<?php

class Paging

{

    private $totalStrip;  //总条数

    private $pageStrip;   //每页条数

    private $totalPages;  //总页数

    private $url;         //当前页面的url

    private $nowPage;     //当前的页码

    private $aroundPage;  //当前页左右条数

    public function __construct($totalStrip,$pageStrip,$aroundPage)

    {

        $this->totalStrip = $totalStrip;           //总条数

        $this->pageStrip = $pageStrip??5;          //每页条数

        $this->totalPages = $this->getTotalPages();//总页数

        $this->url = $this->getUrl();              //当前页面的url

        $this->nowPage = $this->getNowPage();      //当前的页码

        $this->aroundPage = $aroundPage??2;        //当前页左右条数

    }

    //总页数

    private function getTotalPages()

    {

        return ceil($this->totalStrip/$this->pageStrip);

    }

    //当前页面的url

    private function getUrl()

    {

        return $_SERVER['REQUEST_SCHEME'].'://'.$_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF'];

    }

    //当前的页码

    private function getNowPage()

    {

        return isset($_GET['page'])?$_GET['page']:1;

    }

    //首页

    private function firstPage()

    {

        return "<a href='{$this->url}?page=1'>首页</a>";

    }

    //上一页

    private function prevPage()

    {

        $prevPage = $this->nowPage - 1;

        return "<a href='{$this->url}?page={$prevPage}'>上一页</a>";

    }

    //当前页之前

    private function leftPage()

    {

        $str = '';

        for($i=$this->aroundPage; $i >= 1; $i--){

            $Page = $this->nowPage-$i;

            if($Page > 0){

                $str .= "<a href='{$this->url}?page=$Page'>$Page</a>";

            }

        }

        return $str;

    }

    //当前页

    private function toNowPage()

    {

        return "<a>$this->nowPage</a>";

    }

    //当前页之后

    private function rightPage()

    {

        $str = '';

        for($i=1; $i <= $this->aroundPage; $i++){

            $Page = $this->nowPage+$i;

            if($Page < $this->totalPages) {

                $str .= "<a href='{$this->url}?page=$Page'>$Page</a>";

            }

        }

        return $str;

    }

    //下一页

    private function nextPage()

    {

        $nextPage = $this->nowPage + 1;

        return "<a href='{$this->url}?page={$nextPage}'>下一页</a>";

    }

    //尾页

    private function lastPage()

    {

        return "<a href='{$this->url}?page=$this->totalPages'>尾页</a>";

    }

    public function show()

    {

        $str = "";

        if($this->nowPage > 1){

            $str .= $this->firstPage();

            $str .= $this->prevPage();

            $str .= $this->leftPage();

        }

        $str .= $this->toNowPage();

        if($this->nowPage < $this->totalPages){

            $str .= $this->rightPage();

            $str .= $this->nextPage();

            $str .= $this->lastPage();

        }

        return $str;

    }

}

//$a = new Paging(20,3,2);

//echo $a->show();