lemoncurry/entries/pagination.py

from typing import Callable

from django.core.paginator import Page, Paginator
from django.shortcuts import redirect

from lemoncurry.middleware import ResponseException


def paginate(queryset, reverse: Callable[[int], str], page: int | None) -> Page:
    def redirect_to_page(i: int):
        raise ResponseException(redirect(reverse(i)))

    def reversible(p: Page) -> Page:
        p.reverse = reverse
        return p

    paginator = Paginator(queryset, 10)

    # If no page number was specified, return page one.
    if page is None:
        return reversible(paginator.page(1))

    # If the first page was explicitly requested, or the page number was negative, redirect to page one with no URL suffix.
    if page <= 1:
        redirect_to_page(1)

    # If the page requested is larger than the last page, then redirect to the last page.
    if page > paginator.num_pages:
        redirect_to_page(paginator.num_pages)

    # Just return the current page! Hooray!
    return reversible(paginator.page(page))