'use client'

import { useState, useCallback, useEffect } from 'react'
import { createPortal } from 'react-dom'
import { GraduationCap, Loader2, Sparkles, X } from 'lucide-react'
import { useLanguage } from '@/lib/i18n'
import { useAiConsent } from '@/components/legal/ai-consent-provider'
import { toast } from 'sonner'
import { cn } from '@/lib/utils'

export type FlashcardStyle = 'qa' | 'cloze' | 'concept'

export interface PreviewCard {
  front: string
  back: string
  type: FlashcardStyle
}

interface FlashcardGenerateDialogProps {
  open: boolean
  onClose: () => void
  noteId: string
  noteTitle: string
  onSaved?: (deckId: string) => void
}

export function FlashcardGenerateDialog({
  open,
  onClose,
  noteId,
  noteTitle,
  onSaved,
}: FlashcardGenerateDialogProps) {
  const { t } = useLanguage()
  const { requestAiConsent } = useAiConsent()
  const [count, setCount] = useState(10)
  const [style, setStyle] = useState<FlashcardStyle>('qa')
  const [loading, setLoading] = useState(false)
  const [saving, setSaving] = useState(false)
  const [cards, setCards] = useState<PreviewCard[] | null>(null)
  const [mounted, setMounted] = useState(false)

  useEffect(() => {
    setMounted(true)
  }, [])

  useEffect(() => {
    if (!open) return
    const onKey = (e: KeyboardEvent) => {
      if (e.key === 'Escape') onClose()
    }
    document.addEventListener('keydown', onKey)
    return () => document.removeEventListener('keydown', onKey)
  }, [open, onClose])

  const handleGenerate = useCallback(async () => {
    if (!(await requestAiConsent())) return
    setLoading(true)
    try {
      const res = await fetch('/api/flashcards/generate', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ noteId, count, style }),
      })
      const data = await res.json()
      if (!res.ok) {
        if (data.errorKey) {
          toast.error(t(data.errorKey) || data.error)
        } else {
          toast.error(data.error || t('flashcards.generateFailed'))
        }
        return
      }
      setCards(data.cards || [])
    } catch {
      toast.error(t('flashcards.generateFailed'))
    } finally {
      setLoading(false)
    }
  }, [count, noteId, requestAiConsent, style, t])

  const handleSave = useCallback(async () => {
    if (!cards?.length) return
    setSaving(true)
    try {
      const res = await fetch('/api/flashcards/save', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ noteId, cards }),
      })
      const data = await res.json()
      if (!res.ok) {
        toast.error(
          (data.errorKey ? t(data.errorKey) : null) || data.error || t('flashcards.saveFailed'),
        )
        return
      }
      toast.success(t('flashcards.savedCount', { count: data.savedCount }))
      onSaved?.(data.deckId)
      onClose()
      setCards(null)
    } catch {
      toast.error(t('flashcards.saveFailed'))
    } finally {
      setSaving(false)
    }
  }, [cards, noteId, onClose, onSaved, t])

  const updateCard = (index: number, field: 'front' | 'back', value: string) => {
    setCards((prev) => {
      if (!prev) return prev
      const next = [...prev]
      next[index] = { ...next[index], [field]: value }
      return next
    })
  }

  if (!open || !mounted) return null

  return createPortal(
    <div
      className="fixed inset-0 z-[100] flex items-start sm:items-center justify-center overflow-y-auto bg-black/40 backdrop-blur-sm p-4 sm:p-6"
      onClick={onClose}
    >
      <div
        className="bg-card border border-border rounded-2xl shadow-xl w-full max-w-lg max-h-[min(90dvh,calc(100dvh-2rem))] my-auto overflow-hidden flex flex-col shrink-0"
        onClick={(e) => e.stopPropagation()}
      >
        <div className="flex shrink-0 items-center justify-between px-5 py-4 border-b border-border/60">
          <div className="flex items-center gap-2">
            <GraduationCap size={18} className="text-brand-accent" />
            <div>
              <h2 className="text-sm font-semibold">{t('flashcards.generateTitle')}</h2>
              <p className="text-[11px] text-muted-foreground truncate max-w-[280px]">{noteTitle}</p>
            </div>
          </div>
          <button type="button" onClick={onClose} className="p-1.5 rounded-lg hover:bg-black/5">
            <X size={16} />
          </button>
        </div>

        <div className="flex-1 min-h-0 overflow-y-auto overscroll-contain p-5 space-y-5 custom-scrollbar">
          {!cards ? (
            <>
              <div>
                <label className="text-[11px] font-bold uppercase tracking-wider text-concrete block mb-2">
                  {t('flashcards.cardCount')} ({count})
                </label>
                <input
                  type="range"
                  min={5}
                  max={20}
                  value={count}
                  onChange={(e) => setCount(Number(e.target.value))}
                  className="w-full accent-brand-accent"
                />
              </div>
              <div>
                <label className="text-[11px] font-bold uppercase tracking-wider text-concrete block mb-2">
                  {t('flashcards.styleLabel')}
                </label>
                <div className="flex flex-wrap gap-2">
                  {(['qa', 'cloze', 'concept'] as const).map((s) => (
                    <button
                      key={s}
                      type="button"
                      onClick={() => setStyle(s)}
                      className={cn(
                        'px-3 py-1.5 rounded-lg text-xs font-medium border transition-colors',
                        style === s
                          ? 'bg-brand-accent/10 border-brand-accent/40 text-brand-accent'
                          : 'border-border text-muted-foreground hover:border-brand-accent/30',
                      )}
                    >
                      {t(`flashcards.style.${s}`)}
                    </button>
                  ))}
                </div>
              </div>
            </>
          ) : (
            <div className="space-y-3">
              <p className="text-xs text-muted-foreground">{t('flashcards.previewHint')}</p>
              {cards.map((card, i) => (
                <div key={i} className="p-3 rounded-xl border border-border/60 space-y-2 bg-paper/30">
                  <input
                    value={card.front}
                    onChange={(e) => updateCard(i, 'front', e.target.value)}
                    className="w-full text-sm font-medium bg-transparent border-b border-border/40 pb-1 outline-none"
                    placeholder={t('flashcards.frontPlaceholder')}
                  />
                  <textarea
                    value={card.back}
                    onChange={(e) => updateCard(i, 'back', e.target.value)}
                    rows={2}
                    className="w-full text-xs text-muted-foreground bg-transparent outline-none resize-none"
                    placeholder={t('flashcards.backPlaceholder')}
                  />
                </div>
              ))}
            </div>
          )}
        </div>

        <div className="shrink-0 px-5 py-4 border-t border-border/60 flex gap-2 justify-end">
          <button
            type="button"
            onClick={onClose}
            className="px-4 py-2 text-xs font-medium rounded-lg border border-border hover:bg-black/[0.03]"
          >
            {t('general.cancel')}
          </button>
          {!cards ? (
            <button
              type="button"
              onClick={handleGenerate}
              disabled={loading}
              className="px-4 py-2 text-xs font-bold rounded-lg bg-brand-accent text-white flex items-center gap-1.5 disabled:opacity-60"
            >
              {loading ? <Loader2 size={14} className="animate-spin" /> : <Sparkles size={14} />}
              {t('flashcards.generateAction')}
            </button>
          ) : (
            <button
              type="button"
              onClick={handleSave}
              disabled={saving}
              className="px-4 py-2 text-xs font-bold rounded-lg bg-brand-accent text-white flex items-center gap-1.5 disabled:opacity-60"
            >
              {saving && <Loader2 size={14} className="animate-spin" />}
              {t('flashcards.confirmSave')}
            </button>
          )}
        </div>
      </div>
    </div>,
    document.body,
  )
}