I'm creating an extremely difficult challenge that combines multiple advanced regex concepts including:
1. Mixed format IP addresses (IPv4 and IPv6) with valid and invalid examples
2. Credit card numbers with varied formatting and only certain valid ones
3. Dates in multiple formats with specific validation rules
4. Product codes with similar patterns but subtle differences
5. URLs with query parameters where only some should match
6. Items requiring negative lookahead/lookbehind to properly ide... (truncated)