# 1. Goal
A car dealership group sells vehicles through several dealerships. The sales
office needs a summary of the vehicle sales of one period. It uses the summary
to compare the dealerships of the group.

# 2. Open questions
None.

# 3. Context
- Table {{P}}DEALER exists in package $TMP. It contains the dealerships.
  Fields: DEALER_ID (CHAR 4, key), DEALER_NAME (CHAR 30), CITY (CHAR 20).
- Table {{P}}VSALE exists in package $TMP. It contains the vehicle sales.
  Fields: SALE_ID (INT4, key), DEALER_ID (CHAR 4), SALE_DATE (DATS),
  MODEL_CODE (CHAR 10), PRICE (DEC 15,2).

# 4. Contract
- Create the executable program {{P}}DEALER_SUM in package $TMP.
- Selection screen:
  - Parameter P_FROM, type DATS, mandatory: the first sale date to include.
  - Parameter P_TO, type DATS, mandatory: the last sale date to include.
  - Parameter P_CITY, type {{P}}DEALER-CITY, optional: the city of the
    dealership.
- Show the result with CL_SALV_TABLE. The output table has these columns with
  these names: DEALER, CITY, SALES, REVENUE, TOP_MODEL.

# 5. Business rules
1. Include a sale only if its SALE_DATE is on or after P_FROM and on or before
   P_TO.
2. If P_CITY is initial, include the sales of all dealerships. If P_CITY is not
   initial, include only the sales of dealerships whose CITY equals P_CITY.
3. Show one line for each dealership that has at least one included sale.
4. DEALER is the name of the dealership. CITY is the city of the dealership.
5. SALES is the number of included sales of the dealership.
6. REVENUE is the sum of the PRICE values of the included sales.
7. TOP_MODEL is the model code with the highest total price in the dealership.
   If two model codes of the dealership have the same total price, TOP_MODEL is
   the code that comes first in ascending alphabetical order.
8. Sort the lines by REVENUE, the highest revenue first. If two dealerships have
   the same revenue, sort them by DEALER in ascending order.

# 6. Constraints
- Release target: 8.16.
- Coding standards: Clean ABAP. A method has fewer than 40 statements. Do not
  access the database inside a loop.
- Out of scope: do not change {{P}}DEALER and {{P}}VSALE.

# 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.