"""Signing keys: identity in this system is a keypair, so these must be airtight."""

from __future__ import annotations

import pytest

from tests.helpers import generate_keypair, sign_message, signature_ok

MESSAGE = b"the rules bind the rulers"


def test_keypair_generation_yields_distinct_strings():
    private_key, public_key = generate_keypair()
    assert isinstance(private_key, str) and private_key
    assert isinstance(public_key, str) and public_key
    assert private_key != public_key


def test_two_keypairs_are_different():
    _, pub_a = generate_keypair()
    _, pub_b = generate_keypair()
    assert pub_a != pub_b


def test_sign_verify_roundtrip():
    private_key, public_key = generate_keypair()
    signature = sign_message(private_key, MESSAGE)
    assert signature_ok(public_key, MESSAGE, signature)


def test_tampered_message_fails_verification():
    private_key, public_key = generate_keypair()
    signature = sign_message(private_key, MESSAGE)
    assert not signature_ok(public_key, b"the rulers bind the rules", signature)


def test_wrong_key_fails_verification():
    private_key, _ = generate_keypair()
    _, other_public = generate_keypair()
    signature = sign_message(private_key, MESSAGE)
    assert not signature_ok(other_public, MESSAGE, signature)


def test_tampered_signature_fails_verification():
    private_key, public_key = generate_keypair()
    signature = sign_message(private_key, MESSAGE)
    sig_text = signature if isinstance(signature, str) else bytes(signature).hex()
    flipped = ("0" if sig_text[0] != "0" else "1") + sig_text[1:]
    assert not signature_ok(public_key, MESSAGE, flipped)


@pytest.mark.parametrize("payload", [b"", b"x", b"a" * 10_000])
def test_roundtrip_various_message_sizes(payload):
    private_key, public_key = generate_keypair()
    signature = sign_message(private_key, payload)
    assert signature_ok(public_key, payload, signature)