document.addEventListener("DOMContentLoaded", () => {
    
    var mymap = L.map("locationmap").setView([38.891, 139.824], 16);
    L.tileLayer('https://{s}.tile.osm.org/{z}/{x}/{y}.png', {
        attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
    }).addTo(mymap);

    var locmarker = L.marker(mymap.getCenter()).addTo(mymap);
    locmarker.bindPopup("STARTを押してね").openPopup();

    let watchId = null;
    let polyline = L.polyline([], { color: 'blue' }).addTo(mymap);
    let totalDistance = 0;
    let lastLatLng = null;

    function startLogging() {
        if (watchId !== null) return;

        watchId = navigator.geolocation.watchPosition(
            (position) => {
                const { latitude, longitude } = position.coords;
                const latLng = L.latLng(latitude, longitude);

                polyline.addLatLng(latLng);
                mymap.setView(latLng, 13);

                if (lastLatLng) {
                    const distance = lastLatLng.distanceTo(latLng);
                    totalDistance += distance;
                    document.getElementById("distance").textContent = totalDistance.toFixed(2);
                }

                lastLatLng = latLng;
            },
            (error) => {
                console.error("Geolocation error:", error);
            },
            {
                enableHighAccuracy: true,
                maximumAge: 0,
                timeout: 5000
            }
        );
    }

    function stopLogging() {
        if (watchId !== null) {
            navigator.geolocation.clearWatch(watchId);
            watchId = null;
        }
    }

    function calculateDistance(latLng1, latLng2) {
        const R = 6371000; // 地球の半径(m)
        const rad = Math.PI / 180;
        const dLat = (latLng2.lat - latLng1.lat) * rad;
        const dLng = (latLng2.lng - latLng1.lng) * rad;

        const a = Math.sin(dLat / 2) ** 2 +
                  Math.cos(latLng1.lat * rad) * Math.cos(latLng2.lat * rad) *
                  Math.sin(dLng / 2) ** 2;

        const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

        return R * c; // 距離(m)
    }

   
    mymap.on("click", (e) => {
        const latLng = e.latlng;
        const distance = lastLatLng ? lastLatLng.distanceTo(latLng).toFixed(2) : "計測しています";
        L.marker(latLng)
            .addTo(mymap)
            .bindPopup(`距離: ${distance} m`)
            .openPopup();
    });

    
    document.getElementById("start").addEventListener("click", startLogging);
    
    document.getElementById("stop").addEventListener("click", stopLogging);
});