# 1. Goal
Calculate the fee of hiring a marquee tent for an event. A booking program
calls the calculation before it confirms a booking. The program needs the
gross price in euro.

# 2. Open questions
None.

# 3. Context
- Interface {{P}}IF_TENT_HIRE exists in package $TMP. It is active.
- The interface has the type TY_AMOUNT (P LENGTH 15 DECIMALS 2), the constant
  structures C_RATE_S, C_RATE_M and C_RATE_L, the constants C_VAT,
  C_DISCOUNT and C_LONG_RENTAL_DAYS, and one method:
  CALCULATE_FEE IMPORTING iv_tent_size TYPE string
                          iv_days      TYPE i
                RETURNING VALUE(rv_fee) TYPE ty_amount.
- Each rate structure has the components RATE_DAY and SETUP_FEE.
  C_RATE_S belongs to tent size S, C_RATE_M to tent size M and C_RATE_L to
  tent size L.
- C_VAT is the value added tax rate. C_DISCOUNT is the discount rate.
  C_LONG_RENTAL_DAYS is the number of days from which the discount applies.

# 4. Contract
- Create the class {{P}}TENT_HIRE_FEE in package $TMP.
- The class is public, final, and has a public constructor without parameters.
- The class implements {{P}}IF_TENT_HIRE.
- Do not add other public methods.

# 5. Business rules
Apply the rules in this sequence.
1. Read the daily rate and the setup fee for the tent size. Tent size S uses
   C_RATE_S, tent size M uses C_RATE_M and tent size L uses C_RATE_L. If the
   tent size is not S, M or L, return 0.
2. The net price is the number of days multiplied by the daily rate plus the
   setup fee.
3. If the number of days is C_LONG_RENTAL_DAYS or more, reduce the net price by
   C_DISCOUNT.
4. Add value added tax of C_VAT to the net price. The result is the gross price
   in euro. The gross price must have two decimal places.

# 6. Constraints
- Release target: 8.16.
- Coding standards: Clean ABAP. Method length below 40 statements. No global
  variables. No comment that restates the code.
- Out of scope: do not change {{P}}IF_TENT_HIRE.

# 7. Acceptance
- The class is active and has no syntax error.
- Write your own ABAP Unit tests for the class.