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import { elem, Element } from "../dom.ts";
type Props = {
currentPage: number;
totalPages: number;
basePath: string;
};
export default function Pagination(
{ currentPage, totalPages, basePath }: Props,
): Element {
if (totalPages <= 1) {
return elem("div", {});
}
const pages = generatePageNumbers(currentPage, totalPages);
return elem(
"nav",
{ class: "pagination" },
elem(
"div",
{ class: "pagination-prev" },
currentPage > 1
? elem("a", { href: pageUrlAt(basePath, currentPage - 1) }, "前へ")
: null,
),
...pages.map((page) => {
if (page === "...") {
return elem("div", { class: "pagination-elipsis" }, "…");
} else if (page === currentPage) {
return elem(
"div",
{ class: "pagination-page pagination-page-current" },
elem("span", {}, String(page)),
);
} else {
return elem(
"div",
{ class: "pagination-page" },
elem("a", { href: pageUrlAt(basePath, page) }, String(page)),
);
}
}),
elem(
"div",
{ class: "pagination-next" },
currentPage < totalPages
? elem("a", { href: pageUrlAt(basePath, currentPage + 1) }, "次へ")
: null,
),
);
}
type PageItem = number | "...";
/**
* Generates page numbers for pagination display.
*
* - Always show the first page
* - Always show the last page
* - Always show the current page
* - Always show the page before and after the current page
* - If there's only one page gap between displayed pages, fill it
* - If there are two or more pages gap between displayed pages, show ellipsis
*/
function generatePageNumbers(
currentPage: number,
totalPages: number,
): PageItem[] {
const pages = new Set<number>();
pages.add(1);
pages.add(Math.max(1, currentPage - 1));
pages.add(currentPage);
pages.add(Math.min(totalPages, currentPage + 1));
pages.add(totalPages);
const sorted = Array.from(pages).sort((a, b) => a - b);
const result: PageItem[] = [];
for (let i = 0; i < sorted.length; i++) {
if (i > 0) {
const gap = sorted[i] - sorted[i - 1];
if (gap === 2) {
result.push(sorted[i - 1] + 1);
} else if (gap > 2) {
result.push("...");
}
}
result.push(sorted[i]);
}
return result;
}
function pageUrlAt(basePath: string, page: number): string {
return page === 1 ? basePath : `${basePath}${page}/`;
}
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