# ============================================================
# 完整 Merkle 树黄金测试（plan.md §3.6 / 矩阵「全审计」剩余项）
# 覆盖：确定性、顺序/数量/内容敏感、成员证明校验、篡改检测、导出携带根。
# ============================================================
from __future__ import annotations

import copy
import hashlib
import json

from server.agent_core.audit_export import export_events
from server.agent_core.audit_ledger import GENESIS_ROOT
from server.agent_core.audit_merkle import (
    _leaf_hash,
    merkle_proof,
    merkle_root,
    verify_proof,
)


def _events(n: int = 5) -> list[dict]:
    out: list[dict] = []
    prev = "GENESIS"
    for i in range(n):
        ev = {"id": i + 1, "action": f"action-{i}", "prevHash": prev}
        prev = hashlib.sha256((prev + json.dumps(ev, sort_keys=True)).encode()).hexdigest()
        ev["hash"] = prev
        out.append(ev)
    return out


def test_merkle_root_deterministic_and_sensitive():
    """Merkle 根：同事件同根；空树=创世根；顺序/数量/内容变化均断根。"""
    evs = _events()
    assert merkle_root(evs) == merkle_root(evs)
    assert merkle_root([]) == GENESIS_ROOT
    assert merkle_root(evs) != merkle_root(list(reversed(evs)))
    assert merkle_root(evs) != merkle_root(evs[:-1])
    tampered = copy.deepcopy(evs)
    tampered[2]["hash"] = "0" * 64
    assert merkle_root(evs) != merkle_root(tampered)


def test_merkle_proof_every_index_verifies():
    """成员证明：每个事件都能给出 O(log n) proof 且 verify_proof 通过。"""
    evs = _events(8)
    root = merkle_root(evs)
    for i in range(len(evs)):
        proof = merkle_proof(evs, i)
        assert proof["root"] == root
        assert verify_proof(root, _leaf_hash(evs[i]), proof) is True
        # sibling 数应等于树高（8 叶 → 3 层）
        assert len(proof["siblings"]) >= 2


def test_merkle_proof_rejects_wrong_leaf():
    """错误叶子无法通过证明校验（防伪造成员）。"""
    evs = _events(6)
    root = merkle_root(evs)
    proof = merkle_proof(evs, 1)
    other_leaf = _leaf_hash(evs[4])
    assert verify_proof(root, other_leaf, proof) is False


def test_merkle_proof_out_of_range():
    """越界索引返回错误，不抛异常。"""
    evs = _events(3)
    assert merkle_proof(evs, -1)["error"]
    assert merkle_proof(evs, 99)["error"]


def test_merkle_single_and_empty():
    """单事件/空事件边界：根互异且可复算。"""
    one = _events(1)
    root1 = merkle_root(one)
    assert root1 != GENESIS_ROOT
    assert merkle_root(_events(1)) == root1
    proof = merkle_proof(one, 0)
    assert verify_proof(root1, _leaf_hash(one[0]), proof) is True


def test_export_json_carries_merkle_root():
    """合规导出 JSON 携带 merkleRoot，且与本地复算一致。"""
    evs = _events(4)
    payload = json.loads(export_events(evs, fmt="json"))
    assert payload["merkleRoot"] == merkle_root(evs)