"""Runtime UI translation: English / Japanese / Vietnamese.

``tr(key, **kwargs)`` returns the string for the current language (falling
back to English, then the key itself so a missing entry is still visible
instead of crashing). ``.format(**kwargs)`` is applied when placeholders are
passed, so callers can do e.g. ``tr("composer.attachments", n=3)``.

Persistent, long-lived widgets (the main window chrome, the tabs, the
sidebar, the composer, ...) must reflect a language change immediately, so
they register a zero-arg callback via :func:`on_language_changed` that
re-applies ``tr()`` to their own text; the callback runs once right away and
again every time the language changes. Transient dialogs (Settings, Skills,
Flow, Permission...) are rebuilt from scratch each time they are opened, so
they simply call ``tr()`` while constructing their widgets and need no
registration.
"""
from __future__ import annotations

from typing import Callable, Dict, List

LANGUAGES: Dict[str, str] = {"en": "English", "ja": "日本語", "vi": "Tiếng Việt"}
# Short codes shown in the compact top-bar switcher (Settings keeps the full names above).
LANGUAGE_SHORT: Dict[str, str] = {"en": "EN", "ja": "JP", "vi": "VN"}
DEFAULT_LANGUAGE = "vi"

_current = DEFAULT_LANGUAGE
_listeners: List[Callable[[], None]] = []

# key -> {"en": ..., "ja": ..., "vi": ...}
from . import i18n_login_dialog as _i18n_login_dialog
from . import i18n_sidebar as _i18n_sidebar
from . import i18n_composer as _i18n_composer
from . import i18n_hint as _i18n_hint
from . import i18n_cowork_tab as _i18n_cowork_tab
from . import i18n_settings_dialog as _i18n_settings_dialog
from . import i18n_skills_dialog as _i18n_skills_dialog
from . import i18n_libreoffice_view as _i18n_libreoffice_view
from . import i18n_agents_admin_tab as _i18n_agents_admin_tab
from . import i18n_monitoring_overview as _i18n_monitoring_overview

# Gộp theo đúng thứ tự cũ: khoá trùng thì cụm sau thắng, y như khi tất cả
# còn nằm chung một dict literal.
STRINGS: Dict[str, Dict[str, str]] = {
    **_i18n_login_dialog.STRINGS,
    **_i18n_sidebar.STRINGS,
    **_i18n_composer.STRINGS,
    **_i18n_hint.STRINGS,
    **_i18n_cowork_tab.STRINGS,
    **_i18n_settings_dialog.STRINGS,
    **_i18n_skills_dialog.STRINGS,
    **_i18n_libreoffice_view.STRINGS,
    **_i18n_agents_admin_tab.STRINGS,
    **_i18n_monitoring_overview.STRINGS,
}


def set_language(lang: str) -> None:
    """Switch the active language and notify every registered persistent widget."""
    global _current
    if lang not in LANGUAGES:
        lang = DEFAULT_LANGUAGE
    if lang == _current:
        return
    _current = lang
    for fn in list(_listeners):
        try:
            fn()
        except RuntimeError:
            # The widget behind this callback was already destroyed — drop it.
            try:
                _listeners.remove(fn)
            except ValueError:
                pass


def get_language() -> str:
    return _current


def tr(key: str, **kwargs) -> str:
    entry = STRINGS.get(key)
    if not entry:
        return key
    text = entry.get(_current) or entry.get("en") or next(iter(entry.values()), key)
    return text.format(**kwargs) if kwargs else text


def on_language_changed(fn: Callable[[], None]) -> None:
    """Register a callback that re-applies translations to a persistent widget.

    Called once immediately (to apply the current language) and again on every
    future call to :func:`set_language`."""
    _listeners.append(fn)
    fn()