import React, { useState, useRef, useEffect } from 'react';
import { ChatIcon, CloseIcon, SendIcon } from './Icons';
import { ChatMessage } from '../types';

interface AIChatProps {
  onSendMessage: (text: string) => Promise<string>;
  isOpen: boolean;
  setIsOpen: (open: boolean) => void;
}

const ModelMessage: React.FC<{ text: string }> = ({ text }) => {
  const elements: React.ReactNode[] = [];
  let listItems: React.ReactNode[] = [];

  const flushList = () => {
    if (listItems.length > 0) {
      elements.push(
        <ul key={`ul-${elements.length}`} className="list-disc list-inside space-y-1 my-2 pl-2">
          {listItems}
        </ul>
      );
      listItems = [];
    }
  };
  
  const parseBold = (content: string, keyPrefix: string) => {
      const parts = content.split(/(\*\*.*?\*\*)/g);
      return parts.map((part, i) => {
        if (part.startsWith('**') && part.endsWith('**')) {
          return <strong key={`${keyPrefix}-${i}`}>{part.slice(2, -2)}</strong>;
        }
        return part;
      });
  }

  text.split('\n').forEach((line, index) => {
    const trimmedLine = line.trim();
    if (trimmedLine.startsWith('* ') || trimmedLine.startsWith('- ')) {
      const content = trimmedLine.substring(2);
      listItems.push(<li key={index}>{parseBold(content, `li-${index}`)}</li>);
    } else {
      flushList();
      if (line.trim() !== '') {
          elements.push(
            <p key={`p-${index}`} className="my-1">
              {parseBold(line, `p-${index}`)}
            </p>
          );
      }
    }
  });

  flushList(); // Flush any remaining list items at the end

  return <>{elements.length > 0 ? elements : <p>{text}</p>}</>;
};


const AIChat: React.FC<AIChatProps> = ({ onSendMessage, isOpen, setIsOpen }) => {
  const [messages, setMessages] = useState<ChatMessage[]>([
    { role: 'model', text: 'Hello! I am your Sales Data Assistant. Ask me anything about the loaded data.', timestamp: new Date() }
  ]);
  const [input, setInput] = useState('');
  const [isTyping, setIsTyping] = useState(false);
  const messagesEndRef = useRef<HTMLDivElement>(null);

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

  useEffect(scrollToBottom, [messages, isOpen]);

  const handleSend = async () => {
    if (!input.trim()) return;

    const userMsg: ChatMessage = { role: 'user', text: input, timestamp: new Date() };
    setMessages(prev => [...prev, userMsg]);
    setInput('');
    setIsTyping(true);

    const responseText = await onSendMessage(userMsg.text);
    
    setIsTyping(false);
    setMessages(prev => [...prev, { role: 'model', text: responseText, timestamp: new Date() }]);
  };

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

  return (
    <>
      {/* Trigger Button */}
      <button
        onClick={() => setIsOpen(!isOpen)}
        className={`fixed bottom-6 right-6 z-50 p-4 rounded-full shadow-2xl transition-all duration-300 hover:scale-110 
          ${isOpen ? 'bg-slate-700 rotate-90 opacity-0 pointer-events-none' : 'bg-primary text-white rotate-0 opacity-100'}`}
      >
        <ChatIcon />
      </button>

      {/* Chat Window */}
      <div 
        className={`fixed z-50 bg-slate-900 border border-border shadow-2xl transition-all duration-300 flex flex-col overflow-hidden
        ${isOpen 
          ? 'bottom-6 right-6 w-96 h-[600px] rounded-2xl opacity-100 translate-y-0' 
          : 'bottom-6 right-6 w-96 h-0 opacity-0 translate-y-10 pointer-events-none'}`}
      >
        {/* Header */}
        <div className="bg-primary/10 p-4 border-b border-border flex justify-between items-center backdrop-blur">
          <div className="flex items-center gap-2">
            <div className="w-2 h-2 rounded-full bg-green-400 animate-pulse"></div>
            <h3 className="font-bold text-slate-100">Data Assistant</h3>
          </div>
          <button onClick={() => setIsOpen(false)} className="text-slate-400 hover:text-white transition-colors">
            <CloseIcon />
          </button>
        </div>

        {/* Messages */}
        <div className="flex-1 overflow-y-auto p-4 space-y-4 bg-slate-950/50">
          {messages.map((msg, idx) => (
            <div key={idx} className={`flex ${msg.role === 'user' ? 'justify-end' : 'justify-start'}`}>
              <div 
                className={`max-w-[85%] rounded-2xl p-3 text-sm leading-relaxed shadow-sm
                  ${msg.role === 'user' 
                    ? 'bg-primary text-white rounded-br-none' 
                    : 'bg-slate-800 text-slate-200 border border-border rounded-bl-none'}`}
              >
                {msg.role === 'model' ? <ModelMessage text={msg.text} /> : msg.text}
              </div>
            </div>
          ))}
          {isTyping && (
             <div className="flex justify-start">
               <div className="bg-slate-800 border border-border rounded-2xl rounded-bl-none p-4 flex gap-1 items-center">
                 <div className="w-2 h-2 bg-slate-500 rounded-full animate-bounce"></div>
                 <div className="w-2 h-2 bg-slate-500 rounded-full animate-bounce delay-100"></div>
                 <div className="w-2 h-2 bg-slate-500 rounded-full animate-bounce delay-200"></div>
               </div>
             </div>
          )}
          <div ref={messagesEndRef} />
        </div>

        {/* Input */}
        <div className="p-4 bg-slate-900 border-t border-border">
          <div className="relative">
            <input
              type="text"
              value={input}
              onChange={(e) => setInput(e.target.value)}
              onKeyDown={handleKeyDown}
              placeholder="Ask about trends, totals..."
              className="w-full bg-slate-950 border border-slate-700 text-slate-200 rounded-full py-3 pl-4 pr-12 focus:outline-none focus:border-primary transition-colors placeholder-slate-500 text-sm"
            />
            <button 
              onClick={handleSend}
              disabled={!input.trim() || isTyping}
              className="absolute right-2 top-1/2 -translate-y-1/2 p-2 bg-primary text-white rounded-full hover:bg-indigo-400 disabled:opacity-50 transition-colors"
            >
              <SendIcon />
            </button>
          </div>
        </div>
      </div>
    </>
  );
};

export default AIChat;