"""LLM 状态/成本/控制 API (MVP-3 / D34)

提供给前端的 RESTful 接口:

- ``GET  /llm/status``   返回 LLM 是否启用、provider、熔断状态、降级原因
- ``GET  /llm/cost``     返回今日费用 / 预算 / token 用量
- ``GET  /llm/cost/history`` 返回最近 N 天的日级统计
- ``GET  /llm/cost/records`` 返回最近 N 次调用明细
- ``POST /llm/disable``  手动禁用 LLM 调用 (运维)
- ``POST /llm/enable``   手动重新启用
- ``POST /llm/reset``    重置成本统计 + 熔断状态

设计要点:

- ``llm_service`` 与 ``cost_tracker`` 都通过 ``main.py`` 在 lifespan 中注入，
  此处仅暴露读取接口
- 前端的"规则配置 / LLM 状态面板"通过本接口拿到实时数据
"""

from __future__ import annotations

import logging
from typing import Any, Dict, List, Optional

from fastapi import APIRouter, HTTPException, Query
from pydantic import BaseModel, Field

from core.settings import get_settings
from services.llm_analysis_service import LLMAnalysisService
from services.llm_cost_tracker import LLMCostTracker

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/llm", tags=["LLM 二次判断"])


# ---------------------------------------------------------------------------
# 全局注入 (由 main.py 调用)
# ---------------------------------------------------------------------------


_llm_service: Optional[LLMAnalysisService] = None
_cost_tracker: Optional[LLMCostTracker] = None


def init_llm_api(
    llm_service: Optional[LLMAnalysisService],
    cost_tracker: Optional[LLMCostTracker],
) -> None:
    """由 main.py 在启动阶段注入服务实例。"""

    global _llm_service, _cost_tracker
    _llm_service = llm_service
    _cost_tracker = cost_tracker
    logger.info(
        "LLM API 已初始化: service=%s tracker=%s",
        bool(llm_service),
        bool(cost_tracker),
    )


def _require_tracker() -> LLMCostTracker:
    if _cost_tracker is None:
        raise HTTPException(
            status_code=503, detail="LLMCostTracker 未初始化"
        )
    return _cost_tracker


# ---------------------------------------------------------------------------
# 响应模型
# ---------------------------------------------------------------------------


class LLMStatusResponse(BaseModel):
    enabled: bool
    provider: str
    model: str
    api_base: Optional[str] = None
    triggers: Dict[str, Any] = Field(default_factory=dict)
    fusion: Dict[str, Any] = Field(default_factory=dict)
    cost: Dict[str, Any] = Field(default_factory=dict)


# ---------------------------------------------------------------------------
# API 路由
# ---------------------------------------------------------------------------


@router.get("/status", response_model=LLMStatusResponse)
async def get_llm_status() -> LLMStatusResponse:
    """获取 LLM 当前运行状态 (供前端 LLM 状态面板)。"""

    settings = get_settings()
    llm_cfg = settings.llm
    trigger_cfg = settings.llm_trigger
    fusion_cfg = settings.fusion

    cost_data: Dict[str, Any]
    if _cost_tracker is not None:
        cost_data = _cost_tracker.stats()
    else:
        cost_data = {"enabled": llm_cfg.enabled, "circuit_state": "n/a"}

    provider_name = llm_cfg.provider
    if _llm_service is not None:
        provider_name = getattr(_llm_service.provider, "name", provider_name)

    return LLMStatusResponse(
        enabled=llm_cfg.enabled,
        provider=provider_name,
        model=llm_cfg.model,
        api_base=llm_cfg.api_base,
        triggers={
            "enabled": trigger_cfg.enabled,
            "window_seconds": trigger_cfg.window_seconds,
            "min_consecutive_hits": trigger_cfg.min_consecutive_hits,
            "min_avg_confidence": trigger_cfg.min_avg_confidence,
            "cooldown_seconds": trigger_cfg.cooldown_seconds,
            "severity_bypass": trigger_cfg.severity_bypass,
        },
        fusion={
            "strategy": fusion_cfg.strategy,
            "yolo_weight": fusion_cfg.yolo_weight,
            "llm_weight": fusion_cfg.llm_weight,
            "suppress_on_llm_negative": fusion_cfg.suppress_on_llm_negative,
            "fallback_to_yolo": fusion_cfg.fallback_to_yolo,
        },
        cost=cost_data,
    )


@router.get("/cost")
async def get_llm_cost() -> Dict[str, Any]:
    """获取今日 LLM 成本概览。"""

    return _require_tracker().stats()


@router.get("/cost/history")
async def get_llm_cost_history(
    days: int = Query(default=7, ge=1, le=30),
) -> Dict[str, List[Dict[str, Any]]]:
    """最近 N 天的日级成本/调用统计。"""

    summary = _require_tracker().daily_summary()
    return {"days": summary[-days:]}


@router.get("/cost/records")
async def get_llm_cost_records(
    limit: int = Query(default=20, ge=1, le=200),
) -> Dict[str, List[Dict[str, Any]]]:
    """最近 N 次 LLM 调用明细。"""

    return {"records": _require_tracker().recent_records(limit=limit)}


@router.post("/disable")
async def disable_llm() -> Dict[str, Any]:
    """手动禁用 LLM 调用。"""

    tracker = _require_tracker()
    tracker.disable()
    return {"success": True, "enabled": tracker.is_enabled}


@router.post("/enable")
async def enable_llm() -> Dict[str, Any]:
    """手动重新启用 LLM 调用 (重置熔断)。"""

    tracker = _require_tracker()
    tracker.enable()
    return {"success": True, "enabled": tracker.is_enabled}


@router.post("/reset")
async def reset_llm() -> Dict[str, Any]:
    """重置成本统计与熔断状态。"""

    tracker = _require_tracker()
    tracker.reset()
    return {"success": True, "stats": tracker.stats()}


__all__ = ["router", "init_llm_api"]