'use client'

import { useState, useMemo } from 'react'
import { Note } from '@/lib/types'
import { formatDistanceToNow } from 'date-fns'
import { fr } from 'date-fns/locale/fr'
import { enUS } from 'date-fns/locale/en-US'
import { faIR } from 'date-fns/locale/fa-IR'
import { formatAbsoluteDateLocalized } from '@/lib/utils/format-localized-date'
import { X, Info, Clock, Hash, Book, FileText, Calendar, Tag, ChevronRight, Trash2, RotateCcw, Loader2, Check, History as HistoryIcon, Network, Copy, ExternalLink } from 'lucide-react'
import { cn } from '@/lib/utils'
import { useLanguage } from '@/lib/i18n'
import { useNotebooks } from '@/context/notebooks-context'
import { LabelBadge } from './label-badge'
import { NoteHistoryModal } from './note-history-modal'
import { NoteNetworkTab } from './note-network-tab'
import { enableNoteHistory, commitNoteHistory, getNoteHistory, deleteNoteHistoryEntry, restoreNoteVersion } from '@/app/actions/notes'
import { useEffect } from 'react'

type Tab = 'info' | 'versions' | 'network'

interface NoteDocumentInfoPanelProps {
  note: Note
  content: string
  onClose: () => void
  onNoteRestored?: (note: Note) => void
}

function getLocale(lang: string) {
  if (lang === 'fr') return fr
  if (lang === 'fa') return faIR
  return enUS
}

function wordCount(text: string) {
  return text.replace(/<[^>]+>/g, ' ').trim().split(/\s+/).filter(Boolean).length
}

function charCount(text: string) {
  return text.replace(/<[^>]+>/g, '').length
}

function lineCount(text: string) {
  const plain = text.replace(/<[^>]+>/g, '\n')
  return plain.trim() ? plain.split('\n').length : 0
}

function equationCount(text: string) {
  const block = (text.match(/\$\$[\s\S]+?\$\$/g) || []).length
  const inline = (text.match(/\$[^$\n]+?\$/g) || []).length
  return block + inline
}

function imageCount(text: string) {
  const md = (text.match(/!\[[^\]]*\]\([^)]+\)/g) || []).length
  const html = (text.match(/<img\s/gi) || []).length
  return md + html
}

export function NoteDocumentInfoPanel({ note, content, onClose, onNoteRestored }: NoteDocumentInfoPanelProps) {
  const { t, language } = useLanguage()
  const { notebooks } = useNotebooks()
  const [activeTab, setActiveTab] = useState<Tab>('info')
  const [showHistory, setShowHistory] = useState(false)
  const [historyEnabled, setHistoryEnabled] = useState(note.historyEnabled ?? false)
  const [isSavingVersion, setIsSavingVersion] = useState(false)
  const [versionSaved, setVersionSaved] = useState(false)
  const [historyEntries, setHistoryEntries] = useState<any[]>([])
  const [isLoadingHistory, setIsLoadingHistory] = useState(false)
  const [isDeleting, setIsDeleting] = useState<string | null>(null)
  const [isRestoring, setIsRestoring] = useState<string | null>(null)
  const [copiedId, setCopiedId] = useState(false)
  const locale = getLocale(language)

  const displayNoteType = useMemo(() => {
    if (note.sourceUrl) return t('notes.noteTypes.clip')
    const map: Record<string, string> = {
      richtext: t('notes.noteTypes.richtext'),
      markdown: t('notes.noteTypes.markdown'),
      text: t('notes.noteTypes.text'),
      checklist: t('notes.noteTypes.checklist'),
    }
    return map[note.type] || note.type
  }, [t, note.type, note.sourceUrl])

  useEffect(() => {
    if (activeTab === 'versions' && historyEnabled) {
      loadHistory()
    }
  }, [activeTab, historyEnabled, note.id])

  const loadHistory = async () => {
    setIsLoadingHistory(true)
    try {
      const entries = await getNoteHistory(note.id, 50)
      setHistoryEntries(entries)
    } catch (e) {
      console.error(e)
    } finally {
      setIsLoadingHistory(false)
    }
  }

  const handleDeleteVersion = async (entryId: string) => {
    if (!confirm(t('documentInfo.deleteVersionConfirm'))) return
    setIsDeleting(entryId)
    try {
      await deleteNoteHistoryEntry(note.id, entryId)
      setHistoryEntries(prev => prev.filter(e => e.id !== entryId))
    } catch (e) {
      console.error(e)
    } finally {
      setIsDeleting(null)
    }
  }

  const handleRestoreVersion = async (entryId: string) => {
    setIsRestoring(entryId)
    try {
      const restored = await restoreNoteVersion(note.id, entryId)
      onNoteRestored?.(restored)
      loadHistory()
    } catch (e) {
      console.error(e)
    } finally {
      setIsRestoring(null)
    }
  }

  const notebook = useMemo(
    () => notebooks.find(nb => nb.id === note.notebookId),
    [notebooks, note.notebookId]
  )

  const words = useMemo(() => wordCount(content), [content])
  const chars = useMemo(() => charCount(content), [content])
  const lines = useMemo(() => lineCount(content), [content])
  const equations = useMemo(() => equationCount(content), [content])
  const images = useMemo(() => imageCount(content), [content])

  const createdAt = note.createdAt ? new Date(note.createdAt as unknown as string) : null
  const updatedAt = note.contentUpdatedAt ? new Date(note.contentUpdatedAt as unknown as string) : null

  return (
    <>
      <div className="flex w-full h-full flex-col bg-background overflow-hidden">

        {/* Header tabs */}
        <div className="flex items-center justify-between px-5 py-4 border-b border-border/40">
          <div className="flex gap-1">
            {(['info', 'versions', 'network'] as Tab[]).map(tab => (
              <button
                key={tab}
                onClick={() => setActiveTab(tab)}
                className={cn(
                  'flex items-center gap-1.5 px-3 py-1.5 rounded-full text-xs font-semibold transition-all',
                  activeTab === tab
                    ? 'bg-foreground text-background'
                    : 'text-muted-foreground hover:text-foreground hover:bg-black/5 dark:hover:bg-white/5'
                )}
              >
                {tab === 'info' && <Info className="h-3 w-3" />}
                {tab === 'versions' && <Clock className="h-3 w-3" />}
                {tab === 'network' && <Network className="h-3 w-3" />}
                {tab === 'info'
                  ? t('documentInfo.tabInfo')
                  : tab === 'versions'
                    ? t('documentInfo.tabVersions')
                    : t('documentInfo.tabNetwork')}
              </button>
            ))}
          </div>
          <button
            onClick={onClose}
            className="p-1.5 rounded-full text-muted-foreground hover:text-foreground hover:bg-black/5 dark:hover:bg-white/5 transition-colors"
          >
            <X className="h-4 w-4" />
          </button>
        </div>

        {/* Body */}
        <div className="flex-1 overflow-y-auto">

          {/* ── INFO TAB ── */}
          {activeTab === 'info' && (
            <div>
              {/* Stats — grand display numbers */}
              <div className="grid grid-cols-2 border-b border-border/30">
                <div className="flex flex-col items-center gap-1 py-6 border-r border-border/30">
                  <span className="text-4xl font-bold font-memento-serif tabular-nums tracking-tight">{words}</span>
                  <span className="text-[10px] uppercase tracking-[0.2em] text-muted-foreground font-semibold">{t('documentInfo.wordsLabel')}</span>
                </div>
                <div className="flex flex-col items-center gap-1 py-6">
                  <span className="text-4xl font-bold font-memento-serif tabular-nums tracking-tight">{chars}</span>
                  <span className="text-[10px] uppercase tracking-[0.2em] text-muted-foreground font-semibold">{t('documentInfo.charactersLabel')}</span>
                </div>
              </div>

              <div className="grid grid-cols-3 border-b border-border/30 divide-x divide-border/30">
                {[
                  { value: lines, label: t('documentInfo.linesLabel') },
                  { value: equations, label: t('documentInfo.equationsLabel') },
                  { value: images, label: t('documentInfo.imagesLabel') },
                ].map(({ value, label }) => (
                  <div key={label} className="flex flex-col items-center gap-0.5 py-3">
                    <span className="text-lg font-bold font-memento-serif tabular-nums">{value}</span>
                    <span className="text-[8px] uppercase tracking-widest text-muted-foreground font-semibold">{label}</span>
                  </div>
                ))}
              </div>

              <div className="divide-y divide-border/30">
                {notebook && (
                  <div className="flex items-start gap-3 px-4 py-3">
                    <Book className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                    <div>
                      <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-0.5">{t('documentInfo.notebookLabel')}</p>
                      <p className="text-sm font-medium">{notebook.name}</p>
                    </div>
                  </div>
                )}

                <div className="flex items-start gap-3 px-4 py-3">
                  <FileText className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                  <div>
                    <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-0.5">{t('documentInfo.typeLabel')}</p>
                    <p className="text-sm font-medium">{displayNoteType}</p>
                  </div>
                </div>

                {note.sourceUrl && (
                  <div className="flex items-start gap-3 px-4 py-3">
                    <ExternalLink className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                    <div className="min-w-0">
                      <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-0.5">{t('documentInfo.sourceWebLabel')}</p>
                      <a
                        href={note.sourceUrl}
                        target="_blank"
                        rel="noopener noreferrer"
                        className="text-sm font-medium text-brand-accent hover:underline break-all"
                      >
                        {note.sourceUrl}
                      </a>
                    </div>
                  </div>
                )}

                {createdAt && (
                  <div className="flex items-start gap-3 px-4 py-3">
                    <Calendar className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                    <div>
                      <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-0.5">{t('documentInfo.createdLabel')}</p>
                      <p className="text-sm font-medium">{formatAbsoluteDateLocalized(createdAt, language, 'd MMM yyyy', locale)}</p>
                      <p className="text-[11px] text-muted-foreground mt-0.5">
                        {formatDistanceToNow(createdAt, { addSuffix: true, locale })}
                      </p>
                    </div>
                  </div>
                )}

                {updatedAt && (
                  <div className="flex items-start gap-3 px-4 py-3">
                    <Clock className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                    <div>
                      <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-0.5">{t('documentInfo.modifiedLabel')}</p>
                      <p className="text-sm font-medium">{formatAbsoluteDateLocalized(updatedAt, language, 'd MMM yyyy · HH:mm', locale)}</p>
                      <p className="text-[11px] text-muted-foreground mt-0.5">
                        {formatDistanceToNow(updatedAt, { addSuffix: true, locale })}
                      </p>
                    </div>
                  </div>
                )}

                {(note.labels ?? []).length > 0 && (
                  <div className="flex items-start gap-3 px-4 py-3">
                    <Tag className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                    <div className="min-w-0">
                      <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-1.5">{t('documentInfo.labelsSection')}</p>
                      <div className="flex flex-wrap gap-1">
                        {(note.labels ?? []).map(label => (
                          <LabelBadge key={label} label={label} />
                        ))}
                      </div>
                    </div>
                  </div>
                )}

                <div className="flex items-start gap-3 px-4 py-3">
                  <Hash className="h-3.5 w-3.5 text-muted-foreground mt-0.5 shrink-0" />
                  <div className="min-w-0 flex-1">
                    <p className="text-[10px] uppercase tracking-widest text-muted-foreground mb-0.5">{t('documentInfo.idLabel')}</p>
                    <div className="flex items-center gap-1.5 min-w-0">
                      <p className="text-[11px] text-muted-foreground font-mono truncate">{note.id}</p>
                      <button
                        type="button"
                        onClick={() => {
                          navigator.clipboard.writeText(note.id).then(() => {
                            setCopiedId(true)
                            setTimeout(() => setCopiedId(false), 2000)
                          })
                        }}
                        className="p-1 rounded hover:bg-muted text-muted-foreground shrink-0"
                        title={t('documentInfo.copyId')}
                      >
                        {copiedId ? <Check className="h-3 w-3 text-emerald-500" /> : <Copy className="h-3 w-3" />}
                      </button>
                    </div>
                  </div>
                </div>
              </div>
            </div>
          )}

          {/* ── VERSIONS TAB ── */}
          {activeTab === 'versions' && (
            <div className="p-4 space-y-4">
              {!historyEnabled ? (
                <div className="text-center py-6 space-y-3">
                  <Clock className="h-8 w-8 text-muted-foreground/30 mx-auto" />
                  <p className="text-sm text-muted-foreground">{t('documentInfo.historyDisabled')}</p>
                  <button
                    className="text-xs px-4 py-2 rounded-lg bg-foreground text-background font-medium hover:opacity-80 transition-opacity"
                    onClick={async () => {
                      await enableNoteHistory(note.id)
                      setHistoryEnabled(true)
                      setShowHistory(true)
                    }}
                  >
                    {t('documentInfo.enableHistory')}
                  </button>
                </div>
              ) : (
              <div className="space-y-4">
                  <p className="text-[10px] uppercase tracking-widest text-muted-foreground font-bold">{t('documentInfo.savedVersions')}</p>

                  {/* Save version button */}
                  <button
                    disabled={isSavingVersion}
                    className={cn(
                      'w-full flex items-center justify-center gap-2 p-3 rounded-xl border transition-all text-xs font-bold uppercase tracking-widest',
                      versionSaved
                        ? 'border-emerald-500/40 bg-emerald-50 dark:bg-emerald-950/30 text-emerald-700 dark:text-emerald-400'
                        : 'border-foreground/10 bg-foreground text-background hover:opacity-90 shadow-sm',
                      isSavingVersion && 'opacity-50 cursor-not-allowed'
                    )}
                    onClick={async () => {
                      setIsSavingVersion(true)
                      try {
                        await commitNoteHistory(note.id)
                        setVersionSaved(true)
                        loadHistory()
                        setTimeout(() => setVersionSaved(false), 3000)
                      } catch (e) {
                        console.error(e)
                      } finally {
                        setIsSavingVersion(false)
                      }
                    }}
                  >
                    {isSavingVersion ? (
                      <><Loader2 className="h-3.5 w-3.5 animate-spin" />{t('documentInfo.savingEllipsis')}</>
                    ) : versionSaved ? (
                      <><Check className="h-3.5 w-3.5" /> {t('documentInfo.versionSaved')}</>
                    ) : (
                      <>{t('documentInfo.saveThisVersion')}</>
                    )}
                  </button>

                  <div className="h-px bg-border/30 my-2" />

                  {/* Timeline */}
                  {isLoadingHistory && historyEntries.length === 0 ? (
                    <div className="flex flex-col items-center justify-center py-10 opacity-40">
                      <Loader2 className="h-6 w-6 animate-spin mb-2" />
                      <p className="text-[10px] uppercase tracking-widest">{t('documentInfo.loading')}</p>
                    </div>
                  ) : historyEntries.length === 0 ? (
                    <div className="text-center py-8 opacity-40 border border-dashed rounded-xl">
                      <Clock className="h-6 w-6 mx-auto mb-2" />
                      <p className="text-[10px] uppercase tracking-widest">{t('documentInfo.noVersion')}</p>
                    </div>
                  ) : (
                    <div className="relative ps-6 space-y-6 before:absolute before:start-[11px] before:top-2 before:bottom-2 before:w-px before:bg-border/40">
                      {historyEntries.map((entry, idx) => {
                        const colors = ['#E2E8F0', '#ACB995', '#E9ECEF']
                        const dotColor = colors[idx % colors.length]
                        const isLatest = idx === 0

                        return (
                          <div key={entry.id} className="relative group">
                            {/* Dot */}
                            <div 
                              className="absolute -start-[19px] top-1.5 h-3 w-3 rounded-full border-2 border-background z-10 shadow-sm"
                              style={{ backgroundColor: dotColor }}
                            />
                            
                            <div className="flex flex-col gap-1">
                              <div className="flex items-center justify-between">
                                <div className="flex items-center gap-2">
                                  <span className="text-xs font-bold font-mono">v{entry.version}</span>
                                  {isLatest && (
                                    <span className="text-[9px] px-1.5 py-0.5 rounded-md bg-primary/10 text-primary font-bold uppercase tracking-widest">{t('documentInfo.latestBadge')}</span>
                                  )}
                                </div>
                                
                                <div className="flex items-center gap-1 opacity-0 group-hover:opacity-100 transition-opacity">
                                  <button 
                                    onClick={() => handleRestoreVersion(entry.id)}
                                    disabled={!!isRestoring || !!isDeleting}
                                    className="p-1.5 rounded-lg hover:bg-primary/10 text-muted-foreground hover:text-primary transition-colors"
                                    title={t('documentInfo.restoreTooltip')}
                                  >
                                    {isRestoring === entry.id ? <Loader2 className="h-3 w-3 animate-spin" /> : <RotateCcw className="h-3 w-3" />}
                                  </button>
                                  <button 
                                    onClick={() => handleDeleteVersion(entry.id)}
                                    disabled={!!isRestoring || !!isDeleting}
                                    className="p-1.5 rounded-lg hover:bg-red-500/10 text-muted-foreground hover:text-red-500 transition-colors"
                                    title={t('documentInfo.deleteTooltip')}
                                  >
                                    {isDeleting === entry.id ? <Loader2 className="h-3 w-3 animate-spin" /> : <Trash2 className="h-3 w-3" />}
                                  </button>
                                </div>
                              </div>
                              
                              <p className="text-[10px] text-muted-foreground font-medium">
                                {formatAbsoluteDateLocalized(new Date(entry.createdAt), language, 'd MMM · HH:mm', locale)}
                                <span className="mx-1.5 opacity-30">·</span>
                                {formatDistanceToNow(new Date(entry.createdAt), { addSuffix: true, locale })}
                              </p>
                            </div>
                          </div>
                        )
                      })}
                    </div>
                  )}

                  {/* Button to open the full modal (optional, but good to keep if user wants diff) */}
                  <button
                    className="w-full flex items-center justify-between p-3 rounded-xl border border-border/40 hover:bg-muted/50 transition-colors text-start group mt-4"
                    onClick={() => setShowHistory(true)}
                  >
                    <div className="flex items-center gap-3">
                      <div className="w-8 h-8 rounded-full bg-primary/5 flex items-center justify-center text-primary group-hover:bg-primary/10 transition-colors">
                        <HistoryIcon className="h-4 w-4" />
                      </div>
                      <div>
                        <p className="text-xs font-bold uppercase tracking-wider">{t('documentInfo.comparisonMode')}</p>
                        <p className="text-[10px] text-muted-foreground">{t('documentInfo.comparisonSubtitle')}</p>
                      </div>
                    </div>
                    <ChevronRight className="h-4 w-4 text-muted-foreground rtl:scale-x-[-1]" />
                  </button>
                </div>
              )}
            </div>
          )}

          {/* ── NETWORK TAB ── */}
          {activeTab === 'network' && (
            <NoteNetworkTab noteId={note.id} noteTitle={note.title || ''} />
          )}
        </div>
      </div>

      {/* NoteHistoryModal with correct props */}
      {showHistory && (
        <NoteHistoryModal
          open={showHistory}
          onOpenChange={(v) => setShowHistory(v)}
          note={note}
          enabled={historyEnabled}
          onEnableHistory={async () => {
            await enableNoteHistory(note.id)
            setHistoryEnabled(true)
          }}
          onRestored={(restored) => {
            setShowHistory(false)
            onNoteRestored?.(restored)
          }}
        />
      )}
    </>
  )
}