import json
import logging

logger = logging.getLogger(__name__)

DEFAULT_CONFIG = {
    "output_format": "PNG",   # PNG or JPG
    "output_quality": 95,     # JPG quality 1-95
    "output_dir": "",         # empty = use app output/ dir
    "last_garment_dir": "",
    "last_print_dir": "",
    "last_template": "",       # name of the last-selected template
    "last_batch_mode": "full_combo",  # BatchMode value of the last-used mode
}

_CONFIG_FILENAME = "app_config.json"


def load_config():
    """
    从 JSON 文件加载应用配置。

    返回默认配置与文件配置的合并字典。如果配置文件不存在、损坏或无法读取，
    函数不会抛出异常，而是记录日志并返回默认配置。

    Returns:
        dict: 合并后的配置字典
    """
    from services.file_service import get_config_path
    config_file = get_config_path(_CONFIG_FILENAME)

    if not config_file.exists():
        logger.info("Config file not found, using defaults: %s", config_file)
        return dict(DEFAULT_CONFIG)

    try:
        with open(str(config_file), encoding="utf-8") as f:
            data = json.load(f)
        if not isinstance(data, dict):
            raise ValueError("Config root is not a JSON object")
        merged = dict(DEFAULT_CONFIG)
        merged.update(data)
        logger.info("Config loaded from %s", config_file)
        return merged
    except (json.JSONDecodeError, ValueError) as exc:
        logger.warning("Config file damaged (%s), using defaults: %s", exc, config_file)
        return dict(DEFAULT_CONFIG)
    except OSError as exc:
        logger.warning("Config file unreadable (%s), using defaults: %s", exc, config_file)
        return dict(DEFAULT_CONFIG)


def save_config(data):
    """Save config dict to JSON. Logs error on failure, does not raise."""
    from services.file_service import get_config_path
    config_file = get_config_path(_CONFIG_FILENAME)

    try:
        config_file.parent.mkdir(exist_ok=True)
        with open(str(config_file), "w", encoding="utf-8") as f:
            json.dump(data, f, ensure_ascii=False, indent=2)
        logger.info("Config saved to %s", config_file)
    except OSError as exc:
        logger.error("Failed to save config to %s: %s", config_file, exc)