'use client'

import { useRef, useState } from 'react'
import { motion } from 'motion/react'
import { FileText, Upload, Sparkles, CheckCircle, AlertCircle } from 'lucide-react'
import { Button } from '@/components/ui/button'
import { useLanguage } from '@/lib/i18n'
import { markdownToHTML, extractMarkdownTitle } from '@/lib/editor/markdown-export'

interface Props {
  noteCount: number
  onNext: (justCreated: boolean) => void
  onSkip: () => void
  locale: string
}

async function createNote(title: string | null, content: string) {
  const res = await fetch('/api/notes', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ title: title ?? 'Untitled', content }),
  })
  if (!res.ok) throw new Error('Failed to create note')
}

export function OnboardingStepNotes({ noteCount, onNext, onSkip, locale }: Props) {
  const { t } = useLanguage()
  const [loading, setLoading] = useState(false)
  const [created, setCreated] = useState(false)
  const [importError, setImportError] = useState<string | null>(null)
  const [importedCount, setImportedCount] = useState(0)
  const fileInputRef = useRef<HTMLInputElement>(null)

  async function handleCreateDemo() {
    setLoading(true)
    try {
      await fetch('/api/onboarding/seed-demo-notes', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({ locale }),
      })
      setCreated(true)
      setTimeout(() => onNext(true), 1200)
    } finally {
      setLoading(false)
    }
  }

  async function handleImportFiles(e: React.ChangeEvent<HTMLInputElement>) {
    const files = Array.from(e.target.files ?? [])
    if (!files.length) return
    setLoading(true)
    setImportError(null)
    let count = 0
    try {
      for (const file of files) {
        const text = await file.text()
        const isMd = file.name.endsWith('.md')
        const title = extractMarkdownTitle(text) ?? file.name.replace(/\.(md|txt)$/, '')
        const content = isMd ? markdownToHTML(text) : `<p>${text.replace(/\n\n+/g, '</p><p>').replace(/\n/g, '<br/>')}</p>`
        await createNote(title, content)
        count++
      }
      setImportedCount(count)
      setCreated(true)
      setTimeout(() => onNext(false), 1200)
    } catch {
      setImportError(t('onboarding.import_error'))
    } finally {
      setLoading(false)
      if (fileInputRef.current) fileInputRef.current.value = ''
    }
  }

  const hasNotes = noteCount > 0

  return (
    <motion.div
      initial={{ opacity: 0, y: 16 }}
      animate={{ opacity: 1, y: 0 }}
      exit={{ opacity: 0, y: -16 }}
      className="flex flex-col items-center gap-6 text-center"
    >
      <motion.div
        initial={{ scale: 0.7, opacity: 0 }}
        animate={{ scale: 1, opacity: 1 }}
        transition={{ delay: 0.1, type: 'spring', stiffness: 200 }}
        className="flex h-20 w-20 items-center justify-center rounded-2xl bg-blue-500/10 text-blue-500"
      >
        <FileText className="h-10 w-10" />
      </motion.div>

      <div className="space-y-2">
        <h2 className="text-2xl font-bold tracking-tight text-foreground">
          {t('onboarding.step_notes_title')}
        </h2>
        <p className="text-base text-muted-foreground max-w-xs">
          {hasNotes
            ? t('onboarding.step_notes_has_notes', { count: noteCount })
            : t('onboarding.step_notes_empty')}
        </p>
        {!hasNotes && (
          <p className="text-xs text-violet-500/80 max-w-xs">
            {t('onboarding.step_notes_hint')}
          </p>
        )}
      </div>

      {hasNotes ? (
        <div className="flex flex-col gap-2 w-full max-w-xs">
          <Button onClick={() => onNext(false)} size="lg" className="w-full">
            {t('onboarding.step_notes_cta')} →
          </Button>
          <button
            onClick={onSkip}
            className="text-xs text-muted-foreground/60 hover:text-muted-foreground transition-colors py-1"
          >
            {t('onboarding.skip')}
          </button>
        </div>
      ) : (
        <div className="flex flex-col gap-3 w-full max-w-xs">
          {created ? (
            <motion.div
              initial={{ scale: 0.8, opacity: 0 }}
              animate={{ scale: 1, opacity: 1 }}
              className="flex items-center justify-center gap-2 rounded-lg bg-green-500/10 py-3 text-green-600"
            >
              <CheckCircle className="h-5 w-5" />
              <span className="text-sm font-medium">
                {importedCount > 0
                  ? t('onboarding.import_notes_ready', { count: importedCount })
                  : t('onboarding.demo_notes_ready')}
              </span>
            </motion.div>
          ) : (
            <>
              <Button
                onClick={handleCreateDemo}
                size="lg"
                className="w-full gap-2"
                disabled={loading}
              >
                {loading ? (
                  <>
                    <span className="animate-spin h-4 w-4 border-2 border-white/30 border-t-white rounded-full" />
                    {t('onboarding.creating_demo_notes')}
                  </>
                ) : (
                  <>
                    <Sparkles className="h-4 w-4" />
                    {t('onboarding.step_notes_demo')}
                  </>
                )}
              </Button>

              {/* Hidden file input — accepts .md and .txt */}
              <input
                ref={fileInputRef}
                type="file"
                accept=".md,.txt"
                multiple
                className="hidden"
                onChange={handleImportFiles}
              />
              <Button
                onClick={() => fileInputRef.current?.click()}
                size="lg"
                variant="outline"
                className="w-full gap-2"
                disabled={loading}
              >
                <Upload className="h-4 w-4" />
                {t('onboarding.step_notes_import')}
              </Button>
              <p className="text-xs text-muted-foreground/50">
                {t('onboarding.import_formats')}
              </p>
            </>
          )}

          {importError && (
            <motion.div
              initial={{ opacity: 0 }}
              animate={{ opacity: 1 }}
              className="flex items-center gap-2 rounded-lg bg-destructive/10 py-2 px-3 text-destructive text-sm"
            >
              <AlertCircle className="h-4 w-4 shrink-0" />
              {importError}
            </motion.div>
          )}

          <button
            onClick={onSkip}
            className="text-xs text-muted-foreground/60 hover:text-muted-foreground transition-colors py-1"
          >
            {t('onboarding.skip')}
          </button>
        </div>
      )}
    </motion.div>
  )
}