// 获取数据集的特殊点
function getSpecialPointIndex(data) {
    let rs = {
        code: 0,            // 标识是否找到驼峰锅底
        min: -Infinity,     // 锅底所在的点
        minVal: 0,
        max: Infinity,      // 驼峰所在的点
        maxVal: 0,
    };
    if(data.length < 20) {
        rs.code = 0;
        return rs;
    }
    for(let i=0; i<data.length; i++) {
        let item = data[i];
        // 检查当前点是否为锅底
        if(rs.min == -Infinity) {
            let isLow = true;
            for(let k=i-3; k<=i+3; k++) {
                if(k==i) {
                    continue;
                }
                if(data[k] == undefined || data[k]<item) {
                    rs.min = -Infinity;
                    isLow = false;
                    break;
                }
            }

            if(isLow) {
                rs.min = i;
                rs.minVal = item;
            }
        }

        // 检查是否为驼峰
        if(rs.min != -Infinity && rs.max == Infinity) {
            let isHigh = true;
            for(let k=i-2; k<=i+2; k++) {
                if(k==i) {
                    continue;
                }
                if(data[k] == undefined || data[k]>=item) {
                    rs.max = Infinity;
                    isHigh = false;
                    break;
                }
            }

            if(isHigh) {
                rs.max = i;
                rs.maxVal = item;
            }
        }
    }
    if(rs.min != -Infinity && rs.max == Infinity) {
        let index = data.length - 10;
        rs.max = index;
        rs.maxVal = data[index];
    }

    // 未找到锅底
    if(rs.min == -Infinity) {
        rs.code = 0;
    }else {
        rs.code = 1;
    }

    // 驼峰出现在锅底的前面
    if(rs.max < rs.min) {
        rs.code = 0;
    }
    return rs;
}

export default getSpecialPointIndex;