From 4479d261d47e7f038c31e2904b36ff633fd139ac Mon Sep 17 00:00:00 2001
From: Johannes Baumeister <jba@enwelo.de>
Date: Wed, 13 May 2026 12:51:56 +0200
Subject: [PATCH] Feature: Added real-time GPS location tracking for field use

---
 app.js     | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 index.html |  3 ++
 style.css  | 75 ++++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 156 insertions(+), 3 deletions(-)

diff --git a/app.js b/app.js
index e648140..a05bb23 100644
--- a/app.js
+++ b/app.js
@@ -2084,6 +2084,87 @@ document.addEventListener('DOMContentLoaded', async () => {
         reader.readAsText(file);
     });
 
+    // Geolocation Logic
+    let watchId = null;
+    let userMarker = null;
+    let userAccuracyCircle = null;
+    const btnLocate = document.getElementById('btnLocate');
+
+    function stopTracking() {
+        if (watchId !== null) {
+            navigator.geolocation.clearWatch(watchId);
+            watchId = null;
+        }
+        if (userMarker) state.map.removeLayer(userMarker);
+        if (userAccuracyCircle) state.map.removeLayer(userAccuracyCircle);
+        userMarker = null;
+        userAccuracyCircle = null;
+        btnLocate.classList.remove('active');
+        document.getElementById('statusInfo').innerText = "Standortverfolgung beendet.";
+    }
+
+    function startTracking() {
+        if (!("geolocation" in navigator)) {
+            alert("Geolocation wird von Ihrem Browser nicht unterstützt.");
+            return;
+        }
+
+        btnLocate.classList.add('active');
+        document.getElementById('statusInfo').innerText = "Suche Standort...";
+
+        watchId = navigator.geolocation.watchPosition((position) => {
+            const { latitude, longitude, accuracy } = position.coords;
+            const latlng = L.latLng(latitude, longitude);
+
+            if (!userMarker) {
+                userMarker = L.marker(latlng, {
+                    icon: L.divIcon({
+                        className: 'user-location-marker pulse',
+                        iconSize: [16, 16],
+                        iconAnchor: [8, 8]
+                    })
+                }).addTo(state.map);
+                
+                userAccuracyCircle = L.circle(latlng, {
+                    radius: accuracy,
+                    className: 'user-location-accuracy'
+                }).addTo(state.map);
+
+                // Center on first found position
+                state.map.setView(latlng, 16);
+            } else {
+                userMarker.setLatLng(latlng);
+                userAccuracyCircle.setLatLng(latlng);
+                userAccuracyCircle.setRadius(accuracy);
+            }
+
+            document.getElementById('statusInfo').innerText = `Standort aktualisiert (Genauigkeit: ${accuracy.toFixed(0)}m)`;
+        }, (err) => {
+            console.error("Geolocation error:", err);
+            let msg = "Fehler bei der Standorterkennung.";
+            if (err.code === 1) msg = "Standortzugriff verweigert.";
+            else if (err.code === 2) msg = "Standort nicht verfügbar.";
+            else if (err.code === 3) msg = "Zeitüberschreitung.";
+            
+            alert(msg);
+            stopTracking();
+        }, {
+            enableHighAccuracy: true,
+            timeout: 10000,
+            maximumAge: 0
+        });
+    }
+
+    if (btnLocate) {
+        btnLocate.onclick = () => {
+            if (watchId === null) {
+                startTracking();
+            } else {
+                stopTracking();
+            }
+        };
+    }
+
     updateLegend();
     console.log("WindPlaner initialisiert.");
     document.getElementById('statusInfo').innerText = "System bereit. Karte geladen.";
diff --git a/index.html b/index.html
index fb9dbc7..6b95b9a 100644
--- a/index.html
+++ b/index.html
@@ -258,6 +258,9 @@
     </div>
 
     <main id="map"></main>
+    <button id="btnLocate" class="map-overlay-btn" title="Standort anzeigen">
+        <span class="gps-icon">🎯</span>
+    </button>
 
     <!-- JS Dependencies -->
     <script src="libs/proj4.js"></script>
diff --git a/style.css b/style.css
index 35e10ee..53016f6 100644
--- a/style.css
+++ b/style.css
@@ -788,7 +788,76 @@ body {
 /* Grey -> Light Blue */
 
 /* Selection specific styles */
-select.status-select option {
-    background: var(--bg-dark);
-    color: white;
+/* Map Overlay Buttons (GPS, etc.) */
+.map-overlay-btn {
+    position: absolute;
+    bottom: 25px;
+    left: 285px; /* Right of the sidebar */
+    z-index: 1000;
+    width: 44px;
+    height: 44px;
+    background: var(--panel-bg);
+    backdrop-filter: blur(8px);
+    border: 1px solid var(--primary-color);
+    border-radius: 50%;
+    color: var(--primary-color);
+    font-size: 1.2rem;
+    cursor: pointer;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    box-shadow: 0 4px 15px rgba(0,0,0,0.4);
+    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
+}
+
+.sidebar.collapsed ~ .map-overlay-btn {
+    left: 25px;
+}
+
+.map-overlay-btn:hover {
+    background: var(--primary-color);
+    color: black;
+    transform: scale(1.1);
+}
+
+.map-overlay-btn.active {
+    background: var(--primary-color);
+    color: black;
+    box-shadow: 0 0 15px var(--primary-color);
+}
+
+/* User Location Marker */
+.user-location-marker {
+    background: #3498db;
+    border: 3px solid white;
+    border-radius: 50%;
+    box-shadow: 0 0 10px rgba(0,0,0,0.5);
+}
+
+.user-location-accuracy {
+    stroke: #3498db;
+    stroke-width: 2;
+    fill: #3498db;
+    fill-opacity: 0.1;
+    transition: all 0.5s ease;
+}
+
+.pulse {
+    box-shadow: 0 0 0 0 rgba(52, 152, 219, 0.7);
+    animation: pulse-blue 2s infinite;
+}
+
+@keyframes pulse-blue {
+    0% {
+        transform: scale(0.95);
+        box-shadow: 0 0 0 0 rgba(52, 152, 219, 0.7);
+    }
+    70% {
+        transform: scale(1);
+        box-shadow: 0 0 0 15px rgba(52, 152, 219, 0);
+    }
+    100% {
+        transform: scale(0.95);
+        box-shadow: 0 0 0 0 rgba(52, 152, 219, 0);
+    }
 }
\ No newline at end of file