nftmashin/opensea.go

package main

import (
	"encoding/json"
	"math"
	"net/http"
	"strconv"
)

// https://docs.opensea.io/reference/asset-object
type Asset struct {
	Id        string
	TokenId   string
	Permalink string
	ImageUrl  string
	Name      string
	LastSale  AssetLastSale
}

type AssetLastSale struct {
	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
type Assets []Asset

func GetAssets() (Assets, error) {
	parsed := struct {
		Assets []struct {
			Id        uint64 `json:"id"`
			TokenId   string `json:"token_id"`
			Permalink string `json:"permalink"`
			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"`
				} `json:"transaction"`
			} `json:"last_sale"`
		} `json:"assets"`
	}{}
	assets := Assets{}
	res, err := http.DefaultClient.Get("https://api.opensea.io/api/v1/assets" +
		"?order_direction=desc" +
		"&offset=0" +
		"&limit=50" +
		"&order_by=sale_date")
	if err != nil {
		return assets, err
	}
	err = json.NewDecoder(res.Body).Decode(&parsed)
	if err != nil {
		return assets, err
	}
	for _, a := range parsed.Assets {
		tokenUSDPrice, err := strconv.ParseFloat(a.LastSale.PaymentToken.USDPrice, 64)
		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,
			Permalink: a.Permalink,
			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,
				},
				TransactionHash: a.LastSale.Transaction.Hash,
			},
		})

	}
	return assets, nil
}