# -*- coding: utf-8 -*-
"""
Internationalization module.
"""
from typing import Optional, TypeAlias

NestedDict: TypeAlias = dict[str, 'str | NestedDict']

i18n_dict: dict[str, NestedDict] = {
        "en"     : {
                "docstring": {
                        "args"     : "Args",
                        "return"   : "Return",
                        "attribute": "Attribute",
                        "raises"   : "Raises",
                        "example"  : "Examples",
                        "yields"   : "Yields",
                },
                "src": "Source code",
        },
        "zh-Hans": {
                "docstring": {
                        "args"     : "参数",
                        "return"   : "返回",
                        "attribute": "属性",
                        "raises"   : "引发",
                        "example"  : "示例",
                        "yields"   : "产出",
                },
                "src": "源码",
        },
        "zh-Hant": {
                "docstring": {
                        "args"     : "參數",
                        "return"   : "返回",
                        "attribute": "屬性",
                        "raises"   : "引發",
                        "example"  : "示例",
                        "yields"   : "產出",
                },
                "src": "源碼",
        },
        "ja"     : {
                "docstring": {
                        "args"     : "引数",
                        "return"   : "戻り値",
                        "attribute": "属性",
                        "raises"   : "例外",
                        "example"  : "例",
                        "yields"   : "生成",
                },
                "src": "ソースコード",
        },
}


def flat_i18n_dict(data: dict[str, NestedDict]) -> dict[str, dict[str, str]]:
    """
    Flatten i18n_dict.
    Examples:
        ```python
        {
            "en": {
                "docs": {
                    "key1": "val1",
                    "key2": "val2",
                }
            }
        }
        ```

        to

        ```python
        {
            "en": {
                "docs.key1": "val1",
                "docs.key2": "val2",
            }
        }
        ```
    Returns:
    """
    ret: dict[str, dict[str, str]] = {}

    def _flat(_lang_data: NestedDict) -> dict[str, str]:
        res = {}
        for k, v in _lang_data.items():
            if isinstance(v, dict):
                for kk, vv in _flat(v).items():
                    res[f"{k}.{kk}"] = vv
            else:
                res[k] = v
        return res

    for lang, lang_data in data.items():
        ret[lang] = _flat(lang_data)

    return ret


i18n_flat_dict = flat_i18n_dict(i18n_dict)


def get_text(lang: str, key: str, default: Optional[str] = None, fallback: Optional[str] = "en") -> str:
    """
    Get text from i18n_dict.
    Args:
        lang: language name
        key: text key
        default: default text, if None return fallback language or key
        fallback: fallback language, priority is higher than default
    Returns:
        str: text
    """
    if lang in i18n_flat_dict:
        if key in i18n_flat_dict[lang]:
            return i18n_flat_dict[lang][key]

    if fallback is not None:
        return i18n_flat_dict.get(fallback, {}).get(key, default or key)
    else:
        return default or key