transaction.go

//Date: 2017 Q4
//Email: ali.mashatan@gmail.com
//Author: Ali Mashatan

package GoBigChainDBDriver

import (
	"bytes"
	"encoding/hex"
	"encoding/json"
)

const (
	CREATE   = "CREATE"
	GENESIS  = "GENSIS"
	TRANSFER = "TRANSFER"
	VERSION  = "1.0"
)

type transaction struct {
	id        string
	asset     JsonObj
	assetId   string
	input     input
	output    output
	metadata  JsonObj
	operation string
	version   string
}

func NewCreateTransaction(asset JsonObj, metadata JsonObj) transaction {
	trasaction := transaction{}
	trasaction.operation = CREATE
	trasaction.version = VERSION
	trasaction.asset = JsonObj{"data": asset}
	trasaction.assetId = ""
	trasaction.metadata = metadata
	trasaction.input = input{}
	trasaction.output = output{}
	return trasaction
}

func NewTransferTransaction(assetId string, metadata JsonObj) transaction {
	trasaction := transaction{}
	trasaction.operation = TRANSFER
	trasaction.version = VERSION
	trasaction.asset = JsonObj{"id": assetId}
	trasaction.assetId = assetId
	trasaction.metadata = metadata
	trasaction.input = input{}
	trasaction.output = output{}
	return trasaction
}

func (t *transaction) AddOwnerBefore(publicKey *[]PublicKey, privateKey *[]PrivateKey, fulfill *JsonObj) error {
	t.input.Add(publicKey, privateKey, fulfill)
	return nil
}

func (t *transaction) AddOwnerAfter(publicKey *[]PublicKey, amount int) error {
	t.output.Add(publicKey, amount)
	return nil
}

func (t *transaction) Generate(withId bool, removeNull bool) (JsonObj, error) {

	tx := JsonObj{}
	if withId {
		tx["id"] = t.id
	}
	if len(t.asset) != 0 {
		tx["asset"] = t.asset
	}
	inputs := t.input.Generate(removeNull)
	if len(inputs) != 0 {
		tx["inputs"] = inputs
	}
	if len(t.metadata) != 0 {
		tx["metadata"] = t.metadata
	}
	tx["operation"] = t.operation
	outputs := t.output.Generate(removeNull)
	if len(outputs) != 0 {
		tx["outputs"] = outputs
	}
	tx["version"] = VERSION
	return tx, nil
}

func (t *transaction) dump() []byte {
	jo, _ := t.Generate(true, false)
	b, _ := json.Marshal(jo)
	b = bytes.Replace(b, []byte("\\u003c"), []byte("<"), -1)
	b = bytes.Replace(b, []byte("\\u003e"), []byte(">"), -1)
	b = bytes.Replace(b, []byte("\\u0026"), []byte("&"), -1)
	return b
}
func (t *transaction) createId() string {
	jo, _ := t.Generate(false, true)
	b, _ := json.Marshal(jo)

	b = bytes.Replace(b, []byte("\\u003c"), []byte("<"), -1)
	b = bytes.Replace(b, []byte("\\u003e"), []byte(">"), -1)
	b = bytes.Replace(b, []byte("\\u0026"), []byte("&"), -1)
	println("*\nTX Before ID: ", string(b), "\n*\n")
	return hex.EncodeToString(HashData(b))
}

func (t *transaction) Sign() error {
	dm := t.dump()
	t.output.Sign(dm)
	t.id = t.createId()
	dm = t.dump()
	println("*\nTX Before Sign: ", string(dm), "\n*\n")
	t.input.Sign(dm)

	return nil
}