/**
 * Chat Page
 * Native React implementation communicating with OpenClaw Gateway
 * via gateway:rpc IPC. Session selector, thinking toggle, and refresh
 * are in the toolbar; messages render with markdown + streaming.
 */
import { useEffect, useRef } from 'react';
import { AlertCircle, Bot, MessageSquare, Sparkles } from 'lucide-react';
import { Card, CardContent } from '@/components/ui/card';
import { useChatStore } from '@/stores/chat';
import { useGatewayStore } from '@/stores/gateway';
import { LoadingSpinner } from '@/components/common/LoadingSpinner';
import { ChatToolbar } from './ChatToolbar';
import { ChatMessage } from './ChatMessage';
import { ChatInput } from './ChatInput';
import { extractText } from './message-utils';

export function Chat() {
  const gatewayStatus = useGatewayStore((s) => s.status);
  const isGatewayRunning = gatewayStatus.state === 'running';

  const messages = useChatStore((s) => s.messages);
  const loading = useChatStore((s) => s.loading);
  const sending = useChatStore((s) => s.sending);
  const error = useChatStore((s) => s.error);
  const showThinking = useChatStore((s) => s.showThinking);
  const streamingMessage = useChatStore((s) => s.streamingMessage);
  const loadHistory = useChatStore((s) => s.loadHistory);
  const loadSessions = useChatStore((s) => s.loadSessions);
  const sendMessage = useChatStore((s) => s.sendMessage);
  const clearError = useChatStore((s) => s.clearError);

  const messagesEndRef = useRef<HTMLDivElement>(null);

  // Load data when gateway is running
  useEffect(() => {
    if (isGatewayRunning) {
      loadHistory();
      loadSessions();
    }
  }, [isGatewayRunning, loadHistory, loadSessions]);

  // Auto-scroll on new messages or streaming
  useEffect(() => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' });
  }, [messages, streamingMessage, sending]);

  // Gateway not running
  if (!isGatewayRunning) {
    return (
      <div className="flex h-[calc(100vh-8rem)] flex-col items-center justify-center text-center p-8">
        <AlertCircle className="h-12 w-12 text-yellow-500 mb-4" />
        <h2 className="text-xl font-semibold mb-2">Gateway Not Running</h2>
        <p className="text-muted-foreground max-w-md">
          The OpenClaw Gateway needs to be running to use chat.
          It will start automatically, or you can start it from Settings.
        </p>
      </div>
    );
  }

  // Extract streaming text for display
  const streamText = streamingMessage ? extractText(streamingMessage) : '';

  return (
    <div className="flex h-[calc(100vh-4rem)] flex-col">
      {/* Toolbar: session selector, refresh, thinking toggle */}
      <div className="flex items-center justify-between px-4 py-2 border-b">
        <div /> {/* spacer */}
        <ChatToolbar />
      </div>

      {/* Messages Area */}
      <div className="flex-1 overflow-y-auto px-4 py-4">
        <div className="max-w-4xl mx-auto space-y-4">
          {loading ? (
            <div className="flex h-full items-center justify-center py-20">
              <LoadingSpinner size="lg" />
            </div>
          ) : messages.length === 0 && !sending ? (
            <WelcomeScreen />
          ) : (
            <>
              {messages.map((msg, idx) => (
                <ChatMessage
                  key={msg.id || `msg-${idx}`}
                  message={msg}
                  showThinking={showThinking}
                />
              ))}

              {/* Streaming message */}
              {sending && streamText && (
                <ChatMessage
                  message={{
                    role: 'assistant',
                    content: streamingMessage as unknown as string,
                    timestamp: Date.now() / 1000,
                  }}
                  showThinking={showThinking}
                  isStreaming
                />
              )}

              {/* Typing indicator when sending but no stream yet */}
              {sending && !streamText && (
                <TypingIndicator />
              )}
            </>
          )}

          {/* Scroll anchor */}
          <div ref={messagesEndRef} />
        </div>
      </div>

      {/* Error bar */}
      {error && (
        <div className="px-4 py-2 bg-destructive/10 border-t border-destructive/20">
          <div className="max-w-4xl mx-auto flex items-center justify-between">
            <p className="text-sm text-destructive flex items-center gap-2">
              <AlertCircle className="h-4 w-4" />
              {error}
            </p>
            <button
              onClick={clearError}
              className="text-xs text-destructive/60 hover:text-destructive underline"
            >
              Dismiss
            </button>
          </div>
        </div>
      )}

      {/* Input Area */}
      <ChatInput
        onSend={sendMessage}
        disabled={!isGatewayRunning}
        sending={sending}
      />
    </div>
  );
}

// ── Welcome Screen ──────────────────────────────────────────────

function WelcomeScreen() {
  return (
    <div className="flex flex-col items-center justify-center text-center py-20">
      <div className="w-16 h-16 rounded-2xl bg-gradient-to-br from-indigo-500 to-purple-600 flex items-center justify-center mb-6">
        <Bot className="h-8 w-8 text-white" />
      </div>
      <h2 className="text-2xl font-bold mb-2">ClawX Chat</h2>
      <p className="text-muted-foreground mb-8 max-w-md">
        Your AI assistant is ready. Start a conversation below.
      </p>

      <div className="grid grid-cols-2 gap-4 max-w-lg w-full">
        {[
          { icon: MessageSquare, title: 'Ask Questions', desc: 'Get answers on any topic' },
          { icon: Sparkles, title: 'Creative Tasks', desc: 'Writing, brainstorming, ideas' },
        ].map((item, i) => (
          <Card key={i} className="text-left">
            <CardContent className="p-4">
              <item.icon className="h-6 w-6 text-primary mb-2" />
              <h3 className="font-medium">{item.title}</h3>
              <p className="text-sm text-muted-foreground">{item.desc}</p>
            </CardContent>
          </Card>
        ))}
      </div>
    </div>
  );
}

// ── Typing Indicator ────────────────────────────────────────────

function TypingIndicator() {
  return (
    <div className="flex gap-3">
      <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-gradient-to-br from-indigo-500 to-purple-600 text-white">
        <Sparkles className="h-4 w-4" />
      </div>
      <div className="bg-muted rounded-2xl px-4 py-3">
        <div className="flex gap-1">
          <span className="w-2 h-2 bg-muted-foreground/50 rounded-full animate-bounce" style={{ animationDelay: '0ms' }} />
          <span className="w-2 h-2 bg-muted-foreground/50 rounded-full animate-bounce" style={{ animationDelay: '150ms' }} />
          <span className="w-2 h-2 bg-muted-foreground/50 rounded-full animate-bounce" style={{ animationDelay: '300ms' }} />
        </div>
      </div>
    </div>
  );
}

export default Chat;