# 1. Goal
A property management company checks a tenancy application before it offers a
flat to an applicant. The office calls the check for each application. The
office also needs the deposit that the applicant must pay.

# 2. Open questions
None.

# 3. Context
- The office works with one interface and one class that implements the
  interface.
- The interface {{P}}IF_TENANCY_CHECK holds the types, the constants and the
  method signatures of the tenancy check.
- The class {{P}}TENANCY_CHECKER holds the logic.
- The method CHECK returns one reason code for each tenancy application.
- The method DEPOSIT returns the deposit of a tenancy application.

# 4. Contract
Create the interface {{P}}IF_TENANCY_CHECK in package $TMP. The interface is
public. It has these components and no other components.

Types:
- TY_REASON: type c, length 10.
- TY_EMPLOYMENT: type c, length 1.
- TY_AMOUNT: type p, length 8, 2 decimal places.

Constants:
- C_EMPLOYMENT: a constant structure with the components PERMANENT, FIXED and
  SELF. Each component has the type TY_EMPLOYMENT. The values are:
  PERMANENT = 'P', FIXED = 'F', SELF = 'S'.
- C_REASON: a constant structure with the components OK, RENT, INCOME,
  PERSONS, CAPACITY, EMPLOYMENT and RATIO. Each component has the type
  TY_REASON. The values are: OK = 'OK', RENT = 'RENT', INCOME = 'INCOME',
  PERSONS = 'PERSONS', CAPACITY = 'CAPACITY', EMPLOYMENT = 'EMPLOYMENT',
  RATIO = 'RATIO'.

Methods:
- CHECK
  IMPORTING iv_rent       TYPE ty_amount
            iv_income     TYPE ty_amount
            iv_rooms      TYPE i
            iv_persons    TYPE i
            iv_employment TYPE ty_employment
            iv_pets       TYPE abap_bool
  RETURNING VALUE(rv_reason) TYPE ty_reason.
- DEPOSIT
  IMPORTING iv_rent          TYPE ty_amount
            iv_pets          TYPE abap_bool
  RETURNING VALUE(rv_deposit) TYPE ty_amount.

Create the class {{P}}TENANCY_CHECKER in package $TMP.
- The class is public, final, and has a public constructor without parameters.
- The class implements {{P}}IF_TENANCY_CHECK.
- Do not add other public methods.

# 5. Business rules
The method CHECK applies the rules in this sequence. It returns the reason of
the first rule that fails.
1. If iv_rent is less than or equal to zero, return RENT.
2. If iv_income is less than or equal to zero, return INCOME.
3. If iv_persons is less than one, return PERSONS.
4. If iv_persons is greater than two times iv_rooms, return CAPACITY.
5. If iv_employment is not 'P', 'F' or 'S', return EMPLOYMENT.
6. The income factor is 3 for 'P', 4 for 'F' and 5 for 'S'. If iv_pets is
   true, add 1 to the income factor. If iv_income is less than iv_rent
   multiplied by the income factor, return RATIO.
7. Return OK.

The method DEPOSIT applies the rules in this sequence.
1. If iv_rent is less than or equal to zero, return 0.
2. If iv_pets is true, return three times iv_rent.
3. Return two times iv_rent.

# 6. Constraints
- Release target: SAP_BASIS 816 (ABAP Platform 2025).
- Coding standards: Clean ABAP. Method length below 40 statements. No global
  variables. No comment that restates the code.
- Out of scope: do not create database tables, CDS views, reports or function
  modules.

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