# 1. Goal
A laboratory receives blood samples. Each sample has a sample ID, a test type and a
priority. The laboratory groups the samples into batches. One batch belongs to each
test type. A laboratory program adds the samples one by one. Then it reads the
batches.

Create the class {{P}}SAMPLE_BATCHER. The class collects the samples and gives the
batches.

# 2. Open questions
None.

# 3. Context
- The class is new. It is in package $TMP.
- No other object is necessary.
- A laboratory program creates one instance of the class. It adds all samples of a
  shift. Then it reads the batches.

# 4. Contract
Class {{P}}SAMPLE_BATCHER. The class is public and final. It can be created without
parameters.

Public types:
- ty_test_type TYPE c LENGTH 4
- ty_sample_id TYPE c LENGTH 10
- ty_priority TYPE i
- ty_batch with the components test_type (TYPE ty_test_type), total (TYPE i) and
  urgent (TYPE i)
- tt_batches TYPE STANDARD TABLE OF ty_batch WITH EMPTY KEY

Public methods:
- add_sample
  IMPORTING iv_sample_id TYPE ty_sample_id
            iv_test_type TYPE ty_test_type
            iv_priority  TYPE ty_priority
  RETURNING VALUE(rv_added) TYPE abap_bool
- get_batches
  RETURNING VALUE(rt_batches) TYPE tt_batches
- get_batch
  IMPORTING iv_test_type TYPE ty_test_type
  RETURNING VALUE(rs_batch) TYPE ty_batch

Do not add other public methods.

# 5. Business rules

add_sample
1. Normalize the sample ID and the test type. Remove all spaces. Convert all letters
   to upper case.
2. Reject the sample and return abap_false if one of these conditions is true:
   - the normalized sample ID is empty, or
   - the normalized test type is empty, or
   - the priority is not 1, 2 or 3, or
   - the normalized sample ID was already added.
   The state of the object does not change.
3. Else accept the sample and return abap_true. The batch of the test type gets one
   more sample. If the priority is 1, the batch also gets one more urgent sample.

get_batches
4. Return one row for each test type that has at least one sample.
5. Sort the rows by the test type in ascending order.

get_batch
6. Normalize the test type in the same way as in rule 1.
7. If the test type has at least one sample, return its row.
8. Else return a row with this test type, total = 0 and urgent = 0.

# 6. Constraints
- Release target: 8.16.
- Coding standards: Clean ABAP. Methods below 40 statements. No global variables. No
  comment that restates the code.
- Out of scope: no other object is part of this task.

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