/**
 * ConversationHistory.jsx — Chat-style conversation display
 *
 * Features:
 *   - Real-time conversation messages from /social/conversation_text
 *   - User speech input (STT) and robot responses (TTS)
 *   - Timestamped messages with speaker labels
 *   - Auto-scroll to latest message
 *   - Message grouping by speaker
 *   - Scrollback history with max limit
 */

import { useEffect, useRef, useState } from 'react';

const MAX_MESSAGES = 100; // Keep last 100 messages
const AUTO_SCROLL_THRESHOLD = 100; // pixels from bottom

function formatTimestamp(timestamp) {
  const date = new Date(timestamp);
  return date.toLocaleTimeString('en-US', {
    hour: '2-digit',
    minute: '2-digit',
    second: '2-digit',
    hour12: false,
  });
}

function MessageBubble({ message, isUser }) {
  const bgClass = isUser
    ? 'bg-blue-950 border-blue-800'
    : 'bg-green-950 border-green-800';

  const textColorClass = isUser ? 'text-blue-300' : 'text-green-300';
  const labelColorClass = isUser ? 'text-blue-500' : 'text-green-500';

  return (
    <div className={`flex ${isUser ? 'justify-end' : 'justify-start'} mb-3`}>
      <div className={`max-w-xs lg:max-w-md rounded-lg border ${bgClass} p-3 space-y-1`}>
        <div className="flex items-center justify-between gap-2">
          <span className={`text-xs font-bold tracking-widest ${labelColorClass}`}>
            {isUser ? 'USER' : 'ROBOT'}
          </span>
          <span className="text-xs text-gray-600">
            {formatTimestamp(message.timestamp)}
          </span>
        </div>
        <p className={`text-sm ${textColorClass} break-words leading-relaxed`}>
          {message.text}
        </p>
      </div>
    </div>
  );
}

export function ConversationHistory({ subscribe }) {
  const [messages, setMessages] = useState([]);
  const [autoScroll, setAutoScroll] = useState(true);
  const messagesEndRef = useRef(null);
  const scrollContainerRef = useRef(null);
  const messageIdRef = useRef(0);

  // Auto-scroll to latest message
  useEffect(() => {
    if (autoScroll && messagesEndRef.current) {
      messagesEndRef.current.scrollIntoView({ behavior: 'smooth' });
    }
  }, [messages, autoScroll]);

  // Handle scroll detection for auto-scroll toggle
  const handleScroll = () => {
    if (!scrollContainerRef.current) return;

    const { scrollTop, scrollHeight, clientHeight } = scrollContainerRef.current;
    const distanceFromBottom = scrollHeight - scrollTop - clientHeight;

    // Auto-scroll if within threshold
    setAutoScroll(distanceFromBottom < AUTO_SCROLL_THRESHOLD);
  };

  // Subscribe to conversation text topic
  useEffect(() => {
    const unsubConversation = subscribe(
      '/social/conversation_text',
      'saltybot_social_msgs/ConversationMessage',
      (msg) => {
        try {
          // Parse message data
          let speaker = 'unknown';
          let text = '';

          if (msg.speaker !== undefined) {
            // speaker: 0 = user, 1 = robot
            speaker = msg.speaker === 0 ? 'user' : 'robot';
          } else if (msg.is_user !== undefined) {
            speaker = msg.is_user ? 'user' : 'robot';
          }

          if (msg.text) {
            text = msg.text;
          }

          if (!text) return; // Skip empty messages

          const newMessage = {
            id: ++messageIdRef.current,
            text,
            speaker,
            isUser: speaker === 'user',
            timestamp: msg.timestamp || Date.now(),
          };

          setMessages((prev) => [...prev, newMessage].slice(-MAX_MESSAGES));
        } catch (e) {
          console.error('Error parsing conversation message:', e);
        }
      }
    );

    return unsubConversation;
  }, [subscribe]);

  const clearHistory = () => {
    setMessages([]);
    messageIdRef.current = 0;
  };

  const userMessageCount = messages.filter((m) => m.isUser).length;
  const robotMessageCount = messages.filter((m) => !m.isUser).length;

  return (
    <div className="flex flex-col h-full space-y-3">
      {/* Controls */}
      <div className="bg-gray-950 rounded-lg border border-cyan-950 p-3 flex items-center justify-between">
        <div className="flex items-center gap-3">
          <div className="text-cyan-700 text-xs font-bold tracking-widest">
            CONVERSATION HISTORY
          </div>
          <div className="text-gray-600 text-xs">
            {messages.length} messages ({userMessageCount} user, {robotMessageCount} robot)
          </div>
        </div>
        <button
          onClick={clearHistory}
          className="px-3 py-1.5 text-xs font-bold tracking-widest rounded border border-gray-700 text-gray-400 hover:text-red-400 hover:border-red-700 transition-colors"
        >
          CLEAR
        </button>
      </div>

      {/* Messages Container */}
      <div
        ref={scrollContainerRef}
        onScroll={handleScroll}
        className="flex-1 overflow-y-auto bg-gray-950 rounded-lg border border-cyan-950 p-4 space-y-1"
      >
        {messages.length === 0 ? (
          <div className="flex items-center justify-center h-full text-gray-600">
            <div className="text-center">
              <div className="text-sm mb-2">No conversation yet</div>
              <div className="text-xs text-gray-700">
                Messages from /social/conversation_text will appear here
              </div>
            </div>
          </div>
        ) : (
          <>
            {messages.map((message) => (
              <MessageBubble
                key={message.id}
                message={message}
                isUser={message.isUser}
              />
            ))}
            <div ref={messagesEndRef} />
          </>
        )}
      </div>

      {/* Auto-scroll indicator */}
      <div className="bg-gray-950 rounded border border-gray-800 p-2 flex items-center justify-between text-xs text-gray-600">
        <span>Auto-scroll to latest: {autoScroll ? '✓ ON' : '○ OFF'}</span>
        {!autoScroll && (
          <button
            onClick={() => setAutoScroll(true)}
            className="text-cyan-500 hover:text-cyan-400 transition-colors"
          >
            Jump to latest
          </button>
        )}
      </div>

      {/* Topic Info */}
      <div className="bg-gray-950 rounded border border-gray-800 p-2 text-xs text-gray-600 space-y-1">
        <div className="flex justify-between">
          <span>Topic:</span>
          <span className="text-gray-500">/social/conversation_text</span>
        </div>
        <div className="flex justify-between">
          <span>Message Type:</span>
          <span className="text-gray-500">saltybot_social_msgs/ConversationMessage</span>
        </div>
        <div className="flex justify-between">
          <span>Max History:</span>
          <span className="text-gray-500">{MAX_MESSAGES} messages</span>
        </div>
      </div>
    </div>
  );
}