# 1. Goal
Refactor the legacy report {{P}}TRAIN_PUNCT_OLD in package $TMP. The report shows
the punctuality of the railway lines of a regional operator. The operations team
uses the report to find the lines that need attention.
The behaviour of the report stays the same. Only the internal structure changes.

# 2. Open questions
None.

# 3. Context
- Table {{P}}TRUN exists in package $TMP and contains data.
  Fields: RUN_ID (INT4, key), LINE_CODE (CHAR 6), PLAN_DATE (DATS),
  DELAY_MIN (INT4), CANCELLED (CHAR 1).
  One row is one train run of one line on one day. DELAY_MIN is the delay of the
  run in minutes. CANCELLED is 'X' if the run was cancelled.
- The report {{P}}TRAIN_PUNCT_OLD in package $TMP is the legacy report. It is
  active and it produces the correct result. Users report that the code is hard
  to maintain.
- The report reads the table and shows one line per railway line in an ALV list.

# 4. Contract
- The program {{P}}TRAIN_PUNCT_OLD keeps its name and its package $TMP.
- The selection screen keeps these parameters:
  - S_LINE: a select-option for the line code.
  - S_DATE: a select-option for the plan date.
- The report shows the result with CL_SALV_TABLE. The output table keeps these
  column names: LINE_CODE, RUNS, LATE, SUM_DELAY, PUNCT.

# 5. Business rules
The behaviour of the report must not change. The legacy code of
{{P}}TRAIN_PUNCT_OLD contains the business rules. Read the legacy code and keep
every rule. Do not add rules. Do not remove rules.

# 6. Constraints
- Release target: SAP_BASIS 816 (ABAP Platform 2025).
- Coding standards: Clean ABAP. Split the logic into small methods. A method has
  fewer than 40 statements. Do not change the public interface.
- Out of scope: do not change {{P}}TRUN and do not change {{P}}TRAIN_SEED.

# 7. Acceptance
- The program is active and has no syntax error.
- The behaviour of the program is unchanged. The hidden tests pass.
- The code has no ATC finding of priority 1 or 2.
- Write ABAP Unit tests as local test classes in the program.