"""Gate: signatures produced by the Rust engines (libsecp256k1 via rust-secp256k1, RustCrypto k256)
must verify under the pure-Python exact-arithmetic references src/wp34/{ecdsa,schnorr}.py, and the
Python references must re-derive the same deterministic signatures byte for byte.

The triples are written by experiments/signature_benchmarks/sigbench (--crosscheck-out) through
run_bench.py into results/signature_benchmarks/crosscheck_triples_<host>.json. If no such file
exists the test builds the crate and generates a small set itself.
"""
import json, pathlib, subprocess, sys

import pytest

ROOT = pathlib.Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT / "src"))
sys.path.insert(0, str(ROOT / "experiments" / "signature_benchmarks"))
from python_crosscheck import crosscheck  # noqa: E402
from wp34 import schnorr as B  # noqa: E402

RESULTS = ROOT / "results" / "signature_benchmarks"
CRATE = ROOT / "experiments" / "signature_benchmarks" / "sigbench"


def _triples_file(tmp_path_factory) -> pathlib.Path:
    files = sorted(RESULTS.glob("crosscheck_triples_*.json")) if RESULTS.exists() else []
    if files:
        return files[0]
    binary = CRATE / "target" / "release" / "sigbench"
    if not binary.exists():
        subprocess.run(["cargo", "build", "--release"], cwd=CRATE, check=True)
    out = tmp_path_factory.mktemp("sig") / "triples.json"
    subprocess.run([str(binary), "--vectors", str(ROOT / "data/vectors/bip340_test_vectors.csv"),
                    "--reps", "1", "--batch-ops", "50", "--batch-min-sigs", "50", "--batch-sizes", "1,4",
                    "--crosscheck-n", "40", "--python-crosscheck-n", "40", "--bootstrap", "10",
                    "--crosscheck-out", str(out)], check=True, capture_output=True)
    return out


@pytest.fixture(scope="module")
def triples(tmp_path_factory):
    return _triples_file(tmp_path_factory)


def test_rust_signatures_verify_under_python_reference(triples):
    c = crosscheck(triples, resign=True)
    n = c["n"]
    assert n >= 40
    assert c["ecdsa_k256_sig_verified_by_python"] == n
    assert c["ecdsa_libsecp_sig_verified_by_python"] == n
    assert c["schnorr_k256_sig_verified_by_python"] == n
    assert c["schnorr_libsecp_sig_verified_by_python"] == n
    # deterministic nonces: RFC 6979 (ECDSA) and BIP340 aux-rand nonce derivation -> identical bytes
    assert c["ecdsa_python_resign_identical"] == n
    assert c["schnorr_python_resign_identical"] == n
    # negative control: one flipped bit must be rejected by the reference
    assert c["tampered_sig_rejected_by_python"] == n
    assert c["all_pass"]


def test_bip340_vectors_python_reference():
    """The Python reference itself must agree with the official BIP340 vectors (independent of Rust)."""
    rows = (ROOT / "data/vectors/bip340_test_vectors.csv").read_text().splitlines()[1:]
    n_checked = 0
    for row in rows:
        f = row.split(",")
        pk, msg, sig, expected = bytes.fromhex(f[2]), bytes.fromhex(f[4]), bytes.fromhex(f[5]), f[6] == "TRUE"
        assert B.verify(msg, pk, sig) == expected, f"vector {f[0]}: {f[7]}"
        if f[1]:
            assert B.sign(msg, bytes.fromhex(f[1]), bytes.fromhex(f[3])) == sig, f"vector {f[0]} sign"
        n_checked += 1
    assert n_checked == 19