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andrejrakicandrejrakic
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Add How to create a Crypto Coin example (#4)
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12 files changed

+320
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lines changed

12 files changed

+320
-0
lines changed

‎my-crypto-coin/.gitignore

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.idea
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.vscode

‎my-crypto-coin/cli/mcc/balances.go

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package main
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import (
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"github.com/spf13/cobra"
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"my-crypto-coin/ledger"
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"fmt"
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"os"
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)
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func balancesCmd() *cobra.Command {
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var balancesCmd = &cobra.Command{
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Use: "balances",
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Short: "Interact with balances (list...).",
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Run: func(cmd *cobra.Command, args []string) {
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},
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}
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balancesCmd.AddCommand(balancesListCmd)
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return balancesCmd
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}
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var balancesListCmd = &cobra.Command{
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Use: "list",
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Short: "Lists all balances.",
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Run: func(cmd *cobra.Command, args []string) {
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state, err := ledger.SyncState()
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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defer state.Close()
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fmt.Println("Accounts balances:")
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fmt.Println("__________________")
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fmt.Println("")
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for account, balance := range state.Balances {
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fmt.Println(fmt.Sprintf("%s: %d", account, balance))
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}
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},
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}

‎my-crypto-coin/cli/mcc/main.go

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package main
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import (
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"github.com/spf13/cobra"
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"os"
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"fmt"
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)
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func main() {
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var mccCmd = &cobra.Command{
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Use: "mcc",
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Short: "My Crypto Coin CLI",
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Run: func(cmd *cobra.Command, args []string) {
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},
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}
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mccCmd.AddCommand(versionCmd)
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mccCmd.AddCommand(balancesCmd())
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mccCmd.AddCommand(txCmd())
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err := mccCmd.Execute()
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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}

‎my-crypto-coin/cli/mcc/tx.go

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package main
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import (
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"github.com/spf13/cobra"
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"my-crypto-coin/ledger"
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"fmt"
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"os"
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)
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func txCmd() *cobra.Command {
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var txsCmd = &cobra.Command{
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Use: "tx",
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Short: "Interact with transactions (new...).",
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Run: func(cmd *cobra.Command, args []string) {
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},
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}
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txsCmd.AddCommand(newTxCmd())
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return txsCmd
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}
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func newTxCmd() *cobra.Command {
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var cmd = &cobra.Command{
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Use: "new",
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Short: "Adds new TX to the ledger.",
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Run: func(cmd *cobra.Command, args []string) {
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from, _ := cmd.Flags().GetString("from")
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to, _ := cmd.Flags().GetString("to")
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value, _ := cmd.Flags().GetUint("value")
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tx := ledger.NewTx(ledger.NewAccount(from), ledger.NewAccount(to), value)
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state, err := ledger.SyncState()
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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defer state.Close()
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err = state.WriteToLedger(tx)
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if err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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fmt.Println("TX successfully added to the ledger.")
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},
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}
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cmd.Flags().String("from", "", "From what account to send coins")
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cmd.MarkFlagRequired("from")
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cmd.Flags().String("to", "", "To what account to send coins")
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cmd.MarkFlagRequired("to")
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cmd.Flags().Uint("value", 0, "How many coins to send")
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cmd.MarkFlagRequired("value")
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return cmd
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}

‎my-crypto-coin/cli/mcc/version.go

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package main
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import (
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"fmt"
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"github.com/spf13/cobra"
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)
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const Major = "0"
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const Minor = "1"
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const Fix = "0"
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const Verbal = "Genesis"
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var versionCmd = &cobra.Command{
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Use: "version",
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Short: "Describes version.",
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Run: func(cmd *cobra.Command, args []string) {
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fmt.Println(fmt.Sprintf("Version: %s.%s.%s-beta %s", Major, Minor, Fix, Verbal))
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},
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}

‎my-crypto-coin/go.mod

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module my-crypto-coin
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go 1.16
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require github.com/spf13/cobra v1.4.0 // indirect

‎my-crypto-coin/go.sum

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github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
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github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
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github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
4+
github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
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github.com/spf13/cobra v1.4.0 h1:y+wJpx64xcgO1V+RcnwW0LEHxTKRi2ZDPSBjWnrg88Q=
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github.com/spf13/cobra v1.4.0/go.mod h1:Wo4iy3BUC+X2Fybo0PDqwJIv3dNRiZLHQymsfxlB84g=
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github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
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github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
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gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
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gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

‎my-crypto-coin/ledger/genesis.go

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package ledger
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import (
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"io/ioutil"
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"encoding/json"
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)
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type Genesis struct {
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Balances map[Account]uint `json:"balances"`
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}
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func loadGenesis(path string) (Genesis, error) {
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genesisFileContent, err := ioutil.ReadFile(path)
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if err != nil {
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return Genesis{}, err
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}
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var loadedGenesis Genesis
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err = json.Unmarshal(genesisFileContent, &loadedGenesis)
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if err != nil {
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return Genesis{}, err
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}
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return loadedGenesis, nil
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}

‎my-crypto-coin/ledger/genesis.json

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{
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"genesis_time": "2022-04-12T00:00:00.000000000Z",
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"chain_id": "our-blockchain",
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"balances": {
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"alice": 1000000
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}
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}

‎my-crypto-coin/ledger/ledger.db

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{"from":"alice","to":"bob","value":10}
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{"from":"alice","to":"alice","value":3}
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{"from":"alice","to":"alice","value":500}
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{"from":"alice","to":"bob","value":100}
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{"from":"bob","to":"alice","value":5}
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{"from":"bob","to":"carol","value":10}
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{"from":"alice","to":"carol","value":10}

‎my-crypto-coin/ledger/state.go

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package ledger
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import (
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"fmt"
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"os"
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"path/filepath"
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"bufio"
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"encoding/json"
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)
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type State struct {
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Balances map[Account]uint
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txMempool []Tx
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dbFile *os.File
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}
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func SyncState() (*State, error) {
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cwd, err := os.Getwd()
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if err != nil {
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return nil, err
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}
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gen, err := loadGenesis(filepath.Join(cwd, "ledger", "genesis.json"))
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if err != nil {
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return nil, err
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}
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balances := make(map[Account]uint)
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for account, balance := range gen.Balances {
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balances[account] = balance
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}
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file, err := os.OpenFile(filepath.Join(cwd, "ledger", "ledger.db"), os.O_APPEND|os.O_RDWR, 0600)
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if err != nil {
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return nil, err
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}
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scanner := bufio.NewScanner(file)
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state := &State{balances, make([]Tx, 0), file}
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for scanner.Scan() {
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if err := scanner.Err(); err != nil {
46+
return nil, err
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}
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var transaction Tx
50+
json.Unmarshal(scanner.Bytes(), &transaction)
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if err := state.writeTransaction(transaction); err != nil {
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return nil, err
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}
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}
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return state, nil
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}
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func (s *State) writeTransaction(tx Tx) error {
61+
if s.Balances[tx.From] < tx.Value {
62+
return fmt.Errorf("insufficient balance")
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}
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s.Balances[tx.From] -= tx.Value
66+
s.Balances[tx.To] += tx.Value
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return nil
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}
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func (s *State) Close() {
72+
s.dbFile.Close()
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}
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func (s *State) WriteToLedger(tx Tx) error {
76+
if err := s.writeTransaction(tx); err != nil {
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return err
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}
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s.txMempool = append(s.txMempool, tx)
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mempool := make([]Tx, len(s.txMempool))
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copy(mempool, s.txMempool)
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for i := 0; i < len(mempool); i++ {
86+
txJson, err := json.Marshal(mempool[i])
87+
if err != nil {
88+
return err
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}
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if _, err = s.dbFile.Write(append(txJson, '\n')); err != nil {
92+
return err
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}
94+
s.txMempool = s.txMempool[1:]
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}
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return nil
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}

‎my-crypto-coin/ledger/tx.go

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package ledger
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type Account string
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type Tx struct {
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From Account `json:"from"`
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To Account `json:"to"`
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Value uint `json:"value"`
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}
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func NewAccount(value string) Account {
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return Account(value)
13+
}
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func NewTx(from Account, to Account, value uint) Tx {
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return Tx{from, to, value}
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}

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