// Package ssh provides SSH key generation utilities.
package ssh

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

	"golang.org/x/crypto/ssh"
)

// KeyPair contains an SSH key pair.
type KeyPair struct {
	PrivateKey string
	PublicKey  string
}

// GenerateKeyPair generates a new Ed25519 SSH key pair.
func GenerateKeyPair() (*KeyPair, error) {
	// Generate Ed25519 key pair
	publicKey, privateKey, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		return nil, fmt.Errorf("failed to generate key pair: %w", err)
	}

	// Convert private key to PEM format
	privateKeyPEM, err := ssh.MarshalPrivateKey(privateKey, "")
	if err != nil {
		return nil, fmt.Errorf("failed to marshal private key: %w", err)
	}

	// Convert public key to authorized_keys format
	sshPublicKey, err := ssh.NewPublicKey(publicKey)
	if err != nil {
		return nil, fmt.Errorf("failed to create SSH public key: %w", err)
	}

	return &KeyPair{
		PrivateKey: string(pem.EncodeToMemory(privateKeyPEM)),
		PublicKey:  string(ssh.MarshalAuthorizedKey(sshPublicKey)),
	}, nil
}

// ValidatePrivateKey validates that a private key is valid.
func ValidatePrivateKey(privateKeyPEM string) error {
	_, err := ssh.ParsePrivateKey([]byte(privateKeyPEM))
	if err != nil {
		return fmt.Errorf("invalid private key: %w", err)
	}

	return nil
}