from __future__ import annotations

import copy
import json
from pathlib import Path
from typing import Any, Dict

import yaml


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


def deep_merge(base: Dict[str, Any], update: Dict[str, Any]) -> Dict[str, Any]:
    merged = copy.deepcopy(base)
    for key, value in update.items():
        if isinstance(value, dict) and isinstance(merged.get(key), dict):
            merged[key] = deep_merge(merged[key], value)
        else:
            merged[key] = copy.deepcopy(value)
    return merged


def set_dot_key(target: Dict[str, Any], dot_key: str, value: Any) -> None:
    parts = dot_key.split(".")
    current = target
    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


def apply_dot_overrides(target: Dict[str, Any], overrides: Dict[str, Any]) -> Dict[str, Any]:
    out = copy.deepcopy(target)
    for dot_key, value in overrides.items():
        set_dot_key(out, dot_key, value)
    return out


def parse_overrides_json(raw: str | None) -> Dict[str, Any]:
    if not raw:
        return {}
    payload = json.loads(raw)
    if not isinstance(payload, dict):
        raise ValueError("Overrides JSON must be an object.")
    return payload