function detectLiteralEncoding(campaignName) {
  const encoded = campaignName.match(/%[0-9A-Fa-f]{2}/g);
 
  if (encoded) {
    return {
      hasLiteralEncoding: true,
      sequences: encoded,
      message: 'Campaign name shows literal encoded characters',
      recommendation: 'Double-encoding likely - check URL generation process'
    };
  }
 
  return {
    hasLiteralEncoding: false,
    message: 'No literal encoding detected'
  };
}
 
// Usage
console.log(detectLiteralEncoding('summer%20sale'));
// {
//   hasLiteralEncoding: true,
//   sequences: ['%20'],
//   message: 'Campaign name shows literal encoded characters',
//   recommendation: 'Double-encoding likely - check URL generation process'
// }

# System A creates URL
url = "https://example.com"
params = {"utm_campaign": "Summer Sale"}  # Plain text
 
# Encodes properly
encoded_url = url + "?" + urllib.parse.urlencode(params)
# Result: https://example.com?utm_campaign=Summer+Sale
 
# System B receives this URL and "normalizes"
import requests
response = requests.get(encoded_url)  # requests encodes it AGAIN
# Final URL: ?utm_campaign=Summer%2B%2BSale (double-encoded +)
 
# Analytics shows: "Summer%2BSale" (literal +)

CREATE VIEW analytics.cleaned_campaigns AS
SELECT
  event_date,
  user_pseudo_id,
  -- Decode campaign names with literal encoding
  CASE
    WHEN campaign LIKE '%\%%' THEN
      -- Decode once
      SAFE.NET.URL_DECODE(
        SAFE.NET.URL_DECODE(campaign)  -- Decode twice for double-encoding
      )
    ELSE campaign
  END AS cleaned_campaign,
  event_count
FROM `project.dataset.events_*`
WHERE _TABLE_SUFFIX BETWEEN '20240101' AND '20240131';

// ❌ WRONG
function badWorkflow() {
  // Encode here
  const campaign = encodeURIComponent('Summer Sale');  // "Summer%20Sale"
 
  // Pass to email platform
  sendEmail({
    url: `https://example.com?utm_campaign=${"{"}{"{"}campaign{"}"}{"}"}}`
  });
  // Email platform encodes again → double-encoded!
}
 
// ✅ CORRECT
function goodWorkflow() {
  // Don't encode - use clean value
  const campaign = 'summer-sale';  // Clean, no encoding needed
 
  // Pass to email platform
  sendEmail({
    url: `https://example.com?utm_campaign=${"{"}{"{"}campaign{"}"}{"}"}}`
  });
  // Email platform doesn't need to encode → perfect!
}

function testForLiteralEncoding(url) {
  try {
    const urlObj = new URL(url);
    const issues = [];
 
    urlObj.searchParams.forEach((value, key) => {
      if (!key.startsWith('utm_')) return;
 
      // Check if value contains literal % sequences
      if (/%[0-9A-Fa-f]{2}/.test(value)) {
        issues.push({
          param: key,
          value,
          issue: 'Contains literal encoded sequences',
          examples: value.match(/%[0-9A-Fa-f]{2}/g)
        });
      }
    });
 
    if (issues.length > 0) {
      console.error('❌ LITERAL ENCODING DETECTED:');
      issues.forEach(issue => {
        console.error(`  ${issue.param}: ${issue.value}`);
        console.error(`  Found: ${issue.examples.join(', ')}`);
      });
      return false;
    }
 
    console.log('✅ No literal encoding detected');
    return true;
 
  } catch (e) {
    console.error('Invalid URL:', e.message);
    return false;
  }
}
 
// Usage
const testURL = 'https://example.com?utm_campaign=summer%20sale';
testForLiteralEncoding(testURL);
// ❌ LITERAL ENCODING DETECTED:
//   utm_campaign: summer%20sale
//   Found: %20

-- BigQuery: Find campaigns with literal encoding
SELECT
  (SELECT value.string_value FROM UNNEST(event_params) WHERE key = 'campaign') as campaign,
  COUNT(*) as sessions
FROM `project.dataset.events_*`
WHERE _TABLE_SUFFIX BETWEEN FORMAT_DATE('%Y%m%d', DATE_SUB(CURRENT_DATE(), INTERVAL 7 DAY))
  AND FORMAT_DATE('%Y%m%d', CURRENT_DATE())
  AND (SELECT value.string_value FROM UNNEST(event_params) WHERE key = 'campaign') LIKE '%\%%'
GROUP BY campaign
ORDER BY sessions DESC;

// Check the email template URL
const templateURL = getEmailTemplateURL();
console.log(templateURL);
// https://example.com?utm_campaign=summer%20sale%202024
 
// Decode to see original intent
console.log(decodeURIComponent('summer%20sale%202024'));
// "summer sale 2024"
 
// Decode again (for double-encoding)
console.log(decodeURIComponent('summer sale 2024'));
// "summer sale 2024" (same - so it was double-encoded once)

// Changed email template to:
const cleanCampaign = 'summer-sale-2024';
const url = `https://example.com?utm_campaign=${"{"}{"{"}cleanCampaign{"}"}{"}"}}`;
 
// Result: No encoding needed anywhere in the workflow
// Analytics now shows: "summer-sale-2024" perfectly