<?php


/**
 * A query module to enumerate categories the set of pages belong to.
 *
 * @ingroup API
 */
class ApiQueryCategories extends ApiQueryGeneratorBase {

	public function __construct( $query, $moduleName ) {
		parent::__construct( $query, $moduleName, 'cl' );
	}

	public function execute() {
		$this->run();
	}

	public function getCacheMode( $params ) {
		return 'public';
	}

	public function executeGenerator( $resultPageSet ) {
		$this->run( $resultPageSet );
	}

	/**
	 * @param $resultPageSet ApiPageSet
	 */
	private function run( $resultPageSet = null ) {
		if ( $this->getPageSet()->getGoodTitleCount() == 0 ) {
			return; // nothing to do
		}

		$params = $this->extractRequestParams();
		$prop = array_flip( (array)$params['prop'] );
		$show = array_flip( (array)$params['show'] );

		$this->addFields( array(
			'cl_from',
			'cl_to'
		) );

		$this->addFieldsIf( array( 'cl_sortkey', 'cl_sortkey_prefix' ), isset( $prop['sortkey'] ) );
		$this->addFieldsIf( 'cl_timestamp', isset( $prop['timestamp'] ) );

		$this->addTables( 'categorylinks' );
		$this->addWhereFld( 'cl_from', array_keys( $this->getPageSet()->getGoodTitles() ) );
		if ( !is_null( $params['categories'] ) ) {
			$cats = array();
			foreach ( $params['categories'] as $cat ) {
				$title = Title::newFromText( $cat );
				if ( !$title || $title->getNamespace() != NS_CATEGORY ) {
					$this->setWarning( "\"$cat\" is not a category" );
				} else {
					$cats[] = $title->getDBkey();
				}
			}
			$this->addWhereFld( 'cl_to', $cats );
		}

		if ( !is_null( $params['continue'] ) ) {
			$cont = explode( '|', $params['continue'] );
			$this->dieContinueUsageIf( count( $cont ) != 2 );
			$op = $params['dir'] == 'descending' ? '<' : '>';
			$clfrom = intval( $cont[0] );
			$clto = $this->getDB()->addQuotes( $cont[1] );
			$this->addWhere(
				"cl_from $op $clfrom OR " .
				"(cl_from = $clfrom AND " .
				"cl_to $op= $clto)"
			);
		}

		if ( isset( $show['hidden'] ) && isset( $show['!hidden'] ) ) {
			$this->dieUsageMsg( 'show' );
		}
		if ( isset( $show['hidden'] ) || isset( $show['!hidden'] ) || isset( $prop['hidden'] ) )
		{
			$this->addOption( 'STRAIGHT_JOIN' );
			$this->addTables( array( 'page', 'page_props' ) );
			$this->addFieldsIf( 'pp_propname', isset( $prop['hidden'] ) );
			$this->addJoinConds( array(
				'page' => array( 'LEFT JOIN', array(
					'page_namespace' => NS_CATEGORY,
					'page_title = cl_to' ) ),
				'page_props' => array( 'LEFT JOIN', array(
					'pp_page=page_id',
					'pp_propname' => 'hiddencat' ) )
			) );
			if ( isset( $show['hidden'] ) ) {
				$this->addWhere( array( 'pp_propname IS NOT NULL' ) );
			} elseif ( isset( $show['!hidden'] ) ) {
				$this->addWhere( array( 'pp_propname IS NULL' ) );
			}
		}

		$this->addOption( 'USE INDEX', array( 'categorylinks' => 'cl_from' ) );

		$sort = ( $params['dir'] == 'descending' ? ' DESC' : '' );
		// Don't order by cl_from if it's constant in the WHERE clause
		if ( count( $this->getPageSet()->getGoodTitles() ) == 1 ) {
			$this->addOption( 'ORDER BY', 'cl_to' . $sort );
		} else {
			$this->addOption( 'ORDER BY', array(
						'cl_from' . $sort,
						'cl_to' . $sort
			));
		}

		$res = $this->select( __METHOD__ );

		$count = 0;
		if ( is_null( $resultPageSet ) ) {
			foreach ( $res as $row ) {
				if ( ++$count > $params['limit'] ) {
					// We've reached the one extra which shows that
					// there are additional pages to be had. Stop here...
					$this->setContinueEnumParameter( 'continue', $row->cl_from . '|' . $row->cl_to );
					break;
				}

				$title = Title::makeTitle( NS_CATEGORY, $row->cl_to );
				$vals = array();
				ApiQueryBase::addTitleInfo( $vals, $title );
				if ( isset( $prop['sortkey'] ) ) {
					$vals['sortkey'] = bin2hex( $row->cl_sortkey );
					$vals['sortkeyprefix'] = $row->cl_sortkey_prefix;
				}
				if ( isset( $prop['timestamp'] ) ) {
					$vals['timestamp'] = wfTimestamp( TS_ISO_8601, $row->cl_timestamp );
				}
				if ( isset( $prop['hidden'] ) && !is_null( $row->pp_propname ) ) {
					$vals['hidden'] = '';
				}

				$fit = $this->addPageSubItem( $row->cl_from, $vals );
				if ( !$fit ) {
					$this->setContinueEnumParameter( 'continue', $row->cl_from . '|' . $row->cl_to );
					break;
				}
			}
		} else {
			$titles = array();
			foreach ( $res as $row ) {
				if ( ++$count > $params['limit'] ) {
					// We've reached the one extra which shows that
					// there are additional pages to be had. Stop here...
					$this->setContinueEnumParameter( 'continue', $row->cl_from . '|' . $row->cl_to );
					break;
				}

				$titles[] = Title::makeTitle( NS_CATEGORY, $row->cl_to );
			}
			$resultPageSet->populateFromTitles( $titles );
		}
	}

	public function getAllowedParams() {
		return array(
			'prop' => array(
				ApiBase::PARAM_ISMULTI => true,
				ApiBase::PARAM_TYPE => array(
					'sortkey',
					'timestamp',
					'hidden',
				)
			),
			'show' => array(
				ApiBase::PARAM_ISMULTI => true,
				ApiBase::PARAM_TYPE => array(
					'hidden',
					'!hidden',
				)
			),
			'limit' => array(
				ApiBase::PARAM_DFLT => 10,
				ApiBase::PARAM_TYPE => 'limit',
				ApiBase::PARAM_MIN => 1,
				ApiBase::PARAM_MAX => ApiBase::LIMIT_BIG1,
				ApiBase::PARAM_MAX2 => ApiBase::LIMIT_BIG2
			),
			'continue' => null,
			'categories' => array(
				ApiBase::PARAM_ISMULTI => true,
			),
			'dir' => array(
				ApiBase::PARAM_DFLT => 'ascending',
				ApiBase::PARAM_TYPE => array(
					'ascending',
					'descending'
				)
			),
		);
	}

	public function getParamDescription() {
		return array(
			'prop' => array(
				'Which additional properties to get for each category',
				' sortkey    - Adds the sortkey (hexadecimal string) and sortkey prefix (human-readable part) for the category',
				' timestamp  - Adds timestamp of when the category was added',
				' hidden     - Tags categories that are hidden with __HIDDENCAT__',
			),
			'limit' => 'How many categories to return',
			'show' => 'Which kind of categories to show',
			'continue' => 'When more results are available, use this to continue',
			'categories' => 'Only list these categories. Useful for checking whether a certain page is in a certain category',
			'dir' => 'The direction in which to list',
		);
	}

	public function getResultProperties() {
		return array(
			'' => array(
				'ns' => 'namespace',
				'title' => 'string'
			),
			'sortkey' => array(
				'sortkey' => 'string',
				'sortkeyprefix' => 'string'
			),
			'timestamp' => array(
				'timestamp' => 'timestamp'
			),
			'hidden' => array(
				'hidden' => 'boolean'
			)
		);
	}

	public function getDescription() {
		return 'List all categories the page(s) belong to';
	}

	public function getPossibleErrors() {
		return array_merge( parent::getPossibleErrors(), array(
			array( 'show' ),
		) );
	}

	public function getExamples() {
		return array(
			'api.php?action=query&prop=categories&titles=Albert%20Einstein' => 'Get a list of categories [[Albert Einstein]] belongs to',
			'api.php?action=query&generator=categories&titles=Albert%20Einstein&prop=info' => 'Get information about all categories used in the [[Albert Einstein]]',
		);
	}

	public function getHelpUrls() {
		return 'https://www.mediawiki.org/wiki/API:Properties#categories_.2F_cl';
	}
}
