export const UI_LANGUAGES = ["en", "ko"] as const;

export type UiLanguage = (typeof UI_LANGUAGES)[number];

const ENGLISH_STRINGS = {
	"settings.title": "Settings",
	"settings.navigationHint": "(tab to cycle)",
	"settings.selectHint": "  Enter to select · Esc to go back",
	"settings.preview": "Preview:",
	"settings.tab.appearance": "Appearance",
	"settings.tab.model": "Model",
	"settings.tab.interaction": "Interaction",
	"settings.tab.context": "Context",
	"settings.tab.memory": "Memory",
	"settings.tab.editing": "Editing",
	"settings.tab.tools": "Tools",
	"settings.tab.tasks": "Tasks",
	"settings.tab.providers": "Providers",
	"settings.tab.notifications": "Notifications",
	"settings.tab.plugins": "Plugins",
	"settings.tab.gjcBundles": "GJC Bundles",
	"settings.language.label": "Language",
	"settings.language.description": "Language for human-facing interactive UI text",
	"settings.language.english": "English",
	"settings.language.korean": "Korean (한국어)",
	"language.current": "Current UI language:",
	"language.changed": "UI language changed to",
	"language.unknown": "Unknown language",
} as const;

export type UiStringKey = keyof typeof ENGLISH_STRINGS;

const KOREAN_STRINGS: Record<UiStringKey, string> = {
	"settings.title": "설정",
	"settings.navigationHint": "(Tab 키로 전환)",
	"settings.selectHint": "  Enter: 선택 · Esc: 뒤로",
	"settings.preview": "미리보기:",
	"settings.tab.appearance": "화면",
	"settings.tab.model": "모델",
	"settings.tab.interaction": "상호작용",
	"settings.tab.context": "컨텍스트",
	"settings.tab.memory": "메모리",
	"settings.tab.editing": "편집",
	"settings.tab.tools": "도구",
	"settings.tab.tasks": "작업",
	"settings.tab.providers": "공급자",
	"settings.tab.notifications": "알림",
	"settings.tab.plugins": "플러그인",
	"settings.tab.gjcBundles": "GJC 번들",
	"settings.language.label": "언어",
	"settings.language.description": "사람이 읽는 대화형 UI 텍스트의 언어",
	"settings.language.english": "English",
	"settings.language.korean": "한국어",
	"language.current": "현재 UI 언어:",
	"language.changed": "UI 언어를 다음으로 변경했습니다:",
	"language.unknown": "알 수 없는 언어",
};

/** User selection is authoritative; invalid or unavailable values deterministically fall back to English. */
export function resolveUiLanguage(value: unknown): UiLanguage {
	return value === "ko" ? "ko" : "en";
}

export function uiString(language: unknown, key: UiStringKey): string {
	return resolveUiLanguage(language) === "ko" ? KOREAN_STRINGS[key] : ENGLISH_STRINGS[key];
}

/** Endonym shown by `/language` and the language submenu. */
export const UI_LANGUAGE_LABELS: Record<UiLanguage, string> = {
	en: "English",
	ko: "한국어",
};

/** Spellings accepted by `/language`; the canonical codes stay authoritative. */
const UI_LANGUAGE_ALIASES: Readonly<Record<string, UiLanguage>> = {
	en: "en",
	eng: "en",
	english: "en",
	ko: "ko",
	kr: "ko",
	kor: "ko",
	korean: "ko",
	한국어: "ko",
};

export function parseUiLanguage(value: string): UiLanguage | undefined {
	const normalized = value.trim().toLowerCase();
	if (!normalized) return undefined;
	const prefix = normalized.split(/[-_]/)[0] ?? "";
	// Own-property lookups only: untrusted slash-command input must not reach
	// inherited keys (`__proto__`, `constructor`) through either path.
	if (Object.hasOwn(UI_LANGUAGE_ALIASES, normalized)) return UI_LANGUAGE_ALIASES[normalized];
	return Object.hasOwn(UI_LANGUAGE_ALIASES, prefix) ? UI_LANGUAGE_ALIASES[prefix] : undefined;
}