mirror of
https://github.com/nspcc-dev/neo-go.git
synced 2024-11-23 23:30:36 +00:00
125 lines
3.3 KiB
Go
125 lines
3.3 KiB
Go
package client
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import (
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"encoding/json"
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"errors"
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"net/http"
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"sort"
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"github.com/nspcc-dev/neo-go/pkg/core/state"
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"github.com/nspcc-dev/neo-go/pkg/core/transaction"
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"github.com/nspcc-dev/neo-go/pkg/rpc/response/result"
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"github.com/nspcc-dev/neo-go/pkg/util"
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errs "github.com/pkg/errors"
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)
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/*
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Definition of types, helper functions and variables
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required for calculation of transaction inputs using
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NeoScan API.
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*/
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type (
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// NeoScanServer stores NEOSCAN URL and API path.
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NeoScanServer struct {
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URL string // "protocol://host:port/"
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Path string // path to API endpoint without wallet address
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}
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// Unspent stores Unspents per asset
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Unspent struct {
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Unspent state.UnspentBalances
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Asset string // "NEO" / "GAS"
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Amount util.Fixed8 // total unspent of this asset
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}
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// NeoScanBalance is a struct of NeoScan response to 'get_balance' request
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NeoScanBalance struct {
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Balance []*Unspent
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Address string
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}
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)
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// GetBalance performs a request to get balance for the address specified.
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func (s NeoScanServer) GetBalance(address string) ([]*Unspent, error) {
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var (
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err error
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req *http.Request
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res *http.Response
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balance NeoScanBalance
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client = http.Client{}
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balanceURL = s.URL + s.Path
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)
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if req, err = http.NewRequest(http.MethodGet, balanceURL+address, nil); err != nil {
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return nil, errs.Wrap(err, "Failed to compose HTTP request")
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}
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if res, err = client.Do(req); err != nil {
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return nil, errs.Wrap(err, "Failed to perform HTTP request")
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}
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defer res.Body.Close()
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if err = json.NewDecoder(res.Body).Decode(&balance); err != nil {
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return nil, errs.Wrap(err, "Failed to decode HTTP response")
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}
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return balance.Balance, nil
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}
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func filterSpecificAsset(asset string, balance []*Unspent, assetBalance *Unspent) {
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for _, us := range balance {
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if us.Asset == asset {
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assetBalance.Unspent = us.Unspent
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assetBalance.Asset = us.Asset
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assetBalance.Amount = us.Amount
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return
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}
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}
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}
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// CalculateInputs creates input transactions for the specified amount of given asset belonging to specified address.
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func (s NeoScanServer) CalculateInputs(address string, assetIDUint util.Uint256, cost util.Fixed8) ([]transaction.Input, util.Fixed8, error) {
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var (
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err error
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us []*Unspent
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assetUnspent Unspent
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assetID = result.GlobalAssets[assetIDUint.StringLE()]
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)
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if us, err = s.GetBalance(address); err != nil {
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return nil, util.Fixed8(0), errs.Wrapf(err, "Cannot get balance for address %v", address)
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}
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filterSpecificAsset(assetID, us, &assetUnspent)
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return unspentsToInputs(assetUnspent.Unspent, cost)
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}
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// unspentsToInputs uses UnspentBalances to create a slice of inputs for a new
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// transcation containing the required amount of asset.
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func unspentsToInputs(utxos state.UnspentBalances, required util.Fixed8) ([]transaction.Input, util.Fixed8, error) {
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var (
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num, i uint16
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selected = util.Fixed8(0)
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)
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sort.Sort(utxos)
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for _, us := range utxos {
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if selected >= required {
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break
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}
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selected += us.Value
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num++
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}
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if selected < required {
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return nil, util.Fixed8(0), errors.New("cannot compose inputs for transaction; check sender balance")
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}
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inputs := make([]transaction.Input, 0, num)
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for i = 0; i < num; i++ {
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inputs = append(inputs, transaction.Input{
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PrevHash: utxos[i].Tx,
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PrevIndex: utxos[i].Index,
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})
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}
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return inputs, selected, nil
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}
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