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;
  apiKey: string;
  onApiKeyChange: (key: string) => 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 SettingsIcon = () => (
    <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" strokeWidth={1.5} stroke="currentColor" className="w-5 h-5">
      <path strokeLinecap="round" strokeLinejoin="round" d="M10.34 15.84c-.688-.06-1.386-.09-2.09-.09H7.5a4.5 4.5 0 1 1 0-9h.75c.704 0 1.402-.03 2.09-.09a1.692 1.692 0 0 1 1.624 1.374c.11 1.054.547 2.028 1.218 2.822.67.793 1.644 1.23 2.697 1.34a1.694 1.694 0 0 1 1.374 1.625c.06.688.09 1.386.09 2.09v.75a4.5 4.5 0 1 1-9 0v-.75c0-.704-.03-1.402-.09-2.09a1.692 1.692 0 0 1-1.374-1.624 11.264 11.264 0 0 0-1.34-2.698 11.263 11.263 0 0 0-2.822-1.217A1.692 1.692 0 0 1 10.34 15.84Z" />
    </svg>
);


const AIChat: React.FC<AIChatProps> = ({ onSendMessage, isOpen, setIsOpen, apiKey, onApiKeyChange }) => {
  const [messages, setMessages] = useState<ChatMessage[]>([
    { role: 'model', text: 'Hello! I am your AI Data Analyst. I can answer questions about your data, analyze trends, and perform calculations.', timestamp: new Date() }
  ]);
  const [input, setInput] = useState('');
  const [isTyping, setIsTyping] = useState(false);
  const [showConfig, setShowConfig] = useState(!apiKey);
  const messagesEndRef = useRef<HTMLDivElement>(null);

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

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

  useEffect(() => {
      // If no API key is present when opened, show config
      if (!apiKey) setShowConfig(true);
  }, [apiKey]);

  const handleSend = async () => {
    if (!input.trim() || !apiKey) 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();
    }
  };

  const handleSaveKey = (e: React.FormEvent) => {
      e.preventDefault();
      // Input value is already bound to parent state via local var, but we use form submission to switch view
      if (apiKey) setShowConfig(false);
  };

  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 ${apiKey ? 'bg-green-400 animate-pulse' : 'bg-red-500'}`}></div>
            <h3 className="font-bold text-slate-100">AI Data Assistant</h3>
          </div>
          <div className="flex gap-2">
            <button 
                onClick={() => setShowConfig(!showConfig)} 
                className="text-slate-400 hover:text-white transition-colors p-1 rounded hover:bg-white/10"
                title="API Settings"
            >
                <SettingsIcon />
            </button>
            <button onClick={() => setIsOpen(false)} className="text-slate-400 hover:text-white transition-colors p-1 rounded hover:bg-white/10">
                <CloseIcon />
            </button>
          </div>
        </div>

        {/* Configuration Screen */}
        {showConfig ? (
            <div className="flex-1 p-6 flex flex-col justify-center bg-slate-950">
                <div className="mb-6 text-center">
                    <div className="w-12 h-12 bg-indigo-500/20 rounded-full flex items-center justify-center mx-auto mb-4 text-indigo-400">
                        <ChatIcon />
                    </div>
                    <h3 className="text-lg font-bold text-white mb-2">Connect Gemini AI</h3>
                    <p className="text-sm text-slate-400">
                        To enable the AI assistant, please enter your Google Gemini API Key.
                    </p>
                </div>
                
                <form onSubmit={handleSaveKey} className="space-y-4">
                    <div>
                        <label className="block text-xs font-semibold text-slate-500 uppercase mb-1">API Key</label>
                        <input 
                            type="password" 
                            value={apiKey}
                            onChange={(e) => onApiKeyChange(e.target.value)}
                            placeholder="AIzaSy..."
                            className="w-full bg-slate-900 border border-slate-700 rounded-lg px-4 py-3 text-white focus:ring-2 focus:ring-indigo-500 outline-none"
                            required
                        />
                        <p className="text-[10px] text-slate-500 mt-2">
                            Key is stored locally in your browser. 
                            <a href="https://aistudio.google.com/app/apikey" target="_blank" rel="noreferrer" className="text-indigo-400 hover:underline ml-1">Get a key here.</a>
                        </p>
                    </div>
                    <button 
                        type="submit"
                        className="w-full bg-indigo-600 hover:bg-indigo-500 text-white font-bold py-3 rounded-lg transition-colors"
                    >
                        Save & Start Chatting
                    </button>
                </form>
            </div>
        ) : (
            <>
                {/* Messages */}
                <div className="flex-1 overflow-y-auto p-4 space-y-4 bg-slate-950/50 custom-scrollbar">
                {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 revenue, growth, units..."
                    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;