"""errors.py 错误四分类与 scope 级不可用语义测试(M1 设计 §3)。"""

import pytest

from polygateway.errors import (
    AllSourcesExhausted,
    CircuitOpenError,
    GatewayUnavailableError,
    GovernanceBackendError,
    PolyGatewayError,
    RequestRejectedError,
    ResultInvalidError,
    SourceDeadError,
    TransientError,
)


class TestBaseShape:
    def test_base_carries_source_context(self):
        exc = PolyGatewayError("boom", source_name="qwen_1", status_code=502, operation="chat")
        assert exc.source_name == "qwen_1"
        assert exc.status_code == 502
        assert exc.operation == "chat"

    def test_four_way_taxonomy_inherits_base(self):
        for cls in (TransientError, SourceDeadError, RequestRejectedError, ResultInvalidError):
            assert issubclass(cls, PolyGatewayError)

    def test_transient_retry_after_optional(self):
        assert TransientError("429").retry_after_s is None
        assert TransientError("429", retry_after_s=2.5).retry_after_s == 2.5


class TestResultInvalid:
    def test_carries_diagnosis(self):
        exc = ResultInvalidError(
            "bad json",
            raw_text="{oops",
            repair_error="unterminated",
            validation_errors=("field x missing",),
        )
        assert exc.raw_text == "{oops"
        assert exc.repair_error == "unterminated"
        assert exc.validation_errors == ("field x missing",)


class TestGatewayUnavailable:
    def test_fields_and_inheritance(self):
        exc = AllSourcesExhausted(
            scope="LLM",
            reason="retry_exhausted",
            retry_after_s=4.0,
            per_source_reasons={"qwen_1": "timeout"},
        )
        assert isinstance(exc, GatewayUnavailableError)
        assert exc.scope == "llm"  # CHS 同款: scope 归一化小写
        assert exc.reason == "retry_exhausted"
        assert exc.retry_after_s == 4.0
        assert exc.per_source_reasons == {"qwen_1": "timeout"}

    def test_circuit_open_reason_fixed(self):
        exc = CircuitOpenError(scope="LLM", retry_after_s=30.0)
        assert exc.reason == "circuit_open"
        assert isinstance(exc, GatewayUnavailableError)

    def test_scope_reason_domain_enforced(self):
        with pytest.raises(ValueError):
            AllSourcesExhausted(scope="LLM", reason="bad_reason", retry_after_s=0.0)

    def test_per_source_reason_domain_enforced(self):
        with pytest.raises(ValueError):
            AllSourcesExhausted(
                scope="LLM",
                reason="no_sources",
                retry_after_s=0.0,
                per_source_reasons={"qwen_1": "weird"},
            )

    def test_retry_after_non_negative_and_scope_non_empty(self):
        with pytest.raises(ValueError):
            AllSourcesExhausted(scope="LLM", reason="stalled", retry_after_s=-1.0)
        with pytest.raises(ValueError):
            AllSourcesExhausted(scope="  ", reason="stalled", retry_after_s=0.0)


class TestBackendFailure:
    def test_governance_backend_error_is_not_transient(self):
        """限流/熔断后端故障必须报错不放行,且不落入可重试分类。"""
        exc = GovernanceBackendError("redis down")
        assert isinstance(exc, PolyGatewayError)
        assert not isinstance(exc, TransientError)