1 files changed, 84 insertions, 0 deletions
diff --git a/src/ollama_web/i18n/__init__.py b/src/ollama_web/i18n/__init__.py
new file mode 100644
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+++ b/src/ollama_web/i18n/__init__.py
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+"""Internationalization support for ollama-web.
+
+Messages live in JSON files under ``i18n/messages/``. The default language is
+read from ``config.settings.language`` and can be overridden per-call via the
+``lang`` argument.
+"""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+from typing import Any
+
+from ollama_web.config import settings
+
+_DIR = Path(__file__).resolve().parent
+_MESSAGES_DIR = _DIR / "messages"
+
+
+def _load_messages(lang: str) -> dict[str, Any]:
+    """Load messages for a language, falling back to an empty dict on error."""
+    path = _MESSAGES_DIR / f"{lang}.json"
+    try:
+        with path.open("r", encoding="utf-8") as f:
+            return json.load(f)
+    except (FileNotFoundError, json.JSONDecodeError):
+        return {}
+
+
+_MESSAGES_CACHE: dict[str, dict[str, Any]] = {}
+
+
+def get_messages(lang: str | None = None) -> dict[str, Any]:
+    """Return the full message dictionary for the requested language."""
+    lang = resolve_language(lang)
+    if lang not in _MESSAGES_CACHE:
+        _MESSAGES_CACHE[lang] = _load_messages(lang)
+    return _MESSAGES_CACHE[lang]
+
+
+def _resolve(key: str, data: dict[str, Any]) -> Any:
+    """Resolve a dot-separated key in a nested dictionary."""
+    current: Any = data
+    for part in key.split("."):
+        if not isinstance(current, dict) or part not in current:
+            return None
+        current = current[part]
+    return current
+
+
+def resolve_language(lang_source: str | None = None) -> str:
+    """Resolve the effective language.
+
+    Priority:
+        1. Explicit ``lang_source`` argument if it is a supported filename.
+        2. ``settings.language`` if it is supported.
+        3. ``"ja"`` as a safe default.
+
+    Supported languages are determined by the JSON files present in
+    ``i18n/messages/``.
+    """
+    supported = {p.stem for p in _MESSAGES_DIR.glob("*.json")}
+    candidates = [lang_source, settings.language]
+    for candidate in candidates:
+        if candidate and candidate in supported:
+            return candidate
+    return "ja"
+
+
+def t(key: str, lang: str | None = None, fallback: str | None = None) -> str:
+    """Return a localized message string.
+
+    Args:
+        key: Dot-separated path, e.g. ``"chat.input_placeholder"``.
+        lang: Optional language override. Uses ``settings.language`` when omitted.
+        fallback: Value returned when the key is missing. Defaults to the key itself.
+
+    Returns:
+        The localized string, or the fallback value if missing.
+    """
+    value = _resolve(key, get_messages(resolve_language(lang)))
+    if isinstance(value, str):
+        return value
+    return fallback if fallback is not None else key