Modularize bridge and improve control GUI

frigate_camera_control_bridge/i18n.py

@@ -0,0 +1,81 @@
+import gettext
+import logging
+import os
+from pathlib import Path
+
+
+LOG = logging.getLogger("frigate-camera-control-bridge")
+TRANSLATION_DOMAIN = "frigate_camera_control_bridge"
+DEFAULT_LANGUAGE = "en"
+DEFAULT_LOCALE_DIR = Path(__file__).resolve().parents[1] / "locale"
+LOCALE_DIR = Path(os.environ.get("LOCALE_DIR", DEFAULT_LOCALE_DIR))
+
+_TRANSLATIONS = {}
+_AVAILABLE_LANGUAGES = None
+
+
+def parse_po_language_name(path):
+    # gettext compiled catalogs do not expose a friendly language name, so the
+    # editable .po file may carry an optional Language-Name header for the GUI.
+    try:
+        text = path.read_text(encoding="utf-8")
+    except OSError:
+        return None
+    for line in text.splitlines():
+        if line.startswith('"Language-Name:'):
+            return line.split(":", 1)[1].strip().strip("\\n\"")
+    return None
+
+
+def available_languages():
+    # Discover languages dynamically from locale/*/LC_MESSAGES/*.mo. Adding a
+    # language should not require a code change; ship a new .po/.mo pair instead.
+    global _AVAILABLE_LANGUAGES
+    if _AVAILABLE_LANGUAGES is not None:
+        return _AVAILABLE_LANGUAGES
+
+    languages = {DEFAULT_LANGUAGE: DEFAULT_LANGUAGE.upper()}
+    if LOCALE_DIR.exists():
+        for item in sorted(LOCALE_DIR.iterdir()):
+            if not item.is_dir():
+                continue
+            code = item.name
+            catalog = item / "LC_MESSAGES" / f"{TRANSLATION_DOMAIN}.mo"
+            if catalog.exists():
+                languages[code] = (
+                    parse_po_language_name(item / "LC_MESSAGES" / f"{TRANSLATION_DOMAIN}.po")
+                    or code.upper()
+                )
+    _AVAILABLE_LANGUAGES = languages
+    return languages
+
+
+def normalize_language(value):
+    if not value:
+        return DEFAULT_LANGUAGE
+    base = str(value).lower().replace("_", "-").split("-", 1)[0]
+    return base if base in available_languages() else DEFAULT_LANGUAGE
+
+
+def translation_for(lang):
+    # fallback=True makes English msgids work even if a translation file is
+    # missing, which is useful while developing a new language catalog.
+    lang = normalize_language(lang)
+    if lang not in _TRANSLATIONS:
+        _TRANSLATIONS[lang] = gettext.translation(
+            TRANSLATION_DOMAIN,
+            localedir=str(LOCALE_DIR),
+            languages=[lang],
+            fallback=True,
+        )
+    return _TRANSLATIONS[lang]
+
+
+def text_for(lang, msgid, **kwargs):
+    text = translation_for(lang).gettext(msgid)
+    if kwargs:
+        try:
+            return text.format(**kwargs)
+        except KeyError as exc:
+            LOG.warning("missing translation placeholder %s for %s", exc, msgid)
+    return text