"""
Computational domain for isogeometric analysis.
"""
import os.path as op

import numpy as nm

from sfepy.base.base import Struct
from sfepy.discrete.common.domain import Domain
import sfepy.discrete.iga as iga
import sfepy.discrete.iga.io as io
from sfepy.discrete.iga.extmods.igac import eval_in_tp_coors

class NurbsPatch(Struct):
    """
    Single NURBS patch data.
    """

    def __init__(self, knots, degrees, cps,
                 weights, cs, conn):
        Struct.__init__(self, name='nurbs', knots=knots, degrees=degrees,
                        cps=cps, weights=weights, cs=cs, conn=conn)
        self.n_els = [len(ii) for ii in cs]
        self.dim = len(self.n_els)

    def _get_ref_coors_1d(self, pars, axis):
        uk = nm.unique(self.knots[axis])
        indices = nm.searchsorted(uk[1:], pars)
        ref_coors = nm.empty_like(pars)
        for ii in xrange(len(uk) - 1):
            ispan = nm.where(indices == ii)[0]
            pp = pars[ispan]
            ref_coors[ispan] = (pp - uk[ii]) / (uk[ii+1] - uk[ii])

        return uk, indices, ref_coors

    def __call__(self, u=None, v=None, w=None, field=None):
        """
        Igakit-like interface for NURBS evaluation.
        """
        pars = [u]
        if v is not None: pars += [v]
        if w is not None: pars += [w]

        indices = []
        rcs = []
        for ia, par in enumerate(pars):
            uk, indx, rc = self._get_ref_coors_1d(par, ia)
            indices.append(indx.astype(nm.uint32))
            rcs.append(rc)

        out = eval_in_tp_coors(field, indices,
                               rcs, self.cps, self.weights,
                               self.degrees,
                               self.cs, self.conn)

        return out

    def evaluate(self, field, u=None, v=None, w=None):
        """
        Igakit-like interface for NURBS evaluation.
        """
        return self(u, v, w, field)

class IGDomain(Domain):
    """
    Bezier extraction based NURBS domain for isogeometric analysis.
    """

    @staticmethod
    def from_file(filename):
        """
        filename : str
            The name of the IGA domain file.
        """
        (knots, degrees, cps, weights, cs, conn,
         bcps, bweights, bconn, regions) = io.read_iga_data(filename)

        nurbs = NurbsPatch(knots, degrees, cps, weights, cs, conn)
        bmesh = Struct(name='bmesh', cps=bcps, weights=bweights, conn=bconn)

        name = op.splitext(filename)[0]
        domain = IGDomain(name, nurbs=nurbs, bmesh=bmesh, regions=regions)
        return domain

    def __init__(self, name, nurbs, bmesh, regions=None, **kwargs):
        """
        Create an IGA domain.

        Parameters
        ----------
        name : str
            The domain name.
        """
        Domain.__init__(self, name, nurbs=nurbs, bmesh=bmesh, regions=regions,
                        **kwargs)
        from sfepy.discrete.fem.geometry_element import create_geometry_elements
        from sfepy.discrete.fem import Mesh
        from sfepy.discrete.fem.extmods.cmesh import CMesh
        from sfepy.discrete.fem.utils import prepare_remap

        ac = nm.ascontiguousarray
        self.nurbs.cs = [ac(nm.array(cc, dtype=nm.float64)[:, None, ...])
                         for cc in self.nurbs.cs]

        self.nurbs.degrees = self.nurbs.degrees.astype(nm.int32)

        self.facets = iga.get_bezier_element_entities(nurbs.degrees)

        tconn = 
iga.get_bezier_topology(bmesh.conn, nurbs.degrees)