#!/usr/bin/env python

# -*- coding: utf-8 -*-

# Created by Mona on 2017/9/20

from django.utils.safestring import mark_safe

class Paginator:

    '''

    页码的格式依赖于bootstrap；

    使用案例：

    from django.shortcuts import render,redirect,HttpResponse

    from app01.models import *

    from tools import page  导入

    def index(request):

        base_url = request.path_info

        total_item_count = UserInfo.objects.all().count()

        current_page = int(request.GET.get('page',1))

        page_obj = page.Paginator(total_item_count,current_page,base_url)

        user_list = UserInfo.objects.all()[page_obj.start:page_obj.end]

        return render(request,'index.html',{'user_list':user_list,'html_page': page_obj.pager})

    '''

    def __init__(self,total_item_count,current_page,base_url,
　　　　　　　　　　per_page_item_count=10,show_pager_count=11):

        '''

        :param total_item_count: 总记录数

        :param current_page:  当前页码

        :param base_url: 页码的前缀URL

        :param per_page_item_count: 每页显示的记录数

        :param show_pager_count: 显示的页码个数

        '''

        self.total_item_count = total_item_count

        self.current_page = current_page

        self.base_url = base_url

        self.per_page_item_count = per_page_item_count

        self.show_pager_count = show_pager_count

        total_page, res = divmod(self.total_item_count, self.per_page_item_count)

        if res:

            total_page += 1

        self.total_page = total_page

        self.half_show_pager_count = int(total_page/2)

    @property

    def start(self):

        '''

        页码查询数据的开始位置

        :return:

        '''

        return (self.current_page-1)*self.per_page_item_count

    @property

    def end(self):

        '''

        页码查询数据的结束位置

        :return:

        '''

        return self.current_page*self.per_page_item_count

    @property

    def pager(self):

        '''

        返回需要的前端页码

        :return:

        '''

        page_list = []

        ul = ' <ul class="pagination">'

        page_list.append(ul)

        if self.current_page == 1:

            prev = ' <li><a href="#">上一页</a></li>'

        else:

            prev = ' <li><a href="%s?page=%s">上一页</a></li>' % (self.base_url, self.current_page - 1)

        page_list.append(prev)

        # 如果数据特别少：

        if self.total_page < self.show_pager_count:

            pager_start = 1

            pager_end = self.total_page + 1

        else:

            if self.current_page <= self.half_show_pager_count:

                pager_start = 1

                pager_end = self.show_pager_count + 1

            else:

                if self.current_page + self.half_show_pager_count > self.total_page:

                    pager_start = self.total_page - self.show_pager_count + 1

                    pager_end = self.total_page + 1

                else:

                    pager_start = self.current_page - self.half_show_pager_count

                    pager_end = self.current_page + self.half_show_pager_count + 1

        for i in range(pager_start, pager_end):

            if i == self.current_page:

                tpl = ' <li class="active"><a href="%s?page=%s">%s</a></li>' % (self.base_url, i, i,)

            else:

                tpl = ' <li><a href="%s?page=%s">%s</a></li>' % (self.base_url, i, i,)

            page_list.append(tpl)

        if self.current_page == self.total_page:

            nex = ' <li><a href="#">下一页</a></li>'

        else:

            nex = ' <li><a href="%s?page=%s">下一页</a></li>' % (self.base_url, self.current_page + 1,)

        page_list.append(nex)

        lu = ' </ul>'

        page_list.append(lu)

        html_page = mark_safe(''.join(page_list))

        return html_page