diablo2-web/src/i18n/lang.ts

/**
 * Centralized language detection & runtime state (`CHI` / `'zh'` vs `ENG` / `'en'`)
 * for Diablo II v1.13c web port (Issue #503).
 */

import { resolveTblKey } from '../data/canonical-tbl-strings.ts'

export type GameLang = 'zh' | 'en'
export type TblLang = 'CHI' | 'ENG'

export function lookupTbl(key: string, lang: TblLang = getTblLang()): string | undefined {
  return resolveTblKey(key, lang)
}


let overrideLang: GameLang | null = null
const listeners = new Set<(lang: TblLang) => void>()

export function toGameLang(lang: GameLang | TblLang | string): GameLang {
  const norm = String(lang).trim().toLowerCase()
  return norm === 'en' || norm === 'eng' || norm === 'english' ? 'en' : 'zh'
}

export function toTblLang(lang: GameLang | TblLang | string): TblLang {
  return toGameLang(lang) === 'en' ? 'ENG' : 'CHI'
}

export function detectLangFromUrl(urlStr?: string): TblLang {
  if (typeof urlStr === 'string' && urlStr.trim() !== '') {
    try {
      const u = new URL(urlStr, 'http://localhost')
      const q = u.searchParams.get('lang')?.trim().toLowerCase()
      if (q === 'en' || q === 'eng' || q === 'english') return 'ENG'
      if (q === 'zh' || q === 'chi' || q === 'zh-cn' || q === 'cn' || q === 'chinese') return 'CHI'
      const path = u.pathname.toLowerCase()
      if (path.endsWith('/acts-en.html') || path.endsWith('acts-en.html') || path.endsWith('/arena-en.html') || path.endsWith('arena-en.html') || path.endsWith('/bnet.html') || path.endsWith('bnet.html')) {
        return 'ENG'
      }
      if (path.endsWith('/acts-zh.html') || path.endsWith('acts-zh.html') || path.endsWith('/arena-zh.html') || path.endsWith('arena-zh.html')) {
        return 'CHI'
      }
      return 'CHI'
    } catch {
      // fall through
    }
  }
  return detectInitialLang() === 'en' ? 'ENG' : 'CHI'
}

export function detectInitialLang(): GameLang {
  if (typeof window !== 'undefined' && window.location) {
    try {
      const params = new URLSearchParams(window.location.search || '')
      const q = params.get('lang')?.trim().toLowerCase()
      if (q === 'en' || q === 'eng' || q === 'english') return 'en'
      if (q === 'zh' || q === 'chi' || q === 'zh-cn' || q === 'cn' || q === 'chinese') return 'zh'
    } catch {
      // Ignore malformed query string
    }
    const path = (window.location.pathname || '').toLowerCase()
    if (path.endsWith('/acts-en.html') || path.endsWith('acts-en.html') || path.endsWith('/arena-en.html') || path.endsWith('arena-en.html') || path.endsWith('/bnet.html') || path.endsWith('bnet.html')) {
      return 'en'
    }
    if (path.endsWith('/acts-zh.html') || path.endsWith('acts-zh.html') || path.endsWith('/arena-zh.html') || path.endsWith('arena-zh.html')) {
      return 'zh'
    }
  }
  if (typeof document !== 'undefined' && document.documentElement?.lang) {
    const docLang = document.documentElement.lang.trim().toLowerCase()
    if (docLang.startsWith('en')) return 'en'
    if (docLang.startsWith('zh')) return 'zh'
  }
  return 'zh'
}

export function getGameLang(): GameLang {
  return overrideLang ?? detectInitialLang()
}

export function getCurrentLang(): GameLang {
  return getGameLang()
}

export function getTblLang(): TblLang {
  return getGameLang() === 'en' ? 'ENG' : 'CHI'
}

export function isEn(): boolean {
  return getGameLang() === 'en'
}

export function isEnglish(): boolean {
  return getGameLang() === 'en'
}

function notifyListeners(): void {
  const tbl = getTblLang()
  for (const fn of listeners) {
    try {
      fn(tbl)
    } catch {
      // ignore listener errors
    }
  }
}

export function setGameLang(lang: GameLang | TblLang | null): void {
  if (lang === null) {
    overrideLang = null
    notifyListeners()
    return
  }
  overrideLang = toGameLang(lang)
  notifyListeners()
}

export function setCurrentLang(lang: GameLang | TblLang | null): void {
  setGameLang(lang)
}

export function setTblLang(lang: TblLang | GameLang | null): void {
  setGameLang(lang)
}

export function initLangFromBrowser(): TblLang {
  overrideLang = detectInitialLang()
  notifyListeners()
  return getTblLang()
}

export function onTblLangChange(listener: (lang: TblLang) => void): () => void {
  listeners.add(listener)
  return () => {
    listeners.delete(listener)
  }
}

export function buildLangSwitchHref(
  targetLang?: TblLang | GameLang,
  currentPath?: string,
  currentSearch?: string,
): string {
  const target = targetLang ? toTblLang(targetLang) : (getTblLang() === 'ENG' ? 'CHI' : 'ENG')
  const searchStr = currentSearch ?? (typeof window !== 'undefined' && window.location ? window.location.search : '')
  const params = new URLSearchParams(searchStr || '')
  params.delete('lang')
  const qs = params.toString()
  const targetPage = target === 'ENG' ? '/acts-en.html' : '/acts-zh.html'
  void currentPath
  return qs ? `${targetPage}?${qs}` : targetPage
}