# 1. Goal
Refactor the class {{P}}MARINA_FEE in package $TMP. The class calculates the
berthing fee of a boat in a marina. The behavior of the class must not change.
The public interface of the class must not change. Improve the internal quality
of the class.

# 2. Open questions
None.

# 3. Context
- The class {{P}}MARINA_FEE exists in package $TMP. It is active.
- A marina uses the class to calculate the berthing fee of a boat.
- The class is legacy code. The results of the class are correct. The quality of
  the code is poor.
- The class has one public method. This method contains the complete calculation.
- The source code of the class is the specification of the behavior. Read the
  source code before you change it.

# 4. Contract
- Change the class {{P}}MARINA_FEE in package $TMP. Do not create a new class.
- Keep the name of the class {{P}}MARINA_FEE.
- Keep the public interface of the class. The public interface is:
  - The public types TY_BOAT_TYPE (CHAR 1), TY_SEASON (CHAR 1), and TY_FEE
    (PACKED 8, 2 decimal places).
  - The public method CALCULATE_FEE.
  - The importing parameters of CALCULATE_FEE: IV_LENGTH_M (TYPE i), IV_NIGHTS
    (TYPE i), IV_BOAT_TYPE (TYPE ty_boat_type), IV_SEASON (TYPE ty_season), and
    IV_POWER (TYPE abap_bool).
  - The returning parameter RV_FEE (TYPE ty_fee).
- Do not change the names, the types, or the sequence of the parameters.
- Do not add other public methods or public attributes.
- You can change the private section of the class.

# 5. Business rules
- The method CALCULATE_FEE keeps its behavior. The behavior is the behavior of
  the legacy class {{P}}MARINA_FEE in package $TMP.
- Read the legacy source code. The legacy source code is the only specification
  of the calculation.
- Do not change a result value. Do not add a rule. Do not remove a rule.

# 6. Constraints
- Release target: 8.16.
- Coding standards: Clean ABAP. Methods below 40 statements. No nesting deeper
  than two levels. No magic numbers. Use constants. Use meaningful names. No
  comment that restates the code.
- Out of scope: none.

# 7. Acceptance
- The class {{P}}MARINA_FEE is active and has no syntax error.
- The public interface of the class is unchanged.
- The behavior of the class is unchanged. The hidden tests pass.
- The class has no ATC priority 1 finding and no ATC priority 2 finding.
- Write your own ABAP Unit tests for the class.