Dynamic UTM Parameter Capture

<script>
(function() {
  'use strict';
  
  // Dynamic UTM Parameter Capture Script
  // Version: 1.2
  // Description: Captures UTM parameters and stores them for attribution
  // Last Updated: 2025-09-09
  
  // Configuration
  var config = {
    // UTM Parameters to capture
    paramNames: ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content'],
    
    // Additional custom parameters (add more as needed)
    customParams: ['gclid', 'fbclid', 'msclkid', 'ref', 'referrer'],
    
    // LocalStorage key for storing UTM data
    storageKey: 'utm_data',
    
    // DataLayer event name
    dataLayerEvent: 'utm_captured',
    
    // Expiration time in days (30 days default)
    expirationDays: 30,
    
    // Override existing UTM data (false = keep first-touch)
    overrideExisting: false,
    
    // Debug mode (set to true for console logging)
    debug: false
  };

  // Utility functions
  function debugLog(message, data) {
    if (config.debug) {
      console.log('[UTM Capture] ' + message, data || '');
    }
  }

  function getUrlParameters() {
    var params = {};
    var urlParams = new URLSearchParams(window.location.search);
    
    // Capture UTM parameters
    config.paramNames.forEach(function(param) {
      var value = urlParams.get(param);
      if (value) {
        params[param] = value;
      }
    });
    
    // Capture custom parameters
    config.customParams.forEach(function(param) {
      var value = urlParams.get(param);
      if (value) {
        params[param] = value;
      }
    });
    
    return params;
  }

  function getStoredUtmData() {
    try {
      var stored = localStorage.getItem(config.storageKey);
      if (stored) {
        var data = JSON.parse(stored);
        
        // Check if data has expired
        if (data.timestamp && data.expirationDays) {
          var expirationTime = data.timestamp + (data.expirationDays * 24 * 60 * 60 * 1000);
          if (Date.now() > expirationTime) {
            debugLog('UTM data expired, clearing storage');
            localStorage.removeItem(config.storageKey);
            return null;
          }
        }
        
        return data;
      }
    } catch (e) {
      debugLog('Error reading stored UTM data:', e);
    }
    return null;
  }

  function storeUtmData(params) {
    try {
      var dataToStore = {
        ...params,
        timestamp: Date.now(),
        expirationDays: config.expirationDays,
        pageUrl: window.location.href,
        referrer: document.referrer || 'direct'
      };
      
      localStorage.setItem(config.storageKey, JSON.stringify(dataToStore));
      debugLog('UTM data stored:', dataToStore);
      return dataToStore;
    } catch (e) {
      debugLog('Error storing UTM data:', e);
      return null;
    }
  }

  function pushToDataLayer(utmData) {
    // Ensure dataLayer exists
    window.dataLayer = window.dataLayer || [];
    
    // Prepare event data
    var eventData = {
      event: config.dataLayerEvent,
      utm_data: utmData,
      utm_source: utmData.utm_source || '',
      utm_medium: utmData.utm_medium || '',
      utm_campaign: utmData.utm_campaign || '',
      utm_term: utmData.utm_term || '',
      utm_content: utmData.utm_content || '',
      first_touch_timestamp: utmData.timestamp,
      attribution_type: utmData.isNewCapture ? 'first_touch' : 'existing'
    };

    // Add custom parameters to event data
    config.customParams.forEach(function(param) {
      if (utmData[param]) {
        eventData[param] = utmData[param];
      }
    });

    // Push to dataLayer
    window.dataLayer.push(eventData);
    debugLog('Data pushed to dataLayer:', eventData);
  }

  // Main execution
  function initUTMCapture() {
    debugLog('Initializing UTM capture');
    
    // Get current URL parameters
    var currentParams = getUrlParameters();
    var hasNewParams = Object.keys(currentParams).length > 0;
    
    // Get stored UTM data
    var storedData = getStoredUtmData();
    
    debugLog('Current URL params:', currentParams);
    debugLog('Stored UTM data:', storedData);
    
    var finalUtmData = null;
    
    if (hasNewParams) {
      // New UTM parameters found in URL
      if (!storedData || config.overrideExisting) {
        // Store new parameters (first-touch or override mode)
        finalUtmData = storeUtmData(currentParams);
        if (finalUtmData) {
          finalUtmData.isNewCapture = true;
          debugLog('New UTM parameters captured and stored');
        }
      } else {
        // Keep existing stored data (first-touch attribution)
        finalUtmData = storedData;
        finalUtmData.isNewCapture = false;
        debugLog('Using existing stored UTM data (first-touch)');
      }
    } else if (storedData) {
      // No new parameters, but we have stored data
      finalUtmData = storedData;
      finalUtmData.isNewCapture = false;
      debugLog('Using existing stored UTM data');
    }
    
    // Push to dataLayer if we have UTM data
    if (finalUtmData) {
      pushToDataLayer(finalUtmData);
    } else {
      debugLog('No UTM parameters to process');
      
      // Still push an event for direct traffic
      window.dataLayer = window.dataLayer || [];
      window.dataLayer.push({
        event: config.dataLayerEvent,
        utm_source: 'direct',
        utm_medium: 'none',
        attribution_type: 'direct_traffic'
      });
    }
  }

  // Initialize when DOM is ready
  if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', initUTMCapture);
  } else {
    // DOM is already ready
    initUTMCapture();
  }

  // Optional: Expose utility functions for advanced users
  window.utmCapture = {
    getStoredData: function() {
      return getStoredUtmData();
    },
    clearStoredData: function() {
      localStorage.removeItem(config.storageKey);
      debugLog('UTM data cleared from storage');
    },
    refreshCapture: function() {
      initUTMCapture();
    }
  };

})();
</script>