import React, { useState, useRef, useEffect } from 'react';
import { Dialog, DialogContent, DialogDescription, DialogHeader, DialogTitle } from '../ui/dialog';
import { sanitizeHTML } from '../../utils/sanitizer';
import { Button } from '../ui/button';
import { Input } from '../ui/input';
import { Avatar, AvatarFallback } from '../ui/avatar';
import { Badge } from '../ui/badge';
import { Tabs, TabsContent, TabsList, TabsTrigger } from '../ui/tabs';
import { ScrollArea } from '../ui/scroll-area';
import {
  Send,
  Smile,
  Paperclip,
  Users,
  FileText,
  Download,
  Eye,
  MoreHorizontal
} from 'lucide-react';

interface Message {
  id: string;
  user: {
    name: string;
    avatar: string;
    role: string;
  };
  content: string;
  timestamp: string;
  mentions?: string[];
  isSystem?: boolean;
}

interface WorkNoteModalProps {
  open: boolean;
  onClose: () => void;
  requestId: string;
}

export function WorkNoteModal({ open, onClose, requestId }: WorkNoteModalProps) {
  const [message, setMessage] = useState('');
  const messagesEndRef = useRef<HTMLDivElement>(null);

  const participants = [
    { name: 'Sarah Chen', avatar: 'SC', role: 'Initiator', status: 'online' },
    { name: 'Mike Johnson', avatar: 'MJ', role: 'Team Lead', status: 'online' },
    { name: 'Lisa Wong', avatar: 'LW', role: 'Finance Manager', status: 'away' },
    { name: 'Anna Smith', avatar: 'AS', role: 'Spectator', status: 'offline' },
    { name: 'John Doe', avatar: 'JD', role: 'Spectator', status: 'online' }
  ];

  const documents = [
    {
      name: 'Q4_Marketing_Strategy.pdf',
      size: '2.4 MB',
      uploadedBy: 'Sarah Chen',
      uploadedAt: '2024-10-05 14:32'
    },
    {
      name: 'Budget_Breakdown.xlsx',
      size: '1.1 MB',
      uploadedBy: 'Sarah Chen',
      uploadedAt: '2024-10-05 14:35'
    },
    {
      name: 'Previous_Campaign_ROI.pdf',
      size: '856 KB',
      uploadedBy: 'Anna Smith',
      uploadedAt: '2024-10-06 09:15'
    }
  ];

  const [messages, setMessages] = useState<Message[]>([
    {
      id: '1',
      user: { name: 'Sarah Chen', avatar: 'SC', role: 'Initiator' },
      content: 'Hi everyone! I\'ve submitted the marketing campaign budget request. Please review the attached documents.',
      timestamp: '2024-10-05 14:30',
      isSystem: false
    },
    {
      id: '2',
      user: { name: 'System', avatar: 'SY', role: 'System' },
      content: 'Request RE-REQ-001 has been created and assigned to Mike Johnson for initial review.',
      timestamp: '2024-10-05 14:31',
      isSystem: true
    },
    {
      id: '3',
      user: { name: 'Anna Smith', avatar: 'AS', role: 'Spectator' },
      content: 'I\'ve added the previous campaign ROI data to help with the decision. @Mike Johnson @Lisa Wong please check it out.',
      timestamp: '2024-10-06 09:15',
      mentions: ['Mike Johnson', 'Lisa Wong']
    },
    {
      id: '4',
      user: { name: 'Mike Johnson', avatar: 'MJ', role: 'Team Lead' },
      content: 'Thanks @Anna Smith! The numbers look good. I\'m approving this and forwarding to Finance.',
      timestamp: '2024-10-06 10:30',
      mentions: ['Anna Smith']
    },
    {
      id: '5',
      user: { name: 'System', avatar: 'SY', role: 'System' },
      content: 'Request approved by Mike Johnson and forwarded to Lisa Wong for finance review.',
      timestamp: '2024-10-06 10:31',
      isSystem: true
    },
    {
      id: '6',
      user: { name: 'Lisa Wong', avatar: 'LW', role: 'Finance Manager' },
      content: 'I\'m reviewing the budget allocation. @Sarah Chen can you clarify the expected timeline for the LinkedIn ads campaign?',
      timestamp: '2024-10-07 14:20',
      mentions: ['Sarah Chen']
    }
  ]);

  const scrollToBottom = () => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
  };

  useEffect(() => {
    scrollToBottom();
  }, [messages]);

  const handleSendMessage = () => {
    if (message.trim()) {
      const newMessage: Message = {
        id: Date.now().toString(),
        user: { name: 'You', avatar: 'YO', role: 'Current User' },
        content: message,
        timestamp: new Date().toLocaleString(),
        mentions: extractMentions(message)
      };
      setMessages([...messages, newMessage]);
      setMessage('');
    }
  };

  const extractMentions = (text: string): string[] => {
    const mentionRegex = /@(\w+\s?\w+)/g;
    const mentions: string[] = [];
    let match;
    while ((match = mentionRegex.exec(text)) !== null) {
      if (match[1]) {
        mentions.push(match[1]);
      }
    }
    return mentions;
  };

  const handleKeyPress = (e: React.KeyboardEvent) => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      handleSendMessage();
    }
  };

  const getStatusColor = (status: string) => {
    switch (status) {
      case 'online': return 'bg-green-500';
      case 'away': return 'bg-yellow-500';
      case 'offline': return 'bg-gray-400';
      default: return 'bg-gray-400';
    }
  };

  const formatMessage = (content: string) => {
    // Simple mention highlighting
    const formatted = content.replace(/@(\w+\s?\w+)/g, '<span class="text-blue-600 font-medium">@$1</span>');
    return sanitizeHTML(formatted);
  };

  return (
    <Dialog open={open} onOpenChange={onClose}>
      <DialogContent className="max-w-4xl h-[80vh] flex flex-col">
        <DialogHeader>
          <DialogTitle>Work Notes - {requestId}</DialogTitle>
          <DialogDescription>
            Collaborate with all request participants
          </DialogDescription>
        </DialogHeader>

        <div className="flex-1 flex gap-4">
          {/* Main Chat Area */}
          <div className="flex-1 flex flex-col">
            <Tabs defaultValue="chat" className="flex-1 flex flex-col">
              <TabsList className="grid w-full grid-cols-2">
                <TabsTrigger value="chat">Chat</TabsTrigger>
                <TabsTrigger value="media">Media</TabsTrigger>
              </TabsList>

              <TabsContent value="chat" className="flex-1 flex flex-col">
                <ScrollArea className="flex-1 p-4 border rounded-lg">
                  <div className="space-y-4">
                    {messages.map((msg) => (
                      <div key={msg.id} className={`flex gap-3 ${msg.isSystem ? 'justify-center' : ''}`}>
                        {!msg.isSystem && (
                          <Avatar className="h-8 w-8 flex-shrink-0">
                            <AvatarFallback className={`text-white text-xs ${msg.user.role === 'Initiator' ? 'bg-re-green' :
                              msg.user.role === 'Current User' ? 'bg-blue-500' :
                                'bg-re-light-green'
                              }`}>
                              {msg.user.avatar}
                            </AvatarFallback>
                          </Avatar>
                        )}

                        <div className={`flex-1 ${msg.isSystem ? 'text-center' : ''}`}>
                          {msg.isSystem ? (
                            <div className="inline-flex items-center gap-2 px-3 py-1 bg-muted rounded-full text-sm text-muted-foreground">
                              {msg.content}
                              <span className="text-xs">{msg.timestamp}</span>
                            </div>
                          ) : (
                            <>
                              <div className="flex items-center gap-2 mb-1">
                                <span className="font-medium text-sm">{msg.user.name}</span>
                                <Badge variant="outline" className="text-xs">
                                  {msg.user.role}
                                </Badge>
                                <span className="text-xs text-muted-foreground">
                                  {msg.timestamp}
                                </span>
                              </div>
                              <div
                                className="text-sm bg-muted/30 p-3 rounded-lg"
                                dangerouslySetInnerHTML={{ __html: formatMessage(msg.content) }}
                              />
                            </>
                          )}
                        </div>
                      </div>
                    ))}
                    <div ref={messagesEndRef} />
                  </div>
                </ScrollArea>

                {/* Message Input */}
                <div className="mt-4 flex gap-2">
                  <div className="flex-1 relative">
                    <Input
                      placeholder="Type your message... Use @username to mention someone"
                      value={message}
                      onChange={(e) => setMessage(e.target.value)}
                      onKeyPress={handleKeyPress}
                      className="pr-20"
                    />
                    <div className="absolute right-2 top-1/2 transform -translate-y-1/2 flex gap-1">
                      <Button variant="ghost" size="sm">
                        <Smile className="h-4 w-4" />
                      </Button>
                      <Button variant="ghost" size="sm">
                        <Paperclip className="h-4 w-4" />
                      </Button>
                    </div>
                  </div>
                  <Button onClick={handleSendMessage} disabled={!message.trim()}>
                    <Send className="h-4 w-4" />
                  </Button>
                </div>
              </TabsContent>

              <TabsContent value="media" className="flex-1">
                <div className="p-4 border rounded-lg h-full">
                  <h4 className="font-medium mb-4">Documents ({documents.length})</h4>
                  <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
                    {documents.map((doc, index) => (
                      <div key={index} className="border rounded-lg p-4 hover:bg-muted/30 transition-colors">
                        <div className="flex items-start gap-3">
                          <FileText className="h-8 w-8 text-muted-foreground flex-shrink-0 mt-1" />
                          <div className="flex-1 min-w-0">
                            <p className="font-medium truncate">{doc.name}</p>
                            <p className="text-sm text-muted-foreground">
                              {doc.size} • by {doc.uploadedBy}
                            </p>
                            <p className="text-xs text-muted-foreground">
                              {doc.uploadedAt}
                            </p>
                          </div>
                          <div className="flex gap-1">
                            <Button variant="ghost" size="sm">
                              <Eye className="h-4 w-4" />
                            </Button>
                            <Button variant="ghost" size="sm">
                              <Download className="h-4 w-4" />
                            </Button>
                          </div>
                        </div>
                      </div>
                    ))}
                  </div>
                </div>
              </TabsContent>
            </Tabs>
          </div>

          {/* Participants Sidebar */}
          <div className="w-72 border-l pl-4">
            <div className="flex items-center justify-between mb-4">
              <h4 className="font-medium">Participants</h4>
              <Badge variant="outline">{participants.length}</Badge>
            </div>

            <div className="space-y-3">
              {participants.map((participant, index) => (
                <div key={index} className="flex items-center gap-3">
                  <div className="relative">
                    <Avatar className="h-8 w-8">
                      <AvatarFallback className={`text-white text-xs ${participant.role === 'Initiator' ? 'bg-re-green' : 'bg-re-light-green'
                        }`}>
                        {participant.avatar}
                      </AvatarFallback>
                    </Avatar>
                    <div className={`absolute -bottom-1 -right-1 w-3 h-3 rounded-full border-2 border-background ${getStatusColor(participant.status)}`}></div>
                  </div>
                  <div className="flex-1 min-w-0">
                    <p className="font-medium text-sm truncate">{participant.name}</p>
                    <p className="text-xs text-muted-foreground">{participant.role}</p>
                  </div>
                  <Button variant="ghost" size="sm">
                    <MoreHorizontal className="h-4 w-4" />
                  </Button>
                </div>
              ))}
            </div>

            <div className="mt-6">
              <h4 className="font-medium mb-3">Quick Actions</h4>
              <div className="space-y-2">
                <Button variant="outline" size="sm" className="w-full justify-start">
                  <Users className="h-4 w-4 mr-2" />
                  Add Participant
                </Button>
                <Button variant="outline" size="sm" className="w-full justify-start">
                  <Paperclip className="h-4 w-4 mr-2" />
                  Upload File
                </Button>
              </div>
            </div>
          </div>
        </div>
      </DialogContent>
    </Dialog>
  );
}