# 1. Goal
A purchasing department rates its suppliers. A scorecard program calls the rating
before it prints the scorecard. The program needs the weighted score and the grade
of a supplier.

# 2. Open questions
None.

# 3. Context
- All objects are in package $TMP.
- A supplier is rated in three criteria: price, quality, and delivery.
- Each criterion gets an integer rating from 1 (very poor) to 5 (very good).
- The scorecard program passes the three ratings to the class. It reads the score
  and the grade from the result.

# 4. Contract
- Create the class {{P}}SUPPLIER_SCORE in package $TMP.
- The class is public, final, and has a public constructor without parameters.
- The class has these public types:
  - TY_RATING: an integer type for one rating.
  - TY_SCORE: a packed number with length 5 and 1 decimal place.
  - TY_GRADE: a character type with length 1.
  - TY_RESULT: a structure with the components SCORE (type TY_SCORE) and GRADE
    (type TY_GRADE).
- The class has exactly this public method:

  METHODS evaluate
    IMPORTING iv_price    TYPE ty_rating
              iv_quality  TYPE ty_rating
              iv_delivery TYPE ty_rating
    RETURNING VALUE(rs_result) TYPE ty_result.

- Do not add other public methods.

# 5. Business rules
Apply the rules in this sequence.

1. A rating is valid if it is an integer from 1 to 5. If at least one of the three
   ratings is not valid, return score 0.0 and grade 'X'.
2. Quality is a knock-out criterion. If the quality rating is 1, return score 0.0
   and grade 'X'.
3. Calculate the weighted score:
   score = (price * 40 + quality * 35 + delivery * 25) / 100.
4. Round the score to one decimal place. Use commercial rounding, that is, round
   half away from zero.
5. Derive the grade from the rounded score:
   - 4.5 or more: 'A'
   - 3.5 or more: 'B'
   - 2.5 or more: 'C'
   - 1.5 or more: 'D'
   - less than 1.5: 'E'

# 6. Constraints
- Release target: SAP_BASIS 816.
- Coding standards: Clean ABAP. Every method has fewer than 40 statements. No
  global variables. No comment that restates the code.
- Out of scope: database access, ALV, dynpro, and changes to other objects.

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