# 1. Goal
Refactor the legacy class {{P}}DIVE_CHECK. The class checks if a diver may join a
guided dive. A booking program calls the check before it confirms the dive.
The behavior of the class stays the same. Improve the structure and the
readability of the code.

# 2. Open questions
None.

# 3. Context
- The class {{P}}DIVE_CHECK exists in package $TMP. It is active.
- A booking program uses the class. The public interface of the class is fixed.
- The class contains legacy code: one long method, deep nesting, hard-coded
  numbers, and duplicated statements. Users report no defect. The task is a
  refactoring, not a repair.
- Read the current source of the class before you change it.

# 4. Contract
The class {{P}}DIVE_CHECK stays in package $TMP. The class stays public and
final. Do not change the public interface.
- Public type TY_REASON: type c, length 10.
- Public type TY_CERT_LEVEL: type c, length 1.
- Public constant structure C_REASON with the components OK, AGE, CERT, DEPTH,
  DIVES, and RECENT. The component type is TY_REASON. Do not change the values.
- Public instance method CHECK_DIVER with this signature:
    IMPORTING
      iv_cert_level TYPE ty_cert_level
      iv_depth      TYPE i
      iv_dives      TYPE i
      iv_last_dive  TYPE d
      iv_dive_date  TYPE d
      iv_age        TYPE i
    RETURNING
      VALUE(rv_reason) TYPE ty_reason.
- Do not add other public components. Do not remove a public component.

# 5. Business rules
- The class keeps its current behavior. Read the legacy code and keep every
  rule, the sequence of the rules, and every limit.
- Do not add a rule. Do not remove a rule. Do not change a limit. Do not change
  the sequence of the rules.
- The method returns the reason of the first rule that fails. If no rule fails,
  the method returns OK.

# 6. Constraints
- Release target: SAP_BASIS 816 (ABAP Platform 2025).
- Coding standards: Clean ABAP. Methods below 40 statements. No global
  variables. No comment that restates the code. No ATC priority 1 or priority 2
  finding.
- Out of scope: do not change the public interface. Do not create other
  objects. Do not change the behavior.

# 7. Acceptance
- The class {{P}}DIVE_CHECK is active and has no syntax error.
- The hidden tests pass.
- Write your own ABAP Unit tests as local test classes of the class.