from __future__ import annotations

from copy import deepcopy
from pathlib import Path
from typing import Any

import yaml


def load_yaml_config(path: str | Path) -> dict[str, Any]:
    with Path(path).open("r", encoding="utf-8") as handle:
        return yaml.safe_load(handle) or {}


def deep_update(dst: dict[str, Any], src: dict[str, Any]) -> dict[str, Any]:
    for key, value in src.items():
        if isinstance(value, dict) and isinstance(dst.get(key), dict):
            deep_update(dst[key], value)
        else:
            dst[key] = value
    return dst


def apply_dotlist_overrides(cfg: dict[str, Any], overrides: list[str] | None) -> dict[str, Any]:
    if not overrides:
        return cfg

    updated = deepcopy(cfg)
    for item in overrides:
        if "=" not in item:
            raise ValueError(f"Invalid override '{item}'. Expected key=value format.")
        key, raw_value = item.split("=", 1)
        value = yaml.safe_load(raw_value)
        parts = key.split(".")
        current = updated
        for part in parts[:-1]:
            if part not in current or not isinstance(current[part], dict):
                current[part] = {}
            current = current[part]
        current[parts[-1]] = value
    return updated


__all__ = ["load_yaml_config", "deep_update", "apply_dotlist_overrides"]