package transport

import (
	"crypto/ecdsa"
	"encoding/hex"
	"math/big"
	"strconv"

	"github.com/status-im/status-go/eth-node/crypto"
	"github.com/status-im/status-go/eth-node/types"
)

const discoveryTopic = "contact-discovery"

var (
	// The number of partitions.
	nPartitions = big.NewInt(5000)
)

// ToTopic converts a string to a whisper topic.
func ToTopic(s string) []byte {
	return crypto.Keccak256([]byte(s))[:types.TopicLength]
}

func StrToPublicKey(str string) (*ecdsa.PublicKey, error) {
	publicKeyBytes, err := hex.DecodeString(str)
	if err != nil {
		return nil, err
	}
	return crypto.UnmarshalPubkey(publicKeyBytes)
}

func PublicKeyToStr(publicKey *ecdsa.PublicKey) string {
	return hex.EncodeToString(crypto.FromECDSAPub(publicKey))
}

func PersonalDiscoveryTopic(publicKey *ecdsa.PublicKey) string {
	return "contact-discovery-" + PublicKeyToStr(publicKey)
}

// PartitionedTopic returns the associated partitioned topic string
// with the given public key.
func PartitionedTopic(publicKey *ecdsa.PublicKey) string {
	partition := big.NewInt(0)
	partition.Mod(publicKey.X, nPartitions)
	return "contact-discovery-" + strconv.FormatInt(partition.Int64(), 10)
}

func ContactCodeTopic(publicKey *ecdsa.PublicKey) string {
	return "0x" + PublicKeyToStr(publicKey) + "-contact-code"
}

func NegotiatedTopic(publicKey *ecdsa.PublicKey) string {
	return "0x" + PublicKeyToStr(publicKey) + "-negotiated"
}

func DiscoveryTopic() string {
	return discoveryTopic
}