CLASS zcl_sapilot_http_handler DEFINITION
  PUBLIC
  FINAL
  CREATE PUBLIC.

  PUBLIC SECTION.
    INTERFACES if_http_extension.

  PRIVATE SECTION.
    METHODS process_request
      IMPORTING io_server TYPE REF TO if_http_server
      RAISING   zcx_sapilot_error.

    METHODS set_response_headers
      IMPORTING io_server TYPE REF TO if_http_server.

    METHODS send_error_response
      IMPORTING io_server TYPE REF TO if_http_server
                ix_error  TYPE REF TO zcx_sapilot_error.

    METHODS send_success_response
      IMPORTING io_server TYPE REF TO if_http_server
                iv_json   TYPE string
                iv_status TYPE i DEFAULT 200.

    METHODS get_client_ip
      IMPORTING io_server    TYPE REF TO if_http_server
      RETURNING VALUE(rv_ip) TYPE string.

ENDCLASS.


CLASS zcl_sapilot_http_handler IMPLEMENTATION.

  METHOD if_http_extension~handle_request.
    DATA: lx_error TYPE REF TO zcx_sapilot_error.
    DATA: lx_unexpected TYPE REF TO cx_static_check.
    DATA: lo_unexpected TYPE REF TO zcx_sapilot_error.

    TRY.
        process_request( server ).

      CATCH zcx_sapilot_error INTO lx_error.
        send_error_response( io_server = server ix_error = lx_error ).

      CATCH cx_static_check INTO lx_unexpected.
        CREATE OBJECT lo_unexpected
          EXPORTING
            iv_http_status = 500
            iv_error_code  = 'INTERNAL_ERROR'
            iv_message     = 'An unexpected error occurred'
            iv_details     = lx_unexpected->get_text( ).
        send_error_response( io_server = server ix_error = lo_unexpected ).
    ENDTRY.
  ENDMETHOD.

  METHOD process_request.
    DATA: lo_router           TYPE REF TO zcl_sapilot_router,
          lo_response_builder TYPE REF TO zcl_sapilot_response,
          lo_audit            TYPE REF TO zcl_sapilot_audit_logger,
          lo_health           TYPE REF TO zcl_sapilot_op_health,
          lo_getlist          TYPE REF TO zcl_sapilot_op_getlist,
          lo_getdetail        TYPE REF TO zcl_sapilot_op_getdetail,
          lo_use              TYPE REF TO zcl_sapilot_op_use,
          lo_logs             TYPE REF TO zcl_sapilot_op_logs,
          lo_admin            TYPE REF TO zcl_sapilot_op_admin.

    CREATE OBJECT lo_router.
    CREATE OBJECT lo_response_builder.
    CREATE OBJECT lo_audit.

    GET TIME STAMP FIELD DATA(lv_start_ts).
    DATA(lv_request_id) = lo_response_builder->generate_request_id( ).

    DATA(lv_method) = CONV string( io_server->request->get_method( ) ).
    DATA(lv_path)   = CONV string( io_server->request->get_header_field( '~path_info' ) ).
    DATA(lv_query)  = CONV string( io_server->request->get_header_field( '~query_string' ) ).
    DATA(lv_body)   = io_server->request->get_cdata( ).

    DATA(ls_route) = lo_router->route( iv_method = lv_method iv_path = lv_path ).

    DATA: lv_result_json TYPE string.
    DATA: lx_route TYPE REF TO zcx_sapilot_error.

    CASE ls_route-operation.
      WHEN zcl_sapilot_constants=>gc_op_health.
        CREATE OBJECT lo_health.
        lv_result_json = lo_health->execute( ).
      WHEN zcl_sapilot_constants=>gc_op_get_list.
        CREATE OBJECT lo_getlist.
        lv_result_json = lo_getlist->execute( iv_query_string = lv_query ).
      WHEN zcl_sapilot_constants=>gc_op_get_detail.
        CREATE OBJECT lo_getdetail.
        lv_result_json = lo_getdetail->execute( iv_path_info = lv_path ).
      WHEN zcl_sapilot_constants=>gc_op_use.
        CREATE OBJECT lo_use.
        lv_result_json = lo_use->execute( iv_path_info = lv_path iv_request_body = lv_body ).
      WHEN zcl_sapilot_constants=>gc_op_logs.
        CREATE OBJECT lo_logs.
        lv_result_json = lo_logs->execute( iv_query_string = lv_query ).
      WHEN zcl_sapilot_constants=>gc_op_admin_reg OR
           zcl_sapilot_constants=>gc_op_admin_upd OR
           zcl_sapilot_constants=>gc_op_admin_del OR
           zcl_sapilot_constants=>gc_op_admin_act.
        CREATE OBJECT lo_admin.
        lv_result_json = lo_admin->execute(
          iv_operation   = ls_route-operation
          iv_object_type = CONV string( ls_route-object_type )
          iv_object_name = CONV string( ls_route-object_name )
          iv_request_body = lv_body ).
      WHEN OTHERS.
        RAISE EXCEPTION TYPE zcx_sapilot_error
          EXPORTING
            iv_http_status = 404
            iv_error_code  = 'ROUTE_NOT_FOUND'
            iv_message     = |No handler for path: { lv_path }|.
    ENDCASE.

    GET TIME STAMP FIELD DATA(lv_end_ts).
    DATA: lv_duration_ms TYPE i.
    lv_duration_ms = cl_abap_tstmp=>subtract( tstmp1 = lv_end_ts tstmp2 = lv_start_ts ).

    DATA(lv_response) = lo_response_builder->build_success(
      iv_json       = lv_result_json
      iv_request_id = lv_request_id
      iv_duration   = |{ lv_duration_ms }ms| ).

    TRY.
        lo_audit->log(
          iv_request_id  = lv_request_id
          iv_operation   = ls_route-operation
          iv_object_type = CONV string( ls_route-object_type )
          iv_object_name = CONV string( ls_route-object_name )
          iv_input_json  = lv_body
          iv_status      = zcl_sapilot_constants=>gc_status_success
          iv_duration_ms = lv_duration_ms
          iv_remote_ip   = get_client_ip( io_server ) ).
      CATCH cx_static_check.
    ENDTRY.

    send_success_response( io_server = io_server iv_json = lv_response ).

  ENDMETHOD.

  METHOD set_response_headers.
    DATA(lo_response) = io_server->response.
    lo_response->set_content_type( zcl_sapilot_constants=>gc_content_type ).
    lo_response->set_header_field( name = 'charset' value = zcl_sapilot_constants=>gc_charset ).
    lo_response->set_header_field( name = 'Access-Control-Allow-Origin' value = '*' ).
    lo_response->set_header_field( name = 'Access-Control-Allow-Methods' value = 'GET, POST, PUT, DELETE, OPTIONS' ).
    lo_response->set_header_field( name = 'Access-Control-Allow-Headers' value = 'Content-Type, Authorization' ).
  ENDMETHOD.

  METHOD send_error_response.
    DATA: lo_response_builder TYPE REF TO zcl_sapilot_response.
    DATA: lv_request_id TYPE string.
    DATA: lv_duration TYPE string.
    DATA: lv_json TYPE string.
    DATA: lv_error_json TYPE string.
    DATA: lv_metadata TYPE string.

    CREATE OBJECT lo_response_builder.
    lv_request_id = lo_response_builder->generate_request_id( ).
    lv_duration = '0ms'.
    lv_error_json = ix_error->get_json_error( ).
    lv_metadata = lo_response_builder->build_metadata( iv_request_id = lv_request_id iv_duration = lv_duration ).

    DATA: lv_open TYPE c LENGTH 1,
          lv_close TYPE string.
    lv_open = cl_abap_char_utilities=>horizontal_tab.
    FIELD-SYMBOLS: <lv_x> TYPE x.
    ASSIGN lv_open TO <lv_x> CASTING.
    <lv_x> = '7B'.
    lv_close = '}'.

    CONCATENATE lv_open '"success": false, "error": ' lv_error_json ', "metadata": ' lv_metadata lv_close INTO lv_json.

    set_response_headers( io_server ).
    io_server->response->set_status( code = ix_error->mv_http_status reason = ix_error->mv_error_code ).
    io_server->response->set_cdata( lv_json ).
  ENDMETHOD.

  METHOD send_success_response.
    set_response_headers( io_server ).
    io_server->response->set_status( code = iv_status reason = 'OK' ).
    io_server->response->set_cdata( iv_json ).
  ENDMETHOD.

  METHOD get_client_ip.
    DATA: lv_fwd TYPE string,
          lv_real TYPE string.
    lv_fwd = io_server->request->get_header_field( 'X-Forwarded-For' ).
    IF lv_fwd IS NOT INITIAL.
      rv_ip = lv_fwd.
    ELSE.
      lv_real = io_server->request->get_header_field( 'X-Real-IP' ).
      IF lv_real IS NOT INITIAL.
        rv_ip = lv_real.
      ELSE.
        rv_ip = io_server->request->get_header_field( 'REMOTE_ADDR' ).
      ENDIF.
    ENDIF.
  ENDMETHOD.

ENDCLASS.