"""Tests for AES padding and SessionTagManager."""

import os
from i2p_crypto.garlic_crypto import (
    apply_aes_padding, verify_aes_padding, SessionTagManager,
)


def test_aes_padding_roundtrip():
    payload = b"Hello, I2P garlic!"
    padded = apply_aes_padding(payload)
    assert len(padded) % 16 == 0
    recovered = verify_aes_padding(padded)
    assert recovered == payload


def test_aes_padding_empty():
    padded = apply_aes_padding(b"")
    assert len(padded) % 16 == 0
    assert verify_aes_padding(padded) == b""


def test_aes_padding_checksum_mismatch():
    padded = bytearray(apply_aes_padding(b"data"))
    # Corrupt last byte (part of checksum)
    padded[-1] ^= 0xFF
    assert verify_aes_padding(bytes(padded)) is None


def test_aes_padding_large_payload():
    payload = os.urandom(1000)
    padded = apply_aes_padding(payload)
    assert len(padded) % 16 == 0
    assert verify_aes_padding(padded) == payload


def test_tag_bundle_generation():
    stm = SessionTagManager()
    key = os.urandom(32)
    tags = stm.generate_tag_bundle(key, count=5)
    assert len(tags) == 5
    assert stm.remaining_tags(key) == 5


def test_tag_consumption():
    stm = SessionTagManager()
    key = os.urandom(32)
    stm.generate_tag_bundle(key, count=3)
    tag1 = stm.consume_tag(key)
    assert tag1 is not None
    assert len(tag1) == 32
    assert stm.remaining_tags(key) == 2


def test_tag_consume_empty():
    stm = SessionTagManager()
    key = os.urandom(32)
    assert stm.consume_tag(key) is None


def test_tag_receive_and_consume():
    stm = SessionTagManager()
    key = os.urandom(32)
    tags = [os.urandom(32) for _ in range(3)]
    stm.receive_tags(key, tags)
    assert stm.remaining_tags(key) == 3
    consumed = stm.consume_tag(key)
    assert consumed == tags[0]


def test_tag_replenishment_threshold():
    stm = SessionTagManager()
    key = os.urandom(32)
    assert stm.should_replenish(key) is True  # 0 tags
    stm.generate_tag_bundle(key, count=15)
    assert stm.should_replenish(key) is False  # 15 tags > 10


def test_max_tags_limit():
    stm = SessionTagManager(max_tags_per_session=10)
    key = os.urandom(32)
    stm.generate_tag_bundle(key, count=15)
    assert stm.remaining_tags(key) == 10  # capped at max