from __future__ import absolute_import, division, print_function
# -*- coding: utf-8 -*-
from cctbx.xray.structure_factors.manager import managed_calculation_base
from cctbx.xray.structure_factors.manager import default_cos_sin_table
from cctbx.xray.structure_factors import global_counters
from cctbx.xray import ext
from cctbx import miller
from libtbx.utils import user_plus_sys_time

class from_scatterers_direct(managed_calculation_base):

  def __init__(self, xray_structure,
                     miller_set,
                     manager=None,
                     cos_sin_table=False,
                     algorithm="direct"):
    """Evaluate structure factors via direct calculations

    :type xray_structure: cctbx.xray.structure
    :param xray_structure: the X-ray structure to evaluate the structure factors of
    :type miller_set: cctbx.miller.set
    :param miller_set: the set of miller indices to evaluate the structure factors at
    :type manager: cctbx.xray.structure_factors.manager
    :param manager: ? (TODO: doc)
    :type algorithm: string
    :param algorithm: the name of the evaluation method, either \
    "direct", "use_alt_parallel"
    :type cos_sin_table: boolean
    :param cos_sin_table: If set to 'True' a precalculated cos_sin_table is used \
    instead of actual trigonometric functions. Using a manager overrides this \
    setting with the one specified in the manager.

    :rtype: cctbx.xray.structure_factors.from_scatterers_direct
    :retruns: an instance `e` of `cctbx.xray.structure_factors.from_scatterers_direct` \
    providing the evaluated structure factors as `e.f_calc()`
    """
    time_all = user_plus_sys_time()
    managed_calculation_base.__init__(self,
      manager, xray_structure, miller_set, algorithm="direct")
    if hasattr(algorithm,"use_alt_parallel"):
        #enumeration of indices() is fast compared to direct summation
        from cctbx.xray.structure_factors.from_scatterers_direct_parallel import pprocess
        pprocess(self,algorithm)
        return
    timer = user_plus_sys_time()
    if (manager is not None):
      cos_sin_table = manager.cos_sin_table()
    if (cos_sin_table == True):
      cos_sin_table = default_cos_sin_table
    elif (cos_sin_table == False):
      cos_sin_table = None
    if (cos_sin_table is None):
      self._results = ext.structure_factors_direct(
        self._miller_set.unit_cell(),
        self._miller_set.space_group(),
        self._miller_set.indices(),
        self._xray_structure.scatterers(),
        self._xray_structure.scattering_type_registry())
    else:
      self._results = ext.structure_factors_direct(
        cos_sin_table,
        self._miller_set.unit_cell(),
        self._miller_set.space_group(),
        self._miller_set.indices(),
        self._xray_structure.scatterers(),
        self._xray_structure.scattering_type_registry())
    if (manager is not None):
      manager.estimate_time_direct.register(
        xray_structure.scatterers().size() * miller_set.indices().size(),
        timer.elapsed())
    global_counters.from_scatterers_direct.process(time_all.elapsed())

  def f_calc(self):
    return miller.array(self._miller_set, self._results.f_calc())