from __future__ import annotations

import json
from pathlib import Path

import pycountry

LANGUAGE_ALIASES_JSON = Path(__file__).with_name("language_aliases.json")


def _load_json_mapping(path: Path) -> dict[str, object]:
    with path.open(encoding="utf-8") as f:
        data = json.load(f)
    if not isinstance(data, dict):
        raise ValueError(f"Expected JSON object in {path}")
    return data


def _load_language_aliases(path: Path = LANGUAGE_ALIASES_JSON) -> dict[str, tuple[str, ...]]:
    aliases = _load_json_mapping(path)
    normalized: dict[str, tuple[str, ...]] = {}
    for canonical, source_aliases in aliases.items():
        if not isinstance(canonical, str) or not isinstance(source_aliases, list):
            continue
        normalized[canonical] = tuple(alias for alias in source_aliases if isinstance(alias, str) and alias)
    return normalized


LANGUAGE_ALIASES = _load_language_aliases()
ALL_LANGS = list(LANGUAGE_ALIASES.keys())
LATIN_ONLY_LANGS = {
    lang
    for lang in ALL_LANGS
    if lang
    not in {
        "ar",
        "fa",
        "ps",
        "sd",
        "ug",
        "ur",
        "ckb",
        "he",
        "yi",
        "ru",
        "uk",
        "be",
        "bg",
        "mk",
        "kk",
        "mn",
        "tt",
        "ky",
        "tg",
        "ba",
        "ce",
        "el",
        "hy",
        "ka",
        "am",
        "ti",
        "dv",
        "km",
        "lo",
        "my",
        "th",
        "si",
        "bo",
        "hi",
        "mr",
        "ne",
        "bn",
        "as",
        "ta",
        "te",
        "gu",
        "kn",
        "ml",
        "pa",
        "or",
        "ja",
        "zh",
        "ko",
    }
}
LANG_ISO2_TO_ISO3 = {
    lang: (
        getattr(pycountry.languages.get(alpha_2=lang) or pycountry.languages.get(alpha_3=lang), "alpha_3", None)
        or lang
    )
    for lang in ALL_LANGS
}
LANG_ALIASES = {
    alias: canonical
    for canonical, aliases in LANGUAGE_ALIASES.items()
    for alias in aliases
}


def canonical_lang(lang: str) -> str:
    return LANG_ALIASES.get(lang, lang)


def label_script_suffix(label: str) -> str | None:
    label = (label or "").strip()
    if "_" not in label:
        return None
    suffix = label.rsplit("_", 1)[1].strip()
    return suffix or None


def is_latin_script_label(label: str) -> bool:
    return label_script_suffix(label) == "Latn"


def is_latin_script_compatible(lang: str, label: str) -> bool:
    """Return False when a `_Latn` label is used for a non-Latin language."""
    if not is_latin_script_label(label):
        return True
    return canonical_lang(lang) in LATIN_ONLY_LANGS