transaction.go

/*
MIT License

Copyright (c) 2016 Sascha Hanse
Copyright (c) 2017 Shinya Yagyu

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/

package giota

import (
	"encoding/json"
	"errors"
	"time"
)

// Transaction contains all info needed for an iota transaction
type Transaction struct {
	SignatureMessageFragment      Trytes
	Address                       Address
	Value                         int64 `json:",string"`
	ObsoleteTag                   Trytes
	Timestamp                     time.Time `json:",string"`
	CurrentIndex                  int64     `json:",string"`
	LastIndex                     int64     `json:",string"`
	Bundle                        Trytes
	TrunkTransaction              Trytes
	BranchTransaction             Trytes
	Tag                           Trytes
	AttachmentTimestamp           Trytes
	AttachmentTimestampLowerBound Trytes
	AttachmentTimestampUpperBound Trytes
	Nonce                         Trytes
}

// errors for tx
var (
	ErrInvalidTransactionType = errors.New("invalid transaction type")
	ErrInvalidTransactionHash = errors.New("invalid transaction hash")
	ErrInvalidTransaction     = errors.New("malformed transaction")
)

// Trinary sizes and offsets of a transaction
const (
	SignatureMessageFragmentTrinaryOffset = 0
	SignatureMessageFragmentTrinarySize   = 6561
	AddressTrinaryOffset                  = SignatureMessageFragmentTrinaryOffset + SignatureMessageFragmentTrinarySize
	AddressTrinarySize                    = 243
	ValueTrinaryOffset                    = AddressTrinaryOffset + AddressTrinarySize
	ValueTrinarySize                      = 81
	ObsoleteTagTrinaryOffset              = ValueTrinaryOffset + ValueTrinarySize
	ObsoleteTagTrinarySize                = 81
	TimestampTrinaryOffset                = ObsoleteTagTrinaryOffset + ObsoleteTagTrinarySize
	TimestampTrinarySize                  = 27
	CurrentIndexTrinaryOffset             = TimestampTrinaryOffset + TimestampTrinarySize
	CurrentIndexTrinarySize               = 27
	LastIndexTrinaryOffset                = CurrentIndexTrinaryOffset + CurrentIndexTrinarySize
	LastIndexTrinarySize                  = 27
	BundleTrinaryOffset                   = LastIndexTrinaryOffset + LastIndexTrinarySize
	BundleTrinarySize                     = 243
	TrunkTransactionTrinaryOffset         = BundleTrinaryOffset + BundleTrinarySize
	TrunkTransactionTrinarySize           = 243
	BranchTransactionTrinaryOffset        = TrunkTransactionTrinaryOffset + TrunkTransactionTrinarySize
	BranchTransactionTrinarySize          = 243
	TagTrinaryOffset                      = BranchTransactionTrinaryOffset + BranchTransactionTrinarySize
	TagTrinarySize                        = 81
	AttachmentTimestampTrinaryOffset      = TagTrinaryOffset + TagTrinarySize
	AttachmentTimestampTrinarySize        = 27

	AttachmentTimestampLowerBoundTrinaryOffset = AttachmentTimestampTrinaryOffset + AttachmentTimestampTrinarySize
	AttachmentTimestampLowerBoundTrinarySize   = 27
	AttachmentTimestampUpperBoundTrinaryOffset = AttachmentTimestampLowerBoundTrinaryOffset + AttachmentTimestampLowerBoundTrinarySize
	AttachmentTimestampUpperBoundTrinarySize   = 27
	NonceTrinaryOffset                         = AttachmentTimestampUpperBoundTrinaryOffset + AttachmentTimestampUpperBoundTrinarySize
	NonceTrinarySize                           = 81

	transactionTrinarySize = SignatureMessageFragmentTrinarySize + AddressTrinarySize +
		ValueTrinarySize + ObsoleteTagTrinarySize + TimestampTrinarySize +
		CurrentIndexTrinarySize + LastIndexTrinarySize + BundleTrinarySize +
		TrunkTransactionTrinarySize + BranchTransactionTrinarySize +
		TagTrinarySize + AttachmentTimestampTrinarySize +
		AttachmentTimestampLowerBoundTrinarySize + AttachmentTimestampUpperBoundTrinarySize +
		NonceTrinarySize
)

// NewTransaction makes tx from trits.
func NewTransaction(trytes Trytes) (*Transaction, error) {
	t := Transaction{}
	if err := checkTx(trytes); err != nil {
		return nil, err
	}

	err := t.parser(trytes.Trits())
	if err != nil {
		return nil, err
	}

	return &t, nil
}

func checkTx(trytes Trytes) error {
	err := trytes.IsValid()

	switch {
	case err != nil:
		return errors.New("invalid transaction " + err.Error())
	case len(trytes) != transactionTrinarySize/3:
		return errors.New("invalid trits counts in transaction")
	case trytes[2279:2295] != "9999999999999999":
		return errors.New("invalid value in transaction")
	default:
		return nil
	}
}

func (t *Transaction) parser(trits Trits) error {
	var err error
	t.SignatureMessageFragment = trits[SignatureMessageFragmentTrinaryOffset:SignatureMessageFragmentTrinarySize].Trytes()
	t.Address, err = trits[AddressTrinaryOffset : AddressTrinaryOffset+AddressTrinarySize].Trytes().ToAddress()
	if err != nil {
		return err
	}
	t.Value = trits[ValueTrinaryOffset : ValueTrinaryOffset+ValueTrinarySize].Int()
	t.ObsoleteTag = trits[ObsoleteTagTrinaryOffset : ObsoleteTagTrinaryOffset+ObsoleteTagTrinarySize].Trytes()
	timestamp := trits[TimestampTrinaryOffset : TimestampTrinaryOffset+TimestampTrinarySize].Int()
	t.Timestamp = time.Unix(timestamp, 0)
	t.CurrentIndex = trits[CurrentIndexTrinaryOffset : CurrentIndexTrinaryOffset+CurrentIndexTrinarySize].Int()
	t.LastIndex = trits[LastIndexTrinaryOffset : LastIndexTrinaryOffset+LastIndexTrinarySize].Int()
	t.Bundle = trits[BundleTrinaryOffset : BundleTrinaryOffset+BundleTrinarySize].Trytes()
	t.TrunkTransaction = trits[TrunkTransactionTrinaryOffset : TrunkTransactionTrinaryOffset+TrunkTransactionTrinarySize].Trytes()
	t.BranchTransaction = trits[BranchTransactionTrinaryOffset : BranchTransactionTrinaryOffset+BranchTransactionTrinarySize].Trytes()
	t.Tag = trits[TagTrinaryOffset : TagTrinaryOffset+TagTrinarySize].Trytes()
	t.AttachmentTimestamp = trits[AttachmentTimestampTrinaryOffset : AttachmentTimestampTrinaryOffset+AttachmentTimestampTrinarySize].Trytes()
	t.AttachmentTimestampLowerBound = trits[AttachmentTimestampLowerBoundTrinaryOffset : AttachmentTimestampLowerBoundTrinaryOffset+AttachmentTimestampLowerBoundTrinarySize].Trytes()
	t.AttachmentTimestampUpperBound = trits[AttachmentTimestampUpperBoundTrinaryOffset : AttachmentTimestampUpperBoundTrinaryOffset+AttachmentTimestampUpperBoundTrinarySize].Trytes()
	t.Nonce = trits[NonceTrinaryOffset : NonceTrinaryOffset+NonceTrinarySize].Trytes()

	return nil
}

// Trytes converts the transaction to Trytes.
func (t *Transaction) Trytes() Trytes {
	tr := make(Trits, transactionTrinarySize)
	copy(tr, t.SignatureMessageFragment.Trits())
	copy(tr[AddressTrinaryOffset:], Trytes(t.Address).Trits())
	copy(tr[ValueTrinaryOffset:], Int2Trits(t.Value, ValueTrinarySize))
	copy(tr[ObsoleteTagTrinaryOffset:], t.ObsoleteTag.Trits())
	copy(tr[TimestampTrinaryOffset:], Int2Trits(t.Timestamp.Unix(), TimestampTrinarySize))
	copy(tr[CurrentIndexTrinaryOffset:], Int2Trits(t.CurrentIndex, CurrentIndexTrinarySize))
	copy(tr[LastIndexTrinaryOffset:], Int2Trits(t.LastIndex, LastIndexTrinarySize))
	copy(tr[BundleTrinaryOffset:], t.Bundle.Trits())
	copy(tr[TrunkTransactionTrinaryOffset:], t.TrunkTransaction.Trits())
	copy(tr[BranchTransactionTrinaryOffset:], t.BranchTransaction.Trits())
	copy(tr[TagTrinaryOffset:], t.Tag.Trits())
	copy(tr[AttachmentTimestampTrinaryOffset:], t.AttachmentTimestamp.Trits())
	copy(tr[AttachmentTimestampLowerBoundTrinaryOffset:], t.AttachmentTimestampLowerBound.Trits())
	copy(tr[AttachmentTimestampUpperBoundTrinaryOffset:], t.AttachmentTimestampUpperBound.Trits())
	copy(tr[NonceTrinaryOffset:], t.Nonce.Trits())
	return tr.Trytes()
}

// HasValidNonce checks if the transaction has the valid MinWeightMagnitude.
// In order to check the MWM we count trailing 0's of the curlp hash of a
// transaction.
func (t *Transaction) HasValidNonce(mwm int64) bool {
	return t.Hash().Trits().TrailingZeros() >= mwm
}

// Hash returns the hash of the transaction.
func (t *Transaction) Hash() Trytes {
	return t.Trytes().Hash()
}

// UnmarshalJSON makes transaction struct from json.
func (t *Transaction) UnmarshalJSON(b []byte) error {
	var s Trytes
	var err error

	if err = json.Unmarshal(b, &s); err != nil {
		return err
	}

	if err = checkTx(s); err != nil {
		return err
	}

	return t.parser(s.Trits())
}

// MarshalJSON makes trytes ([]byte) from a transaction.
func (t *Transaction) MarshalJSON() ([]byte, error) {
	return []byte(`"` + t.Trytes() + `"`), nil
}