import { useState, useEffect } from 'react'
import { useNavigate, useParams } from 'react-router-dom'
import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
import { api } from '../../api/client'
import ImagePicker from './components/ImagePicker'
import ConfirmDialog from '../../components/ConfirmDialog'

function Field({ label, hint, error, required, children }) {
  return (
    <div className="space-y-1.5">
      <div className="flex items-baseline justify-between">
        <label className="text-sm font-medium text-gray-300">
          {label} {required && <span className="text-red-400">*</span>}
        </label>
        {hint && <span className="text-xs text-gray-500">{hint}</span>}
      </div>
      {children}
      {error && <div className="text-[11px] text-red-400">{error}</div>}
    </div>
  )
}

const inputCls = 'w-full rounded-lg border border-white/10 bg-gray-950 px-3 py-2 text-sm outline-none focus:border-emerald-500/50 transition'

export default function AdminMenuForm() {
  const navigate = useNavigate()
  const queryClient = useQueryClient()
  const { id } = useParams()
  const isEdit = !!id

  const [pickerOpen, setPickerOpen] = useState(false)
  const [confirmDelete, setConfirmDelete] = useState(false)
  const [form, setForm] = useState({
    title: '',
    description: '',
    slug: '', // 사용자 입력 (앞 / 제외)
    image_id: null,
    image: null, // 미리보기용 캐시
  })
  const [errors, setErrors] = useState({})

  // 편집 모드일 때 기존 데이터 로드
  const { data: menuData } = useQuery({
    queryKey: ['admin', 'menus', id],
    queryFn: () => api(`/api/admin/menus/${id}`),
    enabled: isEdit,
  })

  // id 변경 또는 데이터 로드 시 폼 동기화
  useEffect(() => {
    if (!isEdit) {
      setForm({ title: '', description: '', slug: '', image_id: null, image: null })
      return
    }
    if (menuData) {
      setForm({
        title: menuData.title || '',
        description: menuData.description || '',
        slug: (menuData.url || '').replace(/^\/+/, ''),
        image_id: menuData.image_id,
        image: menuData.image,
      })
    }
  }, [isEdit, id, menuData])

  const update = (patch) => setForm((prev) => ({ ...prev, ...patch }))

  // slug에서 / 자동 제거 (붙여넣기 등 대비)
  const handleSlugChange = (value) => {
    update({ slug: value.replace(/^\/+/, '') })
  }

  const fullUrl = `/${form.slug.trim()}`

  const validate = () => {
    const errs = {}
    if (!form.title.trim()) errs.title = '제목을 입력해주세요'
    if (!form.slug.trim()) errs.slug = '경로를 입력해주세요'
    else if (!/^[a-zA-Z0-9\-/]+$/.test(form.slug.trim())) errs.slug = '영문, 숫자, 하이픈(-), 슬래시(/)만 사용할 수 있습니다'
    setErrors(errs)
    return Object.keys(errs).length === 0
  }

  const saveMutation = useMutation({
    mutationFn: async () => {
      const payload = {
        title: form.title.trim(),
        description: form.description.trim(),
        url: fullUrl,
        image_id: form.image_id,
      }
      if (isEdit) {
        return api(`/api/admin/menus/${id}`, { method: 'PATCH', body: payload })
      }
      return api('/api/admin/menus', { method: 'POST', body: payload })
    },
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['admin', 'menus'] })
      queryClient.invalidateQueries({ queryKey: ['menus'] })
      navigate('/admin')
    },
    onError: (err) => alert(err.message),
  })

  const handleSubmit = (e) => {
    e.preventDefault()
    if (!validate()) return
    saveMutation.mutate()
  }

  const deleteMutation = useMutation({
    mutationFn: () => api(`/api/admin/menus/${id}`, { method: 'DELETE' }),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['admin', 'menus'] })
      queryClient.invalidateQueries({ queryKey: ['menus'] })
      navigate('/admin')
    },
    onError: (err) => alert(err.message),
  })

  return (
    <div className="space-y-6 max-w-2xl mx-auto">
      <div>
        <h2 className="text-lg font-semibold">{isEdit ? '메뉴 항목 편집' : '메뉴 항목 추가'}</h2>
        <p className="text-sm text-gray-500 mt-0.5">홈 화면에 표시되는 카드의 정보를 설정합니다</p>
      </div>

      <form onSubmit={handleSubmit} className="space-y-5 rounded-2xl border border-white/5 bg-gray-900/40 p-6">
        {/* 미리보기 */}
        <div className="rounded-xl border border-white/5 bg-gray-950/50 p-4">
          <div className="text-xs text-gray-500 mb-3">미리보기</div>
          <div className="rounded-xl border border-white/10 bg-gradient-to-br from-gray-900/80 to-gray-900/40 p-5">
            <div className="flex items-start gap-4">
              <div className="shrink-0 w-12 h-12 rounded-xl bg-gradient-to-br from-gray-800 to-gray-900 border border-white/5 flex items-center justify-center overflow-hidden">
                <img src={form.image?.url || '/default.png'} alt="" className="w-9 h-9 object-contain" />
              </div>
              <div className="flex-1 min-w-0">
                <h3 className="font-semibold">{form.title || '제목 없음'}</h3>
                <p className="text-sm text-gray-400 mt-1">{form.description || '설명 없음'}</p>
              </div>
            </div>
          </div>
        </div>

        <Field label="제목" required error={errors.title}>
          <input
            type="text"
            value={form.title}
            onChange={(e) => update({ title: e.target.value })}
            placeholder="예: 주간 보스 수익 계산기"
            className={inputCls}
          />
        </Field>

        <Field label="설명" hint="카드에 표시되는 부가 설명">
          <input
            type="text"
            value={form.description}
            onChange={(e) => update({ description: e.target.value })}
            placeholder="예: 캐릭터별 보스 결정석 수익을 계산합니다"
            className={inputCls}
          />
        </Field>

        <Field label="경로" required error={errors.slug}>
          <div className={`flex items-stretch rounded-lg border bg-gray-950 transition focus-within:border-emerald-500/50 ${
            errors.slug ? 'border-red-500/40' : 'border-white/10'
          }`}>
            <span className="flex items-center px-3 text-sm text-gray-500 border-r border-white/10 select-none">/</span>
            <input
              type="text"
              value={form.slug}
              onChange={(e) => handleSlugChange(e.target.value)}
              placeholder="boss-crystal"
              className="flex-1 min-w-0 bg-transparent px-3 py-2 text-sm outline-none"
            />
          </div>
          {form.slug.trim() && !errors.slug && (
            <div className="text-xs text-gray-500 mt-1.5 flex items-center gap-1.5">
              <span>전체 URL:</span>
              <code className="text-emerald-400 bg-gray-950/50 px-1.5 py-0.5 rounded">https://maple.caadiq.co.kr{fullUrl}</code>
            </div>
          )}
        </Field>

        <Field label="아이콘 이미지" hint="선택사항">
          <div className="flex items-center gap-3">
            <button
              type="button"
              onClick={() => setPickerOpen(true)}
              className="w-16 h-16 rounded-lg border border-white/10 hover:border-emerald-500/40 bg-gray-950 flex items-center justify-center overflow-hidden transition shrink-0 cursor-pointer"
            >
              {form.image?.url ? (
                <img src={form.image.url} alt="" className="max-w-[80%] max-h-[80%] object-contain" />
              ) : (
                <span className="text-2xl text-gray-700">+</span>
              )}
            </button>
            <div className="flex-1 min-w-0">
              {form.image ? (
                <>
                  <div className="text-sm font-medium truncate">{form.image.name}</div>
                  <button
                    type="button"
                    onClick={() => update({ image_id: null, image: null })}
                    className="text-xs text-red-400 hover:text-red-300 transition mt-1"
                  >
                    이미지 제거
                  </button>
                </>
              ) : (
                <div className="text-sm text-gray-500">이미지 선택</div>
              )}
            </div>
          </div>
        </Field>

        <div className="flex items-center gap-2 pt-2">
          {isEdit && (
            <button
              type="button"
              onClick={() => setConfirmDelete(true)}
              className="rounded-lg border border-red-500/30 text-red-400 hover:bg-red-500/10 hover:border-red-500/50 px-4 py-2.5 text-sm transition"
            >
              삭제
            </button>
          )}
          <div className="flex-1" />
          <button
            type="button"
            onClick={() => navigate('/admin')}
            className="rounded-lg border border-white/10 px-5 py-2.5 text-sm hover:bg-white/5 transition"
          >
            취소
          </button>
          <button
            type="submit"
            disabled={saveMutation.isPending}
            className="rounded-lg bg-emerald-600 hover:bg-emerald-500 px-5 py-2.5 text-sm font-medium disabled:opacity-50 transition shadow-lg shadow-emerald-500/20"
          >
            {saveMutation.isPending ? '저장 중...' : (isEdit ? '저장' : '추가')}
          </button>
        </div>
      </form>

      <ConfirmDialog
        open={confirmDelete}
        onClose={() => setConfirmDelete(false)}
        onConfirm={() => deleteMutation.mutate()}
        title="메뉴 삭제"
        description={`"${form.title}" 메뉴를 삭제하시겠습니까?\n\n이 작업은 되돌릴 수 없습니다.`}
        confirmText="삭제"
        destructive
        loading={deleteMutation.isPending}
      />

      <ImagePicker
        open={pickerOpen}
        onClose={() => setPickerOpen(false)}
        currentImageId={form.image_id}
        onSelect={(img) => update({ image_id: img?.id || null, image: img })}
      />
    </div>
  )
}