287 lines
9.9 KiB
TypeScript
287 lines
9.9 KiB
TypeScript
"use client";
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/**
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* FindInPage — in-page text search for long reading pages (transcripts etc.).
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*
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* Renders a "Find in page" trigger for a page header; while open, a floating
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* find bar with a query input, match counter, and prev/next navigation.
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* Matches are highlighted by wrapping text nodes in <mark data-find> directly
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* in the DOM, so it works against server-rendered content (including
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* dangerouslySetInnerHTML blocks) without needing the text as props.
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*
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* Matching is case- AND diacritic-insensitive — "krsna" finds "Kṛṣṇa",
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* "sanjaya" finds "Sañjaya" — essential for IAST transliteration content
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* that users can't easily type.
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*
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* The bar is portaled to <body>: the sticky PageHeader animates with a
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* transform when it collapses on scroll, which would hijack any
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* position:fixed descendant and drag the bar off-screen with it.
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*/
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import { useCallback, useEffect, useRef, useState } from "react";
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import { createPortal } from "react-dom";
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import { ChevronDown, ChevronUp, Search, X } from "lucide-react";
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import { cn } from "@/lib/utils";
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const MIN_QUERY = 2;
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const DEBOUNCE_MS = 250;
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const HIT_CLASS = "bg-primary/20 text-inherit rounded-[2px]";
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const CURRENT_CLASS = "bg-primary text-primary-foreground rounded-[2px]";
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/** Case + diacritic fold: "Kṛṣṇa" → "krsna". */
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function fold(s: string): string {
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return s
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.normalize("NFD")
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.replace(/[\u0300-\u036f]/g, "")
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.toLowerCase();
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}
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/**
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* Fold a string keeping a map from each folded char back to the index of
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* the original char it came from, so match offsets translate back.
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*/
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function foldWithMap(s: string): { folded: string; map: number[] } {
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let folded = "";
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const map: number[] = [];
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for (let i = 0; i < s.length; i++) {
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const f = fold(s[i]);
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for (let j = 0; j < f.length; j++) {
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folded += f[j];
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map.push(i);
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}
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}
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return { folded, map };
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}
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/** Unwrap every mark this component added and re-merge the text nodes. */
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function clearHighlights(container: HTMLElement) {
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container.querySelectorAll("mark[data-find]").forEach((mark) => {
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const parent = mark.parentNode;
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if (!parent) return;
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parent.replaceChild(
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document.createTextNode(mark.textContent ?? ""),
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mark,
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);
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parent.normalize();
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});
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}
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/**
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* Highlight every occurrence of `query` inside `container`, returning the
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* created marks in document order. Searches each text node independently
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* (matches spanning inline-tag boundaries are not found — acceptable for
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* prose where emphasis runs are whole words/phrases).
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*/
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function applyHighlights(container: HTMLElement, query: string): HTMLElement[] {
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const foldedQuery = fold(query);
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if (!foldedQuery) return [];
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// Snapshot the nodes first — wrapping mutates the tree under the walker.
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const walker = document.createTreeWalker(container, NodeFilter.SHOW_TEXT);
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const textNodes: Text[] = [];
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for (let n = walker.nextNode(); n; n = walker.nextNode()) {
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textNodes.push(n as Text);
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}
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const marks: HTMLElement[] = [];
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for (const node of textNodes) {
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const text = node.textContent ?? "";
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if (!text.trim()) continue;
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const { folded, map } = foldWithMap(text);
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// Collect match ranges in original-string coordinates.
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const ranges: Array<[number, number]> = [];
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let from = 0;
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for (;;) {
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const at = folded.indexOf(foldedQuery, from);
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if (at === -1) break;
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const endFolded = at + foldedQuery.length;
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const start = map[at];
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const end = endFolded < map.length ? map[endFolded] : text.length;
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if (end > start) ranges.push([start, end]);
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from = endFolded;
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}
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if (ranges.length === 0) continue;
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// Rebuild the node as text/mark fragments.
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const frag = document.createDocumentFragment();
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let cursor = 0;
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for (const [start, end] of ranges) {
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if (start > cursor) {
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frag.appendChild(document.createTextNode(text.slice(cursor, start)));
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}
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const mark = document.createElement("mark");
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mark.setAttribute("data-find", "");
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mark.className = HIT_CLASS;
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mark.textContent = text.slice(start, end);
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frag.appendChild(mark);
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marks.push(mark);
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cursor = end;
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}
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if (cursor < text.length) {
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frag.appendChild(document.createTextNode(text.slice(cursor)));
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}
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node.parentNode?.replaceChild(frag, node);
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}
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return marks;
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}
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/** Style the active mark and bring it into view. */
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function focusMark(marks: HTMLElement[], index: number) {
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marks.forEach((m, i) => {
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m.className = i === index ? CURRENT_CLASS : HIT_CLASS;
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});
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marks[index]?.scrollIntoView({ block: "center", behavior: "smooth" });
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}
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export function FindInPage({
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targetId,
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className,
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}: {
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/** id of the element whose text content is searched. */
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targetId: string;
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className?: string;
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}) {
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const [open, setOpen] = useState(false);
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const [query, setQuery] = useState("");
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const [count, setCount] = useState(0);
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const [current, setCurrent] = useState(0);
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const marksRef = useRef<HTMLElement[]>([]);
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const inputRef = useRef<HTMLInputElement>(null);
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const close = useCallback(() => {
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const el = document.getElementById(targetId);
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if (el) clearHighlights(el);
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marksRef.current = [];
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setOpen(false);
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setQuery("");
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setCount(0);
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setCurrent(0);
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}, [targetId]);
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// Debounced (re)search on every query change while open.
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useEffect(() => {
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if (!open) return;
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const id = window.setTimeout(() => {
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const el = document.getElementById(targetId);
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if (!el) return;
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clearHighlights(el);
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const q = query.trim();
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const marks = q.length >= MIN_QUERY ? applyHighlights(el, q) : [];
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marksRef.current = marks;
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setCount(marks.length);
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setCurrent(0);
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if (marks.length > 0) focusMark(marks, 0);
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}, DEBOUNCE_MS);
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return () => window.clearTimeout(id);
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}, [query, open, targetId]);
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// Focus the input when the bar opens.
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useEffect(() => {
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if (open) inputRef.current?.focus();
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}, [open]);
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// Drop any leftover highlights if the component unmounts mid-search.
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useEffect(() => {
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return () => {
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const el = document.getElementById(targetId);
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if (el) clearHighlights(el);
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};
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}, [targetId]);
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const step = useCallback(
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(dir: 1 | -1) => {
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const marks = marksRef.current;
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if (marks.length === 0) return;
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setCurrent((c) => {
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const next = (c + dir + marks.length) % marks.length;
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focusMark(marks, next);
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return next;
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});
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},
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[],
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);
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return (
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<>
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<button
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type="button"
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onClick={() => setOpen(true)}
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aria-label="Find in page"
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className={cn(
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"inline-flex h-8 items-center gap-1.5 rounded-md border border-border bg-background px-2.5 text-sm text-muted-foreground hover:text-foreground hover:bg-muted transition-colors",
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className,
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)}
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>
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<Search className="size-4" />
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<span className="hidden sm:inline">Find in page</span>
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</button>
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{open &&
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createPortal(
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<div className="fixed top-14 sm:top-16 inset-x-0 z-30 flex justify-center px-4 pointer-events-none">
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<div className="pointer-events-auto flex w-full max-w-md items-center gap-1 rounded-xl border border-border bg-card px-2 py-1.5 shadow-lg">
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<Search className="ml-1 size-4 shrink-0 text-muted-foreground" />
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<input
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ref={inputRef}
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value={query}
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onChange={(e) => setQuery(e.target.value)}
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onKeyDown={(e) => {
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if (e.key === "Enter") {
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e.preventDefault();
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step(e.shiftKey ? -1 : 1);
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} else if (e.key === "Escape") {
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e.preventDefault();
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close();
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}
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}}
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placeholder="Find in page…"
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aria-label="Find in page"
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// text-base (16px), not text-sm: iOS/iPadOS Safari auto-zooms
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// the page when focusing an input with a font-size below 16px.
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className="min-w-0 flex-1 bg-transparent py-1 text-base outline-none placeholder:text-muted-foreground"
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/>
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<span
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aria-live="polite"
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className="shrink-0 select-none text-xs tabular-nums text-muted-foreground"
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>
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{count > 0
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? `${current + 1}/${count}`
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: query.trim().length >= MIN_QUERY
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? "0 results"
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: ""}
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</span>
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<button
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type="button"
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onClick={() => step(-1)}
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disabled={count === 0}
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aria-label="Previous match"
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className="inline-flex size-7 shrink-0 items-center justify-center rounded-md text-muted-foreground hover:bg-muted hover:text-foreground transition-colors disabled:opacity-40 disabled:pointer-events-none"
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>
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<ChevronUp className="size-4" />
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</button>
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<button
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type="button"
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onClick={() => step(1)}
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disabled={count === 0}
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aria-label="Next match"
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className="inline-flex size-7 shrink-0 items-center justify-center rounded-md text-muted-foreground hover:bg-muted hover:text-foreground transition-colors disabled:opacity-40 disabled:pointer-events-none"
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>
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<ChevronDown className="size-4" />
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</button>
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<button
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type="button"
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onClick={close}
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aria-label="Close find bar"
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className="inline-flex size-7 shrink-0 items-center justify-center rounded-md text-muted-foreground hover:bg-muted hover:text-foreground transition-colors"
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>
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<X className="size-4" />
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</button>
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</div>
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</div>,
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document.body,
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)}
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</>
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);
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}
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