'use client'

import { useState, useRef, useEffect } from 'react'
import { Card } from '@/components/ui/card'
import { Input } from '@/components/ui/input'
import { Textarea } from '@/components/ui/textarea'
import { Button } from '@/components/ui/button'
import {
  CheckSquare,
  X,
  Bell,
  Image,
  UserPlus,
  Palette,
  Archive,
  MoreVertical,
  Undo2,
  Redo2,
  FileText,
  Eye,
  Link as LinkIcon
} from 'lucide-react'
import { createNote } from '@/app/actions/notes'
import { fetchLinkMetadata } from '@/app/actions/scrape'
import { CheckItem, NOTE_COLORS, NoteColor, LinkMetadata } from '@/lib/types'
import { Checkbox } from '@/components/ui/checkbox'
import {
  Tooltip,
  TooltipContent,
  TooltipProvider,
  TooltipTrigger,
} from '@/components/ui/tooltip'
import {
  DropdownMenu,
  DropdownMenuContent,
  DropdownMenuTrigger,
} from '@/components/ui/dropdown-menu'
import { cn } from '@/lib/utils'
import { useToast } from '@/components/ui/toast'
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from '@/components/ui/dialog'
import { MarkdownContent } from './markdown-content'
import { LabelSelector } from './label-selector'
import { LabelBadge } from './label-badge'

interface HistoryState {
  title: string
  content: string
}

interface NoteState {
  title: string
  content: string
  checkItems: CheckItem[]
  images: string[]
}

export function NoteInput() {
  const { addToast } = useToast()
  const [isExpanded, setIsExpanded] = useState(false)
  const [type, setType] = useState<'text' | 'checklist'>('text')
  const [isSubmitting, setIsSubmitting] = useState(false)
  const [color, setColor] = useState<NoteColor>('default')
  const [isArchived, setIsArchived] = useState(false)
  const [selectedLabels, setSelectedLabels] = useState<string[]>([])
  const fileInputRef = useRef<HTMLInputElement>(null)
  
  // Simple state without complex undo/redo - like Google Keep
  const [title, setTitle] = useState('')
  const [content, setContent] = useState('')
  const [checkItems, setCheckItems] = useState<CheckItem[]>([])
  const [images, setImages] = useState<string[]>([])
  const [links, setLinks] = useState<LinkMetadata[]>([])
  const [isMarkdown, setIsMarkdown] = useState(false)
  const [showMarkdownPreview, setShowMarkdownPreview] = useState(false)
  
  // Undo/Redo history (title and content only)
  const [history, setHistory] = useState<HistoryState[]>([{ title: '', content: '' }])
  const [historyIndex, setHistoryIndex] = useState(0)
  const isUndoingRef = useRef(false)
  
  // Reminder dialog
  const [showReminderDialog, setShowReminderDialog] = useState(false)
  const [showLinkDialog, setShowLinkDialog] = useState(false)
  const [linkUrl, setLinkUrl] = useState('')
  const [reminderDate, setReminderDate] = useState('')
  const [reminderTime, setReminderTime] = useState('')
  const [currentReminder, setCurrentReminder] = useState<Date | null>(null)
  
  // Save to history after 1 second of inactivity
  useEffect(() => {
    if (isUndoingRef.current) {
      isUndoingRef.current = false
      return
    }
    
    const timer = setTimeout(() => {
      const currentState = { title, content }
      const lastState = history[historyIndex]
      
      if (lastState.title !== title || lastState.content !== content) {
        const newHistory = history.slice(0, historyIndex + 1)
        newHistory.push(currentState)
        
        if (newHistory.length > 50) {
          newHistory.shift()
        } else {
          setHistoryIndex(historyIndex + 1)
        }
        setHistory(newHistory)
      }
    }, 1000)
    
    return () => clearTimeout(timer)
  }, [title, content, history, historyIndex])
  
  // Undo/Redo functions
  const handleUndo = () => {
    if (historyIndex > 0) {
      isUndoingRef.current = true
      const newIndex = historyIndex - 1
      setHistoryIndex(newIndex)
      setTitle(history[newIndex].title)
      setContent(history[newIndex].content)
    }
  }
  
  const handleRedo = () => {
    if (historyIndex < history.length - 1) {
      isUndoingRef.current = true
      const newIndex = historyIndex + 1
      setHistoryIndex(newIndex)
      setTitle(history[newIndex].title)
      setContent(history[newIndex].content)
    }
  }
  
  // Keyboard shortcuts
  useEffect(() => {
    const handleKeyDown = (e: KeyboardEvent) => {
      if (!isExpanded) return
      
      if ((e.ctrlKey || e.metaKey) && e.key === 'z' && !e.shiftKey) {
        e.preventDefault()
        handleUndo()
      }
      if ((e.ctrlKey || e.metaKey) && (e.key === 'y' || (e.key === 'z' && e.shiftKey))) {
        e.preventDefault()
        handleRedo()
      }
    }
    
    window.addEventListener('keydown', handleKeyDown)
    return () => window.removeEventListener('keydown', handleKeyDown)
  }, [isExpanded, historyIndex, history])

  const handleImageUpload = async (e: React.ChangeEvent<HTMLInputElement>) => {
    const files = e.target.files
    if (!files) return

    // Validate file types
    const validTypes = ['image/jpeg', 'image/png', 'image/gif', 'image/webp']
    const maxSize = 5 * 1024 * 1024 // 5MB

    for (const file of Array.from(files)) {
      // Validation
      if (!validTypes.includes(file.type)) {
        addToast(`Invalid file type: ${file.name}. Only JPEG, PNG, GIF, and WebP allowed.`, 'error')
        continue
      }
      
      if (file.size > maxSize) {
        addToast(`File too large: ${file.name}. Maximum size is 5MB.`, 'error')
        continue
      }

      // Upload to server
      const formData = new FormData()
      formData.append('file', file)

      try {
        const response = await fetch('/api/upload', {
          method: 'POST',
          body: formData,
        })

        if (!response.ok) throw new Error('Upload failed')

        const data = await response.json()
        setImages(prev => [...prev, data.url])
      } catch (error) {
        console.error('Upload error:', error)
        addToast(`Failed to upload ${file.name}`, 'error')
      }
    }

    // Reset input
    e.target.value = ''
  }

  const handleAddLink = async () => {
    if (!linkUrl) return
    
    // Optimistic add (or loading state)
    setShowLinkDialog(false)
    
    try {
      const metadata = await fetchLinkMetadata(linkUrl)
      if (metadata) {
        setLinks(prev => [...prev, metadata])
        addToast('Link added', 'success')
      } else {
        addToast('Could not fetch link metadata', 'warning')
        // Fallback: just add the url as title
        setLinks(prev => [...prev, { url: linkUrl, title: linkUrl }])
      }
    } catch (error) {
      console.error('Failed to add link:', error)
      addToast('Failed to add link', 'error')
    } finally {
      setLinkUrl('')
    }
  }

  const handleRemoveLink = (index: number) => {
    setLinks(links.filter((_, i) => i !== index))
  }

  const handleReminderOpen = () => {
    const tomorrow = new Date(Date.now() + 86400000)
    setReminderDate(tomorrow.toISOString().split('T')[0])
    setReminderTime('09:00')
    setShowReminderDialog(true)
  }
  
  const handleReminderSave = () => {
    if (!reminderDate || !reminderTime) {
      addToast('Please enter date and time', 'warning')
      return
    }
    
    const dateTimeString = `${reminderDate}T${reminderTime}`
    const date = new Date(dateTimeString)
    
    if (isNaN(date.getTime())) {
      addToast('Invalid date or time', 'error')
      return
    }
    
    if (date < new Date()) {
      addToast('Reminder must be in the future', 'error')
      return
    }
    
    setCurrentReminder(date)
    addToast(`Reminder set for ${date.toLocaleString()}`, 'success')
    setShowReminderDialog(false)
    setReminderDate('')
    setReminderTime('')
  }

  const handleSubmit = async () => {
    // Validation
    if (type === 'text' && !content.trim()) {
      addToast('Please enter some content', 'warning')
      return
    }
    if (type === 'checklist' && checkItems.length === 0) {
      addToast('Please add at least one item', 'warning')
      return
    }
    if (type === 'checklist' && checkItems.every(item => !item.text.trim())) {
      addToast('Checklist items cannot be empty', 'warning')
      return
    }

    setIsSubmitting(true)
    try {
      await createNote({
        title: title.trim() || undefined,
        content: type === 'text' ? content : '',
        type,
        checkItems: type === 'checklist' ? checkItems : undefined,
        color,
        isArchived,
        images: images.length > 0 ? images : undefined,
        links: links.length > 0 ? links : undefined,
        reminder: currentReminder,
        isMarkdown,
        labels: selectedLabels.length > 0 ? selectedLabels : undefined,
      })

      // Reset form
      setTitle('')
      setContent('')
      setCheckItems([])
      setImages([])
      setLinks([])
      setIsMarkdown(false)
      setShowMarkdownPreview(false)
      setHistory([{ title: '', content: '' }])
      setHistoryIndex(0)
      setIsExpanded(false)
      setType('text')
      setColor('default')
      setIsArchived(false)
      setCurrentReminder(null)
      setSelectedLabels([])
      
      addToast('Note created successfully', 'success')
    } catch (error) {
      console.error('Failed to create note:', error)
      addToast('Failed to create note', 'error')
    } finally {
      setIsSubmitting(false)
    }
  }

  const handleAddCheckItem = () => {
    setCheckItems([
      ...checkItems,
      { id: Date.now().toString(), text: '', checked: false },
    ])
  }
  const handleUpdateCheckItem = (id: string, text: string) => {
    setCheckItems(
      checkItems.map(item => (item.id === id ? { ...item, text } : item))
    )
  }

  const handleRemoveCheckItem = (id: string) => {
    setCheckItems(checkItems.filter(item => item.id !== id))
  }

  const handleClose = () => {
    setIsExpanded(false)
    setTitle('')
    setContent('')
    setCheckItems([])
    setImages([])
    setLinks([])
    setIsMarkdown(false)
    setShowMarkdownPreview(false)
    setHistory([{ title: '', content: '' }])
    setHistoryIndex(0)
    setType('text')
    setColor('default')
    setIsArchived(false)
    setCurrentReminder(null)
    setSelectedLabels([])
  }

  if (!isExpanded) {
    return (
      <Card className="p-4 max-w-2xl mx-auto mb-8 cursor-text shadow-md hover:shadow-lg transition-shadow">
        <div className="flex items-center gap-4">
          <Input
            placeholder="Take a note..."
            onClick={() => setIsExpanded(true)}
            readOnly
            value=""
            className="border-0 focus-visible:ring-0 cursor-text"
          />
          <Button
            variant="ghost"
            size="sm"
            onClick={() => {
              setType('checklist')
              setIsExpanded(true)
            }}
            title="New checklist"
          >
            <CheckSquare className="h-5 w-5" />
          </Button>
        </div>
      </Card>
    )
  }

  const colorClasses = NOTE_COLORS[color] || NOTE_COLORS.default

  return (
    <>
    <Card className={cn(
      "p-4 max-w-2xl mx-auto mb-8 shadow-lg border",
      colorClasses.card
    )}>
      <div className="space-y-3">
        <Input
          placeholder="Title"
          value={title}
          onChange={(e) => setTitle(e.target.value)}
          className="border-0 focus-visible:ring-0 text-base font-semibold"
        />

        {/* Image Preview */}
        {images.length > 0 && (
          <div className="flex flex-col gap-2">
            {images.map((img, idx) => (
              <div key={idx} className="relative group">
                <img 
                  src={img} 
                  alt={`Upload ${idx + 1}`} 
                  className="max-w-full h-auto max-h-96 object-contain rounded-lg" 
                />
                <Button
                  variant="ghost"
                  size="sm"
                  className="absolute top-2 right-2 h-7 w-7 p-0 bg-white/90 hover:bg-white opacity-0 group-hover:opacity-100 transition-opacity"
                  onClick={() => setImages(images.filter((_, i) => i !== idx))}
                >
                  <X className="h-4 w-4" />
                </Button>
              </div>
            ))}
          </div>
        )}

        {/* Link Previews */}
        {links.length > 0 && (
          <div className="flex flex-col gap-2 mt-2">
            {links.map((link, idx) => (
              <div key={idx} className="relative group border rounded-lg overflow-hidden bg-gray-50 dark:bg-zinc-800/50 flex">
                {link.imageUrl && (
                  <div className="w-24 h-24 flex-shrink-0 bg-cover bg-center" style={{ backgroundImage: `url(${link.imageUrl})` }} />
                )}
                <div className="p-2 flex-1 min-w-0 flex flex-col justify-center">
                  <h4 className="font-medium text-sm truncate">{link.title || link.url}</h4>
                  {link.description && <p className="text-xs text-gray-500 truncate">{link.description}</p>}
                  <a href={link.url} target="_blank" rel="noopener noreferrer" className="text-xs text-blue-500 truncate hover:underline block mt-1">
                    {new URL(link.url).hostname}
                  </a>
                </div>
                <Button
                  variant="ghost"
                  size="sm"
                  className="absolute top-1 right-1 h-6 w-6 p-0 bg-white/50 hover:bg-white opacity-0 group-hover:opacity-100 transition-opacity rounded-full"
                  onClick={() => handleRemoveLink(idx)}
                >
                  <X className="h-3 w-3" />
                </Button>
              </div>
            ))}
          </div>
        )}

        {type === 'text' ? (
          <div className="space-y-2">
            {/* Selected Labels Display */}
            {selectedLabels.length > 0 && (
              <div className="flex flex-wrap gap-1 mb-2">
                {selectedLabels.map(label => (
                  <LabelBadge 
                    key={label} 
                    label={label} 
                    onRemove={() => setSelectedLabels(prev => prev.filter(l => l !== label))}
                  />
                ))}
              </div>
            )}

            {/* Markdown toggle button */}
            {isMarkdown && (
              <div className="flex justify-end gap-2">
                <Button
                  variant="ghost"
                  size="sm"
                  onClick={() => setShowMarkdownPreview(!showMarkdownPreview)}
                  className="h-7 text-xs"
                >
                  {showMarkdownPreview ? (
                    <>
                      <FileText className="h-3 w-3 mr-1" />
                      Edit
                    </>
                  ) : (
                    <>
                      <Eye className="h-3 w-3 mr-1" />
                      Preview
                    </>
                  )}
                </Button>
              </div>
            )}

            {showMarkdownPreview && isMarkdown ? (
              <MarkdownContent 
                content={content || '*No content*'} 
                className="min-h-[100px] p-3 rounded-md border border-gray-200 dark:border-gray-700 bg-gray-50 dark:bg-gray-900/50"
              />
            ) : (
              <Textarea
                placeholder={isMarkdown ? "Take a note... (Markdown supported)" : "Take a note..."}
                value={content}
                onChange={(e) => setContent(e.target.value)}
                className="border-0 focus-visible:ring-0 min-h-[100px] resize-none"
                autoFocus
              />
            )}
          </div>
        ) : (
          <div className="space-y-2">
            {checkItems.map((item) => (
              <div key={item.id} className="flex items-start gap-2 group">
                <Checkbox className="mt-2" />
                <Input
                  value={item.text}
                  onChange={(e) => handleUpdateCheckItem(item.id, e.target.value)}
                  placeholder="List item"
                  className="flex-1 border-0 focus-visible:ring-0"
                  autoFocus={checkItems[checkItems.length - 1].id === item.id}
                />
                <Button
                  variant="ghost"
                  size="sm"
                  className="opacity-0 group-hover:opacity-100 h-8 w-8 p-0"
                  onClick={() => handleRemoveCheckItem(item.id)}
                >
                  <X className="h-4 w-4" />
                </Button>
              </div>
            ))}
            <Button
              variant="ghost"
              size="sm"
              onClick={handleAddCheckItem}
              className="text-gray-600 dark:text-gray-400 w-full justify-start"
            >
              + List item
            </Button>
          </div>
        )}

        <div className="flex items-center justify-between pt-2">
          <TooltipProvider>
            <div className="flex items-center gap-1">
              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className={cn(
                      "h-8 w-8",
                      currentReminder && "text-blue-600"
                    )}
                    title="Remind me"
                    onClick={handleReminderOpen}
                  >
                    <Bell className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Remind me</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className={cn(
                      "h-8 w-8",
                      isMarkdown && "text-blue-600"
                    )}
                    onClick={() => {
                      setIsMarkdown(!isMarkdown)
                      if (isMarkdown) setShowMarkdownPreview(false)
                    }}
                    title="Markdown"
                  >
                    <FileText className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Markdown</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className="h-8 w-8" 
                    title="Add image"
                    onClick={() => fileInputRef.current?.click()}
                  >
                    <Image className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Add image</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button variant="ghost" size="icon" className="h-8 w-8" title="Collaborator">
                    <UserPlus className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Collaborator</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className="h-8 w-8" 
                    onClick={() => setShowLinkDialog(true)}
                    title="Add Link"
                  >
                    <LinkIcon className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Add Link</TooltipContent>
              </Tooltip>

              <LabelSelector
                selectedLabels={selectedLabels}
                onLabelsChange={setSelectedLabels}
                triggerLabel=""
                align="start"
              />

              <DropdownMenu>
                <Tooltip>
                  <TooltipTrigger asChild>
                    <DropdownMenuTrigger asChild>
                      <Button variant="ghost" size="icon" className="h-8 w-8" title="Background options">
                        <Palette className="h-4 w-4" />
                      </Button>
                    </DropdownMenuTrigger>
                  </TooltipTrigger>
                  <TooltipContent>Background options</TooltipContent>
                </Tooltip>
                <DropdownMenuContent align="start" className="w-40">
                  <div className="grid grid-cols-5 gap-2 p-2">
                    {Object.entries(NOTE_COLORS).map(([colorName, colorClass]) => (
                      <button
                        key={colorName}
                        onClick={() => setColor(colorName as NoteColor)}
                        className={cn(
                          'w-7 h-7 rounded-full border-2 hover:scale-110 transition-transform',
                          colorClass.bg,
                          color === colorName ? 'border-gray-900 dark:border-gray-100' : 'border-transparent'
                        )}
                        title={colorName}
                      />
                    ))}
                  </div>
                </DropdownMenuContent>
              </DropdownMenu>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className={cn(
                      "h-8 w-8",
                      isArchived && "text-yellow-600"
                    )}
                    onClick={() => setIsArchived(!isArchived)}
                    title="Archive"
                  >
                    <Archive className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>{isArchived ? 'Unarchive' : 'Archive'}</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button variant="ghost" size="icon" className="h-8 w-8" title="More">
                    <MoreVertical className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>More</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className="h-8 w-8" 
                    onClick={handleUndo}
                    disabled={historyIndex === 0}
                  >
                    <Undo2 className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Undo (Ctrl+Z)</TooltipContent>
              </Tooltip>

              <Tooltip>
                <TooltipTrigger asChild>
                  <Button 
                    variant="ghost" 
                    size="icon" 
                    className="h-8 w-8" 
                    onClick={handleRedo}
                    disabled={historyIndex >= history.length - 1}
                  >
                    <Redo2 className="h-4 w-4" />
                  </Button>
                </TooltipTrigger>
                <TooltipContent>Redo (Ctrl+Y)</TooltipContent>
              </Tooltip>
            </div>
          </TooltipProvider>

          <div className="flex gap-2">
            <Button
              onClick={handleSubmit}
              disabled={isSubmitting}
              size="sm"
            >
              {isSubmitting ? 'Adding...' : 'Add'}
            </Button>
            <Button 
              variant="ghost" 
              onClick={handleClose}
              size="sm"
            >
              Close
            </Button>
          </div>
        </div>
      </div>
      <input
        ref={fileInputRef}
        type="file"
        accept="image/*"
        multiple
        className="hidden"
        onChange={handleImageUpload}
      />
    </Card>

    <Dialog open={showReminderDialog} onOpenChange={setShowReminderDialog}>
      <DialogContent>
        <DialogHeader>
          <DialogTitle>Set Reminder</DialogTitle>
        </DialogHeader>
        <div className="space-y-4 py-4">
          <div className="space-y-2">
            <label htmlFor="reminder-date" className="text-sm font-medium">
              Date
            </label>
            <Input
              id="reminder-date"
              type="date"
              value={reminderDate}
              onChange={(e) => setReminderDate(e.target.value)}
              className="w-full"
            />
          </div>
          <div className="space-y-2">
            <label htmlFor="reminder-time" className="text-sm font-medium">
              Time
            </label>
            <Input
              id="reminder-time"
              type="time"
              value={reminderTime}
              onChange={(e) => setReminderTime(e.target.value)}
              className="w-full"
            />
          </div>
        </div>
        <DialogFooter>
          <Button variant="ghost" onClick={() => setShowReminderDialog(false)}>
            Cancel
          </Button>
          <Button onClick={handleReminderSave}>
            Set Reminder
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>

    <Dialog open={showLinkDialog} onOpenChange={setShowLinkDialog}>
      <DialogContent>
        <DialogHeader>
          <DialogTitle>Add Link</DialogTitle>
        </DialogHeader>
        <div className="space-y-4 py-4">
          <Input
            placeholder="https://example.com"
            value={linkUrl}
            onChange={(e) => setLinkUrl(e.target.value)}
            onKeyDown={(e) => {
              if (e.key === 'Enter') {
                e.preventDefault()
                handleAddLink()
              }
            }}
            autoFocus
          />
        </div>
        <DialogFooter>
          <Button variant="ghost" onClick={() => setShowLinkDialog(false)}>
            Cancel
          </Button>
          <Button onClick={handleAddLink}>
            Add
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  </>
  )
}
