package com

import (
	"math"
	"slices"
)

type Slop struct {
	lastCalc  int
	sampleNum int
	Dirt      int     // 大周期斜率方向：1向上，0不明确，-1向下
	rate      float64 // 斜率阈值，推荐0.25
	Data      []float64
	Top       float64
	Btm       float64
}

func NewSlop(sampleNum int, rate float64) *Slop {
	return &Slop{
		Dirt:      0,
		sampleNum: sampleNum,
		rate:      rate,
		Top:       math.NaN(),
		Btm:       math.NaN(),
	}
}

func (s *Slop) Update(barNum int, slop float64) {
	s.Data = append(s.Data, math.Abs(slop))
	if len(s.Data) < s.sampleNum {
		return
	}
	if !math.IsNaN(s.Top) {
		s.Dirt = 0
		if slop >= s.Top {
			s.Dirt = 1
		} else if slop <= s.Btm {
			s.Dirt = -1
		}
	}
	if barNum-s.lastCalc < s.sampleNum/2 {
		return
	}
	if len(s.Data) > s.sampleNum {
		s.Data = s.Data[len(s.Data)-s.sampleNum:]
	}
	thres := CutScore(s.Data, s.rate)
	s.Top = thres
	s.Btm = -thres
	s.lastCalc = barNum
	s.Dirt = 0
	if slop >= s.Top {
		s.Dirt = 1
	} else if slop <= s.Btm {
		s.Dirt = -1
	}
}

func CutScore(vals []float64, rate float64) float64 {
	arr := make([]float64, len(vals))
	copy(arr, vals)
	slices.Sort(arr)
	idx := int(float64(len(vals)) * rate)
	return arr[idx]
}