"""Tests for AES-256-GCM webcrypto variant."""

import os
import pytest
import blake3
from meshbay_common.crypto import generate_gek
from meshbay_common.webcrypto import chunk_key_aes, encrypt_chunk_aes, decrypt_chunk_aes


def test_aes_roundtrip():
    gek  = generate_gek()
    data = os.urandom(1024 * 1024)   # 1 MB
    fh   = blake3.blake3(data).digest()
    key  = chunk_key_aes(gek, fh, 0)
    nonce, ct = encrypt_chunk_aes(key, data)
    assert decrypt_chunk_aes(key, nonce, ct) == data


def test_aes_key_distinct_from_chacha_key():
    """AES and ChaCha20 keys for the same chunk must differ."""
    from meshbay_common.crypto import chunk_key as chacha_key
    gek  = generate_gek()
    data = os.urandom(100)
    fh   = blake3.blake3(data).digest()
    aes_k    = chunk_key_aes(gek, fh, 0)
    chacha_k = chacha_key(gek, fh, 0)
    assert aes_k != chacha_k


def test_aes_wrong_key_rejected():
    gek  = generate_gek()
    data = b"private content"
    fh   = blake3.blake3(data).digest()
    key  = chunk_key_aes(gek, fh, 0)
    nonce, ct = encrypt_chunk_aes(key, data)
    wrong_key = chunk_key_aes(generate_gek(), fh, 0)
    with pytest.raises(Exception):
        decrypt_chunk_aes(wrong_key, nonce, ct)


def test_aes_chunk_keys_unique_per_chunk():
    gek  = generate_gek()
    data = os.urandom(32)
    fh   = blake3.blake3(data).digest()
    keys = {chunk_key_aes(gek, fh, i) for i in range(5)}
    assert len(keys) == 5   # all distinct