// Copyright 2018 Bull S.A.S. Atos Technologies - Bull, Rue Jean Jaures, B.P.68, 78340, Les Clayes-sous-Bois, France.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package mathutil

import "math"

// Round rounds a value val starting at roundOn, and keep places decimal
// Round(123.555555, .5, 3) -> 123.556
// Round(123.558, .5, 2) -> 123.56
// Round(123.00001, 0, 0) -> 124
//
// Credits to https://gist.github.com/pelegm/c48cff315cd223f7cf7b
func Round(val float64, roundOn float64, places int) (newVal float64) {
	var round float64
	pow := math.Pow(10, float64(places))
	digit := pow * val
	_, div := math.Modf(digit)
	_div := math.Copysign(div, val)
	_roundOn := math.Copysign(roundOn, val)
	if _div >= _roundOn {
		round = math.Ceil(digit)
	} else {
		round = math.Floor(digit)
	}
	newVal = round / pow
	return
}