"""Unit tests for i18n translation helper."""

import json
from pathlib import Path

from webdrop_bridge.utils import i18n


class TestI18n:
    """Tests for translation lookup and fallback behavior."""

    def test_tr_lazy_initialization_uses_english_defaults(self):
        """Translator should lazily initialize and resolve known keys."""
        # Force a fresh singleton state for this test.
        i18n._translator = i18n.Translator()  # type: ignore[attr-defined]

        assert i18n.tr("settings.title") == "Settings"

    def test_initialize_with_language_falls_back_to_english(self, tmp_path: Path):
        """Missing keys in selected language should fall back to English."""
        translations = tmp_path / "translations"
        translations.mkdir(parents=True, exist_ok=True)

        (translations / "en.json").write_text(
            json.dumps(
                {
                    "greeting": "Hello {name}",
                    "settings.title": "Settings",
                }
            ),
            encoding="utf-8",
        )
        (translations / "de.json").write_text(
            json.dumps(
                {
                    "settings.title": "Einstellungen",
                }
            ),
            encoding="utf-8",
        )

        i18n._translator = i18n.Translator()  # type: ignore[attr-defined]
        i18n.initialize("de", translations)

        assert i18n.tr("settings.title") == "Einstellungen"
        assert i18n.tr("greeting", name="Alex") == "Hello Alex"

    def test_get_available_languages_reads_translation_files(self, tmp_path: Path):
        """Available languages should be discovered from JSON files."""
        translations = tmp_path / "translations"
        translations.mkdir(parents=True, exist_ok=True)
        (translations / "en.json").write_text("{}", encoding="utf-8")
        (translations / "fr.json").write_text("{}", encoding="utf-8")

        i18n._translator = i18n.Translator()  # type: ignore[attr-defined]
        i18n.initialize("en", translations)

        available = i18n.get_available_languages()
        assert "en" in available
        assert "fr" in available