"""分类规则外置单元测试（T-R2，采纳 llmrouter「规则文档即配置」设计）。"""
import json

from router_system.classifier import (DOMAIN_RULES, RuleClassifier, build_classifier,
                                      load_domain_rules)


def test_load_missing_file_returns_none(tmp_path):
    """文件缺失：返回 None（调用方回退内置），不抛异常。"""
    assert load_domain_rules(tmp_path / "nope.json") is None


def test_external_rules_override_domain(tmp_path):
    """外置文件按 domain 覆盖内置：改写 code 规则即改变路由行为。"""
    f = tmp_path / "routes.json"
    f.write_text(json.dumps({"code": [["速排", 2.0]]}, ensure_ascii=False),
                 encoding="utf-8")
    rules = load_domain_rules(f)
    assert rules is not None and rules["code"] == [("速排", 2.0)]

    clf = RuleClassifier()
    clf.rules = {**DOMAIN_RULES, **rules}
    r = clf.classify("讲讲速排的思路")
    assert r.domain == "code"


def test_build_classifier_merges_over_builtin(tmp_path):
    """build_classifier 合并语义：文件只写 legal，其余领域保持内置。"""
    f = tmp_path / "routes.json"
    f.write_text(json.dumps({"legal": [["劳动合同", 3.0]]}, ensure_ascii=False),
                 encoding="utf-8")
    clf = build_classifier({"type": "rule", "rules_file": str(f)})
    assert clf.rules["legal"] == [("劳动合同", 3.0)]
    assert clf.rules["code"] == DOMAIN_RULES["code"]  # 未覆盖领域保持内置
    r = clf.classify("劳动合同到期不续签需要支付经济补偿吗")
    assert r.domain == "legal"


def test_malformed_file_falls_back_to_builtin(tmp_path):
    """格式非法：整体回退内置（失败安全，编辑错误不打垮路由）。"""
    f = tmp_path / "routes.json"
    f.write_text('{"code": [["坏数据", "不是数字"]]}', encoding="utf-8")
    assert load_domain_rules(f) is None
    clf = build_classifier({"type": "rule", "rules_file": str(f)})
    assert clf.rules == DOMAIN_RULES
    r = clf.classify("用 Python 写一个快速排序函数")
    assert r.domain == "code"


def test_explicit_rules_file_missing_uses_builtin(tmp_path):
    """显式路径不存在：静默回退内置，分类行为不变。"""
    clf = build_classifier({"type": "rule", "rules_file": str(tmp_path / "no.json")})
    assert clf.rules == DOMAIN_RULES