From a35a3d02ea4f9ef4f5461ef8ec71e1175e1f4565 Mon Sep 17 00:00:00 2001
From: lekss361 <47113017+lekss361@users.noreply.github.com>
Date: Tue, 12 May 2026 00:33:49 +0300
Subject: [PATCH] feat(site-finder): deep-link tabs via ?tab= URL param (#86)
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* feat(site-finder): deep-link tabs via ?tab=env|land|market URL param

Tab state now syncs with URL — можно поделиться ссылкой на конкретный
таб (например /site-finder?tab=market для тренда цен по последнему cad).

- useRouter + useSearchParams (Next 15 app router, client-component)
- router.replace (не push) чтобы tab switches не засоряли history
- useEffect on searchParams → back/forward работают
- overview = default, не пишется в URL (clean)
- Type-guard isTabId(): только valid values из URL переключают state

* fix(site-finder): address PR #86 auto-review minor recommendations

- Use usePathname() for router.replace fallback (avoid dangling "?" in Next 15)
- Remove stale-closure guard in useEffect — React bails Object.is, no eslint-disable
- Wrap page in <Suspense> for useSearchParams (Next 15 App Router req for static)
- Lazy useState initializer — skip wasted CPU on re-renders

Per auto-review on c47e56b.

---------

Co-authored-by: lekss361 <claudestars@proton.me>
---
 frontend/src/app/site-finder/page.tsx | 55 +++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 3 deletions(-)

diff --git a/frontend/src/app/site-finder/page.tsx b/frontend/src/app/site-finder/page.tsx
index 04a74bc5..2a20afc0 100644
--- a/frontend/src/app/site-finder/page.tsx
+++ b/frontend/src/app/site-finder/page.tsx
@@ -1,8 +1,9 @@
 "use client";
 
-import { useState } from "react";
+import { Suspense, useEffect, useState } from "react";
 import dynamic from "next/dynamic";
 import Link from "next/link";
+import { usePathname, useRouter, useSearchParams } from "next/navigation";
 import type { FeatureCollection } from "geojson";
 
 import { CadInput } from "@/components/site-finder/CadInput";
@@ -47,6 +48,12 @@ const TABS: Array<{ id: TabId; label: string }> = [
   { id: "market", label: "Рынок" },
 ];
 
+const TAB_IDS = TABS.map((t) => t.id);
+
+function isTabId(v: string | null | undefined): v is TabId {
+  return !!v && (TAB_IDS as readonly string[]).includes(v);
+}
+
 // ── KPI helpers ───────────────────────────────────────────────────────────────
 
 type KpiColor = "neutral" | "amber" | "green" | "red" | "blue";
@@ -73,12 +80,44 @@ function scoreKpiColor(score: number, max: number): KpiColor {
 
 // ── Page ──────────────────────────────────────────────────────────────────────
 
-export default function SiteFinderPage() {
+function SiteFinderContent() {
+  const router = useRouter();
+  const pathname = usePathname();
+  const searchParams = useSearchParams();
+
   const { mutate, data, isPending, error, isIdle } = useSiteAnalysis();
   const [isochrones, setIsochrones] = useState<FeatureCollection | undefined>(
     undefined,
   );
-  const [tab, setTab] = useState<TabId>("overview");
+  // Lazy init: считаем initialTab один раз на mount (useState всё равно
+  // игнорирует initializer после первого render — не тратим CPU).
+  const [tab, setTabState] = useState<TabId>(() => {
+    const t = searchParams.get("tab");
+    return isTabId(t) ? t : "overview";
+  });
+
+  // Sync tab → URL query (?tab=env). overview = default, не пишем в URL.
+  function setTab(next: TabId) {
+    setTabState(next);
+    const params = new URLSearchParams(searchParams.toString());
+    if (next === "overview") {
+      params.delete("tab");
+    } else {
+      params.set("tab", next);
+    }
+    const qs = params.toString();
+    // Используем pathname вместо голого "?" — Next 15 App Router не всегда
+    // чисто чистит query при `router.replace("?")` (dangling `?` остаётся).
+    router.replace(qs ? `${pathname}?${qs}` : pathname, { scroll: false });
+  }
+
+  // Listen to back/forward navigation — reflect URL tab in state.
+  // setState с тем же значением React сам бэйлит через Object.is, поэтому
+  // guard по tab не нужен (и не вводит stale-closure через eslint-disable).
+  useEffect(() => {
+    const urlTab = searchParams.get("tab");
+    setTabState(isTabId(urlTab) ? urlTab : "overview");
+  }, [searchParams]);
 
   function handleAnalyze(cadNum: string) {
     setIsochrones(undefined);
@@ -342,3 +381,13 @@ export default function SiteFinderPage() {
     </main>
   );
 }
+
+// useSearchParams() в Next 15 App Router throw'ит при static rendering без
+// <Suspense> boundary — поэтому оборачиваем page-level.
+export default function SiteFinderPage() {
+  return (
+    <Suspense fallback={null}>
+      <SiteFinderContent />
+    </Suspense>
+  );
+}