from __future__ import annotations

from io import BytesIO

import pytest
from starlette.datastructures import UploadFile

from src.core.security import extract_image_fingerprint, generate_hmac_chain


@pytest.mark.asyncio
async def test_extract_image_fingerprint_is_deterministic_and_resets_pointer() -> None:
    payload = (b"0123456789abcdef" * 8192) + b"end"
    upload = UploadFile(filename="sample.bin", file=BytesIO(payload))

    fp1 = await extract_image_fingerprint(upload)
    prefix = await upload.read(16)
    assert prefix == payload[:16]

    await upload.seek(0)
    fp2 = await extract_image_fingerprint(upload)
    assert fp1 == fp2


def test_generate_hmac_chain_is_stable_and_order_sensitive() -> None:
    secret = b"super-secret"
    ordered_parts = [b"ts", b"POST", b"/v1/predict", b"DEV-1", b"fingerprint"]
    reordered_parts = [b"POST", b"ts", b"/v1/predict", b"DEV-1", b"fingerprint"]

    sig1 = generate_hmac_chain(ordered_parts, secret)
    sig2 = generate_hmac_chain(ordered_parts, secret)
    sig3 = generate_hmac_chain(reordered_parts, secret)

    assert sig1 == sig2
    assert sig1 != sig3