# 1. Goal

A hospital wants a report about the bed days of its wards. The report shows,
for each ward, the number of admissions in a period, the bed days, and the cost
of these bed days. The hospital management compares the wards with this report.

# 2. Open questions

None.

# 3. Context

- The table {{P}}ADMIT exists in package $TMP. The table contains data. The
  fields are:
  - ADM_ID: INT4, key. The admission ID.
  - WARD: CHAR 4. The ward.
  - ADMIT_DATE: DATS. The admission date.
  - DISCHARGE_DATE: DATS. The discharge date. The field is initial while the
    patient is still in the ward.
  - DAILY_RATE: DEC 15,2. The cost of one bed day in this ward.

# 4. Contract

- Create the executable program {{P}}WARD_STAY in package $TMP.
- Selection screen:
  - Parameter P_FROM, type DATS, mandatory. The first admission date to include.
  - Parameter P_TO, type DATS, mandatory. The last admission date to include.
  - Select-option S_WARD for the ward.
- Show the result with CL_SALV_TABLE. The output table has exactly these columns
  with these names and types:
  - WARD: type {{P}}ADMIT-WARD.
  - ADMISSIONS: type I.
  - BED_DAYS: type I.
  - TOTAL_COST: type {{P}}ADMIT-DAILY_RATE.

# 5. Business rules

1. Include an admission only if ADMIT_DATE is on or after P_FROM, ADMIT_DATE is
   on or before P_TO, and WARD is in S_WARD.
2. The bed days of one admission are DISCHARGE_DATE minus ADMIT_DATE.
3. If DISCHARGE_DATE of an admission is initial, use P_TO as the discharge date
   of this admission.
4. The cost of one admission is the bed days of the admission multiplied by
   DAILY_RATE.
5. Show one line for each ward that has at least one included admission.
6. ADMISSIONS is the number of included admissions of the ward.
7. BED_DAYS is the sum of the bed days of the included admissions of the ward.
8. TOTAL_COST is the sum of the costs of the included admissions of the ward.
9. Sort the lines by TOTAL_COST, the highest total first.

# 6. Constraints

- Release target: 7.40 SP05. Do not use ABAP syntax that is newer than
  7.40 SP05. Examples of newer syntax are table expressions, FOR or REDUCE in
  constructor expressions, string aggregation, UNION, and WITH.
- Coding standards: Clean ABAP. Read the admissions with one database access.
- Out of scope: do not change the table {{P}}ADMIT.

# 7. Acceptance

- The program is active and has no syntax error.
- The hidden tests pass.
- Write ABAP Unit tests as local test classes in the program.