from typing import cast
from config.dtype import ArchMgrConfig


def merge_configs(config: ArchMgrConfig, new_config: ArchMgrConfig) -> ArchMgrConfig:
    """Merge two configs, with the new_config taking precedence over the config
        in the conflicting fields with arrays and dicts merged

    Args:
        config: Base config
        new_config: Config to merge into the base config

    Returns:
        The merged config
    """
    if len(new_config) == 0 or len(config) == 0:
        return config

    def combine(a: dict, b: dict):
        combined = {}
        for key in b:
            val = b[key]
            try:
                a[key]
                if isinstance(val, dict):
                    combined[key] = combine(val, a[key])
                elif isinstance(val, list):
                    combined[key] = val
                    for v in a[key]:
                        combined[key].append(v)
                else:
                    combined[key] = val
            except KeyError:
                combined[key] = val

        for key in a:
            try:
                b[key]
            except KeyError:
                combined[key] = a[key]

        return combined

    # Merge configs (using nasty casts)
    return cast(ArchMgrConfig, combine(cast(dict, config), cast(dict, new_config)))