"""
NVIDIA Sidecar — SidecarContext 依赖注入容器 (§BIZ-46 Phase3)

将所有模块级全局状态收敛为单一 dataclass，通过 FastAPI app.state 注入，
消除 webui.py → server 的反向导入，支持可测试性和多实例扩展。

设计文档: docs/architecture/BIZ-46_Phase3_Architecture_Design.md §1
"""

from __future__ import annotations

import asyncio
import time
from dataclasses import dataclass, field
from typing import TYPE_CHECKING, Any

import httpx

if TYPE_CHECKING:
    from nvidia_sidecar.config import SidecarConfig
    from nvidia_sidecar.rate_limiter import AdaptiveTokenBucket
    from nvidia_sidecar.priority_queue import PriorityRequestQueue
    from nvidia_sidecar.metrics import PrometheusMetrics
    from nvidia_sidecar.health import HealthService


@dataclass
class SidecarContext:
    """Sidecar 全局运行时上下文 — 所有核心组件的唯一容器。

    通过 ``app.state.sidecar`` 注入 FastAPI，路由通过 ``Depends(get_context)`` 获取。
    """

    # ---- 核心组件 ----
    config: SidecarConfig
    http_client: httpx.AsyncClient
    token_bucket: AdaptiveTokenBucket
    priority_queue: PriorityRequestQueue
    prometheus: PrometheusMetrics
    health: HealthService

    # ---- 运行时状态 ----
    pending_requests: dict[str, tuple["asyncio.Future[Any]", float]] = field(default_factory=dict)
    """request_id → (response future, enqueued_at) 的映射。"""

    stats: dict[str, int] = field(default_factory=lambda: {
        "total_requests": 0,
        "nvidia_requests": 0,
        "passthrough_requests": 0,
        "ratelimited_requests": 0,
        "queue_full_rejects": 0,
        "upstream_errors": 0,
        "start_time": 0,
    })

    stats_lock: asyncio.Lock = field(default_factory=asyncio.Lock)

    # ---- 缓存 ----
    snapshot_cache: tuple["dict[str, Any]", float] | None = None
    """SSE 快照共享缓存: (data, timestamp)。"""
    snapshot_cache_lock: asyncio.Lock = field(default_factory=asyncio.Lock)
    SNAPSHOT_CACHE_TTL: float = 1.0

    # ---- 便捷方法 ----

    async def increment_stat(self, key: str, delta: int = 1) -> None:
        """线程安全的统计计数器自增。"""
        async with self.stats_lock:
            self.stats[key] = self.stats.get(key, 0) + delta

    @property
    def uptime_seconds(self) -> int:
        """服务运行时长（秒）。"""
        st = self.stats.get("start_time", 0)
        return int(time.time() - st) if st else 0