from __future__ import annotations

import dataclasses
import os
from pathlib import Path
from typing import Any

import yaml

from configs.models import (
    AppConfig,
    AudioConfig,
    DeadBugConfig,
    LoggingConfig,
    ModelConfig,
    ServerConfig,
    VideoConfig,
)

_PROJECT_ROOT = Path(__file__).resolve().parent.parent

_ENV_MAP = {
    "POSEFIT_WS_HOST": ("server", "host"),
    "POSEFIT_WS_PORT": ("server", "port", int),
    "POSEFIT_WS_MAX_SIZE": ("server", "max_ws_size", int),
    "POSEFIT_PROCESS_EVERY_N_FRAMES": ("video", "process_every_n_frames", int),
    "POSEFIT_MODEL_PATH": ("model", "path"),
    "POSEFIT_PREFER_GPU": ("model", "prefer_gpu", lambda v: v not in ("0", "false", "False")),
    "POSEFIT_VISIBILITY_THRESHOLD": ("dead_bug", "visibility_threshold", float),
    "POSEFIT_EXTENSION_CONFIRM_FRAMES": ("dead_bug", "extension_confirm_frames", int),
    "POSEFIT_RESET_CONFIRM_FRAMES": ("dead_bug", "reset_confirm_frames", int),
    "POSEFIT_REP_ANNOUNCER_ENABLED": ("audio", "rep_announcer_enabled", lambda v: v not in ("0", "false", "False")),
    "POSEFIT_REP_ANNOUNCER_RATE": ("audio", "rep_announcer_rate", int),
    "POSEFIT_REP_ANNOUNCER_VOLUME": ("audio", "rep_announcer_volume", float),
    "POSEFIT_LOG_ROTATION": ("logging", "rotation"),
    "POSEFIT_LOG_RETENTION": ("logging", "retention"),
    "POSEFIT_LOG_DIR": ("logging", "dir"),
}

_SECTION_CLASS = {
    "server": ServerConfig,
    "video": VideoConfig,
    "model": ModelConfig,
    "dead_bug": DeadBugConfig,
    "audio": AudioConfig,
    "logging": LoggingConfig,
}


def _dict_to_dataclass(cls: type, data: dict[str, Any] | None) -> dict[str, Any]:
    if data is None:
        return {}
    field_names = {f.name for f in dataclasses.fields(cls)}
    return {k: v for k, v in data.items() if k in field_names}


def _read_yaml(path: Path) -> dict[str, Any]:
    if not path.exists():
        return {}
    with open(path, encoding="utf-8") as f:
        return yaml.safe_load(f) or {}


def _apply_env_overrides(raw: dict[str, Any]) -> None:
    for env_var, (section, key, *rest) in _ENV_MAP.items():
        value = os.getenv(env_var)
        if value is None:
            continue
        if rest:
            value = rest[0](value)
        raw.setdefault(section, {})[key] = value


def load_config(config_path: str | Path | None = None) -> AppConfig:
    if config_path is None:
        config_path = _PROJECT_ROOT / "config.yaml"

    raw = _read_yaml(Path(config_path))
    _apply_env_overrides(raw)

    return AppConfig(**{
        section: cls(**_dict_to_dataclass(cls, raw.get(section)))
        for section, cls in _SECTION_CLASS.items()
    })


config = load_config()