"""备份失败不得伪装成功，损坏文件及断链不得进入恢复。"""

import importlib.util
import json
from pathlib import Path
from types import SimpleNamespace

import pytest

spec = importlib.util.spec_from_file_location(
    "payroll_backup", Path(__file__).resolve().parents[3] / "scripts/payroll_backup.py"
)
backup = importlib.util.module_from_spec(spec)
spec.loader.exec_module(backup)


@pytest.fixture
def chain(tmp_path):
    data = tmp_path / "full.sql.gz"
    data.write_bytes(b"fixture")
    baseline = {"kind": "FULL", "database": "payroll", "server_uuid": "server-a",
                "point": {"file": "binlog.000001", "position": 100},
                "entries": [{"file": data.name, "sha256": backup.checksum(data)}]}
    backup.json_write(tmp_path / "full.json", baseline)
    state = {"full": "full.json", "point": baseline["point"], "increments": []}
    backup.json_write(tmp_path / "state.json", state)
    return SimpleNamespace(directory=tmp_path, container="test", database="payroll"), baseline, state


def test_备份篡改与路径越界必须拒绝(chain):
    args, _, _ = chain
    (args.directory / "full.sql.gz").write_bytes(b"corrupted")
    with pytest.raises(backup.BackupError, match="SHA-256"):
        backup.checked_chain(args)
    with pytest.raises(backup.BackupError, match="文件名"):
        backup.load_manifest(args.directory, "../external.json")


def test_跨全量与位点断链拒绝恢复(chain):
    args, _, state = chain
    change = {"full": "other.json", "start": state["point"], "end": state["point"], "entries": []}
    backup.json_write(args.directory / "increment.json", change)
    state["increments"] = ["increment.json"]
    backup.json_write(args.directory / "state.json", state)
    with pytest.raises(backup.BackupError, match="不连续"):
        backup.checked_chain(args)


def test_无更新不轮转日志也不生成增量(chain, monkeypatch):
    args, baseline, state = chain
    calls = []
    def sql(*values):
        calls.append(values)
        return baseline["server_uuid"]
    monkeypatch.setattr(backup, "mysql", sql)
    monkeypatch.setattr(backup, "position", lambda _: state["point"])
    assert backup.incremental(args)["status"] == "UNCHANGED"
    assert len(calls) == 1
    assert not list(args.directory.glob("increment*"))


def test_服务器更换后不续接旧链(chain, monkeypatch):
    args, _, _ = chain
    monkeypatch.setattr(backup, "mysql", lambda *a: "server-b")
    with pytest.raises(backup.BackupError, match="身份已变化"):
        backup.incremental(args)


def test_备份检查拒绝同服务器上的其他数据库(chain, monkeypatch):
    args, _, _ = chain
    args.database = "other_payroll"
    calls = []
    monkeypatch.setattr(backup, "mysql", lambda *a: calls.append(a))
    with pytest.raises(backup.BackupError, match="检查目标不符"):
        backup.check(args)
    assert not calls


def test_轮转后的并发事务归档到末位点且续接不跳过(chain, monkeypatch):
    args, baseline, state = chain
    start = state["point"]
    end = {"file": "binlog.000002", "position": 400}
    monkeypatch.setattr(backup, "mysql", lambda *a: baseline["server_uuid"])
    monkeypatch.setattr(backup, "position", lambda _: end)
    monkeypatch.setattr(backup, "logs", lambda _: ["binlog.000001", "binlog.000002"])
    commands = []

    def archive(command, path):
        commands.append(command)
        path.write_bytes(b"archived")
        return {"file": path.name, "sha256": backup.checksum(path)}

    monkeypatch.setattr(backup, "stream_gzip", archive)
    first = backup.incremental(args)
    manifest = backup.load_manifest(args.directory, first["manifest"])
    assert manifest["start"] == start
    assert manifest["end"] == end
    assert [entry["binlog"] for entry in manifest["entries"]] == [
        "binlog.000001", "binlog.000002"
    ]
    assert commands[-1][-4:] == ["head", "-c", "400", "/var/lib/mysql/binlog.000002"]

    # 下一轮仍从上一轮已归档的末位点续接，跨轮不会遗漏或重复计算事务。
    next_end = {"file": "binlog.000003", "position": 157}
    monkeypatch.setattr(backup, "position", lambda _: next_end)
    monkeypatch.setattr(backup, "logs", lambda _: ["binlog.000002", "binlog.000003"])
    second = backup.incremental(args)
    next_manifest = backup.load_manifest(args.directory, second["manifest"])
    assert next_manifest["start"] == end
    assert [entry["binlog"] for entry in next_manifest["entries"]] == [
        "binlog.000002", "binlog.000003"
    ]
    assert backup.checked_chain(args)[1] == [manifest, next_manifest]


def test_损坏清单不得启动任何恢复容器(chain, monkeypatch):
    args, _, _ = chain
    (args.directory / "full.sql.gz").write_bytes(b"broken")
    commands = []
    monkeypatch.setattr(backup, "run", lambda command, **kw: commands.append(command))
    with pytest.raises(backup.BackupError):
        backup.restore(args)
    assert commands == []


def test_清单原子落盘不留下半成品(tmp_path):
    target = tmp_path / "manifest.json"
    backup.json_write(target, {"status": "SUCCEEDED"})
    assert json.loads(target.read_text())["status"] == "SUCCEEDED"
    assert not list(tmp_path.glob("*.partial"))


def test_MySQL探活使用TCP避开镜像初始化临时服务(monkeypatch):
    commands = []

    def run(command, **kwargs):
        commands.append(command)
        assert kwargs["data"] == b"SELECT 1"
        return b"1\n"

    monkeypatch.setattr(backup, "run", run)
    assert backup.mysql("isolated-test", "SELECT 1") == "1"
    command = commands[0]
    assert "--host=127.0.0.1 --protocol=TCP" in command[command.index("-c") + 1]