etherscan.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"math"
+	"net/http"
+	"os"
+	"strconv"
+)
+
+type Transaction struct {
+	Value float64
+}
+
+func GetTransaction(id string) (Transaction, error) {
+	transaction := Transaction{}
+	key, exists := os.LookupEnv("ETHERSCAN_KEY")
+	if !exists {
+		return transaction, errors.New("No tengo ETHERSCAN_KEY, conseguir en https://etherscan.io/apis")
+	}
+	res, err := http.DefaultClient.Get("https://api.etherscan.io/api?module=proxy" +
+		"&action=eth_getTransactionByHash" +
+		"&txhash=" + id +
+		"&apikey=" + key)
+	if err != nil {
+		return transaction, err
+	}
+	result := struct {
+		Result struct {
+			Value string `json:"value"`
+		} `json:"result,omitempty"`
+		Error struct {
+			Message string `json:"message"`
+		} `json:"error,omitempty"`
+	}{}
+	err = json.NewDecoder(res.Body).Decode(&result)
+	if err != nil {
+		return transaction, err
+	}
+	if len(result.Error.Message) > 0 {
+		return transaction, errors.New(result.Error.Message)
+	}
+	parsed, err := strconv.ParseUint(result.Result.Value[2:], 16, 64)
+	if err != nil {
+		return transaction, err
+	}
+	transaction.Value = float64(parsed) / math.Pow10(18)
+	return transaction, nil
+}

main.go

@@ -82,7 +82,7 @@ func getRandomOpenSeaAsset() (Asset, error) {
 	assets, err := GetAssets()
 	if err != nil {
 		log.Println("Error hablandole a OpenSea:", err)
-		return Asset{}, err
+		return Asset{}, nil
 	}
 	for _, a := range assets {
 		if len(a.ImageUrl) == 0 {
@@ -100,19 +100,20 @@ func getRandomOpenSeaAsset() (Asset, error) {
 }
 
 type downloadedOpenSeaAsset struct {
-	Id       string `json:"Id"`
-	Asset    `json:"Asset"`
-	FileName string `json:"FileName"`
+	Id          string `json:"Id"`
+	Asset       `json:"Asset"`
+	Transaction `json:"Transaction"`
+	FileName    string `json:"FileName"`
 }
 
 func (d downloadedOpenSeaAsset) GetUSDPrice() float64 {
-	return d.Asset.LastSale.TotalPrice * d.Asset.LastSale.PaymentToken.USDPrice
+	return d.Transaction.Value * d.Asset.LastSale.TokenUSDPrice
 }
 func (d downloadedOpenSeaAsset) IsVideo() bool {
 	return path.Ext(d.FileName) == ".mp4"
 }
 
-func downloadOpenSeaAsset(asset Asset) (string, error) {
+func downloadOpenSeaAsset(asset Asset, transaction Transaction) (string, error) {
 	id := getOpenSeaId(asset.Id)
 
 	u, err := url.Parse(asset.ImageUrl)
@@ -140,9 +141,10 @@ func downloadOpenSeaAsset(asset Asset) (string, error) {
 		return "", err
 	}
 	err = json.NewEncoder(jsonFile).Encode(downloadedOpenSeaAsset{
-		Id:       id,
-		Asset:    asset,
-		FileName: filename,
+		Id:          id,
+		Asset:       asset,
+		Transaction: transaction,
+		FileName:    filename,
 	})
 	if err != nil {
 		return "", err
@@ -188,7 +190,15 @@ func main() {
 		}
 		log.Println(asset)
 
-		id, err := downloadOpenSeaAsset(asset)
+		transaction, err := GetTransaction(asset.LastSale.TransactionHash)
+		if err != nil {
+			log.Println("Error consiguiendo transacción de Etherscan", err)
+			internalError(w, "Error hablandole a Etherscan.")
+			return
+		}
+		log.Println(transaction)
+
+		id, err := downloadOpenSeaAsset(asset, transaction)
 		if err != nil {
 			log.Println("Error descargando OpenSea asset", err)
 			internalError(w, "Error descargando NFT.")

opensea.go

@@ -2,7 +2,6 @@ package main
 
 import (
 	"encoding/json"
-	"math"
 	"net/http"
 	"strconv"
 )
@@ -18,17 +17,8 @@ type Asset struct {
 }
 
 type AssetLastSale struct {
+	TokenUSDPrice   float64
 	TransactionHash string
-	PaymentToken
-	// TotalPrice has 16 decimals trimmed off if PaymentToken.decimals > 16
-	TotalPrice float64
-}
-
-type PaymentToken struct {
-	Id       uint64
-	Symbol   string
-	USDPrice float64
-	Decimals int
 }
 
 // https://docs.opensea.io/reference/getting-assets
@@ -43,12 +33,8 @@ func GetAssets() (Assets, error) {
 			ImageUrl  string `json:"image_url"`
 			Name      string `json:"name"`
 			LastSale  struct {
-				TotalPrice   string `json:"total_price"`
 				PaymentToken struct {
-					Id       uint64 `json:"id"`
-					Symbol   string `json:"symbol"`
 					USDPrice string `json:"usd_price"`
-					Decimals int    `json:"decimals"`
 				} `json:"payment_token"`
 				Transaction struct {
 					Hash string `json:"transaction_hash"`
@@ -74,17 +60,6 @@ func GetAssets() (Assets, error) {
 		if err != nil {
 			return assets, err
 		}
-		trimmed := a.LastSale.TotalPrice
-		decimals := a.LastSale.PaymentToken.Decimals
-		if a.LastSale.PaymentToken.Decimals > 16 {
-			trimmed = trimmed[:len(trimmed)-16]
-			decimals = decimals - 16
-		}
-		totalprice, err := strconv.ParseFloat(trimmed, 64)
-		if err != nil {
-			return assets, err
-		}
-		totalprice = totalprice / math.Pow10(decimals)
 		assets = append(assets, Asset{
 			Id:        strconv.FormatUint(a.Id, 10),
 			TokenId:   a.TokenId,
@@ -92,13 +67,7 @@ func GetAssets() (Assets, error) {
 			ImageUrl:  a.ImageUrl,
 			Name:      a.Name,
 			LastSale: AssetLastSale{
-				TotalPrice: totalprice,
-				PaymentToken: PaymentToken{
-					Id:       a.LastSale.PaymentToken.Id,
-					Symbol:   a.LastSale.PaymentToken.Symbol,
-					Decimals: decimals,
-					USDPrice: tokenUSDPrice,
-				},
+				TokenUSDPrice:   tokenUSDPrice,
 				TransactionHash: a.LastSale.Transaction.Hash,
 			},
 		})

templates/index.tmpl

@@ -3,20 +3,14 @@
 	<h1>NFTmashin</h1>
 	<p><em>Beta: las copias pueden ser eliminadas en el futuro.</em></p>
 	<p>NFTs descargados: {{ .NFTNum }}</p>
-	<p>
-		Valor total:
-		<span class=dinero>USD ${{ printf "%.2f" .TotalUSDValue }}</span>
-	</p>
+	<p>Valor total: <span class=dinero>USD ${{ printf "%.2f" .TotalUSDValue }}</span></p>
 	<a style=font-size:3rem href=/copiar>¡Copiar un NFT!</a>
 </section>
 <section>
 	<h2>Algunos NFTs descargados</h2>
 	{{range .NFTs}}
 		<figure>
-			<h3>
-				<a href="/nfts/{{.Id}}">{{.Asset.Name}}</a>
-				(<span class=dinero>${{printf "%.2f" .GetUSDPrice}}</span>)
-			</h3>
+			<h3><a href="/nfts/{{.Id}}">{{.Asset.Name}}</a> (<span class=dinero>${{printf "%.2f" .GetUSDPrice}})</h3>
 			{{template "embed-nft" .}}
 		</figure>
 		<hr>