"""YAML configs with `extends:` inheritance and dotted CLI overrides."""
from __future__ import annotations

import copy
from pathlib import Path
from typing import Any

import yaml


def deep_merge(base: dict, override: dict) -> dict:
    out = copy.deepcopy(base)
    for k, v in override.items():
        if isinstance(v, dict) and isinstance(out.get(k), dict):
            out[k] = deep_merge(out[k], v)
        else:
            out[k] = copy.deepcopy(v)
    return out


def _load(path: Path) -> dict:
    cfg = yaml.safe_load(path.read_text()) or {}
    parent = cfg.pop("extends", None)
    return deep_merge(_load(path.parent / parent), cfg) if parent else cfg


def load_config(path: str | Path, overrides: list[str] | None = None) -> dict:
    path = Path(path)
    raw = yaml.safe_load(path.read_text()) or {}
    cfg = _load(path)
    cfg["name"] = raw.get("name", path.stem)
    for ov in overrides or []:
        key, _, val = ov.partition("=")
        set_dotted(cfg, key.strip(), _parse_value(val))
    return cfg


def _parse_value(val: str) -> Any:
    v = yaml.safe_load(val)
    if isinstance(v, str):  # YAML 1.1 reads "3e-4" as a string
        try:
            return float(v)
        except ValueError:
            pass
    return v


def set_dotted(cfg: dict, key: str, value: Any) -> None:
    node = cfg
    parts = key.split(".")
    for p in parts[:-1]:
        node = node.setdefault(p, {})
    node[parts[-1]] = value


def get_dotted(cfg: dict, key: str, default: Any = None) -> Any:
    node = cfg
    for p in key.split("."):
        if not isinstance(node, dict) or p not in node:
            return default
        node = node[p]
    return node