import os

from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives.asymmetric import rsa
from cryptography.hazmat.primitives.serialization import (
    Encoding,
    PublicFormat,
    PrivateFormat,
    NoEncryption,
)

from twilio.http.validation_client import ValidationClient
from twilio.rest import Client


ACCOUNT_SID = os.environ.get("TWILIO_ACCOUNT_SID")
AUTH_TOKEN = os.environ.get("TWILIO_AUTH_TOKEN")


def example():
    """
    Example of using the ValidationClient for signed requests to Twilio.
    This is only available to enterprise customers.

    This will walkthrough creating an API Key, generating an RSA keypair, setting up a
    ValidationClient with these values and making requests with the client.
    """
    client = Client(ACCOUNT_SID, AUTH_TOKEN)

    # Using Client Validation requires using API Keys for auth
    # First create an API key using the standard account sid, auth token client
    print("Creating new api key...")
    api_key = client.new_keys.create(friendly_name="ClientValidationApiKey")

    # Generate a new RSA Keypair
    print("Generating RSA key pair...")
    key_pair = rsa.generate_private_key(
        public_exponent=65537, key_size=2048, backend=default_backend()
    )
    public_key = key_pair.public_key().public_bytes(
        Encoding.PEM, PublicFormat.SubjectPublicKeyInfo
    )
    private_key = key_pair.private_bytes(
        Encoding.PEM, PrivateFormat.PKCS8, NoEncryption()
    )

    # Register the public key with Twilio
    print("Registering public key with Twilio...")
    credential = client.accounts.credentials.public_key.create(
        public_key, friendly_name="ClientValidationPublicKey"
    )

    # Create a new ValidationClient with the keys we created
    validation_client = ValidationClient(
        ACCOUNT_SID, api_key.sid, credential.sid, private_key
    )

    # Create a REST Client using the validation_client
    client = Client(
        api_key.sid, api_key.secret, ACCOUNT_SID, http_client=validation_client
    )

    # Use the library as usual
    print("Trying out client validation...")
    messages = client.messages.list(limit=10)
    for m in messages:
        print("Message {}".format(m.sid))

    print("Client validation works!")


if __name__ == "__main__":
    example()