"""pricing.py 价格表与 TelemetryEmitter 成本换算(M2 设计 §6)。

零内置单价(实验室走中转网关,内置表必然过时掩盖真实成本,P5);
价格由使用方经 JSON 文件或 dict 注入;查不到 → cost=None + 每 model
仅首次 warning,不阻塞调用;计算点收敛在 Emitter(单一 helper 铁律)。
"""

import json

import pytest

from polygateway.middleware.telemetry import TelemetryEmitter
from polygateway.pricing import ModelPrice, PricingTable
from polygateway.types import ChatRequest, LLMResponse, SourceConfig

_TABLE = PricingTable(
    {
        "qwen-max": ModelPrice(input_per_1m=2.4, output_per_1m=9.6),
        "free-model": ModelPrice(input_per_1m=0.0, output_per_1m=0.0),
    }
)


class TestPricingTable:
    def test_cost_formula_per_million(self):
        # 1M prompt + 0.5M completion: 2.4 + 4.8
        assert _TABLE.cost("qwen-max", 1_000_000, 500_000) == pytest.approx(7.2)
        assert _TABLE.cost("qwen-max", 1000, 2000) == pytest.approx(0.0216)
        assert _TABLE.cost("free-model", 999, 999) == 0.0

    def test_unknown_model_returns_none(self):
        assert _TABLE.cost("mystery", 100, 100) is None

    def test_from_file_roundtrip(self, tmp_path):
        path = tmp_path / "prices.json"
        path.write_text(
            json.dumps({"m1": {"input_per_1m": 1.0, "output_per_1m": 2.0}}), encoding="utf-8"
        )
        table = PricingTable.from_file(path)
        assert table.cost("m1", 1_000_000, 1_000_000) == pytest.approx(3.0)

    def test_from_file_missing_or_bad_fails_loudly(self, tmp_path):
        with pytest.raises(ValueError, match="价格表"):
            PricingTable.from_file(tmp_path / "nope.json")
        bad = tmp_path / "bad.json"
        bad.write_text("not json", encoding="utf-8")
        with pytest.raises(ValueError, match="价格表"):
            PricingTable.from_file(bad)
        malformed = tmp_path / "malformed.json"
        malformed.write_text(json.dumps({"m": {"input_per_1m": 1.0}}), encoding="utf-8")
        with pytest.raises(ValueError, match="output_per_1m"):
            PricingTable.from_file(malformed)

    def test_negative_price_rejected(self):
        with pytest.raises(ValueError):
            ModelPrice(input_per_1m=-1.0, output_per_1m=0.0)


class TestCachedInputTier:
    """issue #3: 供应商 prompt cache 命中部分按更低单价计费,不配则不猜折扣。"""

    _CACHED = PricingTable(
        {"m": ModelPrice(input_per_1m=10.0, output_per_1m=20.0, cached_input_per_1m=2.0)}
    )
    _PLAIN = PricingTable({"m": ModelPrice(input_per_1m=10.0, output_per_1m=20.0)})

    def test_hit_is_billed_at_the_cached_rate(self):
        # 1M prompt 中 600k 命中: 400k×10 + 600k×2 = 4.0 + 1.2
        assert self._CACHED.cost("m", 1_000_000, 0, 600_000) == pytest.approx(5.2)

    def test_without_the_tier_the_result_is_unchanged(self):
        """未配缓存档 = 退化为现状全额计价,绝不按经验折扣率猜(P5)。"""
        full = self._PLAIN.cost("m", 1_000_000, 0)
        assert self._PLAIN.cost("m", 1_000_000, 0, 600_000) == full == pytest.approx(10.0)

    @pytest.mark.parametrize("cached", [None, 0])
    def test_no_hit_is_billed_in_full(self, cached):
        assert self._CACHED.cost("m", 1_000_000, 0, cached) == pytest.approx(10.0)

    def test_cached_over_prompt_is_clamped_and_never_negative(self):
        """网关口径异常时按输入总数夹取: 全部按缓存价,不得算出负成本。"""
        clamped = self._CACHED.cost("m", 1_000_000, 0, 5_000_000)
        assert clamped == pytest.approx(2.0) and clamped >= 0

    def test_legacy_three_arg_call_still_works(self):
        """embedding.py 的三参调用形态必须零改动可用。"""
        assert self._CACHED.cost("m", 1_000_000, 0) == pytest.approx(10.0)

    def test_from_file_accepts_and_validates_the_tier(self, tmp_path):
        path = tmp_path / "p.json"
        path.write_text(
            json.dumps(
                {"m": {"input_per_1m": 10.0, "output_per_1m": 20.0, "cached_input_per_1m": 2.0}}
            ),
            encoding="utf-8",
        )
        assert PricingTable.from_file(path).cost("m", 1_000_000, 0, 1_000_000) == pytest.approx(2.0)

    @pytest.mark.parametrize("bad", [-1.0, "x"])
    def test_from_file_rejects_a_bad_tier(self, tmp_path, bad):
        path = tmp_path / "bad.json"
        path.write_text(
            json.dumps(
                {"m": {"input_per_1m": 1.0, "output_per_1m": 2.0, "cached_input_per_1m": bad}}
            ),
            encoding="utf-8",
        )
        with pytest.raises(ValueError, match="cached_input_per_1m"):
            PricingTable.from_file(path)

    def test_legacy_price_file_without_the_tier_still_loads(self, tmp_path):
        path = tmp_path / "old.json"
        path.write_text(
            json.dumps({"m": {"input_per_1m": 1.0, "output_per_1m": 2.0}}), encoding="utf-8"
        )
        assert PricingTable.from_file(path).cost("m", 1_000_000, 0, 500_000) == pytest.approx(1.0)

    def test_negative_tier_rejected_on_construction(self):
        with pytest.raises(ValueError):
            ModelPrice(input_per_1m=1.0, output_per_1m=1.0, cached_input_per_1m=-0.1)


class _MemoryRecorder:
    def __init__(self):
        self.rows = []

    async def record_llm_call(self, **fields):
        self.rows.append(fields)


_REQ = ChatRequest(messages=[{"role": "user", "content": "hi"}])


def _resp(**overrides):
    base = {
        "content": "ok",
        "thinking": "",
        "model": "qwen-max",
        "provider": "qwen",
        "prompt_tokens": 1_000_000,
        "completion_tokens": 500_000,
        "latency_ms": 30,
        "ttft_ms": None,
        "max_inter_token_ms": None,
        "cache_hit": False,
        "call_id": "cid-1",
        "source_name": "s1",
        "usage_source": "measured",
    }
    base.update(overrides)
    return LLMResponse(**base)


def _source(model="qwen-max"):
    return SourceConfig(
        name="s1",
        provider="qwen",
        base_url="https://gw.example/v1",
        api_key="sk",
        model=model,
        timeout_s=10.0,
    )


class TestEmitterCost:
    async def test_success_row_costed(self):
        rec = _MemoryRecorder()
        emitter = TelemetryEmitter(rec, pricing=_TABLE)
        await emitter.emit_attempt(
            request=_REQ,
            source=_source(),
            call_id="c",
            latency_ms=1,
            response=_resp(),
            error=None,
        )
        assert rec.rows[0]["cost"] == pytest.approx(7.2)

    async def test_cache_hit_row_costs_zero(self):
        rec = _MemoryRecorder()
        emitter = TelemetryEmitter(rec, pricing=_TABLE)
        await emitter.emit_cache_hit(request=_REQ, response=_resp(cache_hit=True))
        assert rec.rows[0]["cost"] == 0.0

    async def test_failure_row_cost_none(self):
        rec = _MemoryRecorder()
        emitter = TelemetryEmitter(rec, pricing=_TABLE)
        await emitter.emit_attempt(
            request=_REQ,
            source=_source(),
            call_id="c",
            latency_ms=1,
            response=None,
            error="TransientError: boom",
        )
        assert rec.rows[0]["cost"] is None

    async def test_unknown_model_none_without_blocking(self):
        rec = _MemoryRecorder()
        emitter = TelemetryEmitter(rec, pricing=_TABLE)
        await emitter.emit_attempt(
            request=_REQ,
            source=_source(model="mystery"),
            call_id="c",
            latency_ms=1,
            response=_resp(model="mystery"),
            error=None,
        )
        assert rec.rows[0]["cost"] is None

    async def test_no_pricing_keeps_none(self):
        """未注入价格表 = M1 现状: cost 恒 None(回归)。"""
        rec = _MemoryRecorder()
        emitter = TelemetryEmitter(rec)
        await emitter.emit_attempt(
            request=_REQ,
            source=_source(),
            call_id="c",
            latency_ms=1,
            response=_resp(),
            error=None,
        )
        assert rec.rows[0]["cost"] is None