// 初始化地图
var map = new google.maps.Map(document.getElementById('map'), {
  zoom: 10,
  center: {lat: 39.9042, lng: 116.4074} // 北京坐标
});

// 创建折线
var polyline = new google.maps.Polyline({
  path: [
    {lat: 39.9042, lng: 116.4074}, // 点1
    {lat: 39.9139, lng: 116.3917}, // 点2
    {lat: 39.9177, lng: 116.3664}  // 点3
  ],
  strokeColor: '#FF0000',
  strokeOpacity: 1.0,
  strokeWeight: 3,
  map: map
});

// 添加折线点击事件监听
google.maps.event.addListener(polyline, 'click', function(event) {
  // 获取折线当前所有点
  var path = polyline.getPath();
  var points = path.getArray();
  
  // 找出距离点击位置最近的两个相邻点
  var closestSegment = findClosestSegment(points, event.latLng);
  
  if (closestSegment) {
    // 在两点之间插入新点
    var newPoint = event.latLng;
    path.insertAt(closestSegment.index + 1, newPoint);
    
    // 可选：添加标记显示新点
    new google.maps.Marker({
      position: newPoint,
      map: map,
      title: '新添加的点'
    });
  }
});

// 辅助函数：找到距离点击位置最近的线段
function findClosestSegment(points, clickPoint) {
  var minDistance = Number.MAX_VALUE;
  var closestSegment = null;
  
  for (var i = 0; i < points.length - 1; i++) {
    var segmentStart = points[i];
    var segmentEnd = points[i + 1];
    
    // 计算点到线段的距离
    var distance = pointToSegmentDistance(clickPoint, segmentStart, segmentEnd);
    
    if (distance < minDistance) {
      minDistance = distance;
      closestSegment = {
        index: i,
        start: segmentStart,
        end: segmentEnd,
        distance: distance
      };
    }
  }
  
  return closestSegment;
}

// 辅助函数：计算点到线段的距离
function pointToSegmentDistance(point, segmentStart, segmentEnd) {
  var x = point.lng();
  var y = point.lat();
  var x1 = segmentStart.lng();
  var y1 = segmentStart.lat();
  var x2 = segmentEnd.lng();
  var y2 = segmentEnd.lat();
  
  // 计算线段长度平方
  var l2 = (x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1);
  if (l2 === 0) return Math.sqrt((x - x1) * (x - x1) + (y - y1) * (y - y1));
  
  // 计算投影比例
  var t = Math.max(0, Math.min(1, ((x - x1) * (x2 - x1) + (y - y1) * (y2 - y1)) / l2));
  
  // 计算投影点坐标
  var projectionX = x1 + t * (x2 - x1);
  var projectionY = y1 + t * (y2 - y1);
  
  // 返回点到投影点的距离
  return Math.sqrt((x - projectionX) * (x - projectionX) + (y - projectionY) * (y - projectionY));
}