Tell us about Clean Architecture — how is it structured, layers, dependencies?.

Clean Architecture is an architectural approach aimed at creating flexible, easily testable, and maintainable applications.

Main layers of Clean Architecture:

1. Entities — business logic and business rules. These are the most abstract objects, independent of external details.

2. Use Cases — implementation of specific business processes that use entities to perform tasks.

3. Interface Adapters — transform data from a format convenient for use cases and entities into a format suitable for external systems (UI, databases, web services).

4. Frameworks and Drivers — external details: UI, databases, web servers, devices, etc.

Dependency rule: Dependencies always point inward, from outer layers to inner layers. Inner layers do not know about outer layers.

This allows:

• Changing UI or database without affecting business logic.
• Easily testing business logic without external dependencies.
• Ensuring independence from frameworks and technologies.

Example:

• Classes and interfaces of business objects are described in the Entities layer.
• Services that use these entities are implemented in Use Cases.
• Controllers, repositories that transform data are implemented in Interface Adapters.
• Specific databases, UI, etc., are implemented in Frameworks.