feat(frontend): search results show deleted, edited and earlier version marks with highlighted words, filter chips live in the url, results load on scroll

frontend/src/lib/format/search.ts

@@ -0,0 +1,58 @@
+export interface Segment {
+  hit: boolean;
+  text: string;
+}
+
+const WORD = /[\p{L}\p{N}_]+/gu;
+const SPACE = /\s/;
+const PREFIX_MIN = 3;
+const REACH = 20;
+const LEAD = 10;
+
+function fold(word: string): string {
+  return word.toLowerCase().replaceAll("ё", "е");
+}
+
+function matches(word: string, terms: string[]): boolean {
+  const folded = fold(word);
+  return terms.some((term) =>
+    term.length >= PREFIX_MIN ? folded.startsWith(term) : folded === term
+  );
+}
+
+function windowed(text: string, terms: string[]): string {
+  for (const match of text.matchAll(WORD)) {
+    if (!matches(match[0], terms)) {
+      continue;
+    }
+    if (match.index <= REACH) {
+      return text;
+    }
+    let start = match.index - LEAD;
+    while (start > 0 && !SPACE.test(text[start - 1])) {
+      start -= 1;
+    }
+    return `…${text.slice(start)}`;
+  }
+  return text;
+}
+
+export function highlight(text: string, terms: string[]): Segment[] {
+  const shown = windowed(text, terms);
+  const segments: Segment[] = [];
+  let last = 0;
+  for (const match of shown.matchAll(WORD)) {
+    if (!matches(match[0], terms)) {
+      continue;
+    }
+    if (match.index > last) {
+      segments.push({ hit: false, text: shown.slice(last, match.index) });
+    }
+    segments.push({ hit: true, text: match[0] });
+    last = match.index + match[0].length;
+  }
+  if (last < shown.length) {
+    segments.push({ hit: false, text: shown.slice(last) });
+  }
+  return segments;
+}