"use client"

import React, { useState, useEffect, useRef } from "react";
import { useRouter } from "next/navigation";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Avatar, AvatarFallback } from "@/components/ui/avatar";
import { cn } from "@/lib/utils/general";
import { formatDistanceToNow } from "date-fns";
import axios from "axios";
import { toast } from "sonner";
import { ArrowLeft, Send, RefreshCw, File, FileText, Image as ImageIcon, Download } from "lucide-react";
import { getCookie, clientFetch } from "@/lib/api";
import { ImageViewerModal } from "@/components/modals/image-viewer-modal";
import BuyerOrderInfo from "./BuyerOrderInfo";

interface Message {
  _id: string;
  sender: "buyer" | "vendor";
  content: string;
  attachments: string[];
  read: boolean;
  createdAt: string;
  buyerId: string;
  vendorId: string;
}

interface Chat {
  _id: string;
  buyerId: string;
  vendorId: string;
  storeId: string;
  messages: Message[];
  lastUpdated: string;
  orderId?: string;
  telegramUsername?: string | null;
}

// Helper function to extract filename from URL
const getFileNameFromUrl = (url: string): string => {
  // Try to extract filename from the URL path
  const pathParts = url.split('/');
  const lastPart = pathParts[pathParts.length - 1];
  
  // Remove query parameters if any
  const fileNameParts = lastPart.split('?');
  let fileName = fileNameParts[0];
  
  // If filename is too long or not found, create a generic name
  if (!fileName || fileName.length > 30) {
    return 'attachment';
  }
  
  // URL decode the filename (handle spaces and special characters)
  try {
    fileName = decodeURIComponent(fileName);
  } catch (e) {
    // If decoding fails, use the original
  }
  
  return fileName;
};

// Helper function to get file icon based on extension or URL pattern
const getFileIcon = (url: string): React.ReactNode => {
  const fileName = url.toLowerCase();
  
  // Image files
  if (/\.(jpg|jpeg|png|gif|webp|svg|bmp|tiff)($|\?)/i.test(fileName) || 
      url.includes('/photos/') || url.includes('/photo/')) {
    return <ImageIcon className="h-5 w-5" />;
  }
  
  // Document files
  if (/\.(pdf|doc|docx|xls|xlsx|ppt|pptx|txt|rtf|csv)($|\?)/i.test(fileName)) {
    return <FileText className="h-5 w-5" />;
  }
  
  // Default file icon
  return <File className="h-5 w-5" />;
};

export default function ChatDetail({ chatId }: { chatId: string }) {
  const router = useRouter();
  const [chat, setChat] = useState<Chat | null>(null);
  const [loading, setLoading] = useState(true);
  const [message, setMessage] = useState("");
  const [sending, setSending] = useState(false);
  const [messages, setMessages] = useState<Message[]>([]);
  const [chatData, setChatData] = useState<any>(null);
  const messagesEndRef = useRef<HTMLDivElement>(null);
  const [previousMessageCount, setPreviousMessageCount] = useState<number>(0);
  const audioRef = useRef<HTMLAudioElement | null>(null);
  const markReadTimeoutRef = useRef<NodeJS.Timeout | null>(null);
  const isPollingRef = useRef<boolean>(false);
  const [selectedImage, setSelectedImage] = useState<string | null>(null);
  const [selectedMessageIndex, setSelectedMessageIndex] = useState<number | null>(null);
  const [selectedAttachmentIndex, setSelectedAttachmentIndex] = useState<number | null>(null);
  const seenMessageIdsRef = useRef<Set<string>>(new Set());
  
  // Scroll to bottom utility functions
  const scrollToBottom = () => {
    messagesEndRef.current?.scrollIntoView({ behavior: "smooth" });
  };
  
  const isNearBottom = () => {
    if (!messagesEndRef.current) return true;
    
    const container = messagesEndRef.current.parentElement;
    if (!container) return true;
    
    const { scrollTop, scrollHeight, clientHeight } = container;
    // Consider "near bottom" if within 100px of the bottom
    return scrollHeight - (scrollTop + clientHeight) < 100;
  };
  
  // Initialize audio element
  useEffect(() => {
    // Create audio element for notification sound
    audioRef.current = new Audio('/notification.mp3');
    
    // Fallback if notification.mp3 doesn't exist - use browser API for a simple beep
    audioRef.current.addEventListener('error', () => {
      audioRef.current = null;
    });
    
    return () => {
      if (audioRef.current) {
        audioRef.current = null;
      }
      
      // Clear any pending timeouts when component unmounts
      if (markReadTimeoutRef.current) {
        clearTimeout(markReadTimeoutRef.current);
      }
    };
  }, []);
  
  // Function to play notification sound
  const playNotificationSound = () => {
    if (audioRef.current) {
      audioRef.current.currentTime = 0;
      audioRef.current.play().catch(err => {
        console.log('Error playing sound:', err);
        // Fallback to simple beep if audio file fails
        try {
          const context = new (window.AudioContext || (window as any).webkitAudioContext)();
          const oscillator = context.createOscillator();
          oscillator.type = 'sine';
          oscillator.frequency.setValueAtTime(800, context.currentTime);
          oscillator.connect(context.destination);
          oscillator.start();
          oscillator.stop(context.currentTime + 0.2);
        } catch (e) {
          console.error('Could not play fallback audio', e);
        }
      });
    } else {
      // Fallback to simple beep if audio element is not available
      try {
        const context = new (window.AudioContext || (window as any).webkitAudioContext)();
        const oscillator = context.createOscillator();
        oscillator.type = 'sine';
        oscillator.frequency.setValueAtTime(800, context.currentTime);
        oscillator.connect(context.destination);
        oscillator.start();
        oscillator.stop(context.currentTime + 0.2);
      } catch (e) {
        console.error('Could not play fallback audio', e);
      }
    }
  };
  
  // Function to mark messages as read
  const markMessagesAsRead = async () => {
    try {
      // Use clientFetch instead of direct axios
      await clientFetch(`/chats/${chatId}/mark-read`, {
        method: 'POST'
      });
      console.log("Marked messages as read");
    } catch (error) {
      console.error("Error marking messages as read:", error);
    }
  };
  
  // Loading effect
  useEffect(() => {
    if (chatId) {
      fetchChatData();
    }
  }, [chatId]);

  // Get a fresh auth axios instance
  const getAuthAxios = () => {
    const authToken = getCookie("Authorization");
    if (!authToken) return null;
    
    return axios.create({
      baseURL: process.env.NEXT_PUBLIC_API_URL,
      headers: {
        Authorization: `Bearer ${authToken}`,
        "Content-Type": "application/json",
      }
    });
  };
  
  // Fetch chat information and messages
  const fetchChatData = async () => {
    if (!chatId) return;
    
    try {
      setLoading(true);
      
      // Use clientFetch to load chat data
      // For now, we're only loading chat data, but this could be extended
      // to load additional data in parallel (user profiles, order details, etc.)
      const response = await clientFetch(`/chats/${chatId}`);
      
      setChatData(response);
      setChat(response); // Set chat data to maintain compatibility
      
      // Set messages with a transition effect
      // If we already have messages, append new ones to avoid jumpiness
      if (messages.length > 0) {
        const existingMessageIds = new Set(messages.map(m => m._id));
        const newMessages = response.messages.filter(
          (msg: Message) => !existingMessageIds.has(msg._id)
        );
        
        if (newMessages.length > 0) {
          setMessages(prev => [...prev, ...newMessages]);
          
          // Mark all these messages as seen to avoid notification sounds
          newMessages.forEach((msg: Message) => {
            seenMessageIdsRef.current.add(msg._id);
          });
        } else {
          // If we need to replace all messages (e.g., first load or refresh)
          setMessages(Array.isArray(response.messages) ? response.messages : []);
          
          // Mark all messages as seen
          if (Array.isArray(response.messages)) {
            response.messages.forEach((msg: Message) => {
              seenMessageIdsRef.current.add(msg._id);
            });
          }
        }
      } else {
        // Initial load
        const initialMessages = Array.isArray(response.messages) ? response.messages : [];
        setMessages(initialMessages);
        
        // Mark all initial messages as seen
        initialMessages.forEach((msg: Message) => {
          seenMessageIdsRef.current.add(msg._id);
        });
      }
      
      // Scroll to bottom on initial load
      setTimeout(() => {
        scrollToBottom();
      }, 100);
    } catch (error) {
      console.error("Error fetching chat data:", error);
      toast.error("Failed to load chat");
    } finally {
      setLoading(false);
    }
  };
  
  // Setup polling for new messages
  useEffect(() => {
    // Set up a polling interval to check for new messages
    const pollInterval = setInterval(() => {
      if (chatId && !isPollingRef.current) {
        pollNewMessages();
      }
    }, 3000); // Poll every 3 seconds
    
    return () => {
      clearInterval(pollInterval);
    };
  }, [chatId]);
  
  // Poll for new messages without replacing existing ones
  const pollNewMessages = async () => {
    if (!chatId || isPollingRef.current) return;
    
    isPollingRef.current = true;
    
    try {
      const response = await clientFetch(`/chats/${chatId}`);
      
      // Update chat metadata
      setChatData(response);
      setChat(response);
      
      // Check if there are new messages
      if (Array.isArray(response.messages) && response.messages.length > 0) {
        // Get existing message IDs to avoid duplicates
        const existingIds = new Set(messages.map(m => m._id));
        const newMessages = response.messages.filter((msg: Message) => !existingIds.has(msg._id));
        
        if (newMessages.length > 0) {
          // Add only new messages to avoid re-rendering all messages
          setMessages(prev => [...prev, ...newMessages]);
          
          // Play notification sound only for new buyer messages we haven't seen before
          const unseenBuyerMessages = newMessages.filter((msg: Message) => 
            msg.sender === 'buyer' && !seenMessageIdsRef.current.has(msg._id)
          );
          
          // If we have unseen buyer messages, play sound and mark them as seen
          if (unseenBuyerMessages.length > 0) {
            playNotificationSound();
            
            // Add these messages to our seen set
            unseenBuyerMessages.forEach((msg: Message) => {
              seenMessageIdsRef.current.add(msg._id);
            });
          }
          
          // If near bottom, scroll to new messages
          if (isNearBottom()) {
            setTimeout(scrollToBottom, 50);
          }
          
          // Set timeout to mark new messages as read
          if (markReadTimeoutRef.current) {
            clearTimeout(markReadTimeoutRef.current);
          }
          
          markReadTimeoutRef.current = setTimeout(() => {
            markMessagesAsRead();
          }, 1000);
        }
      }
    } catch (error) {
      console.error("Error polling new messages:", error);
    } finally {
      isPollingRef.current = false;
    }
  };

  // Handle form submit for sending messages
  const handleSendMessage = (e: React.FormEvent) => {
    e.preventDefault();
    if (!message.trim()) return;
    sendMessage(message);
  };

  // Handle keyboard shortcuts for sending message
  const handleKeyDown = (e: React.KeyboardEvent<HTMLInputElement>) => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault();
      if (message.trim()) {
        sendMessage(message);
      }
    }
  };

  // Function to send a new message
  const sendMessage = async (newMessage: string, file?: File | null) => {
    // Don't send empty messages
    if (!newMessage.trim() && !file) return;
    
    if (!chatId || !chatData) return;
    
    // Create a temporary message with a unique temporary ID
    const tempId = `temp-${Date.now()}`;
    const tempMessage: Message = {
      _id: tempId,
      sender: 'vendor',
      content: newMessage,
      attachments: file ? [URL.createObjectURL(file)] : [],
      read: true,
      createdAt: new Date().toISOString(),
      buyerId: chatData.buyerId || '',
      vendorId: chatData.vendorId || ''
    };
    
    // Add the temp message ID to seen messages
    seenMessageIdsRef.current.add(tempId);
    
    // Optimistically add the temp message to the UI
    setMessages(prev => [...prev, tempMessage]);
    
    // Scroll to bottom to show the new message
    setTimeout(scrollToBottom, 50);
    
    try {
      setSending(true);
      
      let response;
      
      if (file) {
        // Use FormData for file uploads
        const formData = new FormData();
        formData.append('content', newMessage);
        formData.append('attachment', file);
        
        response = await clientFetch(`/chats/${chatId}/message`, {
          method: 'POST',
          body: formData,
          // Don't set Content-Type with FormData - browser will set it with boundary
        });
      } else {
        // Use JSON for text-only messages
        response = await clientFetch(`/chats/${chatId}/message`, {
          method: 'POST',
          body: JSON.stringify({ 
            content: newMessage 
          }),
          headers: {
            'Content-Type': 'application/json'
          }
        });
      }
      
      // Replace the temporary message with the real one from the server
      setMessages(prev => prev.map(msg => 
        msg._id === tempId ? response : msg
      ));
      
      // Add the real message ID to seen messages
      if (response && response._id) {
        seenMessageIdsRef.current.add(response._id);
      }
      
      // Update the textarea value to empty
      setMessage('');
      
      // Clear the file if there was one
      if (file) {
        setSelectedImage(null);
        setSelectedMessageIndex(null);
        setSelectedAttachmentIndex(null);
      }
      
      // Update the chat's last message
      if (chatData) {
        setChatData({
          ...chatData,
          lastUpdated: new Date().toISOString()
        });
      }
      
    } catch (error) {
      console.error('Error sending message:', error);
      toast.error('Failed to send message');
      
      // Remove the temporary message if sending failed
      setMessages(prev => prev.filter(msg => msg._id !== tempId));
    } finally {
      setSending(false);
    }
  };
  
  const handleBackClick = () => {
    router.push("/dashboard/chats");
  };
  
  // Add function to handle image navigation
  const handleImageNavigation = (direction: 'prev' | 'next') => {
    if (!chat || selectedMessageIndex === null || selectedAttachmentIndex === null) return;

    // Get all images from all messages
    const allImages: { messageIndex: number; attachmentIndex: number; url: string }[] = [];
    
    chat.messages.forEach((msg, msgIndex) => {
      msg.attachments.forEach((att, attIndex) => {
        if (/\.(jpg|jpeg|png|gif|webp|svg|bmp|tiff)($|\?)/i.test(att) || 
            att.includes('/photos/') || 
            att.includes('/photo/')) {
          allImages.push({ messageIndex: msgIndex, attachmentIndex: attIndex, url: att });
        }
      });
    });

    if (allImages.length === 0) return;

    // Find current image index
    const currentIndex = allImages.findIndex(img => 
      img.messageIndex === selectedMessageIndex && 
      img.attachmentIndex === selectedAttachmentIndex
    );

    if (currentIndex === -1) return;

    // Calculate new index
    let newIndex;
    if (direction === 'next') {
      newIndex = (currentIndex + 1) % allImages.length;
    } else {
      newIndex = currentIndex === 0 ? allImages.length - 1 : currentIndex - 1;
    }

    // Update state with new image
    const newImage = allImages[newIndex];
    setSelectedMessageIndex(newImage.messageIndex);
    setSelectedAttachmentIndex(newImage.attachmentIndex);
    setSelectedImage(newImage.url);
  };

  // Update the image click handler
  const handleImageClick = (imageUrl: string, messageIndex: number, attachmentIndex: number) => {
    setSelectedImage(imageUrl);
    setSelectedMessageIndex(messageIndex);
    setSelectedAttachmentIndex(attachmentIndex);
  };
  
  if (loading) {
    return (
      <div className="flex flex-col h-screen w-full relative">
        <div className="border-b py-2 px-4 flex items-center space-x-2 bg-card z-10">
          <Button variant="ghost" size="icon" onClick={handleBackClick}>
            <ArrowLeft className="h-5 w-5" />
          </Button>
          <span className="text-lg font-semibold">Loading conversation...</span>
        </div>
        <div className="flex-1 flex items-center justify-center">
          <RefreshCw className="h-8 w-8 animate-spin text-muted-foreground" />
        </div>
      </div>
    );
  }
  
  if (!chat) {
    return (
      <div className="flex flex-col h-screen w-full relative">
        <div className="border-b py-2 px-4 flex items-center space-x-2 bg-card z-10">
          <Button variant="ghost" size="icon" onClick={handleBackClick}>
            <ArrowLeft className="h-5 w-5" />
          </Button>
          <span className="text-lg font-semibold">Chat not found</span>
        </div>
        <div className="flex-1 flex items-center justify-center">
          <div className="text-center">
            <p className="text-muted-foreground mb-4">This conversation doesn't exist or you don't have access to it.</p>
            <Button onClick={handleBackClick}>Back to Chats</Button>
          </div>
        </div>
      </div>
    );
  }
  
  return (
    <div className="flex flex-col h-screen w-full relative">
      <div className="border-b h-16 px-4 flex items-center justify-between bg-card z-10">
        <div className="flex items-center space-x-2">
          <Button variant="ghost" size="icon" onClick={handleBackClick}>
            <ArrowLeft className="h-5 w-5" />
          </Button>
          <div className="flex flex-col">
            <h3 className="text-lg font-semibold">
              Chat with Customer {chat.buyerId}
            </h3>
            {chat.telegramUsername && (
              <span className="text-sm text-muted-foreground">
                @{chat.telegramUsername}
              </span>
            )}
          </div>
        </div>
        
        <BuyerOrderInfo buyerId={chat.buyerId} chatId={chatId} />
      </div>
      
      <div className="flex-1 overflow-y-auto p-2 space-y-2 pb-[80px]">
        {chat.messages.length === 0 ? (
          <div className="h-full flex items-center justify-center">
            <p className="text-muted-foreground">No messages yet. Send one to start the conversation.</p>
          </div>
        ) : (
          chat.messages.map((msg, messageIndex) => (
            <div
              key={msg._id || messageIndex}
              className={cn(
                "flex mb-4",
                msg.sender === "vendor" ? "justify-end" : "justify-start"
              )}
            >
              <div
                className={cn(
                  "max-w-[90%] rounded-lg p-3",
                  msg.sender === "vendor"
                    ? "bg-primary text-primary-foreground"
                    : "bg-muted"
                )}
              >
                <div className="flex items-center space-x-2 mb-1">
                  {msg.sender === "buyer" && (
                    <Avatar className="h-6 w-6">
                      <AvatarFallback className="text-xs">
                        {chat.buyerId.slice(0, 2).toUpperCase()}
                      </AvatarFallback>
                    </Avatar>
                  )}
                  <span className="text-xs opacity-70">
                    {formatDistanceToNow(new Date(msg.createdAt), { addSuffix: true })}
                  </span>
                </div>
                <p className="whitespace-pre-wrap break-words">{msg.content}</p>
                {/* Show attachments if any */}
                {msg.attachments && msg.attachments.length > 0 && (
                  <div className="mt-2 space-y-2">
                    {msg.attachments.map((attachment, attachmentIndex) => {
                      const isImage = /\.(jpg|jpeg|png|gif|webp|svg|bmp|tiff)($|\?)/i.test(attachment) || 
                                    attachment.includes('/photos/') || 
                                    attachment.includes('/photo/');
                      
                      const fileName = getFileNameFromUrl(attachment);
                      
                      return isImage ? (
                        <div 
                          key={`attachment-${attachmentIndex}`} 
                          className="rounded-md overflow-hidden bg-background/20 p-1"
                          onClick={() => handleImageClick(attachment, messageIndex, attachmentIndex)}
                        >
                          <div className="flex justify-between items-center mb-1">
                            <span className="text-xs opacity-70 flex items-center">
                              <ImageIcon className="h-3 w-3 mr-1" />
                              {fileName}
                            </span>
                            <a 
                              href={attachment} 
                              download={fileName}
                              target="_blank" 
                              rel="noopener noreferrer"
                              className="text-xs opacity-70 hover:opacity-100"
                              onClick={(e) => e.stopPropagation()}
                            >
                              <Download className="h-3 w-3" />
                            </a>
                          </div>
                          <img 
                            src={attachment} 
                            alt={fileName} 
                            className="max-w-full max-h-60 object-contain cursor-pointer hover:opacity-90 transition-opacity rounded"
                            onError={(e) => {
                              (e.target as HTMLImageElement).src = "/placeholder-image.svg";
                            }}
                          />
                        </div>
                      ) : (
                        // Render file attachment
                        <div key={`attachment-${attachmentIndex}`} className="flex items-center bg-background/20 rounded-md p-2 hover:bg-background/30 transition-colors">
                          <div className="mr-2">
                            {getFileIcon(attachment)}
                          </div>
                          <div className="flex-1 min-w-0">
                            <div className="text-sm truncate font-medium">
                              {fileName}
                            </div>
                          </div>
                          <a 
                            href={attachment} 
                            download={fileName}
                            target="_blank"
                            rel="noopener noreferrer"
                            className="ml-2 p-1 rounded-sm hover:bg-background/50"
                          >
                            <Download className="h-4 w-4" />
                          </a>
                        </div>
                      );
                    })}
                  </div>
                )}
              </div>
            </div>
          ))
        )}
        <div ref={messagesEndRef} />
      </div>
      
      <div className="absolute bottom-0 left-0 right-0 border-t border-border bg-background p-4">
        <form onSubmit={handleSendMessage} className="flex space-x-2">
          <Input
            value={message}
            onChange={(e) => setMessage(e.target.value)}
            placeholder="Type your message..."
            disabled={sending}
            className="flex-1"
            onKeyDown={handleKeyDown}
            autoFocus
          />
          <Button type="submit" disabled={sending || !message.trim()}>
            {sending ? <RefreshCw className="h-4 w-4 animate-spin" /> : <Send className="h-4 w-4" />}
          </Button>
        </form>
      </div>

      {/* Update the image viewer modal */}
      <ImageViewerModal
        isOpen={!!selectedImage}
        onClose={() => {
          setSelectedImage(null);
          setSelectedMessageIndex(null);
          setSelectedAttachmentIndex(null);
        }}
        imageUrl={selectedImage || ""}
        onNavigate={handleImageNavigation}
      />
    </div>
  );
}