boards/abstracts/paginator.py

from django.core.paginator import Paginator
from boards.abstracts.constants import PARAM_PAGE

__author__ = 'neko259'

PATTERN_PAGE_URL = '<a {} href="{}">{}</a>'
PAGINATOR_LOOKAROUND_SIZE = 2


def get_paginator(*args, **kwargs):
    return DividedPaginator(*args, **kwargs)


class DividedPaginator(Paginator):

    lookaround_size = PAGINATOR_LOOKAROUND_SIZE

    def __init__(self, object_list, per_page, orphans=0,
                 allow_empty_first_page=True, current_page=1, link=None, params=None):
        super().__init__(object_list, per_page, orphans, allow_empty_first_page)

        self.link = link
        self.params = params
        self.current_page = current_page

    def _left_range(self):
        return self.page_range[:self.lookaround_size]

    def _right_range(self):
        pages = self.num_pages-self.lookaround_size
        if pages <= 0:
            return []
        else:
            return self.page_range[pages:]

    def _center_range(self):
        index = self.page_range.index(self.current_page)

        start = max(self.lookaround_size, index - self.lookaround_size)
        end = min(self.num_pages - self.lookaround_size, index + self.lookaround_size + 1)
        return self.page_range[start:end]

    def get_divided_range(self):
        dr = list()

        dr += self._left_range()
        dr += self._center_range()
        dr += self._right_range()

        # Remove duplicates
        dr = list(set(dr))
        dr.sort()

        return dr

    def get_dividers(self):
        dividers = []

        prev_page = 1
        for page in self.get_divided_range():
            if page - prev_page > 1:
                dividers.append(page)

                # There can be no more than 2 dividers, so don't bother going
                # further
                if len(dividers) > 2:
                    break
            prev_page = page

        return dividers

    def get_page_url(self, page):
        self.params[PARAM_PAGE] = page
        url_params = '&'.join(['{}={}'.format(key, self.params[key])
                               for key in self.params.keys()])
        return '{}?{}'.format(self.link, url_params)

    def supports_urls(self):
        return self.link is not None and self.params is not None

    def get_next_page_url(self):
        current = self.page(self.current_page)
        if current.has_next():
            return self.get_page_url(current.next_page_number())

    def get_prev_page_url(self):
        current = self.page(self.current_page)
        if current.has_previous():
            return self.get_page_url(current.previous_page_number())

    def get_page_url_list(self):
        output = []

        dividers = self.get_dividers()
        for page in self.get_divided_range():
            if page in dividers:
                output.append('...')

            if page == self.current_page:
                cls = 'class="current_page"'
            else:
                cls = ''
            output.append(PATTERN_PAGE_URL.format(cls, self.get_page_url(page),
                                                  page))

        return ', '.join(output)