from cryptography.hazmat.primitives.asymmetric import ed25519
from cryptography.hazmat.primitives import serialization

PRIVATE_KEY_PATH = "ed25519_private_key.pem"
PUBLIC_KEY_PATH = "ed25519_public_key.pem"

def generate_and_save_keypair(private_key_path, public_key_path):
    private_key = ed25519.Ed25519PrivateKey.generate()
    public_key = private_key.public_key()

    # Serialize the private key to PEM format without encryption
    pem_private = private_key.private_bytes(
        encoding=serialization.Encoding.PEM,
        format=serialization.PrivateFormat.PKCS8,
        encryption_algorithm=serialization.NoEncryption(),
    )

    # Serialize the public key to PEM format
    pem_public = public_key.public_bytes(
        encoding=serialization.Encoding.PEM,
        format=serialization.PublicFormat.SubjectPublicKeyInfo,
    )

    for key in [{
            'path': private_key_path,
            'pem': pem_private
    }, {
            'path': public_key_path,
            'pem': pem_public
    }]:
        with open(key["path"], "wb") as f:
            f.write(key["pem"])


def load_keypair(private_key_path, public_key_path):
    # Load private key from PEM file
    with open(private_key_path, "rb") as f:
        private_key = serialization.load_pem_private_key(
            f.read(),
            password=None,
        )

    # Load public key from PEM file
    with open(public_key_path, "rb") as f:
        public_key = serialization.load_pem_public_key(f.read())

    # Type check (optional but good for Ed25519-specific code)
    if not isinstance(private_key, ed25519.Ed25519PrivateKey):
        raise TypeError("The private key is not an Ed25519 key")
    if not isinstance(public_key, ed25519.Ed25519PublicKey):
        raise TypeError("The public key is not an Ed25519 key")

    return private_key, public_key