Time control
============

A factory uses a time stamping system that controls its employees
entry and exit times and these data is recorded daily into a file. Each
entry or exit of an employee results in a line of this file with the
following data: NIF, name and surname, the entry or exit time (in
format HH:MM) and a character that indicates whether the employee
entered or left work (``'E'`` or ``'L'``). These data are separated by
``', '`` (comma-whitespace) and lines are ordered chronologically. The
file contains two initial lines that describe the fields. For
example:

.. literalinclude:: examples/entryexit.txt
   :language: python

You can download the example file 
:download:`entryexit.txt<examples/entryexit.txt>`

Save these functions into a file named ``control.py``.
	  
#. Write the function :py:func:`control` that given the name of a file
   as described above and an integer indicating a time (hour), ``h``,
   returns the number of workers that have entered to work between
   ``h`` (included) and ``h+1`` (excluded). Examples:

   .. literalinclude:: test-control.txt
      :language: python3
      :lines: 3-

   .. note::

      More tests are provided in file :download:`test-control.txt`
      
#. Write the function :py:func:`add_time` that given 4 integers
   corresponding to the hours and minutes of a first time and the
   hours and minutes of a second time, returns two integers
   corresponding to the hours and minutes of the sum of the two given
   times. Hours and minutes must be positive and minutes must be less
   than 60. Examples:
   
   .. literalinclude:: add_time.txt
      :language: python3
      :lines: 3-

   .. note::

      More tests are provided in file :download:`add_time.txt`

#. Write the function :py:func:`subtract_time` that given 4 integers
   corresponding to the hours and minutes of a first time and the
   hours and minutes of a second time, returns two integers
   corresponding to the hours and minutes of the difference between the
   first time and the second time. Hours and minutes must be positive
   and minutes must be less than 60. Examples:

   .. literalinclude:: subtract_time.txt
      :language: python3
      :lines: 3-

   .. note::

      More tests are provided in file :download:`subtract_time.txt`

#. Write the function :py:func:`control_1` that given the name of a
   file as described above and the NIF of a worker of the company,
   calculates how long this worker has been working. The function must
   return two integers corresponding to the hours and minutes of the
   working time. This function must use the previous two. A worker may
   come in and out more than once. Examples:

   .. literalinclude:: test-control_1.txt
      :language: python3
      :lines: 3-

   .. note::

      More tests are provided in file :download:`test-control_1.txt`
   
#. Write the function :py:func:`control_2` that given the name of a
   file as described above and the NIF of the factory CEO, returns
   ``True`` if, and only if, the CEO has been the last one to come
   into work. If the CEO did not come into work, the function must
   also return ``True``. With the given data, if the CEO is Maria
   Sans, the function has to return ``True``; however, if the CEO is
   any of the other four employees, the function must return
   ``False``. Tip: build an auxiliary dictionary in which the key is the
   NIF and the value the first time that the worker has come into
   work. Examples:

   .. literalinclude:: test-control_2.txt
      :language: python3
      :lines: 3-

   .. note::

      More tests are provided in file :download:`test-control_2.txt`

.. rubric:: Solutions

A solution of these functions is provided in file :download:`control.py <solutions/control.py>`