# 1. Goal
A tool hire shop rents power tools to its customers. The checkout program calls
the class {{P}}TOOL_HIRE for each hire request before it prints the hire
contract. The program needs the fee of the hire and one reason code.

# 2. Open questions
None.

# 3. Context
- Interface {{P}}IF_TOOL_HIRE exists in package $TMP. It is active.
- The interface has these types: TY_TOOL (CHAR 1), TY_DAYS (integer),
  TY_AMOUNT (packed, 13 digits, 2 decimals), TY_REASON (CHAR 12).
- The interface has the structure TY_RESULT with the components FEE and REASON.
- The interface has the constant structure C_REASON with the values OK,
  UNKNOWN_TOOL and TOO_SHORT.
- The interface has one method:
  CALCULATE IMPORTING iv_tool TYPE ty_tool
                     iv_days TYPE ty_days
            RETURNING VALUE(rs_result) TYPE ty_result.

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

# 5. Business rules
1. The tool category is one character. These categories exist: 'D' is a drill,
   'S' is a sander, 'C' is a tile cutter. Every other category is unknown. For
   an unknown category return the reason UNKNOWN_TOOL and the fee 0.00.
2. A hire of less than 1 day is not possible. Return the reason TOO_SHORT and
   the fee 0.00.
3. The daily rate is 12.00 for 'D', 9.00 for 'S' and 15.00 for 'C'. A hire of
   1 to 6 days costs the daily rate multiplied by the number of days.
4. A hire of 7 days or more costs the weekly rate instead of the daily rate.
   The weekly rate is 60.00 for 'D', 45.00 for 'S' and 75.00 for 'C'.
5. A hire of 28 days or more costs the monthly rate instead of the weekly rate.
   The monthly rate is 180.00 for 'D', 135.00 for 'S' and 225.00 for 'C'.
6. The shop accepts hires of at most 90 days.
7. For every accepted hire return the reason OK and the fee of the hire.
8. The checkout program calls the class for every hire request, also for
   requests that the shop cannot accept.

# 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_TOOL_HIRE.

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