import numpy as np

from ase import Atoms

from ase.visualize.vtk.sources import vtkAtomSource, vtkForceSource, \
                                      vtkVelocitySource
from ase.visualize.vtk.cell import vtkUnitCellModule, vtkAxesModule
from ase.visualize.vtk.grid import vtkAtomicPositions
from ase.visualize.vtk.module import vtkModuleAnchor, vtkGlyphModule

# -------------------------------------------------------------------

class vtkAtoms(vtkModuleAnchor, vtkAtomicPositions):
    """Provides fundamental representation for ``Atoms``-specific data in VTK.

    The ``vtkAtoms`` class plots atoms during simulations, extracting the
    relevant information from the list of atoms. It is created using
    the list of atoms as an argument to the constructor. Then one or more
    visualization modules can be attached using add_module(name, module).

    Example:

    >>> va = vtkAtoms(atoms)
    >>> va.add_forces()
    >>> va.add_axes()
    >>> XXX va.add_to_renderer(vtk_ren)

    """
    def __init__(self, atoms, scale=1):
        """Construct a fundamental VTK-representation of atoms.

        atoms: Atoms object or list of Atoms objects
            The atoms to be plotted.

        scale = 1: float or int
            Relative scaling of all Atoms-specific visualization.

        """
        assert isinstance(atoms, Atoms)
        self.atoms = atoms

        self.scale = scale

        vtkModuleAnchor.__init__(self)
        vtkAtomicPositions.__init__(self, self.atoms.get_positions(),
                                    vtkUnitCellModule(self.atoms))

        self.force = None
        self.velocity = None

        symbols = self.atoms.get_chemical_symbols()
        for symbol in np.unique(symbols):
            # Construct mask for all atoms with this symbol
            mask = np.array(symbols) == symbol
            if mask.all():
                subset = None
            else:
                subset = np.argwhere(mask).ravel()

            # Get relevant VTK unstructured grid
            vtk_ugd = self.get_unstructured_grid(subset)

            # Create atomic glyph source for this symbol
            glyph_source = vtkAtomSource(symbol, self.scale)

            # Create glyph module and anchor it
            self.add_module(symbol, vtkGlyphModule(vtk_ugd, glyph_source))

    def has_forces(self):
        return self.force is not None

    def has_velocities(self):
        return self.velocity is not None

    def add_cell(self):
        """Add a box outline of the cell using atoms.get_cell(). The existing
        ``vtkUnitCellModule`` is added to the module anchor under ``cell``."""
        self.add_module('cell', self.cell)

    def add_axes(self):
        """Add an orientation indicator for the cartesian axes. An appropriate
        ``vtkAxesModule`` is added to the module anchor under ``axes``."""
        self.add_module('axes', vtkAxesModule(self.cell))

    def add_forces(self):
        """Add force vectors for the atoms using atoms.get_forces(). A
        ``vtkGlyphModule`` is added to the module anchor under ``force``."""
        if self.has_forces():
            raise RuntimeError('Forces already present.')
        elif self.has_velocities():
            raise NotImplementedError('Can\'t add forces due to velocities.')

        # Add forces to VTK unstructured grid as vector data
        vtk_fda = self.add_vector_property(self.atoms.get_forces(), 'force')

        # Calculate max norm of the forces
        fmax = vtk_fda.GetMaxNorm()

        # Get relevant VTK unstructured grid
        vtk_ugd = self.get_unstructured_grid()

        self.force = vtkGlyphModule(vtk_ugd, vtkForceSource(fmax, self.scale),
                                    scalemode='vector', colormode=None)
        self.add_module('force', self.force)

    def add_velocities(self):
        """Add velocity vectors for the atoms using atoms.get_velocities(). A
        ``vtkGlyphModule`` is added to the module anchor under ``velocity``."""
        if self.has_velocities():
            raise RuntimeError('Velocities already present.')
        elif self.has_forces():
            raise NotImplementedError('Can\'t add velocities due to forces.')

        # Add velocities to VTK unstructured grid as vector data
        vtk_vda = self.add_vector_property(self.atoms.get_velocities(), 'velocity')

        # Calculate max norm of the velocities
        vmax = vtk_vda.GetMaxNorm()

        # Get relevant VTK unstructured grid
        vtk_ugd = self.get_unstructured_grid()

        self.velocity = vtkGlyphModule(vtk_ugd, vtkVelocitySource(vmax, self.scale),
                                       scalemode='vector', colormode=None)
        self.add_module('velocity', self.velocity)