package entropy

import (
	"crypto/rand"
	"sync"
)

type OSEntropySource struct {
	mu sync.Mutex
}

func (e *OSEntropySource) GetEntropy(minEntropy int64, minEntropyInputLength int64, maxEntropyInputLength int64) ([]byte, error) {
	//使用互斥锁保证熵源的独占性
	e.mu.Lock()
	defer e.mu.Unlock()

	n := minEntropy
	if n < minEntropyInputLength {
		n = minEntropyInputLength
	}
	entropy := make([]byte, n)
	if _, err := rand.Reader.Read(entropy); err != nil {
		return nil, err
	}

	return entropy, nil
}