1package core
 2
 3import (
 4	"bytes"
 5	"crypto/sha256"
 6	"encoding/binary"
 7	"encoding/hex"
 8)
 9
10// Hash is the type for a hash data packet
11type Hash [32]byte
12
13// IsZero returns true if the Hash is empty (all zeroes)
14func (h *Hash) IsZero() bool {
15	z := Hash{}
16	if bytes.Equal(z[:], h[:]) {
17		return true
18	}
19	return false
20}
21func (h *Hash) String() string {
22	return hex.EncodeToString(h[:])
23}
24
25// HashBytes performs a hash over a given byte array
26func HashBytes(b []byte) Hash {
27	h := sha256.Sum256(b)
28	return h
29}
30
31// PoWData is the interface for the data that have the Nonce parameter to calculate the Proof-of-Work
32type PoWData interface {
33	Bytes() []byte
34	GetNonce() uint64
35	IncrementNonce()
36}
37
38// CheckPoW verifies the PoW difficulty of a Hash
39func CheckPoW(hash Hash, difficulty uint64) bool {
40	var empty [32]byte
41	if !bytes.Equal(hash[:][0:difficulty], empty[0:difficulty]) {
42		return false
43	}
44	return true
45}
46
47// CalculatePoW calculates the nonce for the given data in order to fit in the current Proof of Work difficulty
48func CalculatePoW(data PoWData, difficulty uint64) (uint64, error) {
49	hash := HashBytes(data.Bytes())
50	for !CheckPoW(hash, difficulty) {
51		data.IncrementNonce()
52
53		hash = HashBytes(data.Bytes())
54	}
55	return data.GetNonce(), nil
56}
57
58func Uint64ToBytes(u uint64) []byte {
59	buff := new(bytes.Buffer)
60	err := binary.Write(buff, binary.LittleEndian, u)
61	if err != nil {
62		panic(err)
63	}
64	return buff.Bytes()
65
66}
67
68func Uint64FromBytes(b []byte) uint64 {
69	return binary.LittleEndian.Uint64(b)
70}