// cmd/peerid — prints the libp2p peer ID for a key file.
// Usage: peerid --key node1.json
package main

import (
	"crypto/ed25519"
	"encoding/hex"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"os"

	libp2pcrypto "github.com/libp2p/go-libp2p/core/crypto"
	"github.com/libp2p/go-libp2p/core/peer"
)

type keyJSON struct {
	PubKey  string `json:"pub_key"`
	PrivKey string `json:"priv_key"`
}

func main() {
	keyFile := flag.String("key", "", "path to key JSON file")
	listenIP := flag.String("ip", "0.0.0.0", "IP for multiaddr output")
	port := flag.String("port", "4001", "port for multiaddr output")
	flag.Parse()

	if *keyFile == "" {
		log.Fatal("--key is required")
	}

	data, err := os.ReadFile(*keyFile)
	if err != nil {
		log.Fatalf("read key: %v", err)
	}
	var kj keyJSON
	if err := json.Unmarshal(data, &kj); err != nil {
		log.Fatalf("parse key: %v", err)
	}

	privBytes, err := hexDecode(kj.PrivKey)
	if err != nil {
		log.Fatalf("decode priv key: %v", err)
	}

	privStd := ed25519.PrivateKey(privBytes)
	lk, _, err := libp2pcrypto.KeyPairFromStdKey(&privStd)
	if err != nil {
		log.Fatalf("convert key: %v", err)
	}

	pid, err := peer.IDFromPrivateKey(lk)
	if err != nil {
		log.Fatalf("peer ID: %v", err)
	}

	fmt.Printf("pub_key:  %s\n", kj.PubKey)
	fmt.Printf("peer_id:  %s\n", pid)
	fmt.Printf("multiaddr: /ip4/%s/tcp/%s/p2p/%s\n", *listenIP, *port, pid)
}

func hexDecode(s string) ([]byte, error) {
	return hex.DecodeString(s)
}