import * as Cesium from 'cesium'
export default class MeasureDistance {
    constructor(viewer) {
        this.viewer = viewer
        this.isMeasure = false
        this.initEvents()
        this.positions = []
        this.temPositions = []      // 鼠标移动时产生的临时点
        this.vertexEntities = []    // 节点元素
        this.lineEntity = undefined // 折线元素
        this.totalDistance = 0  // 总距离
    }

    initEvents(){
        this.handler = new Cesium.ScreenSpaceEventHandler(this.viewer.scene.canvas)

    }
    //激活
    activate() {
        this.registerEvents(); //注册鼠标事件
        this.isMeasure = true;
        this.totalDistance = 0  // 总距离
        //设置鼠标样式
        this.viewer._element.style.cursor = 'crosshair';
        this.viewer.enableCursorStyle = true;
        this.temPositions = [];
        this.positions = [];
        this.viewer.scene.globe.depthTestAgainstTerrain = true
    }

    //禁用
    deactivate() {
        if (!this.isMeasure) return;
        this.unRegisterEvents();
        this.viewer._element.style.cursor = 'default';
        this.viewer.enableCursorStyle = true;
        this.isMeasure = false;
        this.viewer.scene.globe.depthTestAgainstTerrain = false
    }

    //清空绘制
    clear() {
        //清除线对象
        this.viewer.entities.remove(this.lineEntity);
        this.lineEntity = undefined;

        //清除节点
        this.vertexEntities.forEach(item => {
            this.viewer.entities.remove(item);
        });
        this.vertexEntities = [];
    }
    //创建线对象
    createLineEntity() {
        this.lineEntity = this.viewer.entities.add({
            polyline: {
                positions: new Cesium.CallbackProperty(e => {
                    return this.temPositions;
                }, false),
                width: 2,
                material: Cesium.Color.YELLOW,
                // depthFailMaterial: Cesium.Color.YELLOW,
                clampToGround: true,
                disableDepthTestDistance:99000000,
                heightReference:Cesium.HeightReference.CLAMP_TO_GROUND
            }
        })
    }
    //创建线节点
    createVertex() {
        let vertexEntity = new Cesium.Entity({
            id: "MeasureDistanceVertex" + this.positions[this.positions.length - 1],
            position:  this.positions[this.positions.length - 1],
            point: {
                color: Cesium.Color.FUCHSIA,
                pixelSize: 6,
                disableDepthTestDistance:99000000,
                heightReference:Cesium.HeightReference.CLAMP_TO_GROUND,
            },
            label:{
                text: this.spaceDistance(this.positions) + "km",
                font: "2rem sans-serif",
                fillColor: Cesium.Color.WHITE,
                style: Cesium.LabelStyle.FILL,
                pixelOffset: new Cesium.Cartesian2(20, -10),
                eyeOffset: new Cesium.Cartesian3(0, 0, 0),
                horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
                verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
                // distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 20000),
                scale: 0.5,
                showBackground: true,
                backgroundColor: new Cesium.Color(0.165, 0.165, 0.165, 0.5),
                backgroundPadding: new Cesium.Cartesian2(10, 10),
                disableDepthTestDistance:99000000,
                heightReference:Cesium.HeightReference.CLAMP_TO_GROUND
            },
        });
        this.vertexEntities.push(vertexEntity)
        this.viewer.entities.add(vertexEntity)
    }
    //创建起点
    createStartEntity() {
        let vertexEntity = this.viewer.entities.add({
            position: this.positions[0],
            type: "MeasureDistanceVertex",
            point: {
                show: true,
                pixelSize: 10,
                color: Cesium.Color.RED,
                outlineColor: Cesium.Color.WHITE,
                outlineWidth: 1,
                disableDepthTestDistance:99000000,
                heightReference:Cesium.HeightReference.CLAMP_TO_GROUND,
            },
        });
        this.vertexEntities.push(vertexEntity)
    }
    //创建终点节点
    createEndEntity() {
        let vertexEntity = this.viewer.entities.add({
            position: this.positions[this.positions.length - 1],
            type: "MeasureDistanceVertex",
            label:{
                text: "总距离：" + this.totalDistance.toFixed(3) + "km",
                font: "2.5rem sans-serif",
                fillColor: Cesium.Color.WHITE,
                style: Cesium.LabelStyle.FILL,
                pixelOffset: new Cesium.Cartesian2(20, -60),
                eyeOffset: new Cesium.Cartesian3(0, 0, 30),
                horizontalOrigin: Cesium.HorizontalOrigin.CENTER,
                verticalOrigin: Cesium.VerticalOrigin.BOTTOM,
                // distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 20000),
                scale: 0.5,
                showBackground: true,
                backgroundColor: new Cesium.Color(0.165, 0.165, 0.165, 0.99),
                backgroundPadding: new Cesium.Cartesian2(10, 10),
                disableDepthTestDistance:99000000,
                heightReference:Cesium.HeightReference.CLAMP_TO_GROUND
            },
            // billboard: {
            //     // image: "../../static/images/end.png",
            //     scaleByDistance: new Cesium.NearFarScalar(300, 1, 1200, 0.4), //设置随图缩放距离和比例
            //     distanceDisplayCondition: new Cesium.DistanceDisplayCondition(0, 20000), //设置可见距离 10000米可见
            //     verticalOrigin: Cesium.VerticalOrigin.BOTTOM
            // },
            point: {
                pixelSize: 10,
                color: Cesium.Color.RED,
                outlineColor: Cesium.Color.WHITE,
                outlineWidth: 1,
                heightReference:Cesium.HeightReference.CLAMP_TO_GROUND,
                disableDepthTestDistance:99000000
            },
        });
        this.vertexEntities.push(vertexEntity)
    }
    //注册鼠标事件
    registerEvents() {
        this.leftClickEvent();
        this.rightClickEvent();
        this.mouseMoveEvent();
    }
    //左键点击事件
    leftClickEvent() {
        //单击鼠标左键画点点击事件
        this.handler.setInputAction(e => {
            let position = this.viewer.scene.pickPosition(e.position);
            if (!position) {
                const ellipsoid = this.viewer.scene.globe.ellipsoid;
                position = this.viewer.scene.camera.pickEllipsoid(e.position, ellipsoid);
            }
            if (!position) return;
            this.positions.push(position);
            if (this.positions.length === 1) {  //首次点击
                this.createLineEntity();
                this.createStartEntity();
                return;
            }
            this.createVertex();
        }, Cesium.ScreenSpaceEventType.LEFT_CLICK);
    }

    //鼠标移动事件
    mouseMoveEvent() {
        this.handler.setInputAction(e => {
            if (!this.isMeasure) return;
            let position = this.viewer.scene.pickPosition(e.endPosition);
            if (!position) {
                position = this.viewer.scene.camera.pickEllipsoid(e.startPosition, this.viewer.scene.globe.ellipsoid);
            }
            if (!position) return;
            this.handleMoveEvent(position);
        }, Cesium.ScreenSpaceEventType.MOUSE_MOVE);
    }

    //处理鼠标移动
    handleMoveEvent(position) {
        if (this.positions.length < 1) return;
        this.temPositions = this.positions.concat(position);
    }

    //右键事件
    rightClickEvent() {
        this.handler.setInputAction(e => {
            if (!this.isMeasure || this.positions.length < 1) {
                this.deactivate();
                this.clear()
            } else {
                this.createEndEntity();
                this.lineEntity.polyline = {
                    positions: this.positions,
                    width: 2,
                    material: Cesium.Color.YELLOW,
                    depthFailMaterial: Cesium.Color.YELLOW
                };
                this.deactivate();
            }
        }, Cesium.ScreenSpaceEventType.RIGHT_CLICK);
    }

    //解除鼠标事件
    unRegisterEvents() {
        this.handler.removeInputAction(Cesium.ScreenSpaceEventType.RIGHT_CLICK);
        this.handler.removeInputAction(Cesium.ScreenSpaceEventType.LEFT_CLICK);
        this.handler.removeInputAction(Cesium.ScreenSpaceEventType.MOUSE_MOVE);
    }

    /**
     * 计算距离
     * @param positions 长度大于1的Cartesian3数组
     */
    spaceDistance(positions) {
        let l = positions.length
        let point1cartographic = Cesium.Cartographic.fromCartesian(positions[l-1]);
        let point2cartographic = Cesium.Cartographic.fromCartesian(positions[l-2]);
        /**根据经纬度计算出距离**/
        let geodesic = new Cesium.EllipsoidGeodesic();
        geodesic.setEndPoints(point1cartographic, point2cartographic);
        this.totalDistance += geodesic.surfaceDistance/1000
        return (geodesic.surfaceDistance/1000).toFixed(3);
    }
}