"""OcrClient: 治理化 OCR 调用(M3 设计 §5,方案 A)。

独立精简治理循环,**复用**库的算法件: `RateLimiter`/`ProviderGate` 端口与
两种后端、错误四分类、`backoff_delay` 退避公式、`SourceCooldownMemo`、
`TelemetryEmitter`(遥测单一 helper 铁律)、选源器(含 OutcomeAwareSelector
喂数)。循环与 EmbeddingClient 同构——设计 §2.A 已声明的第三份有限重复
(chat 循环的 AIMD/429 免预算/流式看门狗/缓存均不适用于 OCR)。

与 embedding 循环的有意差异(设计 §5): ① settle 恒为 0(OCR 无 token
计费,失败也不按 est 保守结算);② 无批处理外循环;③ 接
OutcomeAwareSelector 喂数(多实例 LAN 服务单机可挂,健康选源正为此设计)。
"""

from __future__ import annotations

import asyncio
import random
import time
import uuid
from dataclasses import dataclass
from typing import TYPE_CHECKING, Literal

from loguru import logger

from polygateway.errors import (
    AllSourcesExhausted,
    CircuitOpenError,
    GovernanceBackendError,
    PolyGatewayError,
    RequestRejectedError,
    ResultInvalidError,
    SourceDeadError,
    SourceNotConfiguredError,
    TransientError,
)
from polygateway.middleware.breaker import BreakerGate
from polygateway.middleware.ratelimit import QuotaGate
from polygateway.middleware.retry import _failure_reason, backoff_delay
from polygateway.middleware.telemetry import TelemetryEmitter
from polygateway.ports import OutcomeAwareSelector
from polygateway.sources import SourceCooldownMemo
from polygateway.types import (
    ChatRequest,
    LLMResponse,
    OcrLayoutResult,
    OcrTextResult,
    Usage,
    strip_unsupported_extra_body,
)

if TYPE_CHECKING:
    from collections.abc import Awaitable, Callable, Mapping

    from polygateway.config import OcrSettings
    from polygateway.ports import (
        GateDecision,
        OcrTransport,
        Permit,
        ProviderGate,
        RateLimiter,
        SourceSelector,
        TelemetryRecorder,
    )
    from polygateway.types import (
        BackpressurePolicy,
        OcrLayoutTransportResult,
        OcrTextTransportResult,
        RetryPolicy,
        SourceConfig,
    )

_RESPONSE_TEXT_CAP = 200  # 遥测行 text 截断长度(与 embedding 口径一致)

_OcrKind = Literal["text", "layout"]


@dataclass(frozen=True)
class _FailedAttempt:
    exc: PolyGatewayError
    immediate: bool


@dataclass(frozen=True)
class _AttemptOutcome:
    result: OcrTextTransportResult | OcrLayoutTransportResult
    source: SourceConfig
    call_id: str
    latency_ms: int


class OcrClient:
    """治理化 OCR 入口: 同时实现 OcrTextPort 与 OcrLayoutPort(D9 端口族)。

    两端点打同一服务实例池,共享同一 scope 的限流/熔断/选源状态;
    与其他 scope 共享后端实例即共享全局闸(显式传入,禁止隐式全局)。
    """

    def __init__(
        self,
        *,
        scope: str,
        sources: list[SourceConfig],
        selector: SourceSelector,
        limiter: RateLimiter,
        breaker: ProviderGate,
        transport: OcrTransport,
        retry: RetryPolicy,
        backpressure: BackpressurePolicy,
        quota_full: str = "wait",
        telemetry: TelemetryRecorder | None = None,
        now: Callable[[], float] = time.monotonic,
        sleep: Callable[[float], Awaitable[None]] = asyncio.sleep,
        rng: Callable[[], float] = random.random,
    ) -> None:
        if quota_full not in ("wait", "fail_fast"):
            raise ValueError(f"quota_full 必须是 wait|fail_fast: {quota_full!r}")
        self._scope = scope
        # MonkeyOCR 只发 multipart 表单,带 extra_body 的源必须先剥离,否则
        # 遥测会记录一个从未发出的采样参数(issue #4 决策 G)
        self._sources = strip_unsupported_extra_body(list(sources), path="OCR")
        self._selector = selector
        self._feed_health = isinstance(selector, OutcomeAwareSelector)
        self._quota = QuotaGate(limiter, scope=self._scope)
        self._breaker = BreakerGate(breaker, scope=self._scope)
        self._transport = transport
        self._retry = retry
        self._bp = backpressure
        self._quota_full = quota_full
        self._emitter = TelemetryEmitter(telemetry) if telemetry else None
        self._telemetry = telemetry
        self._memo = SourceCooldownMemo(now=now)
        self._now = now
        self._sleep = sleep
        self._rng = rng
        self._closed = False

    # —— 公共端口(OcrTextPort / OcrLayoutPort)——

    async def recognize_text(
        self,
        image: bytes,
        *,
        session_id: str | None = None,
        parent_call_id: str | None = None,
    ) -> OcrTextResult:
        """一次治理文本转录(/ocr/text);text 空串 = 合法"无文字"。"""
        outcome = await self._call("text", image, session_id, parent_call_id)
        result = outcome.result
        return OcrTextResult(
            text=result.text,
            source_name=outcome.source.name,
            usage=Usage(0, 0),
            latency_ms=outcome.latency_ms,
            call_id=outcome.call_id,
            raw=result.raw,
        )

    async def parse_layout(
        self,
        image: bytes,
        *,
        session_id: str | None = None,
        parent_call_id: str | None = None,
    ) -> OcrLayoutResult:
        """一次治理版面解析(/parse → ZIP);elements 空 = 合法"无元素"。"""
        outcome = await self._call("layout", image, session_id, parent_call_id)
        result = outcome.result
        return OcrLayoutResult(
            elements=result.elements,
            page_sizes=result.page_sizes,
            source_name=outcome.source.name,
            usage=Usage(0, 0),
            latency_ms=outcome.latency_ms,
            call_id=outcome.call_id,
            raw=result.raw,
        )

    async def check_health(self) -> dict[str, bool]:
        """逐源并发健康预检(R10);探测失败=False 不上抛,取消穿透。"""
        names = [s.name for s in self._sources]
        results = await asyncio.gather(
            *(self._transport.check_health(source=s) for s in self._sources)
        )
        health = dict(zip(names, results, strict=True))
        for name, ok in health.items():
            if not ok:
                logger.warning("OCR 源 {} 健康预检未通过", name)
        return health

    # —— 治理循环(与 EmbeddingClient._embed_batch 同构;设计 §2.A)——

    async def _call(
        self,
        kind: _OcrKind,
        image: bytes,
        session_id: str | None,
        parent_call_id: str | None,
    ) -> _AttemptOutcome:
        if not isinstance(image, bytes):
            raise TypeError("image 必须是 bytes(路径读取/批量拼帧留业务侧,D9)")
        if not image:
            raise ValueError("image 不能为空")
        if not self._sources:
            raise AllSourcesExhausted(scope=self._scope, reason="no_sources", retry_after_s=0.0)
        fails = 0
        reasons: dict[str, str] = {}
        entered_at = self._now()
        while True:
            picked, gate_rejections = await self._pick_runnable(reasons)
            if picked is None:
                await self._on_no_runnable(gate_rejections, reasons, entered_at)
                continue
            outcome = await self._attempt(kind, image, *picked, reasons, session_id, parent_call_id)
            if isinstance(outcome, _AttemptOutcome):
                return outcome
            fails += 1
            if fails >= self._retry.max_attempts:
                raise AllSourcesExhausted(
                    scope=self._scope,
                    reason="retry_exhausted",
                    retry_after_s=self._retry.backoff_base_s,
                    per_source_reasons=reasons,
                ) from outcome.exc
            if not outcome.immediate:
                await self._sleep(backoff_delay(self._retry, fails, outcome.exc, self._rng))

    async def _pick_runnable(
        self, reasons: dict[str, str]
    ) -> tuple[tuple[SourceConfig, Permit, GateDecision] | None, int]:
        stats = {s.name: await self._quota.stats(s) for s in self._sources}
        gate_rejections = 0
        for cand in self._selector.order(self._sources, stats):
            if self._memo.active(cand.name):
                gate_rejections += 1
                reasons[cand.name] = "cooldown"
                continue
            permit = await self._quota.try_acquire(cand)
            if permit is None:
                reasons.setdefault(cand.name, "rate_limited")
                continue
            entry = None
            try:
                entry = await self._breaker.try_enter(cand, uuid.uuid4().hex)
            finally:
                if entry is None:
                    await self._settle_and_release(permit)
            if entry.allowed:
                return (cand, permit, entry), gate_rejections
            gate_rejections += 1
            reasons[cand.name] = "circuit_open"
            self._memo.set_until(cand.name, self._now() + entry.retry_after_s)
            await self._settle_and_release(permit)
        return None, gate_rejections

    async def _on_no_runnable(
        self, gate_rejections: int, reasons: dict[str, str], entered_at: float
    ) -> None:
        if gate_rejections == len(self._sources):
            names = tuple(s.name for s in self._sources)
            raise CircuitOpenError(
                scope=self._scope,
                retry_after_s=await self._breaker.retry_after_s(names),
                per_source_reasons=reasons,
            )
        if self._quota_full == "fail_fast":
            raise AllSourcesExhausted(
                scope=self._scope,
                reason="quota_exhausted",
                retry_after_s=self._bp.poll_interval_s,
                per_source_reasons=reasons,
            )
        stall = self._bp.stall_window_s
        if self._now() - entered_at > stall and await self._quota.progress_age_s() > stall:
            names = tuple(s.name for s in self._sources)
            raise AllSourcesExhausted(
                scope=self._scope,
                reason="stalled",
                retry_after_s=await self._breaker.retry_after_s(names),
                per_source_reasons=reasons,
            )
        await self._sleep(self._bp.poll_interval_s * (0.5 + 0.5 * self._rng()))

    async def _attempt(
        self,
        kind: _OcrKind,
        image: bytes,
        source: SourceConfig,
        permit: Permit,
        entry: GateDecision,
        reasons: dict[str, str],
        session_id: str | None,
        parent_call_id: str | None,
    ) -> _AttemptOutcome | _FailedAttempt:
        call_id = str(uuid.uuid4())
        started = self._now()
        try:
            result = await self._invoke(kind, image, source, call_id)
            await self._record_quietly(self._breaker.record_success(entry))
            await self._record_quietly(self._quota.mark_progress())
            self._feed_outcome(source.name, ok=True)
            latency_ms = int((self._now() - started) * 1000)
            await self._emit(
                kind, image, source, call_id, started, session_id, parent_call_id, result
            )
            return _AttemptOutcome(result, source, call_id, latency_ms)
        except (RequestRejectedError, ResultInvalidError) as exc:
            await self._gate_on_terminal(exc, entry)
            await self._emit(
                kind, image, source, call_id, started, session_id, parent_call_id, error=exc
            )
            raise
        except asyncio.CancelledError:
            if entry.is_probe:
                await self._record_quietly(self._breaker.release_probe(entry))
            await self._emit(
                kind, image, source, call_id, started, session_id, parent_call_id, error="cancelled"
            )
            raise
        except (SourceDeadError, TransientError) as exc:
            dead = isinstance(exc, SourceDeadError)
            reason = _failure_reason(exc)
            reasons[source.name] = reason
            await self._record_quietly(self._breaker.record_failure(entry, reason, dead))
            self._feed_outcome(source.name, ok=False)
            await self._emit(
                kind, image, source, call_id, started, session_id, parent_call_id, error=exc
            )
            return _FailedAttempt(exc, immediate=dead)
        finally:
            await self._settle_and_release(permit)

    async def _invoke(
        self, kind: _OcrKind, image: bytes, source: SourceConfig, call_id: str
    ) -> OcrTextTransportResult | OcrLayoutTransportResult:
        if kind == "text":
            return await self._transport.recognize_text(image=image, source=source, call_id=call_id)
        return await self._transport.parse_layout(image=image, source=source, call_id=call_id)

    # —— 辅助(与 embedding 同口径)——

    async def _gate_on_terminal(self, exc: PolyGatewayError, entry: GateDecision) -> None:
        """终态异常门控写回: 坏结果/服务的业务拒绝(有 HTTP 响应)≠ 坏服务
        → 记成功不计窗口样本;服务没响应的本地拒绝若持探针则归还。"""
        if isinstance(exc, ResultInvalidError) or exc.status_code is not None:
            await self._record_quietly(self._breaker.record_success(entry, count_attempt=False))
        elif entry.is_probe:
            await self._record_quietly(self._breaker.release_probe(entry))

    def _feed_outcome(self, source_name: str, *, ok: bool) -> None:
        """健康喂数(M2.5 口径): 真实成败喂,ResultInvalid/健康拒绝不喂;
        选源器异常吞并降级 warning(喂数失败不得影响调用)。"""
        if not self._feed_health:
            return
        try:
            self._selector.record_outcome(source_name, ok)
        except Exception as exc:  # noqa: BLE001 — 喂数侧故障降级,不冒泡
            logger.warning("OCR 健康喂数失败(不冒泡): {}", exc)

    async def _record_quietly(self, write_back: Awaitable[object]) -> None:
        try:
            await write_back
        except asyncio.CancelledError:
            raise
        except (GovernanceBackendError, SourceNotConfiguredError) as exc:
            logger.warning("OCR 治理记账写回降级(不冒泡): {}", exc)

    async def _settle_and_release(self, permit: Permit) -> None:
        """settle 恒 0: OCR 无 token 计费(设计 §5 差异①)。"""
        try:
            try:
                await permit.settle(0)
            finally:
                await permit.release()
        except asyncio.CancelledError:
            raise
        except Exception as exc:
            logger.warning("OCR permit 结算/释放失败(不掩盖主异常): {}", exc)

    async def _emit(
        self,
        kind: _OcrKind,
        image: bytes,
        source: SourceConfig,
        call_id: str,
        started: float,
        session_id: str | None,
        parent_call_id: str | None,
        result: OcrTextTransportResult | OcrLayoutTransportResult | None = None,
        error: object | None = None,
    ) -> None:
        """逐尝试遥测(单一 Emitter): messages 占位摘要,图像 bytes 绝不入库。"""
        if self._emitter is None:
            return
        request = ChatRequest(
            messages=[{"role": "user", "content": f"<ocr:{kind} image_bytes={len(image)}>"}],
            session_id=session_id,
            parent_call_id=parent_call_id,
        )
        latency_ms = int((self._now() - started) * 1000)
        response = None
        if result is not None:
            response = LLMResponse(
                content=self._summarize(result),
                thinking="",
                model=source.model,
                provider=source.provider,
                prompt_tokens=0,
                completion_tokens=0,
                latency_ms=latency_ms,
                ttft_ms=None,
                max_inter_token_ms=None,
                cache_hit=False,
                call_id=call_id,
                source_name=source.name,
                usage_source="measured",
            )
        # 错误带异常类名前缀(metric ocr-call-success 注册口径: 按类名归组)
        if error is None or isinstance(error, str):
            error_text = error
        else:
            error_text = f"{type(error).__name__}: {error}"
        await self._emitter.emit_attempt(
            request=request,
            source=source,
            call_id=call_id,
            latency_ms=latency_ms,
            response=response,
            error=error_text,
        )

    @staticmethod
    def _summarize(result: OcrTextTransportResult | OcrLayoutTransportResult) -> str:
        if hasattr(result, "text"):
            return result.text[:_RESPONSE_TEXT_CAP]
        return f"<elements n={len(result.elements)} pages={len(result.page_sizes)}>"

    # —— 生命周期 ——

    async def aclose(self) -> None:
        """幂等释放 transport 连接池与遥测连接(与 EmbeddingClient 对称)。"""
        if self._closed:
            return
        self._closed = True
        transport_aclose = getattr(self._transport, "aclose", None)
        if transport_aclose is not None:
            await transport_aclose()
        telemetry_aclose = getattr(self._telemetry, "aclose", None)
        if telemetry_aclose is not None:
            await telemetry_aclose()
        else:
            telemetry_close = getattr(self._telemetry, "close", None)
            if telemetry_close is not None:
                telemetry_close()

    async def __aenter__(self) -> OcrClient:
        return self

    async def __aexit__(self, *exc_info: object) -> None:
        await self.aclose()

    # —— 工厂(与 EmbeddingClient 对称)——

    @classmethod
    def from_settings(
        cls,
        settings: OcrSettings,
        *,
        limiter: RateLimiter | None = None,
        breaker: ProviderGate | None = None,
        telemetry: TelemetryRecorder | None = None,
    ) -> OcrClient:
        """按配置装配;显式传入的后端实例即共享(与其他 scope 共享全局闸)。"""
        from polygateway.client import (
            _build_breaker,
            _build_limiter,
            _build_selector,
            _build_telemetry,
        )
        from polygateway.transports.monkey_ocr import MonkeyOcrTransport

        gw = settings.gateway
        sources = list(gw.sources)
        # 装配防御(D9 GLM 预留档): 配了非 monkey 源必须失败,
        # 严禁静默用 MonkeyOcrTransport 打别家端点(默认值掩盖错误)
        alien = sorted({s.provider for s in sources if s.provider != "monkey"})
        if alien:
            raise ValueError(f"OCR 装配仅支持 provider=monkey(D9 其余后端预留未实现): 发现 {alien}")
        return cls(
            scope=gw.scope,
            sources=sources,
            selector=_build_selector(gw.selector),
            limiter=limiter or _build_limiter(gw, sources),
            breaker=breaker or _build_breaker(gw),
            transport=MonkeyOcrTransport(),
            retry=gw.retry,
            backpressure=gw.backpressure,
            quota_full=gw.quota_full,
            telemetry=telemetry if telemetry is not None else _build_telemetry(gw),
        )

    @classmethod
    def from_env(
        cls,
        scope: str = "OCR",
        *,
        limiter: RateLimiter | None = None,
        breaker: ProviderGate | None = None,
        telemetry: TelemetryRecorder | None = None,
        env: Mapping[str, str] | None = None,
    ) -> OcrClient:
        """从 .env/环境变量装配一个 OCR scope 的 client。"""
        from polygateway.config import OcrSettings

        return cls.from_settings(
            OcrSettings.from_env(scope, env=env),
            limiter=limiter,
            breaker=breaker,
            telemetry=telemetry,
        )