package stats

import (
	"fmt"
	"math"
	"reflect"
	"testing"
)

var (
	datasets [][]float64 = [][]float64{
		// set 0
		{
			22.90, 28.55, 36.33, 33.71, 26.29, 34.64, 30.14, 34.31,
			25.69, 30.09, 28.69, 11.61, 10.68, 24.70, 22.83, 38.08,
			24.22, 41.08, 29.70, 26.01, 38.47, 40.25,
		},
		// set 1
		{
			15.054, 19.106, 16.926, 16.243, 20.345, 18.615, 15.050,
			18.716, 13.691, 18.296, 16.816, 21.415, 20.756, 13.696,
			22.679, 16.277, 18.738, 20.271, 20.967, 19.157, 20.338,
		},
	}
	expectedMethodResults map[string][]float64 = map[string][]float64{
		"Mean":              {29.044091, 18.2453333333333},
		"StandardDeviation": {8.06420820019572, 2.56887224932135},
		// Population kurtosis
		"Kurtosis": {0.14431032604193028, -0.8979764294956452},
		"Variance": {65.0314538961039, 6.59910463333333},
		// Population skewness
		"Skewness":  {-0.6233147473136348, -0.2757248239748126},
		"NumValues": {22, 21},
		"Min":       {10.68, 13.691},
		"Max":       {41.08, 22.679},
	}
)

func TestStats(t *testing.T) {
	for i, set := range datasets {
		s := &Stats{}
		for _, n := range set {
			s.Push(n)
		}
		for method, values := range expectedMethodResults {
			t.Run(fmt.Sprintf("%s for set %d", method, i), func(t *testing.T) {
				m := reflect.ValueOf(s).MethodByName(method).Call([]reflect.Value{})
				// Round to three decimal places
				got := math.Round(m[0].Float()*1000) / 1000
				expected := math.Round(values[i]*1000) / 1000
				if got != expected {
					t.Errorf("Method %s failure: \n"+
						"\tOn set: %d\n"+
						"\tExpected: %f\n"+
						"\tGot: %f\n",
						method, i, expected, got)
				}
			})
		}
	}

}