"""Content-addressed gzip blob store (D-012)."""

from __future__ import annotations

import gzip
import hashlib

import pytest

from mimic.storage.blob import blob_path, store_blob


def test_blob_path_uses_two_byte_pairs(tmp_path) -> None:
    digest = "ab" + "cd" + "ef" * 30
    path = blob_path(tmp_path, digest)
    assert path == tmp_path / "ab" / "cd" / f"{digest}.gz"


def test_blob_path_rejects_invalid_digest(tmp_path) -> None:
    with pytest.raises(ValueError, match="invalid sha256"):
        blob_path(tmp_path, "not-a-digest")


def test_store_blob_writes_gzip_and_returns_digest(tmp_path) -> None:
    payload = b"hello world\n"
    expected = hashlib.sha256(payload).hexdigest()
    digest, path = store_blob(tmp_path, payload)
    assert digest == expected
    assert path == tmp_path / expected[0:2] / expected[2:4] / f"{expected}.gz"
    with gzip.open(path, "rb") as fh:
        assert fh.read() == payload


def test_store_blob_is_idempotent(tmp_path) -> None:
    payload = b"same content"
    digest1, path1 = store_blob(tmp_path, payload)
    mtime_before = path1.stat().st_mtime_ns
    digest2, path2 = store_blob(tmp_path, payload)
    assert digest1 == digest2
    assert path1 == path2
    assert path2.stat().st_mtime_ns == mtime_before


def test_store_blob_dedupes_distinct_payloads(tmp_path) -> None:
    _, p1 = store_blob(tmp_path, b"alpha")
    _, p2 = store_blob(tmp_path, b"beta")
    assert p1 != p2
    assert p1.exists()
    assert p2.exists()