refactor

Break the long function into smaller focused functions using extract method, keeping behavior identical. Ensure tests exist first, make one small change at a time, run tests after each step, and commit whenever tests pass.

Common smells include long methods, duplicated code, large classes, long parameter lists, magic numbers, and nested conditionals. Fixes include extracting methods, introducing parameter objects, named constants, guard clauses, and splitting classes by responsibility.

Avoid refactoring stable code that will not change, critical production code without test coverage, or when under a tight deadline. Add tests first before touching untested critical paths, and always have a clear purpose.

Replace nested conditionals with guard clauses that return early on invalid states, flattening the arrow-shaped code. For complex validation, use a Chain of Responsibility pattern or a Result type to compose checks.

Refactoring preserves external behavior while improving internal structure through small verified steps. Rewriting replaces the implementation entirely, which carries higher risk and is appropriate only when gradual improvement is not viable.