<?php
/**
 * 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\Navigation;

use MediaWiki\Linker\LinkTarget;
use MessageLocalizer;
use Html;

/**
 * Helper class for generating prev/next links for paging.
 *
 * @since 1.34
 */
class PrevNextNavigationRenderer {

	/**
	 * @var MessageLocalizer
	 */
	private $messageLocalizer;

	public function __construct( MessageLocalizer $messageLocalizer ) {
		$this->messageLocalizer = $messageLocalizer;
	}

	/**
	 * Generate (prev x| next x) (20|50|100...) type links for paging
	 *
	 * @param LinkTarget $title LinkTarget object to link
	 * @param int $offset
	 * @param int $limit
	 * @param array $query Optional URL query parameter string
	 * @param bool $atend Optional param for specified if this is the last page
	 * @return string
	 */
	public function buildPrevNextNavigation( LinkTarget $title, $offset, $limit,
											 array $query = [], $atend = false
	) {
		# Make 'previous' link
		$prev = $this->messageLocalizer->msg( 'prevn' )->title( $title )
			->numParams( $limit )->text();

		if ( $offset > 0 ) {
			$plink = $this->numLink( $title, max( $offset - $limit, 0 ), $limit, $query,
				$prev, 'prevn-title', 'mw-prevlink' );
		} else {
			$plink = htmlspecialchars( $prev );
		}

		# Make 'next' link
		$next = $this->messageLocalizer->msg( 'nextn' )->title( $title )
			->numParams( $limit )->text();
		if ( $atend ) {
			$nlink = htmlspecialchars( $next );
		} else {
			$nlink = $this->numLink( $title, $offset + $limit, $limit,
				$query, $next, 'nextn-title', 'mw-nextlink' );
		}

		# Make links to set number of items per page
		$numLinks = [];
		$lang = $this->messageLocalizer->getLanguage();
		foreach ( [ 20, 50, 100, 250, 500 ] as $num ) {
			$numLinks[] = $this->numLink( $title, $offset, $num, $query,
				$lang->formatNum( $num ), 'shown-title', 'mw-numlink' );
		}

		return $this->messageLocalizer->msg( 'viewprevnext' )->title( $title
		)->rawParams( $plink, $nlink, $lang->pipeList( $numLinks ) )->escaped();
	}

	/**
	 * Helper function for buildPrevNextNavigation() that generates links
	 *
	 * @param LinkTarget $title LinkTarget object to link
	 * @param int $offset
	 * @param int $limit
	 * @param array $query Extra query parameters
	 * @param string $link Text to use for the link; will be escaped
	 * @param string $tooltipMsg Name of the message to use as tooltip
	 * @param string $class Value of the "class" attribute of the link
	 * @return string HTML fragment
	 */
	private function numLink( LinkTarget $title, $offset, $limit, array $query, $link,
							  $tooltipMsg, $class
	) {
		$query = [ 'limit' => $limit, 'offset' => $offset ] + $query;
		$tooltip = $this->messageLocalizer->msg( $tooltipMsg )->title( $title )
			->numParams( $limit )->text();
		return Html::element( 'a', [ 'href' => $title->getLocalURL( $query ),
			'title' => $tooltip, 'class' => $class ], $link );
	}

}