package utils

import (
	"fmt"
	"github.com/gonum/stat"
	"github.com/shopspring/decimal"
	"math"
	"strings"
)

type Series []Coordinate

type Coordinate struct {
	X, Y float64
}

func GetLinearResult(s []Coordinate) (gradient, intercept float64) {
	if len(s) <= 1 {
		return
	}

	var sum [5]float64

	i := 0
	for ; i < len(s); i++ {
		sum[0] += s[i].X
		sum[1] += s[i].Y
		sum[2] += s[i].X * s[i].X
		sum[3] += s[i].X * s[i].Y
		sum[4] += s[i].Y * s[i].Y
	}

	f := float64(i)
	gradient = (f*sum[3] - sum[0]*sum[1]) / (f*sum[2] - sum[0]*sum[0])
	intercept = (sum[1] / f) - (gradient * sum[0] / f)


	return
}

func CalculateCorrelationByIntArr(xArr, yArr []float64) (ratio float64) {
	xLen := float64(len(xArr))
	yLen := float64(len(yArr))
	if xLen == 0 || xLen != yLen {
		return
	}

	var Xa, Ya float64
	for i := range xArr {
		Xa += xArr[i]
	}
	Mx := Xa / xLen
	for i := range yArr {
		Ya += yArr[i]
	}
	My := Ya / yLen

	var Xb, Yb, SDx, SDy float64
	for i := range xArr {
		Xb += (xArr[i] - Mx) * (xArr[i] - Mx)
	}
	SDx = math.Sqrt(1 / (xLen - 1) * Xb)
	for i := range yArr {
		Yb += (yArr[i] - My) * (yArr[i] - My)
	}
	SDy = math.Sqrt(1 / (yLen - 1) * Yb)

	var Nume, Deno float64
	for i := 0; i < int(xLen); i++ {
		Nume += (xArr[i] - Mx) * (yArr[i] - My)
	}
	Deno = (xLen - 1) * (SDx * SDy)
	ratio = Nume / Deno
	if math.IsNaN(ratio) {
		ratio = 0
	}
	return
}

func ComputeCorrelation(sList []Coordinate) (r float64) {
	var xBar, yBar float64
	lenSList := len(sList)
	if lenSList < 2 {
		return
	}
	decimalX := decimal.NewFromFloat(0)
	decimalY := decimal.NewFromFloat(0)

	for _, coordinate := range sList {
		decimalX = decimalX.Add(decimal.NewFromFloat(coordinate.X))
		decimalY = decimalY.Add(decimal.NewFromFloat(coordinate.Y))
	}
	xBar, _ = decimalX.Div(decimal.NewFromInt(int64(lenSList))).Round(4).Float64()
	yBar, _ = decimalY.Div(decimal.NewFromInt(int64(lenSList))).Round(4).Float64()

	varXDeci := decimal.NewFromFloat(0)
	varYDeci := decimal.NewFromFloat(0)
	ssrDeci := decimal.NewFromFloat(0)

	for _, coordinate := range sList {
		diffXXbarDeci := decimal.NewFromFloat(coordinate.X).Sub(decimal.NewFromFloat(xBar))
		diffYYbarDeci := decimal.NewFromFloat(coordinate.Y).Sub(decimal.NewFromFloat(yBar))
		ssrDeci = ssrDeci.Add(diffXXbarDeci.Mul(diffYYbarDeci))
		varXDeci = varXDeci.Add(diffXXbarDeci.Mul(diffXXbarDeci))
		varYDeci = varYDeci.Add(diffYYbarDeci.Mul(diffYYbarDeci))
	}
	if varXDeci.IsZero() && varYDeci.IsZero() {
		r = 1
		return
	}
	sqrtVal, _ := varXDeci.Mul(varYDeci).Round(4).Float64()
	sst := math.Sqrt(sqrtVal) // 平方根
	if sst == 0 {
		return
	}
	r, _ = ssrDeci.Div(decimal.NewFromFloat(sst)).Round(4).Float64()

	return
}

func CalculationDecisive(sList []Coordinate) (r2 float64) {
	r := ComputeCorrelation(sList)
	r2, _ = decimal.NewFromFloat(r).Mul(decimal.NewFromFloat(r)).Round(4).Float64()

	return
}

func CalculateStandardDeviation(data []float64) float64 {
	return stat.StdDev(data, nil)
}

func ReplaceFormula(valArr map[string]float64, formulaStr string) string {
	funMap := getFormulaMap()
	for k, v := range funMap {
		formulaStr = strings.Replace(formulaStr, k, v, -1)
	}

	replaceCount := 0
	for tag, val := range valArr {
		dvStr := fmt.Sprintf("%v", val)
		formulaStr = strings.Replace(formulaStr, tag, dvStr, -1)
		replaceCount++
	}
	for k, v := range funMap {
		formulaStr = strings.Replace(formulaStr, v, k, -1)
	}
	return formulaStr
}

type CellPosition struct {
	Tag   string
	Row   int
	Value float64
}

func ReplaceFormulaByCellList(cellList []CellPosition, formulaStr string) string {
	funMap := getFormulaMap()
	for k, v := range funMap {
		formulaStr = strings.Replace(formulaStr, k, v, -1)
	}

	replaceCount := 0
	for _, cell := range cellList {
		dvStr := fmt.Sprintf("%v", cell.Value)
		formulaStr = strings.Replace(formulaStr, fmt.Sprint(cell.Tag, cell.Row), dvStr, -1)
		replaceCount++
	}
	for k, v := range funMap {
		formulaStr = strings.Replace(formulaStr, v, k, -1)
	}
	return formulaStr
}

func getFormulaMap() map[string]string {
	funMap := make(map[string]string)
	funMap["MAX"] = "[@@]"
	funMap["MIN"] = "[@!]"
	funMap["ABS"] = "[@#]"
	funMap["CEIL"] = "[@$]"
	funMap["COS"] = "[@%]"
	funMap["FLOOR"] = "[@^]"
	funMap["MOD"] = "[@&]"
	funMap["POW"] = "[@*]"
	funMap["ROUND"] = "[@(]"
	return funMap
}