->fsFile ) {
				$this->fsFile = false; // null => false; cache negative hits
			}
		}

		return ( $this->fsFile )
			? $this->fsFile->getPath()
			: false;
	}

	/**
	 * Add the file to a Shellbox command as an input file
	 *
	 * @since 1.43
	 * @param BoxedCommand $command
	 * @param string $boxedName
	 * @return StatusValue
	 */
	public function addToShellboxCommand( BoxedCommand $command, string $boxedName ) {
		return $this->repo->addShellboxInputFile( $command, $boxedName, $this->getVirtualUrl() );
	}

	/**
	 * Return the width of the image. Returns false if the width is unknown
	 * or undefined.
	 *
	 * STUB
	 * Overridden by LocalFile, UnregisteredLocalFile
	 *
	 * @stable to override
	 * @param int $page
	 * @return int|false
	 */
	public function getWidth( $page = 1 ) {
		return false;
	}

	/**
	 * Return the height of the image. Returns false if the height is unknown
	 * or undefined
	 *
	 * STUB
	 * Overridden by LocalFile, UnregisteredLocalFile
	 *
	 * @stable to override
	 * @param int $page
	 * @return int|false False on failure
	 */
	public function getHeight( $page = 1 ) {
		return false;
	}

	/**
	 * Return the smallest bucket from $wgThumbnailBuckets which is at least
	 * $wgThumbnailMinimumBucketDistance larger than $desiredWidth. The returned bucket, if any,
	 * will always be bigger than $desiredWidth.
	 *
	 * @param int $desiredWidth
	 * @param int $page
	 * @return int|false
	 */
	public function getThumbnailBucket( $desiredWidth, $page = 1 ) {
		$thumbnailBuckets = MediaWikiServices::getInstance()
			->getMainConfig()->get( MainConfigNames::ThumbnailBuckets );
		$thumbnailMinimumBucketDistance = MediaWikiServices::getInstance()
			->getMainConfig()->get( MainConfigNames::ThumbnailMinimumBucketDistance );
		$imageWidth = $this->getWidth( $page );

		if ( $imageWidth === false ) {
			return false;
		}

		if ( $desiredWidth > $imageWidth ) {
			return false;
		}

		if ( !$thumbnailBuckets ) {
			return false;
		}

		$sortedBuckets = $thumbnailBuckets;

		sort( $sortedBuckets );

		foreach ( $sortedBuckets as $bucket ) {
			if ( $bucket >= $imageWidth ) {
				return false;
			}

			if ( $bucket - $thumbnailMinimumBucketDistance > $desiredWidth ) {
				return $bucket;
			}
		}

		// Image is bigger than any available bucket
		return false;
	}

	/**
	 * Get the width and height to display image at.
	 *
	 * @param int $maxWidth Max width to display at
	 * @param int $maxHeight Max height to display at
	 * @param int $page
	 * @return array Array (width, height)
	 * @since 1.35
	 */
	public function getDisplayWidthHeight( $maxWidth, $maxHeight, $page = 1 ) {
		if ( !$maxWidth || !$maxHeight ) {
			// should never happen
			throw new ConfigException( 'Using a choice from $wgImageLimits that is 0x0' );
		}

		$width = $this->getWidth( $page );
		$height = $this->getHeight( $page );
		if ( !$width || !$height ) {
			return [ 0, 0 ];
		}

		// Calculate the thumbnail size.
		if ( $width <= $maxWidth && $height <= $maxHeight ) {
			// Vectorized image, do nothing.
		} elseif ( $width / $height >= $maxWidth / $maxHeight ) {
			# The limiting factor is the width, not the height.
			$height = round( $height * $maxWidth / $width );
			$width = $maxWidth;
			// Note that $height <= $maxHeight now.
		} else {
			$newwidth = floor( $width * $maxHeight / $height );
			$height = round( $height * $newwidth / $width );
			$width = $newwidth;
			// Note that $height <= $maxHeight now, but might not be identical
			// because of rounding.
		}
		return [ $width, $height ];
	}

	/**
	 * Get the duration of a media file in seconds
	 *
	 * @stable to override
	 * @return float|int
	 */
	public function getLength() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getLength( $this );
		} else {
			return 0;
		}
	}

	/**
	 * Return true if the file is vectorized
	 *
	 * @return bool
	 */
	public function isVectorized() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->isVectorized( $this );
		} else {
			return false;
		}
	}

	/**
	 * Gives a (possibly empty) list of IETF languages to render
	 * the file in.
	 *
	 * If the file doesn't have translations, or if the file
	 * format does not support that sort of thing, returns
	 * an empty array.
	 *
	 * @return string[]
	 * @since 1.23
	 */
	public function getAvailableLanguages() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getAvailableLanguages( $this );
		} else {
			return [];
		}
	}

	/**
	 * Get the IETF language code from the available languages for this file that matches the language
	 * requested by the user
	 *
	 * @param string $userPreferredLanguage
	 * @return string|null
	 */
	public function getMatchedLanguage( $userPreferredLanguage ) {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getMatchedLanguage(
				$userPreferredLanguage,
				$handler->getAvailableLanguages( $this )
			);
		}

		return null;
	}

	/**
	 * In files that support multiple language, what is the default language
	 * to use if none specified.
	 *
	 * @return string|null IETF Lang code, or null if filetype doesn't support multiple languages.
	 * @since 1.23
	 */
	public function getDefaultRenderLanguage() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getDefaultRenderLanguage( $this );
		} else {
			return null;
		}
	}

	/**
	 * Will the thumbnail be animated if one would expect it to be.
	 *
	 * Currently used to add a warning to the image description page
	 *
	 * @return bool False if the main image is both animated
	 *   and the thumbnail is not. In all other cases must return
	 *   true. If image is not renderable whatsoever, should
	 *   return true.
	 */
	public function canAnimateThumbIfAppropriate() {
		$handler = $this->getHandler();
		if ( !$handler ) {
			// We cannot handle image whatsoever, thus
			// one would not expect it to be animated
			// so true.
			return true;
		}

		return !$this->allowInlineDisplay()
			// Image is not animated, so one would
			// not expect thumb to be
			|| !$handler->isAnimatedImage( $this )
			// Image is animated, but thumbnail isn't.
			// This is unexpected to the user.
			|| $handler->canAnimateThumbnail( $this );
	}

	/**
	 * Get handler-specific metadata
	 * Overridden by LocalFile, UnregisteredLocalFile
	 * STUB
	 * @deprecated since 1.37 use getMetadataArray() or getMetadataItem()
	 * @return string|false
	 */
	public function getMetadata() {
		return false;
	}

	public function getHandlerState( string $key ) {
		return $this->handlerState[$key] ?? null;
	}

	public function setHandlerState( string $key, $value ) {
		$this->handlerState[$key] = $value;
	}

	/**
	 * Get the unserialized handler-specific metadata
	 * STUB
	 * @since 1.37
	 * @return array
	 */
	public function getMetadataArray(): array {
		return [];
	}

	/**
	 * Get a specific element of the unserialized handler-specific metadata.
	 *
	 * @since 1.37
	 * @param string $itemName
	 * @return mixed
	 */
	public function getMetadataItem( string $itemName ) {
		$items = $this->getMetadataItems( [ $itemName ] );
		return $items[$itemName] ?? null;
	}

	/**
	 * Get multiple elements of the unserialized handler-specific metadata.
	 *
	 * @since 1.37
	 * @param string[] $itemNames
	 * @return array
	 */
	public function getMetadataItems( array $itemNames ): array {
		return array_intersect_key(
			$this->getMetadataArray(),
			array_fill_keys( $itemNames, true ) );
	}

	/**
	 * Like getMetadata but returns a handler independent array of common values.
	 * @see MediaHandler::getCommonMetaArray()
	 * @return array|false Array or false if not supported
	 * @since 1.23
	 */
	public function getCommonMetaArray() {
		$handler = $this->getHandler();
		return $handler ? $handler->getCommonMetaArray( $this ) : false;
	}

	/**
	 * get versioned metadata
	 *
	 * @param array $metadata Array of unserialized metadata
	 * @param int|string $version Version number.
	 * @return array Array containing metadata, or what was passed to it on fail
	 */
	public function convertMetadataVersion( $metadata, $version ) {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->convertMetadataVersion( $metadata, $version );
		} else {
			return $metadata;
		}
	}

	/**
	 * Return the bit depth of the file
	 * Overridden by LocalFile
	 * STUB
	 * @stable to override
	 * @return int
	 */
	public function getBitDepth() {
		return 0;
	}

	/**
	 * Return the size of the image file, in bytes
	 * Overridden by LocalFile, UnregisteredLocalFile
	 * STUB
	 * @stable to override
	 * @return int|false
	 */
	public function getSize() {
		return false;
	}

	/**
	 * Returns the MIME type of the file.
	 * Overridden by LocalFile, UnregisteredLocalFile
	 * STUB
	 *
	 * @stable to override
	 * @return string
	 */
	public function getMimeType() {
		return 'unknown/unknown';
	}

	/**
	 * Return the type of the media in the file.
	 * Use the value returned by this function with the MEDIATYPE_xxx constants.
	 * Overridden by LocalFile,
	 * STUB
	 * @stable to override
	 * @return string
	 */
	public function getMediaType() {
		return MEDIATYPE_UNKNOWN;
	}

	/**
	 * Checks if the output of transform() for this file is likely to be valid.
	 *
	 * In other words, this will return true if a thumbnail can be provided for this
	 * image (e.g. if [[File:...|thumb]] produces a result on a wikitext page).
	 *
	 * If this is false, various user elements will display a placeholder instead.
	 *
	 * @return bool
	 */
	public function canRender() {
		if ( !isset( $this->canRender ) ) {
			$this->canRender = $this->getHandler() && $this->handler->canRender( $this ) && $this->exists();
		}

		return $this->canRender;
	}

	/**
	 * Accessor for __get()
	 * @return bool
	 */
	protected function getCanRender() {
		return $this->canRender();
	}

	/**
	 * Return true if the file is of a type that can't be directly
	 * rendered by typical browsers and needs to be re-rasterized.
	 *
	 * This returns true for everything but the bitmap types
	 * supported by all browsers, i.e. JPEG; GIF and PNG. It will
	 * also return true for any non-image formats.
	 *
	 * @stable to override
	 * @return bool
	 */
	public function mustRender() {
		return $this->getHandler() && $this->handler->mustRender( $this );
	}

	/**
	 * Alias for canRender()
	 *
	 * @return bool
	 */
	public function allowInlineDisplay() {
		return $this->canRender();
	}

	/**
	 * Determines if this media file is in a format that is unlikely to
	 * contain viruses or malicious content. It uses the global
	 * $wgTrustedMediaFormats list to determine if the file is safe.
	 *
	 * This is used to show a warning on the description page of non-safe files.
	 * It may also be used to disallow direct [[media:...]] links to such files.
	 *
	 * Note that this function will always return true if allowInlineDisplay()
	 * or isTrustedFile() is true for this file.
	 *
	 * @return bool
	 */
	public function isSafeFile() {
		if ( !isset( $this->isSafeFile ) ) {
			$this->isSafeFile = $this->getIsSafeFileUncached();
		}

		return $this->isSafeFile;
	}

	/**
	 * Accessor for __get()
	 *
	 * @return bool
	 */
	protected function getIsSafeFile() {
		return $this->isSafeFile();
	}

	/**
	 * Uncached accessor
	 *
	 * @return bool
	 */
	protected function getIsSafeFileUncached() {
		$trustedMediaFormats = MediaWikiServices::getInstance()->getMainConfig()
			->get( MainConfigNames::TrustedMediaFormats );

		if ( $this->allowInlineDisplay() ) {
			return true;
		}
		if ( $this->isTrustedFile() ) {
			return true;
		}

		$type = $this->getMediaType();
		$mime = $this->getMimeType();

		if ( !$type || $type === MEDIATYPE_UNKNOWN ) {
			return false; # unknown type, not trusted
		}
		if ( in_array( $type, $trustedMediaFormats ) ) {
			return true;
		}

		if ( $mime === "unknown/unknown" ) {
			return false; # unknown type, not trusted
		}
		if ( in_array( $mime, $trustedMediaFormats ) ) {
			return true;
		}

		return false;
	}

	/**
	 * Returns true if the file is flagged as trusted. Files flagged that way
	 * can be linked to directly, even if that is not allowed for this type of
	 * file normally.
	 *
	 * This is a dummy function right now and always returns false. It could be
	 * implemented to extract a flag from the database. The trusted flag could be
	 * set on upload, if the user has sufficient privileges, to bypass script-
	 * and html-filters. It may even be coupled with cryptographic signatures
	 * or such.
	 *
	 * @return bool
	 */
	protected function isTrustedFile() {
		# this could be implemented to check a flag in the database,
		# look for signatures, etc
		return false;
	}

	/**
	 * Load any lazy-loaded file object fields from source
	 *
	 * This is only useful when setting $flags
	 *
	 * Overridden by LocalFile to actually query the DB
	 *
	 * @stable to override
	 * @param int $flags Bitfield of IDBAccessObject::READ_* constants
	 */
	public function load( $flags = 0 ) {
	}

	/**
	 * Returns true if file exists in the repository.
	 *
	 * Overridden by LocalFile to avoid unnecessary stat calls.
	 *
	 * @stable to override
	 * @return bool Whether file exists in the repository.
	 */
	public function exists() {
		return $this->getPath() && $this->repo->fileExists( $this->path );
	}

	/**
	 * Returns true if file exists in the repository and can be included in a page.
	 * It would be unsafe to include private images, making public thumbnails inadvertently
	 *
	 * @stable to override
	 * @return bool Whether file exists in the repository and is includable.
	 */
	public function isVisible() {
		return $this->exists();
	}

	/**
	 * @return string|false
	 */
	private function getTransformScript() {
		if ( !isset( $this->transformScript ) ) {
			$this->transformScript = false;
			if ( $this->repo ) {
				$script = $this->repo->getThumbScriptUrl();
				if ( $script ) {
					$this->transformScript = wfAppendQuery( $script, [ 'f' => $this->getName() ] );
				}
			}
		}

		return $this->transformScript;
	}

	/**
	 * Get a ThumbnailImage which is the same size as the source
	 *
	 * @param array $handlerParams
	 *
	 * @return ThumbnailImage|MediaTransformOutput|false False on failure
	 */
	public function getUnscaledThumb( $handlerParams = [] ) {
		$hp =& $handlerParams;
		$page = $hp['page'] ?? false;
		$width = $this->getWidth( $page );
		if ( !$width ) {
			return $this->iconThumb();
		}
		$hp['width'] = $width;
		// be sure to ignore any height specification as well (T64258)
		unset( $hp['height'] );

		return $this->transform( $hp );
	}

	/**
	 * Return the file name of a thumbnail with the specified parameters.
	 * Use File::THUMB_FULL_NAME to always get a name like "<params>-<source>".
	 * Otherwise, the format may be "<params>-<source>" or "<params>-thumbnail.<ext>".
	 *
	 * The parameters used here must be the same as those used by media handlers'
	 * implementation of {@link MediaHandler::doTransform}. Otherwise, the decision
	 * of whether thumbnailing is needed may be wrong, and the actual size of the
	 * thumbnail generated may not match the name (T415598).
	 *
	 * @stable to override
	 * @param array $params Handler-specific parameters
	 * @param int $flags Bitfield that supports THUMB_* constants
	 * @return string|null
	 */
	public function thumbName( $params, $flags = 0 ) {
		$name = ( $this->repo && !( $flags & self::THUMB_FULL_NAME ) )
			? $this->repo->nameForThumb( $this->getName() )
			: $this->getName();

		return $this->generateThumbName( $name, $params );
	}

	/**
	 * Generate a thumbnail file name from a name and specified parameters
	 * @stable to override
	 *
	 * @param string $name
	 * @param array $params Parameters which will be passed to MediaHandler::makeParamString
	 * @return string|null
	 */
	public function generateThumbName( $name, $params ) {
		if ( !$this->getHandler() ) {
			return null;
		}
		$extension = $this->getExtension();
		[ $thumbExt, ] = $this->getHandler()->getThumbType(
			$extension, $this->getMimeType(), $params );
		$thumbName = $this->getHandler()->makeParamString( $params );

		if ( $this->repo->supportsSha1URLs() ) {
			$thumbName .= '-' . $this->getSha1() . '.' . $thumbExt;
		} else {
			$thumbName .= '-' . $name;

			if ( $thumbExt != $extension ) {
				$thumbName .= ".$thumbExt";
			}
		}

		return $thumbName;
	}

	/**
	 * Create a thumbnail of the image having the specified width/height.
	 * The thumbnail will not be created if the width is larger than the
	 * image's width. Let the browser do the scaling in this case.
	 * The thumbnail is stored on disk and is only computed if the thumbnail
	 * file does not exist OR if it is older than the image.
	 * Returns the URL.
	 *
	 * Keeps aspect ratio of original image. If both width and height are
	 * specified, the generated image will be no bigger than width x height,
	 * and will also have correct aspect ratio.
	 *
	 * @param int $width Maximum width of the generated thumbnail
	 * @param int $height Maximum height of the image (optional)
	 *
	 * @return string
	 */
	public function createThumb( $width, $height = -1 ) {
		$params = [ 'width' => $width ];
		if ( $height != -1 ) {
			$params['height'] = $height;
		}
		$thumb = $this->transform( $params );
		if ( !$thumb || $thumb->isError() ) {
			return '';
		}

		return $thumb->getUrl();
	}

	/**
	 * Return either a MediaTransformError or placeholder thumbnail (if $wgIgnoreImageErrors)
	 *
	 * @param string $thumbPath Thumbnail storage path
	 * @param string $thumbUrl Thumbnail URL
	 * @param array $params
	 * @param int $flags
	 * @return MediaTransformOutput
	 */
	protected function transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags ) {
		$ignoreImageErrors = MediaWikiServices::getInstance()->getMainConfig()
			->get( MainConfigNames::IgnoreImageErrors );

		$handler = $this->getHandler();
		if ( $handler && $ignoreImageErrors && !( $flags & self::RENDER_NOW ) ) {
			return $handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
		} else {
			return new MediaTransformError( 'thumbnail_error',
				$params['width'], 0, wfMessage( 'thumbnail-dest-create' ) );
		}
	}

	/**
	 * Transform a media file
	 * @stable to override
	 *
	 * @param array $params An associative array of handler-specific parameters.
	 *   Typical keys are width, height and page.
	 * @param int $flags A bitfield, may contain self::RENDER_NOW to force rendering
	 * @return ThumbnailImage|MediaTransformOutput|false False on failure
	 */
	public function transform( $params, $flags = 0 ) {
		$thumbnailEpoch = MediaWikiServices::getInstance()->getMainConfig()
			->get( MainConfigNames::ThumbnailEpoch );

		do {
			if ( !$this->canRender() ) {
				$thumb = $this->iconThumb();
				break; // not a bitmap or renderable image, don't try
			}

			// Get the descriptionUrl to embed it as comment into the thumbnail. T21791.
			$descriptionUrl = $this->getDescriptionUrl();
			if ( $descriptionUrl ) {
				$params['descriptionUrl'] = MediaWikiServices::getInstance()->getUrlUtils()
					->expand( $descriptionUrl, PROTO_CANONICAL );
			}

			$handler = $this->getHandler();
			$script = $this->getTransformScript();
			if ( $script && !( $flags & self::RENDER_NOW ) ) {
				// Use a script to transform on client request, if possible
				$thumb = $handler->getScriptedTransform( $this, $script, $params );
				if ( $thumb ) {
					break;
				}
			}

			$normalisedParams = $params;
			$handler->normaliseParams( $this, $normalisedParams );

			$thumbName = $this->thumbName( $normalisedParams );
			$thumbUrl = $this->getThumbUrl( $thumbName );
			// final thumb path, if the media handler decides to use a thumbnail for the given params
			$thumbPath = $this->getThumbPath( $thumbName );
			if ( isset( $normalisedParams['isFilePageThumb'] ) && $normalisedParams['isFilePageThumb'] ) {
				// Use a versioned URL on file description pages
				$thumbUrl = $this->getFilePageThumbUrl( $thumbUrl );
			}

			if ( $this->repo ) {
				// Defer rendering if a 404 handler is set up...
				if ( $this->repo->canTransformVia404() && !( $flags & self::RENDER_NOW ) ) {
					// XXX: Pass in the storage path even though we are not rendering anything
					// and the path is supposed to be an FS path. This is due to getScalerType()
					// getting called on the path and clobbering $thumb->getUrl() if it's false.
					$thumb = $handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
					break;
				}
				// Check if an up-to-date thumbnail already exists...
				wfDebug( __METHOD__ . ": Doing stat for $thumbPath" );
				if ( !( $flags & self::RENDER_FORCE ) && $this->repo->fileExists( $thumbPath ) ) {
					$timestamp = $this->repo->getFileTimestamp( $thumbPath );
					if ( $timestamp !== false && $timestamp >= $thumbnailEpoch ) {
						// XXX: Pass in the storage path even though we are not rendering anything
						// and the path is supposed to be an FS path. This is due to getScalerType()
						// getting called on the path and clobbering $thumb->getUrl() if it's false.
						$thumb = $handler->getTransform( $this, $thumbPath, $thumbUrl, $params );
						$thumb->setStoragePath( $thumbPath );
						break;
					}
				} elseif ( $flags & self::RENDER_FORCE ) {
					wfDebug( __METHOD__ . " forcing rendering per flag File::RENDER_FORCE" );
				}

				// If the backend is ready-only, don't keep generating thumbnails
				// only to return transformation errors, just return the error now.
				if ( $this->repo->getReadOnlyReason() !== false ) {
					$thumb = $this->transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags );
					break;
				}

				// Check to see if local transformation is disabled.
				if ( !$this->repo->canTransformLocally() ) {
					LoggerFactory::getInstance( 'thumbnail' )
						->error( 'Local transform denied by configuration' );
					$thumb = new MediaTransformError(
						wfMessage(
							'thumbnail_error',
							'MediaWiki is configured to disallow local image scaling'
						),
						$params['width'],
						0
					);
					break;
				}
			}

			$tmpFile = $this->makeTransformTmpFile( $thumbPath );

			if ( !$tmpFile ) {
				$thumb = $this->transformErrorOutput( $thumbPath, $thumbUrl, $params, $flags );
			} else {
				$thumb = $this->generateAndSaveThumb( $tmpFile, $params, $flags );
			}
		} while ( false );

		return is_object( $thumb ) ? $thumb : false;
	}

	/**
	 * Generates a thumbnail according to the given parameters and saves it to storage
	 * @param TempFSFile $tmpFile Temporary file where the rendered thumbnail will be saved
	 * @param array $transformParams
	 * @param int $flags
	 * @return MediaTransformOutput|false
	 */
	public function generateAndSaveThumb( $tmpFile, $transformParams, $flags ) {
		$ignoreImageErrors = MediaWikiServices::getInstance()->getMainConfig()
			->get( MainConfigNames::IgnoreImageErrors );

		if ( !$this->repo->canTransformLocally() ) {
			LoggerFactory::getInstance( 'thumbnail' )
				->error( 'Local transform denied by configuration' );
			return new MediaTransformError(
				wfMessage(
					'thumbnail_error',
					'MediaWiki is configured to disallow local image scaling'
				),
				$transformParams['width'],
				0
			);
		}

		$statsFactory = MediaWikiServices::getInstance()->getStatsFactory();

		$handler = $this->getHandler();

		$normalisedParams = $transformParams;
		$handler->normaliseParams( $this, $normalisedParams );

		$thumbName = $this->thumbName( $normalisedParams );
		$thumbUrl = $this->getThumbUrl( $thumbName );
		// final thumb path, if the media handler decides to use a thumbnail for the given params
		$thumbPath = $this->getThumbPath( $thumbName );
		if ( isset( $normalisedParams['isFilePageThumb'] ) && $normalisedParams['isFilePageThumb'] ) {
			// Use a versioned URL on file description pages
			$thumbUrl = $this->getFilePageThumbUrl( $thumbUrl );
		}

		$tmpThumbPath = $tmpFile->getPath();

		if ( $handler->supportsBucketing() ) {
			$this->generateBucketsIfNeeded( $normalisedParams, $flags );
		}

		# T367110
		# Calls to doTransform() can recur back on $this->transform()
		# depending on implementation. One such example is PagedTiffHandler.
		# TimingMetric->start() and stop() cannot be used in this situation
		# so we will track the time manually.
		$starttime = microtime( true );

		// Actually render the thumbnail...
		$thumb = $handler->doTransform( $this, $tmpThumbPath, $thumbUrl, $transformParams );
		$tmpFile->bind( $thumb ); // keep alive with $thumb

		$statsFactory->getTiming( 'media_thumbnail_generate_transform_seconds' )
			->copyToStatsdAt( 'media.thumbnail.generate.transform' )
			->observe( ( microtime( true ) - $starttime ) * 1000 );

		if ( !$thumb ) { // bad params?
			$thumb = false;
		} elseif ( $thumb->isError() ) { // transform error
			/** @var MediaTransformError $thumb */
			'@phan-var MediaTransformError $thumb';
			$this->lastError = $thumb->toText();
			// Ignore errors if requested
			if ( $ignoreImageErrors && !( $flags & self::RENDER_NOW ) ) {
				$thumb = $handler->getTransform( $this, $tmpThumbPath, $thumbUrl, $transformParams );
			}
		} elseif ( $this->repo && $thumb->hasFile() && !$thumb->fileIsSource() ) {
			// Copy the thumbnail from the file system into storage...

			$timer = $statsFactory->getTiming( 'media_thumbnail_generate_store_seconds' )
				->copyToStatsdAt( 'media.thumbnail.generate.store' );
			$timer->start();

			$disposition = $this->getThumbDisposition( $thumbName );
			$status = $this->repo->quickImport( $tmpThumbPath, $thumbPath, $disposition );
			if ( $status->isOK() ) {
				$thumb->setStoragePath( $thumbPath );
			} else {
				$thumb = $this->transformErrorOutput( $thumbPath, $thumbUrl, $transformParams, $flags );
			}

			$timer->stop();

			// Give extensions a chance to do something with this thumbnail...
			$this->getHookRunner()->onFileTransformed( $this, $thumb, $tmpThumbPath, $thumbPath );
		}

		return $thumb;
	}

	/**
	 * Generates chained bucketed thumbnails if needed
	 * @param array $params
	 * @param int $flags
	 * @return bool Whether at least one bucket was generated
	 */
	protected function generateBucketsIfNeeded( $params, $flags = 0 ) {
		if ( !$this->repo
			|| !isset( $params['physicalWidth'] )
			|| !isset( $params['physicalHeight'] )
		) {
			return false;
		}

		$bucket = $this->getThumbnailBucket( $params['physicalWidth'] );

		if ( !$bucket || $bucket == $params['physicalWidth'] ) {
			return false;
		}

		$bucketPath = $this->getBucketThumbPath( $bucket );

		if ( $this->repo->fileExists( $bucketPath ) ) {
			return false;
		}

		$timer = MediaWikiServices::getInstance()->getStatsFactory()
			->getTiming( 'media_thumbnail_generate_bucket_seconds' )
			->copyToStatsdAt( 'media.thumbnail.generate.bucket' );
		$timer->start();

		$params['physicalWidth'] = $bucket;
		$params['width'] = $bucket;

		$params = $this->getHandler()->sanitizeParamsForBucketing( $params );

		$tmpFile = $this->makeTransformTmpFile( $bucketPath );

		if ( !$tmpFile ) {
			return false;
		}

		$thumb = $this->generateAndSaveThumb( $tmpFile, $params, $flags );

		if ( !$thumb || $thumb->isError() ) {
			return false;
		}

		$timer->stop();

		$this->tmpBucketedThumbCache[$bucket] = $tmpFile->getPath();
		// For the caching to work, we need to make the tmp file survive as long as
		// this object exists
		$tmpFile->bind( $this );

		return true;
	}

	/**
	 * Returns the most appropriate source image for the thumbnail, given a target thumbnail size
	 * @param array $params
	 * @return array Source path and width/height of the source
	 */
	public function getThumbnailSource( $params ) {
		if ( $this->repo
			&& $this->getHandler()->supportsBucketing()
			&& isset( $params['physicalWidth'] )
		) {
			$bucket = $this->getThumbnailBucket( $params['physicalWidth'] );
			if ( $bucket ) {
				if ( $this->getWidth() != 0 ) {
					$bucketHeight = round( $this->getHeight() * ( $bucket / $this->getWidth() ) );
				} else {
					$bucketHeight = 0;
				}

				// Try to avoid reading from storage if the file was generated by this script
				if ( isset( $this->tmpBucketedThumbCache[$bucket] ) ) {
					$tmpPath = $this->tmpBucketedThumbCache[$bucket];

					if ( file_exists( $tmpPath ) ) {
						return [
							'path' => $tmpPath,
							'width' => $bucket,
							'height' => $bucketHeight
						];
					}
				}

				$bucketPath = $this->getBucketThumbPath( $bucket );

				if ( $this->repo->fileExists( $bucketPath ) ) {
					$fsFile = $this->repo->getLocalReference( $bucketPath );

					if ( $fsFile ) {
						return [
							'path' => $fsFile->getPath(),
							'width' => $bucket,
							'height' => $bucketHeight
						];
					}
				}
			}
		}

		// Thumbnailing a very large file could result in network saturation if
		// everyone does it at once.
		if ( $this->getSize() >= 1e7 ) { // 10 MB
			$work = new PoolCounterWorkViaCallback( 'GetLocalFileCopy', sha1( $this->getName() ),
				[
					'doWork' => function () {
						return $this->getLocalRefPath();
					}
				]
			);
			$srcPath = $work->execute();
		} else {
			$srcPath = $this->getLocalRefPath();
		}

		// Original file
		return [
			'path' => $srcPath,
			'width' => $this->getWidth(),
			'height' => $this->getHeight()
		];
	}

	/**
	 * Returns the repo path of the thumb for a given bucket
	 * @param int $bucket
	 * @return string
	 */
	protected function getBucketThumbPath( $bucket ) {
		$thumbName = $this->getBucketThumbName( $bucket );
		return $this->getThumbPath( $thumbName );
	}

	/**
	 * Returns the name of the thumb for a given bucket
	 * @param int $bucket
	 * @return string
	 */
	protected function getBucketThumbName( $bucket ) {
		return $this->thumbName( [ 'physicalWidth' => $bucket ] );
	}

	/**
	 * Creates a temp FS file with the same extension and the thumbnail
	 * @param string $thumbPath Thumbnail path
	 * @return TempFSFile|null
	 */
	protected function makeTransformTmpFile( $thumbPath ) {
		$thumbExt = FileBackend::extensionFromPath( $thumbPath );
		return MediaWikiServices::getInstance()->getTempFSFileFactory()
			->newTempFSFile( 'transform_', $thumbExt );
	}

	/**
	 * @param string $thumbName Thumbnail name
	 * @param string $dispositionType Type of disposition (either "attachment" or "inline")
	 * @return string Content-Disposition header value
	 */
	public function getThumbDisposition( $thumbName, $dispositionType = 'inline' ) {
		$fileName = $this->getName(); // file name to suggest
		$thumbExt = FileBackend::extensionFromPath( $thumbName );
		if ( $thumbExt != '' && $thumbExt !== $this->getExtension() ) {
			$fileName .= ".$thumbExt";
		}

		return FileBackend::makeContentDisposition( $dispositionType, $fileName );
	}

	/**
	 * Get a MediaHandler instance for this file
	 *
	 * @return MediaHandler|false Registered MediaHandler for file's MIME type
	 *   or false if none found
	 */
	public function getHandler() {
		if ( !isset( $this->handler ) ) {
			$this->handler = MediaHandler::getHandler( $this->getMimeType() );
		}

		return $this->handler;
	}

	/**
	 * Get a ThumbnailImage representing a file type icon
	 *
	 * @return ThumbnailImage|null
	 */
	public function iconThumb() {
		global $IP;
		$resourceBasePath = MediaWikiServices::getInstance()->getMainConfig()
			->get( MainConfigNames::ResourceBasePath );
		$assetsPath = "{$resourceBasePath}/resources/assets/file-type-icons/";
		$assetsDirectory = "$IP/resources/assets/file-type-icons/";

		$try = [ 'fileicon-' . $this->getExtension() . '.png', 'fileicon.png' ];
		foreach ( $try as $icon ) {
			if ( file_exists( $assetsDirectory . $icon ) ) { // always FS
				$params = [ 'width' => 120, 'height' => 120 ];

				return new ThumbnailImage( $this, $assetsPath . $icon, false, $params );
			}
		}

		return null;
	}

	/**
	 * Get last thumbnailing error.
	 * Largely obsolete.
	 * @return string
	 */
	public function getLastError() {
		return $this->lastError;
	}

	/**
	 * Get all thumbnail names previously generated for this file
	 * STUB
	 * Overridden by LocalFile
	 * @stable to override
	 * @return string[]
	 */
	protected function getThumbnails() {
		return [];
	}

	/**
	 * Purge shared caches such as thumbnails and DB data caching
	 * STUB
	 * Overridden by LocalFile
	 * @stable to override
	 * @param array $options Options, which include:
	 *   'forThumbRefresh' : The purging is only to refresh thumbnails
	 */
	public function purgeCache( $options = [] ) {
	}

	/**
	 * Purge the file description page, but don't go after
	 * pages using the file. Use when modifying file history
	 * but not the current data.
	 */
	public function purgeDescription() {
		$title = $this->getTitle();
		if ( $title ) {
			$title->invalidateCache();
			$hcu = MediaWikiServices::getInstance()->getHtmlCacheUpdater();
			$hcu->purgeTitleUrls( $title, $hcu::PURGE_INTENT_TXROUND_REFLECTED );
		}
	}

	/**
	 * Purge metadata and all affected pages when the file is created,
	 * deleted, or majorly updated.
	 */
	public function purgeEverything() {
		// Delete thumbnails and refresh file metadata cache
		$this->purgeCache();
		$this->purgeDescription();
		// Purge cache of all pages using this file
		$title = $this->getTitle();
		if ( $title ) {
			$job = HTMLCacheUpdateJob::newForBacklinks(
				$title,
				'imagelinks',
				[ 'causeAction' => 'file-purge' ]
			);
			MediaWikiServices::getInstance()->getJobQueueGroup()->lazyPush( $job );
		}
	}

	/**
	 * Return a fragment of the history of file.
	 *
	 * STUB
	 * @stable to override
	 * @param int|null $limit Limit of rows to return
	 * @param string|int|null $start Only revisions older than $start will be returned
	 * @param string|int|null $end Only revisions newer than $end will be returned
	 * @param bool $inc Include the endpoints of the time range
	 *
	 * @return File[] Guaranteed to be in descending order
	 */
	public function getHistory( $limit = null, $start = null, $end = null, $inc = true ) {
		return [];
	}

	/**
	 * Return the history of this file, line by line. Starts with current version,
	 * then old versions. Should return an object similar to an image/oldimage
	 * database row.
	 *
	 * STUB
	 * @stable to override
	 * Overridden in LocalFile
	 * @return bool
	 */
	public function nextHistoryLine() {
		return false;
	}

	/**
	 * Reset the history pointer to the first element of the history.
	 * Always call this function after using nextHistoryLine() to free db resources
	 * STUB
	 * Overridden in LocalFile.
	 * @stable to override
	 */
	public function resetHistory() {
	}

	/**
	 * Get the filename hash component of the directory including trailing slash,
	 * e.g. f/fa/
	 * If the repository is not hashed, returns an empty string.
	 *
	 * @return string
	 */
	public function getHashPath() {
		if ( $this->hashPath === null ) {
			$this->assertRepoDefined();
			$this->hashPath = $this->repo->getHashPath( $this->getName() );
		}

		return $this->hashPath;
	}

	/**
	 * Get the path of the file relative to the public zone root.
	 * This function is overridden in OldLocalFile to be like getArchiveRel().
	 *
	 * @stable to override
	 * @return string
	 */
	public function getRel() {
		return $this->getHashPath() . $this->getName();
	}

	/**
	 * Get the path of an archived file relative to the public zone root
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of an archived thumbnail file
	 *
	 * @return string
	 */
	public function getArchiveRel( $suffix = false ) {
		$path = 'archive/' . $this->getHashPath();
		if ( $suffix === false ) {
			$path = rtrim( $path, '/' );
		} else {
			$path .= $suffix;
		}

		return $path;
	}

	/**
	 * Get the path, relative to the thumbnail zone root, of the
	 * thumbnail directory or a particular file if $suffix is specified
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getThumbRel( $suffix = false ) {
		$path = $this->getRel();
		if ( $suffix !== false ) {
			$path .= '/' . $suffix;
		}

		return $path;
	}

	/**
	 * Get urlencoded path of the file relative to the public zone root.
	 * This function is overridden in OldLocalFile to be like getArchiveUrl().
	 * @stable to override
	 *
	 * @return string
	 */
	public function getUrlRel() {
		return $this->getHashPath() . rawurlencode( $this->getName() );
	}

	/**
	 * Get the path, relative to the thumbnail zone root, for an archived file's thumbs directory
	 * or a specific thumb if the $suffix is given.
	 *
	 * @param string $archiveName The timestamped name of an archived image
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	private function getArchiveThumbRel( $archiveName, $suffix = false ) {
		$path = $this->getArchiveRel( $archiveName );
		if ( $suffix !== false ) {
			$path .= '/' . $suffix;
		}

		return $path;
	}

	/**
	 * Get the path of the archived file.
	 *
	 * @param string|false $suffix If not false, the name of an archived file.
	 * @return string
	 */
	public function getArchivePath( $suffix = false ) {
		$this->assertRepoDefined();

		return $this->repo->getZonePath( 'public' ) . '/' . $this->getArchiveRel( $suffix );
	}

	/**
	 * Get the path of an archived file's thumbs, or a particular thumb if $suffix is specified
	 *
	 * @param string $archiveName The timestamped name of an archived image
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getArchiveThumbPath( $archiveName, $suffix = false ) {
		$this->assertRepoDefined();

		return $this->repo->getZonePath( 'thumb' ) . '/' .
		$this->getArchiveThumbRel( $archiveName, $suffix );
	}

	/**
	 * Get the path of the thumbnail directory, or a particular file if $suffix is specified
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getThumbPath( $suffix = false ) {
		$this->assertRepoDefined();

		return $this->repo->getZonePath( 'thumb' ) . '/' . $this->getThumbRel( $suffix );
	}

	/**
	 * Get the path of the transcoded directory, or a particular file if $suffix is specified
	 *
	 * @param string|false $suffix If not false, the name of a media file
	 * @return string
	 */
	public function getTranscodedPath( $suffix = false ) {
		$this->assertRepoDefined();

		return $this->repo->getZonePath( 'transcoded' ) . '/' . $this->getThumbRel( $suffix );
	}

	/**
	 * Get the URL of the archive directory, or a particular file if $suffix is specified
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of an archived file
	 * @return string
	 */
	public function getArchiveUrl( $suffix = false ) {
		$this->assertRepoDefined();
		$ext = $this->getExtension();
		$path = $this->repo->getZoneUrl( 'public', $ext ) . '/archive/' . $this->getHashPath();
		if ( $suffix === false ) {
			$path = rtrim( $path, '/' );
		} else {
			$path .= rawurlencode( $suffix );
		}

		return $path;
	}

	/**
	 * Get the URL of the archived file's thumbs, or a particular thumb if $suffix is specified
	 * @stable to override
	 *
	 * @param string $archiveName The timestamped name of an archived image
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getArchiveThumbUrl( $archiveName, $suffix = false ) {
		$this->assertRepoDefined();
		$ext = $this->getExtension();
		$path = $this->repo->getZoneUrl( 'thumb', $ext ) . '/archive/' .
			$this->getHashPath() . rawurlencode( $archiveName );
		if ( $suffix !== false ) {
			$path .= '/' . rawurlencode( $suffix );
		}

		return $path;
	}

	/**
	 * Get the URL of the zone directory, or a particular file if $suffix is specified
	 *
	 * @param string $zone Name of requested zone
	 * @param string|false $suffix If not false, the name of a file in zone
	 * @return string Path
	 */
	private function getZoneUrl( $zone, $suffix = false ) {
		$this->assertRepoDefined();
		$ext = $this->getExtension();
		$path = $this->repo->getZoneUrl( $zone, $ext ) . '/' . $this->getUrlRel();
		if ( $suffix !== false ) {
			$path .= '/' . rawurlencode( $suffix );
		}

		return $path;
	}

	/**
	 * Get the URL of the thumbnail directory, or a particular file if $suffix is specified
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string Path
	 */
	public function getThumbUrl( $suffix = false ) {
		return $this->getZoneUrl( 'thumb', $suffix );
	}

	/**
	 * Append a version parameter to the end of a file URL
	 * Only to be used on File pages.
	 * @internal
	 *
	 * @param string $url Unversioned URL
	 * @return string
	 */
	public function getFilePageThumbUrl( $url ) {
		if ( $this->repo->isLocal() ) {
			return wfAppendQuery( $url, urlencode( $this->getTimestamp() ) );
		} else {
			return $url;
		}
	}

	/**
	 * Get the URL of the transcoded directory, or a particular file if $suffix is specified
	 *
	 * @param string|false $suffix If not false, the name of a media file
	 * @return string Path
	 */
	public function getTranscodedUrl( $suffix = false ) {
		return $this->getZoneUrl( 'transcoded', $suffix );
	}

	/**
	 * Get the public zone virtual URL for a current version source file
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getVirtualUrl( $suffix = false ) {
		$this->assertRepoDefined();
		$path = $this->repo->getVirtualUrl() . '/public/' . $this->getUrlRel();
		if ( $suffix !== false ) {
			$path .= '/' . rawurlencode( $suffix );
		}

		return $path;
	}

	/**
	 * Get the public zone virtual URL for an archived version source file
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getArchiveVirtualUrl( $suffix = false ) {
		$this->assertRepoDefined();
		$path = $this->repo->getVirtualUrl() . '/public/archive/' . $this->getHashPath();
		if ( $suffix === false ) {
			$path = rtrim( $path, '/' );
		} else {
			$path .= rawurlencode( $suffix );
		}

		return $path;
	}

	/**
	 * Get the virtual URL for a thumbnail file or directory
	 * @stable to override
	 *
	 * @param string|false $suffix If not false, the name of a thumbnail file
	 * @return string
	 */
	public function getThumbVirtualUrl( $suffix = false ) {
		$this->assertRepoDefined();
		$path = $this->repo->getVirtualUrl() . '/thumb/' . $this->getUrlRel();
		if ( $suffix !== false ) {
			$path .= '/' . rawurlencode( $suffix );
		}

		return $path;
	}

	/**
	 * @return bool
	 */
	protected function isHashed() {
		$this->assertRepoDefined();

		return (bool)$this->repo->getHashLevels();
	}

	/**
	 * @return never
	 */
	protected function readOnlyError() {
		throw new LogicException( static::class . ': write operations are not supported' );
	}

	/**
	 * Move or copy a file to its public location. If a file exists at the
	 * destination, move it to an archive. Returns a Status object with
	 * the archive name in the "value" member on success.
	 *
	 * The archive name should be passed through to recordUpload3 for database
	 * registration.
	 *
	 * Options to $options include:
	 *   - headers : name/value map of HTTP headers to use in response to GET/HEAD requests
	 *
	 * @param string|FSFile $src Local filesystem path to the source image
	 * @param int $flags A bitwise combination of:
	 *   File::DELETE_SOURCE    Delete the source file, i.e. move rather than copy
	 * @param array $options Optional additional parameters
	 * @return Status On success, the value member contains the
	 *   archive name, or an empty string if it was a new file.
	 *
	 * STUB
	 * Overridden by LocalFile
	 * @stable to override
	 */
	public function publish( $src, $flags = 0, array $options = [] ) {
		$this->readOnlyError();
	}

	/**
	 * @param IContextSource|false $context
	 * @return array[]|false
	 */
	public function formatMetadata( $context = false ) {
		$handler = $this->getHandler();
		return $handler ? $handler->formatMetadata( $this, $context ) : false;
	}

	/**
	 * Returns true if the file comes from the local file repository.
	 *
	 * @return bool
	 */
	public function isLocal() {
		return $this->repo && $this->repo->isLocal();
	}

	/**
	 * Returns the name of the repository.
	 *
	 * @return string
	 */
	public function getRepoName() {
		return $this->repo ? $this->repo->getName() : 'unknown';
	}

	/**
	 * Returns the repository
	 * @stable to override
	 *
	 * @return FileRepo|false
	 */
	public function getRepo() {
		return $this->repo;
	}

	/**
	 * Returns true if the image is an old version
	 * STUB
	 *
	 * @stable to override
	 * @return bool
	 */
	public function isOld() {
		return false;
	}

	/**
	 * Is this file a "deleted" file in a private archive?
	 * STUB
	 *
	 * @stable to override
	 * @param int $field One of DELETED_* bitfield constants
	 * @return bool
	 */
	public function isDeleted( $field ) {
		return false;
	}

	/**
	 * Return the deletion bitfield
	 * STUB
	 * @stable to override
	 * @return int
	 */
	public function getVisibility() {
		return 0;
	}

	/**
	 * Was this file ever deleted from the wiki?
	 *
	 * @return bool
	 */
	public function wasDeleted() {
		$title = $this->getTitle();

		return $title && $title->hasDeletedEdits();
	}

	/**
	 * Move file to the new title
	 *
	 * Move current, old version and all thumbnails
	 * to the new filename. Old file is deleted.
	 *
	 * Cache purging is done; checks for validity
	 * and logging are caller's responsibility
	 *
	 * @stable to override
	 * @param Title $target New file name
	 * @return Status
	 */
	public function move( $target ) {
		$this->readOnlyError();
	}

	/**
	 * Delete all versions of the file.
	 *
	 * @since 1.35
	 *
	 * Moves the files into an archive directory (or deletes them)
	 * and removes the database rows.
	 *
	 * Cache purging is done; logging is caller's responsibility.
	 *
	 * @param string $reason
	 * @param UserIdentity $user
	 * @param bool $suppress Hide content from sysops?
	 * @return Status
	 * STUB
	 * Overridden by LocalFile
	 * @stable to override
	 */
	public function deleteFile( $reason, UserIdentity $user, $suppress = false ) {
		$this->readOnlyError();
	}

	/**
	 * Restore all or specified deleted revisions to the given file.
	 * Permissions and logging are left to the caller.
	 *
	 * May throw database exceptions on error.
	 *
	 * @param int[] $versions Set of record ids of deleted items to restore,
	 *   or empty to restore all revisions.
	 * @param bool $unsuppress Remove restrictions on content upon restoration?
	 * @return Status
	 * STUB
	 * Overridden by LocalFile
	 * @stable to override
	 */
	public function restore( $versions = [], $unsuppress = false ) {
		$this->readOnlyError();
	}

	/**
	 * Returns 'true' if this file is a type which supports multiple pages,
	 * e.g. DJVU or PDF. Note that this may be true even if the file in
	 * question only has a single page.
	 *
	 * @stable to override
	 * @return bool
	 */
	public function isMultipage() {
		return $this->getHandler() && $this->handler->isMultiPage( $this );
	}

	/**
	 * Returns the number of pages of a multipage document, or false for
	 * documents which aren't multipage documents
	 *
	 * @stable to override
	 * @return int|false
	 */
	public function pageCount() {
		if ( !isset( $this->pageCount ) ) {
			if ( $this->getHandler() && $this->handler->isMultiPage( $this ) ) {
				$this->pageCount = $this->handler->pageCount( $this );
			} else {
				$this->pageCount = false;
			}
		}

		return $this->pageCount;
	}

	/**
	 * Calculate the height of a thumbnail using the source and destination width
	 *
	 * @param int $srcWidth
	 * @param int $srcHeight
	 * @param int $dstWidth
	 *
	 * @return int
	 */
	public static function scaleHeight( $srcWidth, $srcHeight, $dstWidth ) {
		// Exact integer multiply followed by division
		if ( $srcWidth == 0 ) {
			return 0;
		} else {
			return (int)round( $srcHeight * $dstWidth / $srcWidth );
		}
	}

	/**
	 * Get the URL of the image description page. May return false if it is
	 * unknown or not applicable.
	 *
	 * @stable to override
	 * @return string|false
	 */
	public function getDescriptionUrl() {
		if ( $this->repo ) {
			return $this->repo->getDescriptionUrl( $this->getName() );
		} else {
			return false;
		}
	}

	/**
	 * Get the HTML text of the description page, if available
	 * @stable to override
	 *
	 * @param Language|null $lang Optional language to fetch description in
	 * @return string|false HTML
	 * @return-taint escaped
	 */
	public function getDescriptionText( ?Language $lang = null ) {
		global $wgLang;

		if ( !$this->repo || !$this->repo->fetchDescription ) {
			return false;
		}

		$lang ??= $wgLang;

		$renderUrl = $this->repo->getDescriptionRenderUrl( $this->getName(), $lang->getCode() );
		if ( $renderUrl ) {
			$cache = MediaWikiServices::getInstance()->getMainWANObjectCache();
			$key = $this->repo->getLocalCacheKey(
				'file-remote-description',
				$lang->getCode(),
				md5( $this->getName() )
			);
			$fname = __METHOD__;

			return $cache->getWithSetCallback(
				$key,
				$this->repo->descriptionCacheExpiry ?: $cache::TTL_UNCACHEABLE,
				static function ( $oldValue, &$ttl, array &$setOpts ) use ( $renderUrl, $fname ) {
					wfDebug( "Fetching shared description from $renderUrl" );
					$res = MediaWikiServices::getInstance()->getHttpRequestFactory()->
						get( $renderUrl, [], $fname );
					if ( !$res ) {
						$ttl = WANObjectCache::TTL_UNCACHEABLE;
					}

					return $res;
				}
			);
		}

		return false;
	}

	/**
	 * Get the identity of the file uploader.
	 *
	 * @note if the file does not exist, this will return null regardless of the permissions.
	 *
	 * @stable to override
	 * @since 1.37
	 * @param int $audience One of:
	 *   File::FOR_PUBLIC       to be displayed to all users
	 *   File::FOR_THIS_USER    to be displayed to the given user
	 *   File::RAW              get the description regardless of permissions
	 * @param Authority|null $performer to check for, only if FOR_THIS_USER is
	 *   passed to the $audience parameter
	 * @return UserIdentity|null
	 */
	public function getUploader( int $audience = self::FOR_PUBLIC, ?Authority $performer = null ): ?UserIdentity {
		return null;
	}

	/**
	 * Get description of file revision
	 * STUB
	 *
	 * @stable to override
	 * @param int $audience One of:
	 *   File::FOR_PUBLIC       to be displayed to all users
	 *   File::FOR_THIS_USER    to be displayed to the given user
	 *   File::RAW              get the description regardless of permissions
	 * @param Authority|null $performer to check for, only if FOR_THIS_USER is
	 *   passed to the $audience parameter
	 * @return null|string
	 */
	public function getDescription( $audience = self::FOR_PUBLIC, ?Authority $performer = null ) {
		return null;
	}

	/**
	 * Get the 14-character timestamp of the file upload
	 *
	 * @stable to override
	 * @return string|false TS_MW timestamp or false on failure
	 */
	public function getTimestamp() {
		$this->assertRepoDefined();

		return $this->repo->getFileTimestamp( $this->getPath() );
	}

	/**
	 * Returns the timestamp (in TS_MW format) of the last change of the description page.
	 * Returns false if the file does not have a description page, or retrieving the timestamp
	 * would be expensive.
	 * @since 1.25
	 * @stable to override
	 * @return string|false
	 */
	public function getDescriptionTouched() {
		return false;
	}

	/**
	 * Get the SHA-1 base 36 hash of the file
	 *
	 * @stable to override
	 * @return string|false
	 */
	public function getSha1() {
		$this->assertRepoDefined();

		return $this->repo->getFileSha1( $this->getPath() );
	}

	/**
	 * Get the deletion archive key, "<sha1>.<ext>"
	 *
	 * @return string|false
	 */
	public function getStorageKey() {
		$hash = $this->getSha1();
		if ( !$hash ) {
			return false;
		}
		$ext = $this->getExtension();
		$dotExt = $ext === '' ? '' : ".$ext";

		return $hash . $dotExt;
	}

	/**
	 * Determine if the current user is allowed to view a particular
	 * field of this file, if it's marked as deleted.
	 * STUB
	 * @stable to override
	 * @param int $field
	 * @param Authority $performer user object to check
	 * @return bool
	 */
	public function userCan( $field, Authority $performer ) {
		return true;
	}

	/**
	 * @return string[] HTTP header name/value map to use for HEAD/GET request responses
	 * @since 1.30
	 */
	public function getContentHeaders() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getContentHeaders( $this->getMetadataArray() );
		}

		return [];
	}

	/**
	 * @return string
	 */
	public function getLongDesc() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getLongDesc( $this );
		} else {
			return MediaHandler::getGeneralLongDesc( $this );
		}
	}

	/**
	 * @return string
	 */
	public function getShortDesc() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getShortDesc( $this );
		} else {
			return MediaHandler::getGeneralShortDesc( $this );
		}
	}

	/**
	 * @return string
	 */
	public function getDimensionsString() {
		$handler = $this->getHandler();
		if ( $handler ) {
			return $handler->getDimensionsString( $this );
		} else {
			return '';
		}
	}

	/**
	 * @return ?string The name that was used to access the file, before
	 *         resolving redirects.
	 */
	public function getRedirected(): ?string {
		return $this->redirected;
	}

	/**
	 * @return Title|null
	 */
	protected function getRedirectedTitle() {
		if ( $this->redirected !== null ) {
			if ( !$this->redirectTitle ) {
				$this->redirectTitle = Title::makeTitle( NS_FILE, $this->redirected );
			}

			return $this->redirectTitle;
		}

		return null;
	}

	/**
	 * @param string $from The name that was used to access the file, before
	 *        resolving redirects.
	 */
	public function redirectedFrom( string $from ) {
		$this->redirected = $from;
	}

	/**
	 * @stable to override
	 * @return bool
	 */
	public function isMissing() {
		return false;
	}

	/**
	 * Check if this file object is small and can be cached
	 * @stable to override
	 * @return bool
	 */
	public function isCacheable() {
		return true;
	}

	/**
	 * Assert that $this->repo is set to a valid FileRepo instance
	 */
	protected function assertRepoDefined() {
		if ( !( $this->repo instanceof $this->repoClass ) ) {
			throw new LogicException( "A {$this->repoClass} object is not set for this File.\n" );
		}
	}

	/**
	 * Assert that $this->title is set to a Title
	 */
	protected function assertTitleDefined() {
		if ( !( $this->title instanceof Title ) ) {
			throw new LogicException( "A Title object is not set for this File.\n" );
		}
	}

	/**
	 * True if creating thumbnails from the file is large or otherwise resource-intensive.
	 * @return bool
	 */
	public function isExpensiveToThumbnail() {
		$handler = $this->getHandler();
		return $handler && $handler->isExpensiveToThumbnail( $this );
	}

	/**
	 * Whether the thumbnails created on the same server as this code is running.
	 * @since 1.25
	 * @stable to override
	 * @return bool
	 */
	public function isTransformedLocally() {
		return true;
	}
}
