/**
 * 使い方:
 *   <script src="/jcjs/cms-ibtracker.js"></script>
 *   → 読み込むだけで、ページ表示完了後に自動で記録処理が実行される
 */
(function (root, factory) {
  if (typeof module === 'object' && module.exports) {
    module.exports = factory(); // CommonJS
  } else if (typeof define === 'function' && define.amd) {
    define(factory); // AMD
  } else {
    root.JcInboundTracker = factory(); // グローバル変数
  }
}(typeof self !== 'undefined' ? self : this, function () {
  'use strict';

  var ENDPOINT = '/jcapi/_jc_ibltrack.php';
  var UTM_KEYS = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content'];

  function collectUtmParams() {
    var params = new URLSearchParams(location.search);
    var result = {};
    UTM_KEYS.forEach(function (key) {
      result[key] = params.get(key) || null;
    });
    return result;
  }

  function buildPayload() {
    return {
      referrer: document.referrer || null,
      landing_url: location.href,
      landing_path: location.pathname,
      query_string: location.search ? location.search.substring(1) : null,
      utm: collectUtmParams(),
      user_agent: navigator.userAgent
    };
  }

  /**
   * 記録リクエストを送信する
   * @returns {Promise<Object|null>} レスポンスJSON。失敗時はnull
   */
  function track() {
    var payload = buildPayload();

    return fetch(ENDPOINT, {
      method: 'POST',
      credentials: 'same-origin',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(payload),
      keepalive: true
    })
      .then(function (res) {
        if (!res.ok) {
          throw new Error('HTTP ' + res.status);
        }
        return res.json();
      })
      .catch(function (err) {
        console.warn('[JcInboundTracker] failed', err);
        return null;
      });
  }

  // ページ表示完了後に自動実行
  if (document.readyState === 'complete') {
    track();
  } else {
    window.addEventListener('load', track);
  }

  return {
    track: track
  };
}));