Targets.php

<?php
namespace LinkTitles;

class Targets {
  private static $instance;

  public static function singleton( \Title $title, Config $config ) {
    if ( ( self::$instance === null ) || ( self::$instance->sourceNamespace != $title->getNamespace() ) ) {
      self::$instance = new Targets( $title, $config );
    }
    return self::$instance;
  }

  public static function invalidate() {
    self::$instance = null;
  }

  public $queryResult;

  public $sourceNamespace;

  private $config;

  private $charLengthFunction;

  private function __construct( \Title $title, Config $config) {
    $this->config = $config;
    $this->sourceNamespace = $title->getNamespace();
    $this->fetch();
  }

  //
  private function fetch() {
    ( $this->config->preferShortTitles ) ? $sortOrder = 'ASC' : $sortOrder = 'DESC';

    // Build a blacklist of pages that are not supposed to be link
    // targets. This includes the current page.
    if ( $this->config->blackList ) {
      $blackList = 'page_title NOT IN ' .
        str_replace( ' ', '_', '("' . implode( '","', str_replace( '"', '\"', $this->config->blackList ) ) . '")' );
    } else {
      $blackList = null;
    }

    if ( $this->config->sameNamespace ) {
      // Build our weight list. Make sure current namespace is first element
      $namespaces = array_diff( $this->config->targetNamespaces, [ $this->sourceNamespace ] );
      array_unshift( $namespaces, $this->sourceNamespace );
    } else {
      $namespaces = $this->config->targetNamespaces;
    }

    if ( !$namespaces) {
      // If there are absolutely no target namespaces (not even the one of the
      // source page), we can just return.
      return;
    }

    // No need for sanitiy check. we are sure that we have at least one element in the array
    $weightSelect = "CASE page_namespace ";
    $currentWeight = 0;
    foreach ($namespaces as &$namespaceValue) {
        $currentWeight = $currentWeight + 100;
        $weightSelect = $weightSelect . " WHEN " . $namespaceValue . " THEN " . $currentWeight . PHP_EOL;
    }
    $weightSelect = $weightSelect . " END ";
    $namespacesClause = '(' . implode( ', ', $namespaces ) . ')';

    // Build an SQL query and fetch all page titles ordered by length from
    // shortest to longest. Only titles from 'normal' pages (namespace uid
    // = 0) are returned. Since the db may be sqlite, we need a try..catch
    // structure because sqlite does not support the CHAR_LENGTH function.
    $dbr = wfGetDB( DB_SLAVE );
    $this->queryResult = $dbr->select(
      'page',
      array( 'page_title', 'page_namespace' , "weight" => $weightSelect),
      array_filter(
        array(
          'page_namespace IN ' . $namespacesClause,
          $this->charLength() . '(page_title) >= ' . $this->config->minimumTitleLength,
          $blackList,
        )
      ),
      __METHOD__,
      array( 'ORDER BY' => 'weight ASC, ' . $this->charLength() . '(page_title) ' . $sortOrder )
    );
  }

  private function charLength() {
    if ($this->charLengthFunction === null) {
      $this->charLengthFunction = $this->config->sqliteDatabase() ? 'LENGTH' : 'CHAR_LENGTH';
    }
    return $this->charLengthFunction;
  }
}