重构代码以提升可读性和可维护性，同时保持外部行为不变，并逐项说明改动。

Refactor this code to improve readability and maintainability: [paste code] Requirements: - Keep the same external behavior (same inputs/outputs) - Apply SOLID principles where appropriate - Extract magic numbers into named constants - Reduce function length (max 20 lines per function) - Add meaningful variable names - Remove code duplication Show me the refactored version with comments explaining each significant change.