# 1. Goal

A freight forwarder calculates the freight cost of a shipment. A legacy class
calculates this cost today. Write the calculation as a clean class. The cost of
every shipment must stay the same.

# 2. Open questions
None.

# 3. Context
- The interface {{P}}IF_FREIGHT_CALC exists in package $TMP and is active.
- The legacy class {{P}}FREIGHT_LEGACY exists in package $TMP and is active. It
  implements {{P}}IF_FREIGHT_CALC. Its results are the reference for the new class.
- The interface declares the types TY_ZONE (character, length 2), TY_WEIGHT
  (packed number, length 9, 3 decimal places) and TY_AMOUNT (packed number,
  length 7, 2 decimal places), and the method CALCULATE.

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

# 5. Business rules

All amounts are packed numbers with 2 decimal places. Round an amount to
2 decimal places before you use it in the next step. Round half away from zero.

1. Zone
   The zone is a two-character code. These zones exist:

   zone  base   per kg  minimum  surcharge factor
   DE    12.50  0.85    25.00    0.065
   FR    15.00  1.10    30.00    0.075
   NL    10.00  0.75    20.00    0.055
   US    20.00  1.40    45.00    0.085
   CN    25.00  1.25    50.00    0.095

   If the zone is not one of these, the result is 0.00 and no other rule applies.

2. Weight charge
   weight charge = weight * per kg of the zone, rounded to 2 decimal places.

3. Freight
   freight = base of the zone + weight charge.
   If freight is less than the minimum of the zone, freight is the minimum.

4. Surcharge
   surcharge = freight * surcharge factor of the zone, rounded to 2 decimal places.

5. Total
   total = freight + surcharge.

6. Heavy shipment
   If the weight is greater than 1000.000 kg, total = total * 0.95, rounded to
   2 decimal places.

7. The result is total.

# 6. Constraints
- Release target: SAP_BASIS 816 (ABAP Platform 2025).
- 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_FREIGHT_CALC and {{P}}FREIGHT_LEGACY.

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