package utils

import (
	"crypto/ed25519"
	"crypto/rand"
	"crypto/sha256"
	"encoding/base64"
	"fmt"
	"log"

	"git.nutfactory.org/hoernschen/Matrix/config"
)

func CreateToken() (err error, token string) {
	b := make([]byte, 8)
	_, err = rand.Read(b)
	if err != nil {
		log.Fatal(err)
		return
	}
	token = fmt.Sprintf("%x", b)
	return
}

func CreateUUID() (err error, uuid string) {
	b := make([]byte, 16)
	_, err = rand.Read(b)
	if err != nil {
		log.Fatal(err)
		return
	}
	uuid = fmt.Sprintf("%x_%x_%x_%x_%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
	return
}

func Hash(s []byte) (err error, hashString string) {
	h := sha256.New()
	_, err = h.Write(s)
	if nil != err {
		return
	}
	hash := h.Sum(nil)
	hashString = base64.StdEncoding.EncodeToString(hash)
	return
}

func GenerateKeyPair() (publicKey ed25519.PublicKey, privateKey ed25519.PrivateKey, err error) {
	publicKey, privateKey, err = ed25519.GenerateKey(nil)
	return
}

func Sign(message []byte) string {
	signatureBytes := ed25519.Sign(config.PrivateKey, message)
	return base64.RawStdEncoding.EncodeToString(signatureBytes)
}

func SignContent(content []byte) (signatures map[string]map[string]string) {
	signatures = make(map[string]map[string]string)
	signatures[config.Homeserver] = make(map[string]string)
	if !config.Signing {
		return
	}
	signatures[config.Homeserver][config.KeyId] = Sign(content)
	return
}

func VerifySignature(publicKey []byte, message []byte, signature string) bool {
	signatureBytes, err := base64.RawStdEncoding.DecodeString(signature)
	if err != nil {
		return false
	}
	ed25519.Verify(config.PublicKey, message, signatureBytes)
	return true
}