From d2d09d78d2015d802505eb2f11ca8c46265cca2a Mon Sep 17 00:00:00 2001
From: shaojunda <shaojunda@gmail.com>
Date: Fri, 11 Dec 2020 02:44:16 +0800
Subject: [PATCH] feat: implement generate unsigned issuing cheque tx

---
 payment/cheque.go | 129 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 payment/cheque.go

diff --git a/payment/cheque.go b/payment/cheque.go
new file mode 100644
index 00000000..fb5168d2
--- /dev/null
+++ b/payment/cheque.go
@@ -0,0 +1,129 @@
+package payment
+
+import (
+	"fmt"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/nervosnetwork/ckb-sdk-go/address"
+	"github.com/nervosnetwork/ckb-sdk-go/collector"
+	"github.com/nervosnetwork/ckb-sdk-go/indexer"
+	"github.com/nervosnetwork/ckb-sdk-go/rpc"
+	"github.com/nervosnetwork/ckb-sdk-go/transaction"
+	"github.com/nervosnetwork/ckb-sdk-go/types"
+	"github.com/nervosnetwork/ckb-sdk-go/utils"
+	"github.com/pkg/errors"
+	"math"
+	"math/big"
+)
+
+var (
+	chequeCellCapacity = uint64(162 * math.Pow10(8))
+	udtCellCapacity    = uint64(142 * math.Pow10(8))
+)
+
+type Cheque struct {
+	Sender   *types.Script
+	Receiver *types.Script
+	UUID     string
+	Amount   *big.Int
+	FeeRate  uint64
+	tx       *types.Transaction
+}
+
+func NewCheque(senderAddr, receiverAddr, uuid, amount string, feeRate uint64) (*Cheque, error) {
+	parsedSenderAddr, err := address.Parse(senderAddr)
+	if err != nil {
+		return nil, errors.WithMessage(err, "invalid sender address")
+	}
+	parsedReceiverAddr, err := address.Parse(receiverAddr)
+	if err != nil {
+		return nil, errors.WithMessage(err, "invalid receiver address")
+	}
+	n, b := big.NewInt(0).SetString(amount, 10)
+	if !b {
+		return nil, errors.WithMessage(err, "invalid amount")
+	}
+	return &Cheque{
+		Sender:   parsedSenderAddr.Script,
+		Receiver: parsedReceiverAddr.Script,
+		UUID:     uuid,
+		Amount:   n,
+		FeeRate:  feeRate,
+	}, nil
+}
+
+func (c *Cheque) GenerateIssueChequeTx(client rpc.Client) (*types.Transaction, error) {
+	systemScripts, err := utils.NewSystemScripts(client)
+	if err != nil {
+		return nil, err
+	}
+	udtType := &types.Script{
+		CodeHash: systemScripts.SUDTCell.CellHash,
+		HashType: systemScripts.SUDTCell.HashType,
+		Args:     common.FromHex(c.UUID),
+	}
+
+	tx := transaction.NewSecp256k1SingleSigTx(systemScripts)
+	// set sudt and cheque scripts cell deps
+	tx.CellDeps = append(tx.CellDeps, &types.CellDep{
+		OutPoint: systemScripts.SUDTCell.OutPoint,
+		DepType:  systemScripts.SUDTCell.DepType,
+	}, &types.CellDep{
+		OutPoint: systemScripts.ChequeCell.OutPoint,
+		DepType:  systemScripts.ChequeCell.DepType,
+	})
+
+	// cheque output
+	chequeCellArgs, err := utils.ChequeCellArgs(c.Sender, c.Receiver)
+	if err != nil {
+		return nil, err
+	}
+	tx.Outputs = append(tx.Outputs, &types.CellOutput{
+		Capacity: chequeCellCapacity,
+		Lock: &types.Script{
+			CodeHash: systemScripts.ChequeCell.CellHash,
+			HashType: systemScripts.ChequeCell.HashType,
+			Args:     chequeCellArgs,
+		},
+		Type: udtType,
+	})
+	tx.OutputsData = append(tx.OutputsData, utils.GenerateSudtAmount(c.Amount))
+
+	// ckb change output
+	tx.Outputs = append(tx.Outputs, &types.CellOutput{
+		Capacity: 0,
+		Lock:     c.Sender,
+	})
+	tx.OutputsData = append(tx.OutputsData, []byte{})
+
+	// sudt change output
+	tx.Outputs = append(tx.Outputs, &types.CellOutput{
+		Capacity: udtCellCapacity,
+		Lock:     c.Sender,
+		Type:     udtType,
+	})
+	tx.OutputsData = append(tx.OutputsData, utils.GenerateSudtAmount(big.NewInt(0)))
+
+	// collect udt cells
+	searchKey := &indexer.SearchKey{
+		Script:     c.Sender,
+		ScriptType: indexer.ScriptTypeLock,
+	}
+	processor := collector.NewUDTLiveCellProcessor(c.Amount)
+	processor.CkbChangeOutputIndex = &collector.ChangeOutputIndex{Value: 1}
+	processor.SUDTChangeOutputIndex = &collector.ChangeOutputIndex{Value: 2}
+	processor.TypeScript = udtType
+	processor.Tx = tx
+	processor.FeeRate = c.FeeRate
+	nCollector := utils.NewLiveCellCollector(client, searchKey, indexer.SearchOrderAsc, indexer.SearchLimit, "", processor)
+	cells, err := nCollector.Collect()
+	if err != nil {
+		return nil, fmt.Errorf("collect cell error: %v", err)
+	}
+	totalAmount := cells.Options["totalAmount"].(*big.Int)
+	if totalAmount.Cmp(c.Amount) < 0 {
+		return nil, errors.New("insufficient udt balance")
+	}
+	c.tx = tx
+
+	return tx, nil
+}