nftmashin/main.go

package main

import (
	"encoding/json"
	"errors"
	"html/template"
	"io"
	"io/fs"
	"log"
	"math/rand"
	"net/http"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"strings"
	"time"
)

type Status struct {
	NFTNum        int
	TotalUSDValue float64
	NFTs          []downloadedOpenSeaAsset
}

const NFTS_DIR = "./nfts"

func getDownloadedOpenSeaAsset(id string) (downloadedOpenSeaAsset, error) {
	asset := downloadedOpenSeaAsset{}
	file, err := os.Open(filepath.Join(NFTS_DIR, id+".json"))
	if err != nil {
		return asset, err
	}
	err = json.NewDecoder(file).Decode(&asset)
	if err != nil {
		return asset, err
	}
	return asset, nil
}

func getStatus() (Status, error) {
	status := Status{}
	entries, err := os.ReadDir(NFTS_DIR)
	if err != nil {
		return status, err
	}

	// https://yourbasic.org/golang/shuffle-slice-array/
	rand.Seed(time.Now().UnixNano())
	rand.Shuffle(len(entries), func(i, j int) { entries[i], entries[j] = entries[j], entries[i] })

	for _, val := range entries {
		info, err := val.Info()
		if err != nil {
			return status, err
		}
		if filepath.Ext(info.Name()) != ".json" {
			continue
		}

		id := strings.Split(info.Name(), ".")[0]
		asset, err := getDownloadedOpenSeaAsset(id)
		if err != nil {
			return status, err
		}

		if len(status.NFTs) <= 20 {
			status.NFTs = append(status.NFTs, asset)
		}

		status.NFTNum += 1
		status.TotalUSDValue += asset.GetUSDPrice()
	}
	return status, nil
}

func getOpenSeaId(id string) string {
	return "opensea:asset:" + id
}

func getRandomOpenSeaAsset() (Asset, error) {
	assets, err := GetAssets()
	if err != nil {
		log.Println("Error hablandole a OpenSea:", err)
		return Asset{}, err
	}
	for _, a := range assets {
		if len(a.ImageUrl) == 0 {
			continue
		}
		id := getOpenSeaId(a.Id)
		file, err := os.Open(filepath.Join(NFTS_DIR, id+".json"))
		defer file.Close()
		if errors.Is(err, fs.ErrNotExist) {
			return a, nil
		}
	}
	// TODO: paginar y cachear paginación
	return Asset{}, errors.New("No conseguí ningún asset")
}

type downloadedOpenSeaAsset struct {
	Id       string `json:"Id"`
	Asset    `json:"Asset"`
	FileName string `json:"FileName"`
}

func (d downloadedOpenSeaAsset) GetUSDPrice() float64 {
	return d.Asset.LastSale.TotalPrice * d.Asset.LastSale.PaymentToken.USDPrice
}
func (d downloadedOpenSeaAsset) IsVideo() bool {
	return path.Ext(d.FileName) == ".mp4"
}

func downloadOpenSeaAsset(asset Asset) (string, error) {
	id := getOpenSeaId(asset.Id)

	u, err := url.Parse(asset.ImageUrl)
	if err != nil {
		return "", err
	}
	ext := path.Ext(u.Path)
	filename := id + ext

	imageRes, err := http.DefaultClient.Get(asset.ImageUrl)
	if err != nil {
		return "", err
	}
	file, err := os.Create(filepath.Join(NFTS_DIR, filename))
	if err != nil {
		return "", err
	}
	_, err = io.Copy(file, imageRes.Body)
	if err != nil {
		return "", err
	}

	jsonFile, err := os.Create(filepath.Join(NFTS_DIR, id+".json"))
	if err != nil {
		return "", err
	}
	err = json.NewEncoder(jsonFile).Encode(downloadedOpenSeaAsset{
		Id:       id,
		Asset:    asset,
		FileName: filename,
	})
	if err != nil {
		return "", err
	}

	return id, nil
}

func must(err error) {
	if err != nil {
		log.Panicln(err)
	}
}

func main() {
	indexTmpl, err := template.ParseFiles("./templates/base.tmpl", "./templates/embed-nft.tmpl", "./templates/index.tmpl")
	must(err)
	nftsTmpl, err := template.ParseFiles("./templates/base.tmpl", "./templates/embed-nft.tmpl", "./templates/nft.tmpl")
	must(err)

	http.Handle("/static/nfts/", http.StripPrefix("/static/nfts/", http.FileServer(http.Dir(NFTS_DIR))))
	http.Handle("/static/assets/", http.StripPrefix("/static/assets/", http.FileServer(http.Dir("./assets"))))

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		status, err := getStatus()
		if err != nil {
			log.Println("Error en Status:", err)
			internalError(w, "Error consiguiendo el contador de NFTs.")
			return
		}
		w.Header().Add("Content-Type", "text/html")
		err = indexTmpl.Execute(w, status)
		if err != nil {
			log.Panicln("No pude escribir index", err)
		}
	})
	http.HandleFunc("/copiar", func(w http.ResponseWriter, r *http.Request) {
		asset, err := getRandomOpenSeaAsset()
		if err != nil {
			internalError(w, "Error hablandole a OpenSea.")
			return
		}
		log.Println(asset)

		id, err := downloadOpenSeaAsset(asset)
		if err != nil {
			log.Println("Error descargando OpenSea asset", err)
			internalError(w, "Error descargando NFT.")
			return
		}

		w.Header().Add("Location", "/nfts/"+id)
		w.WriteHeader(http.StatusTemporaryRedirect)
		w.Write([]byte("Redirijiendo al NFT..."))
	})
	http.HandleFunc("/nfts/", func(w http.ResponseWriter, r *http.Request) {
		_, id := path.Split(r.URL.Path)
		nft, err := getDownloadedOpenSeaAsset(id)
		if err != nil {
			log.Panicln("No pude conseguir NFT", err)
		}
		w.Header().Add("Content-Type", "text/html")
		err = nftsTmpl.Execute(w, nft)
		if err != nil {
			log.Panicln("No pude escribir nft", err)
		}
	})
	log.Println("Hola")
	http.ListenAndServe(":5050", nil)
}

func internalError(w http.ResponseWriter, err_str string) {
	w.WriteHeader(http.StatusInternalServerError)
	_, err := w.Write([]byte(err_str))
	if err != nil {
		log.Panicln("No pude escribir el error xD")
	}
}