// Author: fruit.com.cn
import { createContext, useCallback, useContext, useEffect, useMemo, useRef, useState } from 'react';
import { getLocale } from '../../i18n';
import { detectLocaleFromIp } from '../../shared/lib/geo';
import { applySeo } from '../../shared/lib/seo';

const LocaleContext = createContext(null);
const UiContext = createContext(null);
const LANG_STORAGE_KEY = 'ymb.lang';
const SUPPORTED_LANGS = ['id', 'en', 'zh'];

function readUrlLang() {
  const value = new URLSearchParams(window.location.search).get('lang');
  return SUPPORTED_LANGS.includes(value) ? value : '';
}

function readStoredLang() {
  try {
    const value = window.localStorage.getItem(LANG_STORAGE_KEY);
    return SUPPORTED_LANGS.includes(value) ? value : '';
  } catch {
    return '';
  }
}

function readNavigatorLang() {
  const code = (navigator.language || '').toLowerCase();
  if (code.startsWith('id')) return 'id';
  if (code.startsWith('zh')) return 'zh';
  return 'en';
}

function detectInitialLang() {
  return readUrlLang() || readStoredLang() || readNavigatorLang();
}

export function AppProviders({ children }) {
  const [lang, setLangState] = useState(detectInitialLang);
  const [query, setQuery] = useState('');
  const [sidebarOpen, setSidebarOpen] = useState(() => window.innerWidth > 760);
  const userSelectedRef = useRef(false);
  const locale = getLocale(lang);

  // 首次进入且没有明确偏好时，按 IP 归属地自动匹配语言
  useEffect(() => {
    if (readUrlLang() || readStoredLang()) return undefined;
    let active = true;
    detectLocaleFromIp().then((detected) => {
      if (active && detected && !userSelectedRef.current) setLangState(detected);
    });
    return () => {
      active = false;
    };
  }, []);

  const setLang = useCallback((next) => {
    userSelectedRef.current = true;
    setLangState(next);
    try {
      window.localStorage.setItem(LANG_STORAGE_KEY, next);
    } catch {
      // 隐私模式下写入失败时仍保证本次会话生效
    }
  }, []);

  useEffect(() => {
    applySeo(locale, window.location.pathname);
  }, [lang, locale]);

  const localeValue = useMemo(() => ({ lang, locale, setLang }), [lang, locale, setLang]);
  const uiValue = useMemo(() => ({ query, setQuery, sidebarOpen, setSidebarOpen }), [query, sidebarOpen]);

  return (
    <LocaleContext.Provider value={localeValue}>
      <UiContext.Provider value={uiValue}>{children}</UiContext.Provider>
    </LocaleContext.Provider>
  );
}

export function useLocale() {
  const value = useContext(LocaleContext);
  if (!value) throw new Error('useLocale must be used within AppProviders');
  return value;
}

export function useUi() {
  const value = useContext(UiContext);
  if (!value) throw new Error('useUi must be used within AppProviders');
  return value;
}