/**
 * visitor.js — Visitor presence protocol for the Workshop.
 *
 * Announces when a visitor enters and leaves the 3D world,
 * sends chat messages, and tracks session duration.
 *
 * Resolves Issue #41 — Visitor presence protocol
 * Resolves Issue #40 — Chat input (visitor message sending)
 */

import { sendMessage, getConnectionState } from './websocket.js';
import { appendChatMessage } from './ui.js';

let sessionStart = Date.now();
let visibilityTimeout = null;
const VISIBILITY_LEAVE_MS = 30000; // 30s hidden = considered "left"

/**
 * Detect device type from UA + touch capability.
 */
function detectDevice() {
  const ua = navigator.userAgent;
  const hasTouch = 'ontouchstart' in window || navigator.maxTouchPoints > 0;

  if (/iPad/.test(ua) || (hasTouch && /Macintosh/.test(ua))) return 'ipad';
  if (/iPhone|iPod/.test(ua)) return 'mobile';
  if (/Android/.test(ua) && hasTouch) return 'mobile';
  if (hasTouch && window.innerWidth < 768) return 'mobile';
  return 'desktop';
}

/**
 * Send visitor_entered event to the backend.
 */
function announceEntry() {
  sessionStart = Date.now();
  sendMessage({
    type: 'visitor_entered',
    device: detectDevice(),
    viewport: { w: window.innerWidth, h: window.innerHeight },
    timestamp: new Date().toISOString(),
  });
}

/**
 * Send visitor_left event to the backend.
 */
function announceLeave() {
  const duration = Math.round((Date.now() - sessionStart) / 1000);
  sendMessage({
    type: 'visitor_left',
    duration_seconds: duration,
    timestamp: new Date().toISOString(),
  });
}

/**
 * Send a chat message from the visitor to Timmy.
 * @param {string} text — the visitor's message
 */
export function sendVisitorMessage(text) {
  const trimmed = text.trim();
  if (!trimmed) return;

  // Show in local chat panel immediately
  const isOffline = getConnectionState() !== 'connected' && getConnectionState() !== 'mock';
  const label = isOffline ? 'YOU (offline)' : 'YOU';
  appendChatMessage(label, trimmed, '#888888', 'visitor');

  // Send via WebSocket
  sendMessage({
    type: 'visitor_message',
    text: trimmed,
    timestamp: new Date().toISOString(),
  });
}

/**
 * Send a visitor_interaction event (e.g., tapped an agent).
 * @param {string} targetId — the ID of the interacted object
 * @param {string} action — the type of interaction
 */
export function sendVisitorInteraction(targetId, action) {
  sendMessage({
    type: 'visitor_interaction',
    target: targetId,
    action: action,
    timestamp: new Date().toISOString(),
  });
}

/**
 * Initialize the visitor presence system.
 * Sets up lifecycle events and chat input handling.
 */
export function initVisitor() {
  // Announce entry after a small delay (let WS connect first)
  setTimeout(announceEntry, 1500);

  // Visibility change handling (iPad tab suspend)
  document.addEventListener('visibilitychange', () => {
    if (document.hidden) {
      // Start countdown — if hidden for 30s, announce leave
      visibilityTimeout = setTimeout(announceLeave, VISIBILITY_LEAVE_MS);
    } else {
      // Returned before timeout — cancel leave
      if (visibilityTimeout) {
        clearTimeout(visibilityTimeout);
        visibilityTimeout = null;
      } else {
        // Was gone long enough that we sent visitor_left — re-announce entry
        announceEntry();
      }
    }
  });

  // Before unload — best-effort leave announcement
  window.addEventListener('beforeunload', () => {
    announceLeave();
  });

  // Chat input handling
  const $input = document.getElementById('chat-input');
  const $send = document.getElementById('chat-send');

  if ($input && $send) {
    $input.addEventListener('keydown', (e) => {
      if (e.key === 'Enter' && !e.shiftKey) {
        e.preventDefault();
        sendVisitorMessage($input.value);
        $input.value = '';
      }
    });

    $send.addEventListener('click', () => {
      sendVisitorMessage($input.value);
      $input.value = '';
      $input.focus();
    });
  }
}