/**
 文件描述：空间分析方法
 创建时间：2024/4/15 9:52
 创建人：Zhaipeixiu
 */

import {getDistance, getElevation} from "@/utils/map/geocomputation.ts";
import {Cartesian3, Viewer} from "cesium";
type ProfileResult = {
 distanceArray:number[],
 elevationArray:number[],
}
/**
 * 两点间地形剖面分析数值计算
 * @param viewer 地图Viewer
 * @param start 起点
 * @param end 终点
 * @param interval 线段采样间隔 m为单位
 * @return 从起点至终点剖面线的海拔高度数组
 */
export function elevationProfile(viewer: Viewer, start:Cartesian3, end:Cartesian3, interval: number)
{
 let breakPointsHeight:number[] = []  //断点的高程m
 let distanceFromStart:number[] = []  //断点至起点的距离m
 // 计算首尾点距离 m
 let totalLen = getDistance(start, end) * 1000
 // 获取起点高度
 breakPointsHeight.push(getElevation(viewer, start))
 distanceFromStart.push(0)
 //断点数量
 let breakNum = Math.floor(totalLen/interval)
 // 如果采样间隔小于首尾点距离，则获取每个断点的坐标 并获取其高度
 if(breakNum>=1){
  for (let i = 1; i <= breakNum; i++) {
   let breakP = Cartesian3.lerp(start, end, i/breakNum, new Cartesian3())
   breakPointsHeight.push(getElevation(viewer, breakP))
   distanceFromStart.push(getDistance(start,breakP)*1000)
  }
 }
 // 获取终点高度
 breakPointsHeight.push(getElevation(viewer, end))
 distanceFromStart.push(totalLen)
 return { distanceArray:distanceFromStart, elevationArray:breakPointsHeight }
}

/**
 * 折线段地形剖面分析数值计算
 * @param viewer 地图Viewer
 * @param polyline 折线点数组
 * @param interval 线段采样间隔 m为单位
 * @return 从折线起点至终点剖面线的海拔高度数组
 */
export function profileAnalyse(viewer: Viewer, polyline:Cartesian3[],interval: number){
 let result:ProfileResult = { distanceArray:[], elevationArray:[] }
 for (let i = 0; i < polyline.length - 2; i++) {
  let temp = elevationProfile(viewer,polyline[i],polyline[i+1],interval)
  result.elevationArray = result.elevationArray.concat(temp.elevationArray)
  result.distanceArray = result.distanceArray.concat(temp.distanceArray)
 }
 return result
}

/**
 * 两点间通视分析（基于最大斜率的算法） <br>
 * 返回值：通视为true，不通视为false，异常返回undefined
 * @param viewer 地图
 * @param viewpoint 视点
 * @param target 目标点
 * @param h 视点地面抬高，默认为1m
 * @param breakNum 采样间隔，默认为100个断点
 */
export function visibilityAnalyse(viewer: Viewer, viewpoint:Cartesian3, target:Cartesian3,
                                  h= 1, breakNum = 100) {
 // 获取视点高度和目标点高度
 let viewpointH = getElevation(viewer, viewpoint) + h
 let targetH = getElevation(viewer, target)
 if (viewpointH === -9999.2024 + h ) {
  console.log("无法获取视点海拔高度！")
  return undefined
 }
 if (targetH === -9999.2024 ) {
  console.log("无法获取目标点海拔高度！")
  return undefined
 }
 // 计算首尾点距离 m
 let totalLen = getDistance(viewpoint, target) * 1000
 // 计算首尾点斜率
 let visibleK = (targetH - viewpointH)/totalLen

 // 逐个计算断点与视点的斜率
 for (let i = 1; i <= breakNum; i++) {
  let breakP = Cartesian3.lerp(viewpoint, target, i/breakNum, new Cartesian3())
  let breakPH = getElevation(viewer, breakP)  //断点海拔
  let breakPDis = getDistance(viewpoint,breakP)*1000  //断点与视点的距离
  // 计算断点与视点的斜率
  let breakPK = (breakPH-viewpointH)/breakPDis
  if(breakPK>visibleK){
   return false
  }
 }
 return true
}