package expr

import (
	"github.com/PaesslerAG/gval"
	"math"
)

func NumericFunctions() []gval.Language {
	return []gval.Language{
		gval.Function("min", min),
		gval.Function("max", max),
		gval.Function("round", round),
		gval.Function("floor", floor),
		gval.Function("ceil", ceil),
	}
}

func min(aa ...interface{}) (min float64) {
	return findMinMax(-1, aa...)
}

func max(aa ...interface{}) (min float64) {
	return findMinMax(1, aa...)
}

func findMinMax(dir int, aa ...interface{}) (mm float64) {
	var (
		set bool
		flt float64
	)
	for i := range aa {
		switch conv := aa[i].(type) {
		case int:
			flt = float64(conv)
		case int64:
			flt = float64(conv)
		case uint:
			flt = float64(conv)
		case uint64:
			flt = float64(conv)
		case float32:
			flt = float64(conv)
		case float64:
			flt = conv
		default:
			continue
		}

		if !set {
			set = true
			mm = flt
		} else if dir < 0 {
			mm = math.Min(mm, flt)
		} else if dir > 0 {
			mm = math.Max(mm, flt)
		}
	}

	return mm
}

func round(f float64, d float64) float64 {
	p := math.Pow(10, d)
	return math.Round(f*p) / p
}

func floor(f float64) float64 {
	return math.Floor(f)
}

func ceil(f float64) float64 {
	return math.Ceil(f)
}