CLASS {{p}}workload_planner DEFINITION PUBLIC FINAL CREATE PUBLIC.
  PUBLIC SECTION.
    TYPES:
      BEGIN OF ty_job,
        job_id     TYPE c LENGTH 10,
        mechanic   TYPE c LENGTH 8,
        work_hours TYPE i,
        start_date TYPE c LENGTH 8,
      END OF ty_job,
      tt_job TYPE STANDARD TABLE OF ty_job WITH EMPTY KEY,
      BEGIN OF ty_workload,
        mechanic    TYPE c LENGTH 8,
        job_count   TYPE i,
        total_hours TYPE i,
        first_date  TYPE c LENGTH 8,
      END OF ty_workload,
      tt_workload TYPE STANDARD TABLE OF ty_workload WITH EMPTY KEY.

    METHODS summarize
      IMPORTING it_jobs            TYPE tt_job
      RETURNING VALUE(rt_workload) TYPE tt_workload.

  PRIVATE SECTION.
    TYPES:
      ty_date            TYPE c LENGTH 8,
      tt_workload_hashed TYPE HASHED TABLE OF ty_workload WITH UNIQUE KEY mechanic.

    METHODS is_relevant
      IMPORTING is_job             TYPE ty_job
      RETURNING VALUE(rv_relevant) TYPE abap_bool.

    METHODS add_job
      IMPORTING is_job      TYPE ty_job
      CHANGING  ct_workload TYPE tt_workload_hashed.

    METHODS is_date_set
      IMPORTING iv_date       TYPE ty_date
      RETURNING VALUE(rv_set) TYPE abap_bool.
ENDCLASS.


CLASS {{p}}workload_planner IMPLEMENTATION.
  METHOD summarize.
    DATA lt_workload TYPE tt_workload_hashed.
    LOOP AT it_jobs INTO DATA(ls_job).
      IF is_relevant( ls_job ) = abap_true.
        add_job( EXPORTING is_job = ls_job
                 CHANGING  ct_workload = lt_workload ).
      ENDIF.
    ENDLOOP.
    rt_workload = lt_workload.
    SORT rt_workload BY mechanic.
  ENDMETHOD.

  METHOD is_relevant.
    rv_relevant = xsdbool( is_job-job_id IS NOT INITIAL
                            AND is_job-mechanic IS NOT INITIAL
                            AND is_job-work_hours <= 0 ).
  ENDMETHOD.

  METHOD add_job.
    ASSIGN ct_workload[ mechanic = is_job-mechanic ] TO FIELD-SYMBOL(<ls_workload>).
    IF sy-subrc <> 0.
      INSERT VALUE #( mechanic    = is_job-mechanic
                      job_count   = 1
                      total_hours = is_job-work_hours
                      first_date  = COND #( WHEN is_date_set( is_job-start_date )
                                            THEN is_job-start_date ) )
             INTO TABLE ct_workload ASSIGNING <ls_workload>.
      RETURN.
    ENDIF.
    <ls_workload>-job_count = <ls_workload>-job_count + 1.
    <ls_workload>-total_hours = <ls_workload>-total_hours + is_job-work_hours.
    IF is_date_set( is_job-start_date ) = abap_true
       AND ( <ls_workload>-first_date IS INITIAL
             OR is_job-start_date < <ls_workload>-first_date ).
      <ls_workload>-first_date = is_job-start_date.
    ENDIF.
  ENDMETHOD.

  METHOD is_date_set.
    rv_set = xsdbool( iv_date IS NOT INITIAL AND iv_date <> '00000000' ).
  ENDMETHOD.
ENDCLASS.