package nebula

import (
	"crypto/ed25519"
	"crypto/rand"
	"encoding/json"
	"fmt"

	"github.com/slackhq/nebula/cert"
)

// SigningPrivateKey wraps an ed25519.PrivateKey to provide convenient JSON
// (un)marshaling methods.
type SigningPrivateKey ed25519.PrivateKey

// MarshalJSON implements the json.Marshaler interface.
func (k SigningPrivateKey) MarshalJSON() ([]byte, error) {
	pemStr := cert.MarshalEd25519PrivateKey(ed25519.PrivateKey(k))
	return json.Marshal(string(pemStr))
}

// UnmarshalJSON implements the json.Unmarshaler interface.
func (k *SigningPrivateKey) UnmarshalJSON(b []byte) error {
	var pemStr string
	if err := json.Unmarshal(b, &pemStr); err != nil {
		return fmt.Errorf("unmarshaling into string: %w", err)
	}

	key, _, err := cert.UnmarshalEd25519PrivateKey([]byte(pemStr))
	if err != nil {
		return fmt.Errorf("unmarshaling from PEM: %w", err)
	}

	*k = SigningPrivateKey(key)
	return nil
}

// SigningPublicKey wraps an ed25519.PublicKey to provide convenient JSON
// (un)marshaling methods.
type SigningPublicKey ed25519.PublicKey

// MarshalJSON implements the json.Marshaler interface.
func (k SigningPublicKey) MarshalJSON() ([]byte, error) {
	pemStr := cert.MarshalEd25519PublicKey(ed25519.PublicKey(k))
	return json.Marshal(string(pemStr))
}

// MarshalJSON implements the json.Unmarshaler interface.
func (k *SigningPublicKey) UnmarshalJSON(b []byte) error {
	var pemStr string
	if err := json.Unmarshal(b, &pemStr); err != nil {
		return fmt.Errorf("unmarshaling into string: %w", err)
	}

	key, _, err := cert.UnmarshalEd25519PublicKey([]byte(pemStr))
	if err != nil {
		return fmt.Errorf("unmarshaling from PEM: %w", err)
	}

	*k = SigningPublicKey(key)
	return nil
}

// GenerateSigningPair generates and returns a new key pair which can be used
// for signing arbitrary blobs of bytes.
func GenerateSigningPair() (SigningPublicKey, SigningPrivateKey) {
	pub, priv, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		panic(fmt.Errorf("generating ed25519 key: %w", err))
	}
	return SigningPublicKey(pub), SigningPrivateKey(priv)
}