"""统一应用配置 (MVP-1 / 新增)

基于 pydantic-settings 的多环境配置管理，集中收敛原先散落在
``main.py``、各 service 模块中的环境变量、路径、阈值等配置。

加载顺序 (优先级从高到低)::

    1. 显式构造参数
    2. 环境变量 (大小写不敏感)
    3. ``.env`` 文件 (位于 apps/server/.env)
    4. 默认值

使用方式::

    from core.settings import get_settings

    settings = get_settings()
    print(settings.api.port)
    print(settings.detection.default_confidence)
"""

from __future__ import annotations

import os
from functools import lru_cache
from pathlib import Path
from typing import List, Optional

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


# 项目根 (apps/server)
SERVER_DIR: Path = Path(__file__).resolve().parent.parent
PROJECT_ROOT: Path = SERVER_DIR.parent.parent


# ---------------------------------------------------------------------------
# 子配置
# ---------------------------------------------------------------------------


class APISettings(BaseSettings):
    """API 与服务器相关配置。"""

    model_config = SettingsConfigDict(env_prefix="API_", extra="ignore")

    host: str = Field(default="0.0.0.0", description="监听地址")
    port: int = Field(default=8000, description="监听端口")
    reload: bool = Field(default=True, description="开发模式自动重载")
    cors_origins: List[str] = Field(
        default_factory=lambda: ["*"], description="允许的跨域来源"
    )


class DetectionSettings(BaseSettings):
    """检测相关全局默认值。"""

    model_config = SettingsConfigDict(env_prefix="DETECTION_", extra="ignore")

    default_confidence: float = Field(default=0.5, ge=0.0, le=1.0)
    default_iou: float = Field(default=0.45, ge=0.0, le=1.0)
    # 决策引擎过滤的最低置信度
    min_confidence: float = Field(default=0.3, ge=0.0, le=1.0)


class ActionDetectionSettings(BaseSettings):
    """ppTSM 行为识别 (Docker) 服务配置。"""

    model_config = SettingsConfigDict(env_prefix="ACTION_DETECTION_", extra="ignore")

    api_url: str = Field(default="http://localhost:8081")
    timeout: int = Field(default=30, ge=1)


class EventEngineSettings(BaseSettings):
    """事件决策 + 聚合 + 规则引擎配置。"""

    model_config = SettingsConfigDict(env_prefix="EVENT_", extra="ignore")

    # 时间窗口去重 (秒)，同一 (source_id, event_type, track_id) 在窗口内只产生一条
    dedup_window_seconds: float = Field(default=30.0, ge=0.0)
    # 规则 YAML 目录 (相对 server 根)
    rules_dir: str = Field(default="config/rules")
    # 事件聚合最大活跃事件数 (超过将按 LRU 淘汰)
    max_active_events: int = Field(default=1000, ge=1)


class RTSPSettings(BaseSettings):
    """RTSP 流接入相关配置 (MVP-2)。"""

    model_config = SettingsConfigDict(env_prefix="RTSP_", extra="ignore")

    max_streams: int = Field(default=16, ge=1, description="最大同时接入流数量")
    buffer_capacity: int = Field(default=300, ge=1, description="每路流帧缓冲区容量")
    reconnect_attempts: int = Field(default=10, ge=0, description="最大重连次数，0=无限")
    reconnect_interval_base: float = Field(default=2.0, ge=0.5, description="首次重连间隔(秒)")
    reconnect_interval_max: float = Field(default=60.0, ge=1.0, description="最大重连间隔(秒)")
    reconnect_backoff_factor: float = Field(default=2.0, ge=1.0, description="退避因子")
    frame_skip: int = Field(default=0, ge=0, description="帧采样间隔，0=每帧都取")
    read_timeout: float = Field(default=5.0, ge=1.0, description="单帧读取超时(秒)")
    detect_interval: float = Field(default=0.0, ge=0.0, description="检测轮询间隔(秒)，0=每帧检测")


class MQTTSettings(BaseSettings):
    """MQTT 预警发布相关配置 (MVP-2 / D16-D18)。"""

    model_config = SettingsConfigDict(env_prefix="MQTT_", extra="ignore")

    enabled: bool = Field(default=False, description="是否启用 MQTT 发布")
    broker_host: str = Field(default="localhost", description="MQTT broker 主机")
    broker_port: int = Field(default=1883, ge=1, le=65535, description="MQTT broker 端口")
    client_id: str = Field(default="jc-video-recognize", description="MQTT 客户端ID")
    username: Optional[str] = Field(default=None, description="MQTT 用户名")
    password: Optional[str] = Field(default=None, description="MQTT 密码")
    keepalive: int = Field(default=60, ge=10, description="心跳间隔(秒)")
    qos: int = Field(default=1, ge=0, le=2, description="QoS 等级")
    retain: bool = Field(default=False, description="是否保留消息")
    # 主题模板
    alert_topic_prefix: str = Field(default="video/alerts", description="预警主题前缀")
    # 重连
    reconnect_min_delay: float = Field(default=1.0, ge=0.1, description="最小重连间隔(秒)")
    reconnect_max_delay: float = Field(default=60.0, ge=1.0, description="最大重连间隔(秒)")


class TrackingSettings(BaseSettings):
    """目标跟踪 (ByteTrack) 配置 (MVP-2 / D19)。"""

    model_config = SettingsConfigDict(env_prefix="TRACKING_", extra="ignore")

    enabled: bool = Field(default=True, description="是否启用目标跟踪")
    track_thresh: float = Field(default=0.5, ge=0.0, le=1.0, description="跟踪置信度阈值")
    high_thresh: float = Field(default=0.6, ge=0.0, le=1.0, description="高置信度阈值")
    match_thresh: float = Field(default=0.8, ge=0.0, le=1.0, description="IOU 匹配阈值")
    max_lost_frames: int = Field(default=30, ge=1, description="目标丢失最大帧数")
    min_box_area: float = Field(default=10.0, ge=0.0, description="最小框面积")


class AggregatorSettings(BaseSettings):
    """事件聚合器扩展配置 (MVP-2 / D20)。"""

    model_config = SettingsConfigDict(env_prefix="AGGREGATOR_", extra="ignore")

    enable_spatial_merge: bool = Field(default=True, description="是否启用空间邻近合并")
    spatial_iou_threshold: float = Field(
        default=0.3, ge=0.0, le=1.0, description="空间合并 IOU 阈值"
    )
    confidence_fusion_strategy: str = Field(
        default="weighted",
        description="置信度融合策略: weighted/max/avg",
    )
    fusion_decay_factor: float = Field(
        default=0.9, ge=0.0, le=1.0, description="历史置信度衰减因子"
    )


class LoggingSettings(BaseSettings):
    """日志配置。"""

    model_config = SettingsConfigDict(env_prefix="LOG_", extra="ignore")

    level: str = Field(default="INFO")
    json_format: bool = Field(default=False)


class PathSettings(BaseSettings):
    """关键路径 (静态资源 / 外部模型) 配置。"""

    model_config = SettingsConfigDict(env_prefix="PATH_", extra="ignore")

    server_dir: Path = SERVER_DIR
    project_root: Path = PROJECT_ROOT
    static_dir: Path = SERVER_DIR / "static"
    results_dir: Path = SERVER_DIR / "static" / "results"
    temp_dir: Path = SERVER_DIR / "static" / "temp"
    uploads_dir: Path = SERVER_DIR / "static" / "uploads"
    external_paddle: Path = (
        PROJECT_ROOT / "external" / "video-recognition-system" / "PaddlePaddle"
    )

    def ensure(self) -> None:
        """确保所有需要的目录存在 (启动时调用)。"""

        for p in (self.static_dir, self.results_dir, self.temp_dir, self.uploads_dir):
            p.mkdir(parents=True, exist_ok=True)


# ---------------------------------------------------------------------------
# 总配置
# ---------------------------------------------------------------------------


class Settings(BaseSettings):
    """应用总配置。

    子配置统一在此聚合，便于以 ``settings.api.port`` 这种命名空间方式访问。
    """

    model_config = SettingsConfigDict(
        env_file=str(SERVER_DIR / ".env"),
        env_file_encoding="utf-8",
        env_nested_delimiter="__",
        case_sensitive=False,
        extra="ignore",
    )

    env: str = Field(default="development", description="运行环境")
    debug: bool = Field(default=True)

    api: APISettings = Field(default_factory=APISettings)
    detection: DetectionSettings = Field(default_factory=DetectionSettings)
    action_detection: ActionDetectionSettings = Field(
        default_factory=ActionDetectionSettings
    )
    event_engine: EventEngineSettings = Field(default_factory=EventEngineSettings)
    rtsp: RTSPSettings = Field(default_factory=RTSPSettings)
    mqtt: MQTTSettings = Field(default_factory=MQTTSettings)
    tracking: TrackingSettings = Field(default_factory=TrackingSettings)
    aggregator: AggregatorSettings = Field(default_factory=AggregatorSettings)
    logging: LoggingSettings = Field(default_factory=LoggingSettings)
    paths: PathSettings = Field(default_factory=PathSettings)


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    """获取全局 Settings 单例 (带缓存)。

    测试场景下可调用 ``get_settings.cache_clear()`` 重新加载。
    """

    settings = Settings()
    settings.paths.ensure()
    return settings


__all__ = [
    "Settings",
    "APISettings",
    "DetectionSettings",
    "ActionDetectionSettings",
    "EventEngineSettings",
    "RTSPSettings",
    "MQTTSettings",
    "TrackingSettings",
    "AggregatorSettings",
    "LoggingSettings",
    "PathSettings",
    "get_settings",
    "SERVER_DIR",
    "PROJECT_ROOT",
]