MikkelHJuul/profaneword

package profaneword

import (
    "crypto/rand"
    "math"
    "math/big"
)

type RandomDevice interface {
    // Rand is a function that returns a random number between 0 and 1
    Rand() *big.Rat
    RandMax(max int) int
}

func getRand(max *big.Int) *big.Int {
    i, _ := rand.Int(rand.Reader, max)
    return i
}

type CryptoRand struct{}

func (c CryptoRand) Rand() *big.Rat {
    max := big.NewInt(math.MaxInt64)
    return big.NewRat(getRand(max).Int64(), max.Int64())
}

func (c CryptoRand) RandMax(max int) int {
    return int(getRand(big.NewInt(int64(max))).Int64())
}

type thresholdRandom struct {
    Rand      RandomDevice
    Threshold *big.Rat
}

func newRandomFormatter(device RandomDevice, threshold *big.Rat) thresholdRandom {
    if threshold == nil {
        threshold = big.NewRat(1, 2)
    }
    if device == nil {
        device = CryptoRand{}
    }
    return thresholdRandom{
        Rand:      device,
        Threshold: threshold,
    }
}

func newFiftyFifty() thresholdRandom {
    return newRandomFormatter(nil, nil)
}