from __future__ import annotations

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

import yaml


def load_config(path: str | Path) -> dict[str, Any]:
    with Path(path).open("r", encoding="utf-8") as handle:
        data = yaml.safe_load(handle)
    if not isinstance(data, dict):
        raise ValueError(f"Config at {path} must deserialize into a mapping.")
    return data


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


def ensure_dir(path: str | Path) -> Path:
    resolved = Path(path)
    resolved.mkdir(parents=True, exist_ok=True)
    return resolved


def save_json(path: str | Path, payload: dict[str, Any]) -> None:
    target = Path(path)
    target.parent.mkdir(parents=True, exist_ok=True)
    with target.open("w", encoding="utf-8") as handle:
        json.dump(payload, handle, indent=2, ensure_ascii=False)


def flatten_for_wandb(payload: dict[str, Any], prefix: str = "") -> dict[str, Any]:
    flat: dict[str, Any] = {}
    for key, value in payload.items():
        full_key = f"{prefix}.{key}" if prefix else key
        if isinstance(value, dict):
            flat.update(flatten_for_wandb(value, prefix=full_key))
        else:
            flat[full_key] = value
    return flat


def fingerprint_payload(payload: dict[str, Any]) -> str:
    serialized = json.dumps(payload, sort_keys=True, ensure_ascii=True, separators=(",", ":"))
    return hashlib.sha256(serialized.encode("utf-8")).hexdigest()[:16]