<?php
/**
 * Copyright © 2003-2008 Brooke Vibber <bvibber@wikimedia.org>
 *
 * 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
 */

namespace MediaWiki\Specials;

use MediaWiki\Export\WikiExporterFactory;
use MediaWiki\HTMLForm\Field\HTMLTextAreaField;
use MediaWiki\HTMLForm\HTMLForm;
use MediaWiki\Linker\LinksMigration;
use MediaWiki\Logger\LoggerFactory;
use MediaWiki\MainConfigNames;
use MediaWiki\Page\PageIdentity;
use MediaWiki\SpecialPage\SpecialPage;
use MediaWiki\Title\Title;
use MediaWiki\Title\TitleFormatter;
use WikiExporter;
use Wikimedia\Rdbms\IConnectionProvider;
use Wikimedia\Rdbms\SelectQueryBuilder;

/**
 * A special page that allows users to export pages in a XML file
 *
 * @ingroup SpecialPage
 * @ingroup Dump
 */
class SpecialExport extends SpecialPage {
	protected bool $curonly;
	protected bool $doExport;
	protected int $pageLinkDepth;
	protected bool $templates;

	private IConnectionProvider $dbProvider;
	private WikiExporterFactory $wikiExporterFactory;
	private TitleFormatter $titleFormatter;
	private LinksMigration $linksMigration;

	/**
	 * @param IConnectionProvider $dbProvider
	 * @param WikiExporterFactory $wikiExporterFactory
	 * @param TitleFormatter $titleFormatter
	 * @param LinksMigration $linksMigration
	 */
	public function __construct(
		IConnectionProvider $dbProvider,
		WikiExporterFactory $wikiExporterFactory,
		TitleFormatter $titleFormatter,
		LinksMigration $linksMigration
	) {
		parent::__construct( 'Export' );
		$this->dbProvider = $dbProvider;
		$this->wikiExporterFactory = $wikiExporterFactory;
		$this->titleFormatter = $titleFormatter;
		$this->linksMigration = $linksMigration;
	}

	public function execute( $par ) {
		$this->setHeaders();
		$this->outputHeader();
		$config = $this->getConfig();

		$this->curonly = true;
		$this->doExport = false;
		$request = $this->getRequest();
		$this->templates = $request->getCheck( 'templates' );
		$this->pageLinkDepth = $this->validateLinkDepth(
			$request->getIntOrNull( 'pagelink-depth' )
		);
		$nsindex = '';
		$exportall = false;

		if ( $request->getCheck( 'addcat' ) ) {
			$page = $request->getText( 'pages' );
			$catname = $request->getText( 'catname' );

			if ( $catname !== '' && $catname !== null && $catname !== false ) {
				$t = Title::makeTitleSafe( NS_MAIN, $catname );
				if ( $t ) {
					/**
					 * @todo FIXME: This can lead to hitting memory limit for very large
					 * categories. Ideally we would do the lookup synchronously
					 * during the export in a single query.
					 */
					$catpages = $this->getPagesFromCategory( $t );
					if ( $catpages ) {
						if ( $page !== '' ) {
							$page .= "\n";
						}
						$page .= implode( "\n", $catpages );
					}
				}
			}
		} elseif ( $request->getCheck( 'addns' ) && $config->get( MainConfigNames::ExportFromNamespaces ) ) {
			$page = $request->getText( 'pages' );
			$nsindex = $request->getText( 'nsindex', '' );

			if ( strval( $nsindex ) !== '' ) {
				/**
				 * Same implementation as above, so same @todo
				 */
				$nspages = $this->getPagesFromNamespace( (int)$nsindex );
				if ( $nspages ) {
					$page .= "\n" . implode( "\n", $nspages );
				}
			}
		} elseif ( $request->getCheck( 'exportall' ) && $config->get( MainConfigNames::ExportAllowAll ) ) {
			$this->doExport = true;
			$exportall = true;

			/* Although $page and $history are not used later on, we
			nevertheless set them to avoid that PHP notices about using
			undefined variables foul up our XML output (see call to
			doExport(...) further down) */
			$page = '';
			$history = '';
		} elseif ( $request->wasPosted() && $par == '' ) {
			// Log to see if certain parameters are actually used.
			// If not, we could deprecate them and do some cleanup, here and in WikiExporter.
			LoggerFactory::getInstance( 'export' )->debug(
				'Special:Export POST, dir: [{dir}], offset: [{offset}], limit: [{limit}]', [
					'dir' => $request->getRawVal( 'dir' ),
					'offset' => $request->getRawVal( 'offset' ),
					'limit' => $request->getRawVal( 'limit' ),
				] );

			$page = $request->getText( 'pages' );
			$this->curonly = $request->getCheck( 'curonly' );
			$rawOffset = $request->getVal( 'offset' );

			if ( $rawOffset ) {
				$offset = wfTimestamp( TS_MW, $rawOffset );
			} else {
				$offset = null;
			}

			$maxHistory = $config->get( MainConfigNames::ExportMaxHistory );
			$limit = $request->getInt( 'limit' );
			$dir = $request->getVal( 'dir' );
			$history = [
				'dir' => 'asc',
				'offset' => false,
				'limit' => $maxHistory,
			];
			$historyCheck = $request->getCheck( 'history' );

			if ( $this->curonly ) {
				$history = WikiExporter::CURRENT;
			} elseif ( !$historyCheck ) {
				if ( $limit > 0 && ( $maxHistory == 0 || $limit < $maxHistory ) ) {
					$history['limit'] = $limit;
				}

				if ( $offset !== null ) {
					$history['offset'] = $offset;
				}

				if ( strtolower( $dir ?? '' ) == 'desc' ) {
					$history['dir'] = 'desc';
				}
			}

			if ( $page != '' ) {
				$this->doExport = true;
			}
		} else {
			// Default to current-only for GET requests.
			$page = $request->getText( 'pages', $par ?? '' );
			$historyCheck = $request->getCheck( 'history' );

			if ( $historyCheck ) {
				$history = WikiExporter::FULL;
			} else {
				$history = WikiExporter::CURRENT;
			}

			if ( $page != '' ) {
				$this->doExport = true;
			}
		}

		if ( !$config->get( MainConfigNames::ExportAllowHistory ) ) {
			// Override
			$history = WikiExporter::CURRENT;
		}

		$list_authors = $request->getCheck( 'listauthors' );
		if ( !$this->curonly || !$config->get( MainConfigNames::ExportAllowListContributors ) ) {
			$list_authors = false;
		}

		if ( $this->doExport ) {
			$this->getOutput()->disable();

			// Cancel output buffering and gzipping if set
			// This should provide safer streaming for pages with history
			wfResetOutputBuffers();
			$request->response()->header( 'Content-type: application/xml; charset=utf-8' );
			$request->response()->header( 'X-Robots-Tag: noindex,nofollow' );

			if ( $request->getCheck( 'wpDownload' ) ) {
				// Provide a sensible filename suggestion
				$filename = urlencode( $config->get( MainConfigNames::Sitename ) . '-' .
					wfTimestampNow() . '.xml' );
				$request->response()->header( "Content-disposition: attachment;filename={$filename}" );
			}

			// @phan-suppress-next-next-line PhanPossiblyUndeclaredVariable
			// @phan-suppress-next-line PhanTypeMismatchArgumentNullable history is set when used
			$this->doExport( $page, $history, $list_authors, $exportall );

			return;
		}

		$out = $this->getOutput();
		$out->addWikiMsg( 'exporttext' );

		if ( $page == '' ) {
			$categoryName = $request->getText( 'catname' );
		} else {
			$categoryName = '';
		}
		$canExportAll = $config->get( MainConfigNames::ExportAllowAll );
		$hideIf = $canExportAll ? [ 'hide-if' => [ '===', 'exportall', '1' ] ] : [];

		$formDescriptor = [
			'catname' => [
				'type' => 'textwithbutton',
				'name' => 'catname',
				'horizontal-label' => true,
				'label-message' => 'export-addcattext',
				'default' => $categoryName,
				'size' => 40,
				'buttontype' => 'submit',
				'buttonname' => 'addcat',
				'buttondefault' => $this->msg( 'export-addcat' )->text(),
			] + $hideIf,
		];
		if ( $config->get( MainConfigNames::ExportFromNamespaces ) ) {
			$formDescriptor += [
				'nsindex' => [
					'type' => 'namespaceselectwithbutton',
					'default' => $nsindex,
					'label-message' => 'export-addnstext',
					'horizontal-label' => true,
					'name' => 'nsindex',
					'id' => 'namespace',
					'cssclass' => 'namespaceselector',
					'buttontype' => 'submit',
					'buttonname' => 'addns',
					'buttondefault' => $this->msg( 'export-addns' )->text(),
				] + $hideIf,
			];
		}

		if ( $canExportAll ) {
			$formDescriptor += [
				'exportall' => [
					'type' => 'check',
					'label-message' => 'exportall',
					'name' => 'exportall',
					'id' => 'exportall',
					'default' => $request->wasPosted() && $request->getCheck( 'exportall' ),
				],
			];
		}

		$formDescriptor += [
			'textarea' => [
				'class' => HTMLTextAreaField::class,
				'name' => 'pages',
				'label-message' => 'export-manual',
				'nodata' => true,
				'rows' => 10,
				'default' => $page,
			] + $hideIf,
		];

		if ( $config->get( MainConfigNames::ExportAllowHistory ) ) {
			$formDescriptor += [
				'curonly' => [
					'type' => 'check',
					'label-message' => 'exportcuronly',
					'name' => 'curonly',
					'id' => 'curonly',
					'default' => !$request->wasPosted() || $request->getCheck( 'curonly' ),
				],
			];
		} else {
			$out->addWikiMsg( 'exportnohistory' );
		}

		$formDescriptor += [
			'templates' => [
				'type' => 'check',
				'label-message' => 'export-templates',
				'name' => 'templates',
				'id' => 'wpExportTemplates',
				'default' => $request->wasPosted() && $request->getCheck( 'templates' ),
			],
		];

		if ( $config->get( MainConfigNames::ExportMaxLinkDepth ) || $this->userCanOverrideExportDepth() ) {
			$formDescriptor += [
				'pagelink-depth' => [
					'type' => 'text',
					'name' => 'pagelink-depth',
					'id' => 'pagelink-depth',
					'label-message' => 'export-pagelinks',
					'default' => '0',
					'size' => 20,
				],
			];
		}

		$formDescriptor += [
			'wpDownload' => [
				'type' => 'check',
				'name' => 'wpDownload',
				'id' => 'wpDownload',
				'default' => !$request->wasPosted() || $request->getCheck( 'wpDownload' ),
				'label-message' => 'export-download',
			],
		];

		if ( $config->get( MainConfigNames::ExportAllowListContributors ) ) {
			$formDescriptor += [
				'listauthors' => [
					'type' => 'check',
					'label-message' => 'exportlistauthors',
					'default' => $request->wasPosted() && $request->getCheck( 'listauthors' ),
					'name' => 'listauthors',
					'id' => 'listauthors',
				],
			];
		}

		$htmlForm = HTMLForm::factory( 'ooui', $formDescriptor, $this->getContext() );
		$htmlForm->setSubmitTextMsg( 'export-submit' );
		$htmlForm->prepareForm()->displayForm( false );
		$this->addHelpLink( 'Help:Export' );
	}

	/**
	 * @return bool
	 */
	protected function userCanOverrideExportDepth() {
		return $this->getAuthority()->isAllowed( 'override-export-depth' );
	}

	/**
	 * Do the actual page exporting
	 *
	 * @param string $page User input on what page(s) to export
	 * @param int $history One of the WikiExporter history export constants
	 * @param bool $list_authors Whether to add distinct author list (when
	 *   not returning full history)
	 * @param bool $exportall Whether to export everything
	 */
	protected function doExport( $page, $history, $list_authors, $exportall ) {
		// If we are grabbing everything, enable full history and ignore the rest
		if ( $exportall ) {
			$history = WikiExporter::FULL;
		} else {
			$pageSet = []; // Inverted index of all pages to look up

			// Split up and normalize input
			foreach ( explode( "\n", $page ) as $pageName ) {
				$pageName = trim( $pageName );
				$title = Title::newFromText( $pageName );
				if ( $title && !$title->isExternal() && $title->getText() !== '' ) {
					// Only record each page once!
					$pageSet[$title->getPrefixedText()] = true;
				}
			}

			// Set of original pages to pass on to further manipulation...
			$inputPages = array_keys( $pageSet );

			// Look up any linked pages if asked...
			if ( $this->templates ) {
				$pageSet = $this->getTemplates( $inputPages, $pageSet );
			}
			$pageSet = $this->getExtraPages( $inputPages, $pageSet );
			$linkDepth = $this->pageLinkDepth;
			if ( $linkDepth ) {
				$pageSet = $this->getPageLinks( $inputPages, $pageSet, $linkDepth );
			}

			$pages = array_keys( $pageSet );

			// Normalize titles to the same format and remove dupes, see T19374
			foreach ( $pages as $k => $v ) {
				$pages[$k] = str_replace( ' ', '_', $v );
			}

			$pages = array_unique( $pages );
		}

		/* Ok, let's get to it... */
		$db = $this->dbProvider->getReplicaDatabase();

		$exporter = $this->wikiExporterFactory->getWikiExporter( $db, $history );
		$exporter->list_authors = $list_authors;
		$exporter->openStream();

		if ( $exportall ) {
			$exporter->allPages();
		} else {
			// @phan-suppress-next-line PhanPossiblyUndeclaredVariable
			foreach ( $pages as $page ) {
				# T10824: Only export pages the user can read
				$title = Title::newFromText( $page );
				if ( $title === null ) {
					// @todo Perhaps output an <error> tag or something.
					continue;
				}

				if ( !$this->getAuthority()->authorizeRead( 'read', $title ) ) {
					// @todo Perhaps output an <error> tag or something.
					continue;
				}

				$exporter->pageByTitle( $title );
			}
		}

		$exporter->closeStream();
	}

	/**
	 * @param PageIdentity $page
	 * @return string[]
	 */
	protected function getPagesFromCategory( PageIdentity $page ) {
		$maxPages = $this->getConfig()->get( MainConfigNames::ExportPagelistLimit );

		$name = $page->getDBkey();

		$dbr = $this->dbProvider->getReplicaDatabase();
		$res = $dbr->newSelectQueryBuilder()
			->select( [ 'page_namespace', 'page_title' ] )
			->from( 'page' )
			->join( 'categorylinks', null, 'cl_from=page_id' )
			->where( [ 'cl_to' => $name ] )
			->limit( $maxPages )
			->caller( __METHOD__ )->fetchResultSet();

		$pages = [];

		foreach ( $res as $row ) {
			$pages[] = Title::makeName( $row->page_namespace, $row->page_title );
		}

		return $pages;
	}

	/**
	 * @param int $nsindex
	 * @return string[]
	 */
	protected function getPagesFromNamespace( $nsindex ) {
		$maxPages = $this->getConfig()->get( MainConfigNames::ExportPagelistLimit );

		$dbr = $this->dbProvider->getReplicaDatabase();
		$res = $dbr->newSelectQueryBuilder()
			->select( [ 'page_namespace', 'page_title' ] )
			->from( 'page' )
			->where( [ 'page_namespace' => $nsindex ] )
			->limit( $maxPages )
			->caller( __METHOD__ )->fetchResultSet();

		$pages = [];

		foreach ( $res as $row ) {
			$pages[] = Title::makeName( $row->page_namespace, $row->page_title );
		}

		return $pages;
	}

	/**
	 * Expand a list of pages to include templates used in those pages.
	 * @param array $inputPages List of titles to look up
	 * @param array $pageSet Associative array indexed by titles for output
	 * @return array Associative array index by titles
	 */
	protected function getTemplates( $inputPages, $pageSet ) {
		[ $nsField, $titleField ] = $this->linksMigration->getTitleFields( 'templatelinks' );
		$queryInfo = $this->linksMigration->getQueryInfo( 'templatelinks' );
		$dbr = $this->dbProvider->getReplicaDatabase();
		$queryBuilder = $dbr->newSelectQueryBuilder()
			->caller( __METHOD__ )
			->select( [ 'namespace' => $nsField, 'title' => $titleField ] )
			->from( 'page' )
			->join( 'templatelinks', null, 'page_id=tl_from' )
			->tables( array_diff( $queryInfo['tables'], [ 'templatelinks' ] ) )
			->joinConds( $queryInfo['joins'] );
		return $this->getLinks( $inputPages, $pageSet, $queryBuilder );
	}

	/**
	 * Add extra pages to the list of pages to export.
	 * @param string[] $inputPages List of page titles to export
	 * @param bool[] $pageSet Initial associative array indexed by string page titles
	 * @return bool[] Associative array indexed by string page titles including extra pages
	 */
	private function getExtraPages( $inputPages, $pageSet ) {
		$extraPages = [];
		$this->getHookRunner()->onSpecialExportGetExtraPages( $inputPages, $extraPages );
		foreach ( $extraPages as $extraPage ) {
			$pageSet[$this->titleFormatter->getPrefixedText( $extraPage )] = true;
		}
		return $pageSet;
	}

	/**
	 * Validate link depth setting, if available.
	 * @param int|null $depth
	 * @return int
	 */
	protected function validateLinkDepth( $depth ) {
		if ( $depth === null || $depth < 0 ) {
			return 0;
		}

		if ( !$this->userCanOverrideExportDepth() ) {
			$maxLinkDepth = $this->getConfig()->get( MainConfigNames::ExportMaxLinkDepth );
			if ( $depth > $maxLinkDepth ) {
				return $maxLinkDepth;
			}
		}

		/*
		 * There's a HARD CODED limit of 5 levels of recursion here to prevent a
		 * crazy-big export from being done by someone setting the depth
		 * number too high. In other words, last resort safety net.
		 */

		return intval( min( $depth, 5 ) );
	}

	/**
	 * Expand a list of pages to include pages linked to from that page.
	 * @param array $inputPages
	 * @param array $pageSet
	 * @param int $depth
	 * @return array
	 */
	protected function getPageLinks( $inputPages, $pageSet, $depth ) {
		for ( ; $depth > 0; --$depth ) {
			[ $nsField, $titleField ] = $this->linksMigration->getTitleFields( 'pagelinks' );
			$queryInfo = $this->linksMigration->getQueryInfo( 'pagelinks' );
			$dbr = $this->dbProvider->getReplicaDatabase();
			$queryBuilder = $dbr->newSelectQueryBuilder()
				->caller( __METHOD__ )
				->select( [ 'namespace' => $nsField, 'title' => $titleField ] )
				->from( 'page' )
				->join( 'pagelinks', null, 'page_id=pl_from' )
				->tables( array_diff( $queryInfo['tables'], [ 'pagelinks' ] ) )
				->joinConds( $queryInfo['joins'] );
			$pageSet = $this->getLinks( $inputPages, $pageSet, $queryBuilder );
			$inputPages = array_keys( $pageSet );
		}

		return $pageSet;
	}

	/**
	 * Expand a list of pages to include items used in those pages.
	 * @param array $inputPages Array of page titles
	 * @param array $pageSet
	 * @param SelectQueryBuilder $queryBuilder
	 * @return array
	 */
	protected function getLinks( $inputPages, $pageSet, SelectQueryBuilder $queryBuilder ) {
		foreach ( $inputPages as $page ) {
			$title = Title::newFromText( $page );
			if ( $title ) {
				$pageSet[$title->getPrefixedText()] = true;
				/// @todo FIXME: May or may not be more efficient to batch these
				///        by namespace when given multiple input pages.
				$result = ( clone $queryBuilder )
					->where( [
						'page_namespace' => $title->getNamespace(),
						'page_title' => $title->getDBkey()
					] )
					->fetchResultSet();

				foreach ( $result as $row ) {
					$template = Title::makeTitle( $row->namespace, $row->title );
					$pageSet[$template->getPrefixedText()] = true;
				}
			}
		}

		return $pageSet;
	}

	protected function getGroupName() {
		return 'pagetools';
	}
}

/** @deprecated class alias since 1.41 */
class_alias( SpecialExport::class, 'SpecialExport' );