/**
 * Central translation helper.
 *
 * The active language lives in module scope so components can call `t(...)`
 * without threading a `language` prop through every layer. Reading `t(...)`
 * inside markup registers a dependency on `activeLanguage`, so switching the
 * language in settings re-renders every translated string.
 */
import { messages, type MessageEntry, type MessageKey } from "./messages";
import type { AppLanguage } from "./types";

let activeLanguage = $state<AppLanguage>("en");

export function setLanguage(next: AppLanguage) {
  activeLanguage = next;
}

export function getLanguage(): AppLanguage {
  return activeLanguage;
}

export function isGermanLanguage(): boolean {
  return activeLanguage === "de";
}

export type TranslationValues = Record<string, string | number>;

/** Look up `key` in the active language and fill in `{placeholders}`. */
export function t(key: MessageKey, values?: TranslationValues): string {
  const entry: MessageEntry | undefined = messages[key];
  let text: string = entry ? entry[activeLanguage] ?? entry.en : key;

  if (values) {
    for (const [name, value] of Object.entries(values)) {
      text = text.split(`{${name}}`).join(String(value));
    }
  }

  return text;
}

/** Pick the singular or plural key based on `count` and pass it as `{count}`. */
export function tPlural(one: MessageKey, many: MessageKey, count: number, values?: TranslationValues): string {
  return t(count === 1 ? one : many, { count, ...values });
}