1package core
 2
 3import (
 4	"crypto/ecdsa"
 5	"encoding/json"
 6
 7	log "github.com/sirupsen/logrus"
 8)
 9
10var GenesisHashTxInput = HashBytes([]byte("genesis"))
11
12type Input struct {
13	TxId  Hash
14	Vout  int // index of the output from the TxId
15	Value uint64
16}
17
18type Output struct {
19	Value uint64
20}
21
22// Tx holds the data structure of a transaction
23type Tx struct {
24	TxId       Hash
25	From       *ecdsa.PublicKey
26	To         *ecdsa.PublicKey
27	InputCount uint64
28	Inputs     []Input
29	Outputs    []Output
30	Signature  []byte
31}
32
33func (tx *Tx) Bytes() []byte {
34	// TODO add parser, to use minimum amount of bytes
35	b, _ := json.Marshal(tx)
36	return b
37}
38
39func (tx *Tx) CalculateTxId() {
40	h := HashBytes(tx.Bytes())
41	tx.TxId = h
42}
43
44func NewTx(from, to *ecdsa.PublicKey, in []Input, out []Output) *Tx {
45	tx := &Tx{
46		From:       from,
47		To:         to,
48		InputCount: uint64(len(in)),
49		Inputs:     in,
50		Outputs:    out,
51		Signature:  []byte{},
52	}
53	tx.CalculateTxId()
54	return tx
55}
56
57// CheckTx checks if the transaction is consistent
58func CheckTx(tx *Tx) bool {
59	// check that inputs == outputs
60	totalIn := 0
61	for _, in := range tx.Inputs {
62		// check that inputs are not empty, to avoid spam tx
63		if in.Value == uint64(0) {
64			return false
65		}
66		totalIn = totalIn + int(in.Value)
67	}
68	totalOut := 0
69	for _, out := range tx.Outputs {
70		totalOut = totalOut + int(out.Value)
71	}
72	if totalIn != totalOut {
73		log.Info("totalIn != totalOut")
74		return false
75	}
76
77	// TODO check signature
78	return true
79}