feat: 耕作履歴ページ作成（#112） (#177)

#112 現在ページの表示を太く

#112 完了

Co-authored-by: miteruzo <miteruzo@naver.com>
Reviewed-on: #177

frontend/src/components/TopNav.tsx

@@ -30,6 +30,7 @@ export default (({ user }: Props) => {
       { name: '広場', to: '/posts', subMenu: [
 	  { name: '一覧', to: '/posts' },
 	  { name: '投稿追加', to: '/posts/new' },
+	  { name: '耕作履歴', to: '/posts/changes' },
 	  { name: 'ヘルプ', to: '/wiki/ヘルプ:広場' }] },
       { name: 'タグ', to: '/tags', subMenu: [
 	  { name: 'タグ一覧', to: '/tags', visible: false },

frontend/src/components/common/Pagination.tsx

@@ -0,0 +1,79 @@
+import { Link, useLocation } from 'react-router-dom'
+
+import type { FC } from 'react'
+
+type Props = { page:          number
+	       totalPages:    number
+	       siblingCount?: number }
+
+
+const range = (start: number, end: number): number[] =>
+    [...Array (end - start + 1).keys ()].map (i => start + i)
+
+
+const getPages = (
+    page:         number,
+    total:        number,
+    siblingCount: number,
+): (number | '…')[] => {
+  if (total <= 1)
+    return [1]
+
+  const first = 1
+  const last = total
+
+  const left = Math.max (page - siblingCount, first)
+  const right = Math.min (page + siblingCount, last)
+
+  const pages: (number | '…')[] = []
+
+  pages.push (first)
+
+  if (left > first + 1)
+    pages.push ('…')
+
+  const midStart = Math.max (left, first + 1)
+  const midEnd = Math.min (right, last - 1)
+  pages.push (...range (midStart, midEnd))
+
+  if (right < last - 1)
+    pages.push ('…')
+
+  if (last !== first)
+    pages.push (last)
+
+  return pages.filter ((v, i, arr) => i === 0 || v !== arr[i - 1])
+}
+
+
+export default (({ page, totalPages, siblingCount = 4 }) => {
+  const location = useLocation ()
+
+  const buildTo = (p: number) => {
+    const qs = new URLSearchParams (location.search)
+    qs.set ('page', String (p))
+    return `${ location.pathname }?${ qs.toString () }`
+  }
+
+  const pages = getPages (page, totalPages, siblingCount)
+
+  return (
+      <nav className="mt-4 flex justify-center" aria-label="Pagination">
+	<div className="flex items-center gap-2">
+	  {(page > 1)
+	   ? <Link to={buildTo (page - 1)} aria-label="前のページ">&lt;</Link>
+	   : <span aria-hidden>&lt;</span>}
+
+	  {pages.map ((p, idx) => (
+	      (p === '…')
+	      ? <span key={`dots-${ idx }`}>…</span>
+	      : ((p === page)
+		 ? <span key={p} className="font-bold" aria-current="page">{p}</span>
+		 : <Link key={p} to={buildTo (p)}>{p}</Link>)))}
+
+	  {(page < totalPages)
+	   ? <Link to={buildTo (page + 1)} aria-label="次のページ">&gt;</Link>
+	   : <span aria-hidden>&gt;</span>}
+	</div>
+      </nav>)
+}) satisfies FC<Props>