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comet.go
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comet.go
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package main
import (
"bytes"
"encoding/json"
"fmt"
"strconv"
"time"
"github.com/hyperledger/fabric/core/chaincode/shim"
pb "github.com/hyperledger/fabric/protos/peer"
)
// ____ __ ___________
// ___ / /___ ___ /__ /_________ __
// __ /_ /__ /_ _ \_ / / /
// _ _ / /_/ /_ /_ / / __/ /_/ /
// /_/ _ \__,_ /_ /_/ \___/_\__, /
// /____/
// Built for Disruption
// Made by Aabo Technologies © Server's Division
// Built on September 1st, 2017
// Perfection on November 7th, 2017
/** This is the Smart Contract Structure */
type SimpleChaincode struct {
}
/* Define the Wallet Structure with 3 properties
/ [ID] <-- Wallet Identifier made up of an md5 hash
/ [Balance] <-- Balance that indicates the amount of money a wallet holds
/ [Owner] <-- Owner that is the holder of a wallet
*/
type Wallet struct {
Address string `json:"address"`
Balance int `json:"balance"`
}
/*
* The main method is only relevant in unit test mode.
* Included here for completeness
*/
func main() {
err := shim.Start(new(SimpleChaincode))
if err != nil {
fmt.Printf("Error starting Transaction Chaincode implementation: %s", err)
}
}
/*
*The Init method is called when the Smart Contract 'Halley' is instantiated by the blockchain network
* Best practice is to have any Ledger initialization as a separate function
*/
func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response {
return shim.Success(nil)
}
/*
* The Invoke method is called as a result of an application request to the Smart Contract 'Halley'
* The calling application program has also specified the particular smart contract function to be called, with arguments
*/
func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
// Retrieve the requested Smart Contract function and arguments
function, args := stub.GetFunctionAndParameters()
fmt.Println("Invoke is running: " + function)
//Route to the appropiate handler function to interact with the ledger appropiately
if function == "initWallet" {
return t.initWallet(stub, args)
} else if function == "transferFunds" {
return t.transferFunds(stub, args)
} else if function == "readWallet" {
return t.readWallet(stub, args)
} else if function == "getWalletsByRange" {
return t.getWalletsByRange(stub, args)
} else if function == "getHistoryForWallet" {
return t.getHistoryForWallet(stub, args)
}
// If nothing was invoked, launch an error
fmt.Println("Invoke didn't find function: " + function)
return shim.Error("Received Unknown function invocation")
}
/*
* initWallet
* This method creates a wallet and initializes it into the system
* [id] = This is a number that identifies the wallet
* [balance] = This is the numerical balance of the account
*/
func (t *SimpleChaincode) initWallet(stub shim.ChaincodeStubInterface, args []string) pb.Response {
var err error
// 0 1
// Address Initial Balance
if len(args) < 2 {
return shim.Error("Incorrect Number of arguments, expecting 2")
}
//Input Sanitation as this part is really important
fmt.Printf(" - Initializing Wallet - ")
if len(args[0]) <= 0 || len(args[0]) <= 0 {
return shim.Error("Arguments can't be non empty")
}
//Variable initialization
address := args[0]
balance, _ := strconv.Atoi(args[1])
if err != nil {
return shim.Error("2nd Argument must be a numeric string")
}
//Create the Wallet object and convert it to bytes to save
Wallet := Wallet{Address: address, Balance: balance}
WalletJSONasBytes, err := json.Marshal(Wallet)
if err != nil {
return shim.Error(err.Error())
}
//Save the Wallet to the blockchain
err = stub.PutState(address, WalletJSONasBytes)
if err != nil {
return shim.Error(err.Error())
}
//Create an Index to look faster for Wallets
indexName := "address~balance"
addressBalanceIndexKey, err := stub.CreateCompositeKey(indexName, []string{Wallet.Address, strconv.Itoa(Wallet.Balance)})
if err != nil {
return shim.Error(err.Error())
}
//Save Index to State
value := []byte{0x00}
stub.PutState(addressBalanceIndexKey, value)
//Wallet saved and indexed, return success
fmt.Println(" - END Wallet Init - ")
return shim.Success(nil)
}
/*
* readWallet
* This method returns the current state of a wallet on the ledger
* [id] = This is an md5 hash that identifies the wallet
* (JSON) = JSON Document with the current state of the wallet
*/
func (t *SimpleChaincode) readWallet(stub shim.ChaincodeStubInterface, args []string) pb.Response {
var address, jsonResp string
var err error
if len(args) < 1 {
return shim.Error("Incorrect number of arguments, expecting the address to query")
}
address = args[0]
valAsBytes, err := stub.GetState(address)
if err != nil {
jsonResp = "{\"Error\":\"Failed to get state for " + address + "\"}"
return shim.Error(jsonResp)
} else if valAsBytes == nil {
jsonResp = "{\"Error\":\"Wallet does not exist: " + address + "\"}"
return shim.Error(jsonResp)
}
return shim.Success(valAsBytes)
}
/*
* transferFunds
* This method is the main driver for the application, it allows the transfer of balance between wallets
* [from] = This is the id for a wallet that's sending money
* [to] = This is the id for a wallet that's receiving money
* [balance] = This is the amount of money that it's being transfered
*/
func (t *SimpleChaincode) transferFunds(stub shim.ChaincodeStubInterface, args []string) pb.Response {
// 0 1 2
// from to balance
if len(args) < 3 {
return shim.Error("Incorrect number of arguments. Expecting 3")
}
//Variable setting from - to - ammount to be transfered
from := args[0]
to := args[1]
transfer, _ := strconv.Atoi(args[2])
//if Wallet 'from' doesn't exist, then the transfer halts
fromAsBytes, err := stub.GetState(from)
if err != nil {
return shim.Error("Failed to get Wallet: " + err.Error())
} else if fromAsBytes == nil {
return shim.Error("Wallet 1 doesn't exist")
}
//if Wallet 'to' doesn't exist, then the transfer halts
toAsBytes, err := stub.GetState(to)
if err != nil {
return shim.Error("Failed to get Wallet: " + err.Error())
} else if toAsBytes == nil {
return shim.Error("Wallet 1 doesn't exist")
}
//Make Wallet 'from' usable for us
WalletFrom := Wallet{}
err = json.Unmarshal(fromAsBytes, &WalletFrom)
if err != nil {
return shim.Error(err.Error())
}
//Make Wallet 'To' usable for us
WalletTo := Wallet{}
err = json.Unmarshal(toAsBytes, &WalletTo)
if err != nil {
return shim.Error(err.Error())
}
//This is the main balance transfer mechanism
//As far as we know, this part is really simple
//1. Checks if an Wallet has enough funds to transfer to another Wallet
//2. Checks if the transfer amount is not negative (that'd be really weird)
//3. Then, it simply 'transfers' it.
WalletTo.Balance += transfer
WalletFrom.Balance -= transfer
//The state is updated to the blockchain for both
//the 'to' Wallet and the 'from' Wallet
WalletToAsBytes, _ := json.Marshal(WalletTo)
err = stub.PutState(to, WalletToAsBytes)
if err != nil {
return shim.Error(err.Error())
}
return shim.Error("I'm a rollback function")
WalletFromAsBytes, _ := json.Marshal(WalletFrom)
err = stub.PutState(from, WalletFromAsBytes)
if err != nil {
return shim.Error(err.Error())
}
fmt.Println(" - END Transaction (success) - ")
return shim.Success(nil)
}
func (t *SimpleChaincode) getWalletsByRange(stub shim.ChaincodeStubInterface, args []string) pb.Response {
if len(args) < 2 {
return shim.Error("Incorrect number of arguments. Expecting 2")
}
startKey := args[0]
endKey := args[1]
resultsIterator, err := stub.GetStateByRange(startKey, endKey)
if err != nil {
return shim.Error(err.Error())
}
defer resultsIterator.Close()
//Buffer is a JSON Array containing QueryResults
var buffer bytes.Buffer
buffer.WriteString("[")
bArrayMemberAlreadyWritten := false
for resultsIterator.HasNext() {
queryResponse, err := resultsIterator.Next()
if err != nil {
return shim.Error(err.Error())
}
//Add a comma before array members, supress ir for the first array member
if bArrayMemberAlreadyWritten == true {
buffer.WriteString(",")
}
buffer.WriteString("{\"Key\":")
buffer.WriteString("\"")
buffer.WriteString(queryResponse.Key)
buffer.WriteString("\"")
buffer.WriteString(", \"Record\":")
//Record is a JSON object, so we write as-is
buffer.WriteString(string(queryResponse.Value))
buffer.WriteString("}")
bArrayMemberAlreadyWritten = true
}
buffer.WriteString("]")
fmt.Printf("- get Wallet by RANGE queryResult:\n%s\n", buffer.String())
return shim.Success(buffer.Bytes())
}
func (t *SimpleChaincode) getHistoryForWallet(stub shim.ChaincodeStubInterface, args []string) pb.Response {
if len(args) < 1 {
return shim.Error("Incorrect number of arguments. Expecting 1")
}
walletID := args[0]
resultsIterator, err := stub.GetHistoryForKey(walletID)
if err != nil {
return shim.Error(err.Error())
}
defer resultsIterator.Close()
// buffer is a JSON array containing historic values for the marble
var buffer bytes.Buffer
buffer.WriteString("[")
bArrayMemberAlreadyWritten := false
for resultsIterator.HasNext() {
response, err := resultsIterator.Next()
if err != nil {
return shim.Error(err.Error())
}
// Add a comma before array members, suppress it for the first array member
if bArrayMemberAlreadyWritten == true {
buffer.WriteString(",")
}
buffer.WriteString("{\"TxId\":")
buffer.WriteString("\"")
buffer.WriteString(response.TxId)
buffer.WriteString("\"")
buffer.WriteString(", \"Value\":")
// if it was a delete operation on given key, then we need to set the
//corresponding value null. Else, we will write the response.Value
//as-is (as the Value itself a JSON wallet)
if response.IsDelete {
buffer.WriteString("null")
} else {
buffer.WriteString(string(response.Value))
}
buffer.WriteString(", \"Timestamp\":")
buffer.WriteString("\"")
buffer.WriteString(time.Unix(response.Timestamp.Seconds, int64(response.Timestamp.Nanos)).String())
buffer.WriteString("\"")
buffer.WriteString(", \"IsDelete\":")
buffer.WriteString("\"")
buffer.WriteString(strconv.FormatBool(response.IsDelete))
buffer.WriteString("\"")
buffer.WriteString("}")
bArrayMemberAlreadyWritten = true
}
buffer.WriteString("]")
return shim.Success(buffer.Bytes())
}