import { useEffect, useMemo, useState } from 'react'
import { Languages, Loader2 } from 'lucide-react'
import { useTranslation } from 'react-i18next'
import { toast } from 'sonner'
import { useAuthStore } from '@/stores/auth-store'
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from '@/components/ui/select'
import { TitledCard } from '@/components/ui/titled-card'
import { updateUserLanguage } from '../api'
import { parseUserSettings } from '../lib'
import type { UserProfile } from '../types'

const LANGUAGE_OPTIONS = [
  { value: 'zh', label: '简体中文' },
  { value: 'en', label: 'English' },
  { value: 'fr', label: 'Français' },
  { value: 'ru', label: 'Русский' },
  { value: 'ja', label: '日本語' },
  { value: 'vi', label: 'Tiếng Việt' },
] as const

function normalizeLanguage(value?: string | null): string {
  if (!value) return 'en'
  const normalized = value.trim().replace(/_/g, '-').toLowerCase()
  if (normalized.startsWith('zh')) return 'zh'
  return LANGUAGE_OPTIONS.some((lang) => lang.value === normalized)
    ? normalized
    : 'en'
}

type LanguagePreferencesCardProps = {
  profile: UserProfile | null
  onProfileUpdate: () => void
}

export function LanguagePreferencesCard(props: LanguagePreferencesCardProps) {
  const { t, i18n } = useTranslation()
  const { auth } = useAuthStore()
  const [saving, setSaving] = useState(false)

  const savedLanguage = useMemo(() => {
    const settings = parseUserSettings(props.profile?.setting)
    return normalizeLanguage(settings.language || i18n.language)
  }, [props.profile?.setting, i18n.language])

  const [currentLanguage, setCurrentLanguage] = useState(savedLanguage)

  useEffect(() => {
    setCurrentLanguage(savedLanguage)
  }, [savedLanguage])

  const handleLanguageChange = async (language: string) => {
    const nextLanguage = normalizeLanguage(language)
    if (nextLanguage === currentLanguage) return

    const previousLanguage = currentLanguage
    setCurrentLanguage(nextLanguage)
    setSaving(true)
    await i18n.changeLanguage(nextLanguage)

    try {
      const response = await updateUserLanguage(nextLanguage)
      if (!response.success) {
        throw new Error(response.message || t('Failed to update settings'))
      }

      if (auth.user) {
        const existingSetting =
          typeof auth.user.setting === 'string'
            ? parseUserSettings(auth.user.setting)
            : (auth.user.setting ?? {})
        auth.setUser({
          ...auth.user,
          setting: JSON.stringify({
            ...existingSetting,
            language: nextLanguage,
          }),
        })
      }

      props.onProfileUpdate()
      toast.success(t('Language preference saved'))
    } catch (_error) {
      setCurrentLanguage(previousLanguage)
      await i18n.changeLanguage(previousLanguage)
      toast.error(t('Failed to update settings'))
    } finally {
      setSaving(false)
    }
  }

  return (
    <TitledCard
      title={t('Language Preferences')}
      description={t('Set the language used across the interface')}
      icon={<Languages className='h-4 w-4' />}
    >
        <div className='flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between sm:gap-4'>
          <div className='space-y-1'>
            <div className='text-sm font-medium'>{t('Interface Language')}</div>
            <p className='text-muted-foreground line-clamp-2 text-xs sm:text-sm'>
              {t(
                'Language preferences sync across your signed-in devices and affect API error messages.'
              )}
            </p>
          </div>
          <div className='flex items-center gap-2 sm:min-w-48'>
            <Select
              value={currentLanguage}
              onValueChange={handleLanguageChange}
              disabled={saving}
            >
              <SelectTrigger className='w-full sm:w-48'>
                <SelectValue placeholder={t('Select language')} />
              </SelectTrigger>
              <SelectContent>
                {LANGUAGE_OPTIONS.map((language) => (
                  <SelectItem key={language.value} value={language.value}>
                    {language.label}
                  </SelectItem>
                ))}
              </SelectContent>
            </Select>
            {saving && (
              <Loader2 className='text-muted-foreground size-4 animate-spin' />
            )}
          </div>
        </div>
    </TitledCard>
  )
}