find a market
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Creat0r
270
supermarket-finder/app.js
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270
supermarket-finder/app.js
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// app.js - Modern, idiot-proof, client-only (Overpass + Leaflet)
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// Features: Dark mode toggle (persist), caching (5 min), top-5 list, multiple Overpass endpoints fallback
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// --- UI elements
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const findBtn = document.getElementById('findBtn');
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const resetBtn = document.getElementById('resetBtn');
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const statusEl = document.getElementById('status');
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const outputEl = document.getElementById('output');
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const themeSwitch = document.getElementById('themeSwitch');
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// --- Map state
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let map, userMarker, shopMarker;
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// --- Overpass endpoints fallback (CORS-friendly mirrors)
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const OVERPASS_ENDPOINTS = [
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'https://overpass-api.de/api/interpreter',
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'https://overpass.kumi.systems/api/interpreter',
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'https://lz4.overpass-api.de/api/interpreter'
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];
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// --- small helpers
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function setStatus(txt) { statusEl.textContent = txt; }
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function showHTML(html) { outputEl.innerHTML = html; outputEl.style.display = 'block'; }
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function clearOutput() { outputEl.innerHTML = ''; outputEl.style.display = 'none'; }
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function roundCoord(x){ return Math.round(x*10000)/10000; } // for cache key
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// --- caching: simple localStorage cache (keyed by rounded coords)
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// stores { ts: timestamp_ms, payload: {...} }
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const CACHE_TTL = 1000 * 60 * 5; // 5 minutes
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function getCacheKey(lat, lon, radius=3000){ return `osm_nearest_${roundCoord(lat)}_${roundCoord(lon)}_${radius}`;}
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function readCache(key){
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try {
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const s = localStorage.getItem(key);
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if(!s) return null;
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const obj = JSON.parse(s);
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if(Date.now() - obj.ts > CACHE_TTL) { localStorage.removeItem(key); return null; }
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return obj.payload;
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} catch(e){ return null; }
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}
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function writeCache(key, payload){
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try { localStorage.setItem(key, JSON.stringify({ ts: Date.now(), payload })); } catch(e){}
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}
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// --- haversine distance (meters)
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function haversine(lat1, lon1, lat2, lon2){
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const R = 6371e3;
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const toRad = d => d * Math.PI / 180;
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const φ1 = toRad(lat1), φ2 = toRad(lat2);
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const Δφ = toRad(lat2 - lat1), Δλ = toRad(lon2 - lon1);
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const a = Math.sin(Δφ/2)**2 + Math.cos(φ1)*Math.cos(φ2)*Math.sin(Δλ/2)**2;
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return R * 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
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}
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// --- build Overpass QL
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function buildQuery(lat, lon, radius=3000, maxResults=30){
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return `
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[out:json][timeout:25];
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(
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node["shop"~"supermarket|grocery|convenience"](around:${radius},${lat},${lon});
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way["shop"~"supermarket|grocery|convenience"](around:${radius},${lat},${lon});
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relation["shop"~"supermarket|grocery|convenience"](around:${radius},${lat},${lon});
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);
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out center ${maxResults};
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`;
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}
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// --- try endpoints sequentially
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async function queryOverpass(query){
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let lastError = null;
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for(const ep of OVERPASS_ENDPOINTS){
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try {
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console.log('Trying Overpass endpoint:', ep);
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const resp = await fetch(ep, {
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method: 'POST',
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headers: { 'Content-Type': 'text/plain' },
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body: query,
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mode: 'cors'
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});
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if(!resp.ok){
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const t = await resp.text().catch(()=>null);
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lastError = { endpoint: ep, status: resp.status, text: t };
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console.warn('Overpass returned non-OK', lastError);
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continue;
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}
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const data = await resp.json();
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return { data, endpoint: ep };
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} catch(err){
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lastError = { endpoint: ep, message: err.message || String(err) };
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console.warn('Overpass fetch error', lastError);
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continue;
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}
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}
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const e = new Error('All Overpass endpoints failed');
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e.details = lastError;
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throw e;
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}
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// --- map helpers
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function initMap(lat=20, lon=0, zoom=2){
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if(!map){
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map = L.map('map', { zoomControl:true, attributionControl: true }).setView([lat, lon], zoom);
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L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', { maxZoom: 19 }).addTo(map);
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} else {
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map.setView([lat, lon], zoom);
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}
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}
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function setMarkers(userLat, userLon, shopLat, shopLon, shopName){
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if(userMarker) userMarker.remove(); if(shopMarker) shopMarker.remove();
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userMarker = L.marker([userLat, userLon]).addTo(map).bindPopup('You are here').openPopup();
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shopMarker = L.marker([shopLat, shopLon]).addTo(map).bindPopup(shopName || 'Supermarket');
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const bounds = L.latLngBounds([[userLat, userLon],[shopLat, shopLon]]);
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map.fitBounds(bounds.pad(0.2));
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}
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// --- main search flow
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async function findNearest(){
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clearOutput();
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setStatus('Requesting your location — please allow location access.');
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if(!navigator.geolocation){
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setStatus('Geolocation not supported by your browser.');
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return;
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}
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navigator.geolocation.getCurrentPosition(async pos=>{
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const lat = pos.coords.latitude;
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const lon = pos.coords.longitude;
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const radius = 3000;
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setStatus(`Location acquired: ${lat.toFixed(5)}, ${lon.toFixed(5)} — searching within ${radius} m...`);
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initMap(lat, lon, 15);
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const cacheKey = getCacheKey(lat, lon, radius);
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const cached = readCache(cacheKey);
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if(cached){
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setStatus(`Using cached result (${Math.round((cached.sourceAge||0)/1000)}s ago).`);
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renderResults(cached.payload, lat, lon);
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return;
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}
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const q = buildQuery(lat, lon, radius, 40);
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try {
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const { data, endpoint } = await queryOverpass(q);
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if(!data || !Array.isArray(data.elements) || data.elements.length === 0){
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setStatus('No supermarkets found within radius. Try increasing radius or moving closer to shops.');
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showHTML(`<div style="color:#d97706;font-weight:700">No supermarkets found within ${radius} m.</div><div style="color:var(--muted);margin-top:8px">Endpoint: ${endpoint || 'none'}</div>`);
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return;
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}
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// build candidate list with usable coords + distance
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const candidates = [];
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for(const el of data.elements){
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let elLat = null, elLon = null;
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if(el.type === 'node'){ elLat = el.lat; elLon = el.lon; }
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else if(el.type === 'way' || el.type === 'relation'){
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if(el.center && typeof el.center.lat === 'number'){ elLat = el.center.lat; elLon = el.center.lon; }
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else continue;
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} else continue;
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const dist = Math.round(haversine(lat, lon, elLat, elLon));
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candidates.push({ el, lat: elLat, lon: elLon, dist });
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}
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if(candidates.length === 0){
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setStatus('No usable coordinates in results.');
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showHTML(`<div style="color:var(--muted)">Overpass returned results, but none had usable coordinates.</div>`);
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return;
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}
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candidates.sort((a,b)=>a.dist - b.dist);
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// prepare a compact payload to cache & render
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const payload = {
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endpoint,
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results: candidates.slice(0,10).map(c => ({
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id: c.el.id,
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type: c.el.type,
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name: c.el.tags?.name || c.el.tags?.operator || 'Unnamed',
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lat: c.lat,
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lon: c.lon,
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dist: c.dist
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}))
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};
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// cache it
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writeCache(cacheKey, { payload, sourceAge:0 });
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// store sourceAge in payload for immediate display clarity
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payload.sourceAge = 0;
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renderResults(payload, lat, lon);
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setStatus(`Found ${payload.results.length} nearby supermarkets (endpoint: ${endpoint}).`);
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} catch(err){
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console.error('Search failed', err);
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const msg = err?.message || 'Search failed';
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setStatus('Search failed — see details below.');
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showHTML(`<div style="color:darkred;font-weight:700">${msg}</div><div style="color:var(--muted);margin-top:8px">Possible reason: Overpass endpoint unreachable or rate-limited. Try again later or use a different network.</div>`);
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}
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}, err=>{
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if(err.code === 1) setStatus('Location access denied. Allow location permissions for this site.');
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else if(err.code === 2) setStatus('Position unavailable.');
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else if(err.code === 3) setStatus('Timeout while getting location.');
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else setStatus('Unknown geolocation error.');
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}, { enableHighAccuracy:true, maximumAge:0, timeout:20000 });
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}
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// --- render results to UI
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function renderResults(payload, originLat, originLon){
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if(!payload || !Array.isArray(payload.results)) { showHTML('<div>No results to display.</div>'); return; }
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const nearest = payload.results[0];
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let html = `<div><h1 class="result-title">${escapeHtml(nearest.name)}</h1>`;
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html += `<div class="distance">${(nearest.dist/1000).toFixed(2)} km · ${nearest.dist} m away</div>`;
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const mapsLink = `https://www.openstreetmap.org/${nearest.type}/${nearest.id}`;
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const directionsLink = `https://www.openstreetmap.org/directions?engine=fossgis_osrm_car&route=${originLat},${originLon};${nearest.lat},${nearest.lon}`;
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html += `<div class="actions"><a class="big-link" href="${mapsLink}" target="_blank" rel="noopener">🗺 View on OSM</a> <a class="big-link" href="${directionsLink}" target="_blank" rel="noopener">🚗 Directions</a></div>`;
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html += `<div style="margin-top:10px;color:var(--muted)">Endpoint: ${escapeHtml(payload.endpoint || 'unknown')}</div>`;
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// top list
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html += `<hr style="margin:12px 0">`;
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html += `<div style="font-weight:700;margin-bottom:8px">Other nearby supermarkets (top ${Math.min(5,payload.results.length)}):</div><ol class="results-list">`;
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const top = payload.results.slice(0,5);
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for(const r of top){
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const rlink = `https://www.openstreetmap.org/${r.type}/${r.id}`;
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html += `<li><a href="${rlink}" target="_blank" rel="noopener">${escapeHtml(r.name)}</a> — ${(r.dist/1000).toFixed(2)} km</li>`;
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}
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html += `</ol></div>`;
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showHTML(html);
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// place markers on map
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initMap(originLat, originLon, 15);
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setMarkers(originLat, originLon, nearest.lat, nearest.lon, nearest.name);
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}
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// small utility to escape html
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function escapeHtml(s){ return String(s).replace(/[&<>"']/g, c => ({'&':'&','<':'<','>':'>','"':'"',"'":'''}[c])); }
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// --- theme handling (persist)
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function applyTheme(dark){
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if(dark) document.documentElement.setAttribute('data-theme','dark');
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else document.documentElement.removeAttribute('data-theme');
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try { localStorage.setItem('theme_dark', dark ? '1' : '0'); } catch(e){}
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}
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function initTheme(){
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const stored = localStorage.getItem('theme_dark');
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if(stored === null){
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// default follow prefers-color-scheme (dark) or light
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const prefersDark = window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches;
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themeSwitch.checked = prefersDark;
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applyTheme(prefersDark);
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} else {
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const dark = stored === '1';
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themeSwitch.checked = dark;
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applyTheme(dark);
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}
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}
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themeSwitch.addEventListener('change', () => applyTheme(themeSwitch.checked));
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initTheme();
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// --- reset
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resetBtn.addEventListener('click', () => {
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clearOutput();
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setStatus('Tap "Find" and allow location access.');
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if(map) { map.setView([20,0],2); if(userMarker){ userMarker.remove(); userMarker=null;} if(shopMarker){ shopMarker.remove(); shopMarker=null;} }
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});
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// --- init minimal map on load
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document.addEventListener('DOMContentLoaded', () => {
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try{ initMap(20,0,2); } catch(e){ console.warn('Leaflet init failed', e); }
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// bind find
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findBtn.addEventListener('click', findNearest);
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});
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