# 1. Goal
Calculate the discount percentage for a wholesale order. A sales program calls the
calculation before it prices the order. The program needs one discount percentage
for each order.

# 2. Open questions
None.

# 3. Context
- The interface {{P}}IF_DISCOUNT exists in package $TMP. It is active.
- The interface has the type TY_GROUP (CHAR 1), the type TY_PERCENT (P length 5
  with 2 decimals), the constants C_GROUP_KEY ('A') and C_GROUP_STANDARD ('S'),
  and one method:
  CALCULATE IMPORTING iv_quantity TYPE i
                    iv_group    TYPE ty_group
            RETURNING VALUE(rv_percent) TYPE ty_percent.

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

# 5. Business rules
The discount percentage is the sum of the customer discount and the volume
discount. The result is at most 12.00.
1. Customer discount:
   - Group C_GROUP_KEY: 6.00.
   - Group C_GROUP_STANDARD: 0.00.
   - Any other group: 0.00.
2. Volume discount. The order quantity is the number of pieces:
   - Less than 100 pieces: 0.00.
   - More than 100 pieces and less than 500 pieces: 3.00.
   - 500 pieces or more: 7.00.
3. Add the customer discount and the volume discount. If the sum is more than
   12.00, the result is 12.00.

# 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_DISCOUNT.
- If a business rule is missing or two business rules contradict, do not create
  the object. Report the gap.

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