import json
import os
import sys


def _get_app_dir():
    if getattr(sys, 'frozen', False):
        return os.path.dirname(sys.executable)
    return os.path.dirname(os.path.abspath(__file__))


def _get_config_path():
    return os.path.join(_get_app_dir(), "config.json")


DEFAULT_CONFIG = {
    "api": {
        "url": "http://localhost:8080/wallpaper",
        "mode": "direct",
        "json_image_field": "url",
        "timeout": 30,
    },
    "wallpaper": {
        "fill_style": "fill",
        "cache_dir": "./cache",
        "max_cache_files": 10,
        "show_notification": True,
    },
    "auto_refresh": {
        "enabled": False,
        "interval_minutes": 10,
    },
}

_config = None


def _resolve_path(path: str) -> str:
    if os.path.isabs(path):
        return path
    return os.path.normpath(os.path.join(_get_app_dir(), path))


def load() -> dict:
    global _config
    if _config is not None:
        return _config
    config_path = _get_config_path()
    if os.path.exists(config_path):
        with open(config_path, "r", encoding="utf-8") as f:
            _config = json.load(f)
    else:
        _config = DEFAULT_CONFIG
    merged = dict(DEFAULT_CONFIG)
    _deep_merge(merged, _config)
    _config = merged
    return _config


def save(cfg: dict = None) -> None:
    global _config
    if cfg is not None:
        _config = cfg
    with open(_get_config_path(), "w", encoding="utf-8") as f:
        json.dump(_config, f, indent=4, ensure_ascii=False)


def reload() -> dict:
    global _config
    _config = None
    return load()


def get(path: str, default=None):
    cfg = load()
    keys = path.split(".")
    for k in keys:
        if isinstance(cfg, dict):
            cfg = cfg.get(k)
            if cfg is None:
                return default
        else:
            return default
    return cfg


def set_(path: str, value):
    global _config
    cfg = load()
    keys = path.split(".")
    d = cfg
    for k in keys[:-1]:
        d = d.setdefault(k, {})
    d[keys[-1]] = value
    save(cfg)


def _deep_merge(base, override):
    for key, value in override.items():
        if key in base and isinstance(base[key], dict) and isinstance(value, dict):
            _deep_merge(base[key], value)
        else:
            base[key] = value