import sys
import pathlib
import hashlib

# Ensure repository root is on sys.path so tests can import the package
sys.path.insert(0, str(pathlib.Path(__file__).resolve().parents[1]))

from cosmic_ledger.delta import DeltaLog, merkle_path_for_index, verify_inclusion


def test_merkle_inclusion_valid_and_tampered():
    dl = DeltaLog()
    # add three simple payloads
    entries = [ {"v": i} for i in range(3) ]
    for e in entries:
        dl.add_entry(e)

    leaves = [en["digest"] for en in dl.entries]
    # for each leaf, compute path and verify inclusion
    for i, digest in enumerate(leaves):
        path_info = merkle_path_for_index(leaves, i)
        root = path_info["root"]
        path = path_info["path"]
        assert verify_inclusion(digest, path, root, i)

    # Tamper with a sibling digest and ensure verification fails
    tampered_path = path.copy()
    # flip one byte in the first sibling (if present) to simulate corruption
    if tampered_path:
        first = tampered_path[0]
        # replace first hex char with something else (safe mutation)
        tampered_path[0] = ("0" if first[0] != "0" else "1") + first[1:]
        assert not verify_inclusion(leaves[0], tampered_path, root, 0)