"""Translations: one JSON file per language in webui/locales/ (e.g. en.json, de.json).

A new language only needs a new file; "_name" is the label shown in the dropdown.
Missing keys fall back to English.
"""
import json
import os

DIR = os.path.join(os.path.dirname(__file__), "locales")
FALLBACK = "en"
LANGS = {}


def load():
    LANGS.clear()
    for fname in sorted(os.listdir(DIR)):
        if fname.endswith(".json"):
            with open(os.path.join(DIR, fname), encoding="utf-8") as fh:
                LANGS[fname[:-5]] = json.load(fh)


def pick(cookie_value, default):
    if cookie_value in LANGS:
        return cookie_value
    return default if default in LANGS else FALLBACK


def catalog(lang):
    """Full dictionary for the browser, English as base."""
    return {**LANGS.get(FALLBACK, {}), **LANGS.get(lang, {})}


def translate(lang, key, **params):
    text = LANGS.get(lang, {}).get(key) or LANGS.get(FALLBACK, {}).get(key) or key
    try:
        return text.format(**params) if params else text
    except (KeyError, IndexError, ValueError):
        return text


def languages():
    return [(code, data.get("_name", code)) for code, data in sorted(LANGS.items())]


load()