Act as a Principal Software Engineer. You have been provided with a snippet of a monolithic legacy codebase. Analyze the code for 'code smells', tight coupling, and violations of SOLID principles. Propose a detailed refactoring plan to break this monolith into modular microservices or a modular monolith. Include specific design patterns to implement (e.g., Factory, Observer, Strategy) and provide pseudocode or a structural outline for the refactored solution.