onw/i18n.py

"""UI language. The UI is written in Japanese; i18n.json maps those strings to English and Simplified Chinese.

  T("ロードできません: {0}", e)    the string in the current language (config "lang": auto / ja / en / zh)
  page(path)                       an HTML page with the table for its language (web/i18n.js does the swapping)
"""
import json, os, time

HERE = os.path.dirname(os.path.abspath(__file__))
LANGS = {"ja": "日本語", "en": "English", "zh": "简体中文"}
_table = None
_cur = (0.0, "ja")


def table():
    global _table
    if _table is None:
        with open(os.path.join(HERE, "i18n.json"), encoding="utf8") as f:
            _table = json.load(f)
    return _table


def system():
    """The OS display language: ja / zh / en (everything else)."""
    try:
        if os.name == "nt":
            import ctypes
            return {0x11: "ja", 0x04: "zh"}.get(ctypes.windll.kernel32.GetUserDefaultUILanguage() & 0x3FF, "en")
        v = next((os.environ[k] for k in ("LANGUAGE", "LC_ALL", "LC_MESSAGES", "LANG") if os.environ.get(k)), "")
        return "ja" if v.startswith("ja") else "zh" if v.startswith("zh") else "en"
    except Exception:
        return "en"


def current(cfg=None):
    global _cur
    if cfg is None:
        if time.time() - _cur[0] < 2:                      # T() is called many times per page refresh
            return _cur[1]
        from . import app
        cfg = app.load_config()
    v = cfg.get("lang", "auto")
    lang = v if v in LANGS else system()
    _cur = (time.time(), lang)
    return lang


def strings(lang):
    """Japanese -> lang (Chinese falls back to English where it has no entry)."""
    if lang == "ja":
        return {}
    t = table()
    return {**t.get("en", {}), **t.get(lang, {})}


def T(s, *a, lang=None):
    lang = lang or current()
    r = s if lang == "ja" else strings(lang).get(s, s)
    return r.format(*a) if a else r


def page(path, lang=None):
    """The page's HTML with its language table and web/i18n.js in place of the <script>/*i18n*/</script> marker."""
    if lang is None:
        from . import app
        lang = current(app.load_config())                  # not the cached value: the page may follow a language change
    html = open(path, encoding="utf8").read()
    js = open(os.path.join(HERE, "web", "i18n.js"), encoding="utf8").read()
    data = json.dumps(strings(lang), ensure_ascii=False).replace("</", "<\\/")
    html = html.replace('<html lang="ja">', f'<html lang="{lang}">', 1)
    zh = ('<style>html:lang(zh) body { font-family: system-ui, "Segoe UI", "Microsoft YaHei UI", "PingFang SC", '
          '"Noto Sans CJK SC", "Noto Sans SC", sans-serif; }</style>\n')
    html = html.replace("<script>/*i18n*/</script>", f"{zh}<script>const LANG = {json.dumps(lang)}, I18N = {data};\n{js}</script>", 1)
    return html.encode("utf8")