govote/voting/quorum/quorum.go

package quorum

import (
	"fmt"
	"strings"
)

// Quorum defines a custom uint8 type for storing a quorum.
type Quorum uint8

// Supported quorums are:
const (
	Simple Quorum = iota
	OneFifth
	OneQuarter
	OneThird
	OneHalf
	TwoFifths
	TwoThirds
	ThreeQuarters
	ThreeFifths
	FourFifths
	Unanimous
)

// ValidQuorums returns a []Quorum of all supported quorums.
func ValidQuorums() []Quorum {
	return []Quorum{
		Simple, Unanimous,
		OneFifth, OneQuarter, OneThird, OneHalf,
		TwoThirds, TwoFifths,
		ThreeQuarters, ThreeFifths,
		FourFifths,
	}
}

// FromString takes a string and returns an initialized Quorum or an error if
// the string could not be parsed.
func FromString(s string) (Quorum, error) {
	for _, q := range ValidQuorums() {
		if strings.ToUpper(q.String()) == strings.ToUpper(s) {
			return q, nil
		}
	}
	return Simple, fmt.Errorf("inalid quorum: %s", s)
}

// String implements fmt.Stringer
func (q Quorum) String() string {
	switch q {
	case Simple:
		return "SIMPLE"
	case OneFifth:
		return "1/5"
	case OneQuarter:
		return "1/4"
	case OneThird:
		return "1/3"
	case OneHalf:
		return "1/2"
	case TwoThirds:
		return "2/3"
	case TwoFifths:
		return "2/5"
	case ThreeQuarters:
		return "3/4"
	case ThreeFifths:
		return "3/5"
	case FourFifths:
		return "4/5"
	case Unanimous:
		return "ALL"
	default:
		panic("this code should never be reached")
	}
}

// IsSatisfied takes the number of eligible and actual votes and returns a bool
// indicating if the quroum is satisfied or not.
func (q Quorum) IsSatisfied(possibleVotes, totalVotes int) bool {
	if totalVotes == 0 {
		return false
	}
	switch q {
	case Simple:
		return true
	case OneFifth:
		return totalVotes*5 >= possibleVotes
	case OneQuarter:
		return totalVotes*4 >= possibleVotes
	case OneThird:
		return totalVotes*3 >= possibleVotes
	case OneHalf:
		return totalVotes*2 >= possibleVotes
	case TwoThirds:
		return totalVotes*3 >= possibleVotes*2
	case TwoFifths:
		return totalVotes*5 >= possibleVotes*2
	case ThreeQuarters:
		return totalVotes*4 >= possibleVotes*3
	case ThreeFifths:
		return totalVotes*5 >= possibleVotes*3
	case FourFifths:
		return totalVotes*5 >= possibleVotes*4
	case Unanimous:
		return totalVotes >= possibleVotes
	default:
		panic("this code should never be reached")
	}
}