# Source code for tecplot.data.face_neighbors

    from builtins import super

    import logging
    import itertools as it

    from collections import namedtuple
    from contextlib import contextmanager
    from ctypes import c_int32, c_int64, c_void_p, POINTER, addressof, cast
    from textwrap import dedent

    from ..tecutil import _tecutil
    from ..constant import *
    from ..exception import *
    from .. import session
    from ..tecutil import IndexSet, array_to_str, lock, lock_attributes

    log = logging.getLogger(__name__)

    @lock_attributes
    class FaceNeighbors(c_void_p):
        r"""Face neighbor definition and control.

        Face neighbors are used when the face of an element overlaps with another
        face from another element. Specifying these two (or more) overlapping faces
        as "face neighbors" indicates element connections outside the implicit
        faces of the nodemap. By specifying face neighbors it ensures that plot
        elements like shading, creases and edges are treated continously even if
        there is a zone or cell boundry.

        The neighbors can be completely "local", within a single zone, or "global"
        conntecting two or more zones together. Furthermore, the connections made
        can be one-to-one meaning there any given face can only neighbor one other
        face, or one-to-many where a single face can neighbor several other faces.

        This example creates two triangles in two different zones. Global
        one-to-one face neighbors are then used to stitch the two triangles into a
        quad. The data created looks like this:

        .. code-block:: none

            Node positions (x,y,z):

                           (1,1,1)
                          *
                         / \
                        /   \
             (0,1,.5)  *-----*  (1,0,.5)
                        \   /
                         \ /
                          *
                           (0,0,0)

        The two triangles will have separate nodes at the shared locations:

        .. code-block:: none

            Nodes:
                               2
                Zone 1:       / \
                             /   \
                            1-----0
                            2-----1
                             \   /
                Zone 0:       \ /
                               0

        .. code-block:: python
            :emphasize-lines: 50-51

            import tecplot as tp
            from tecplot.constant import *

            # Triangle 0
            nodes0 = (
                (0, 0, 0  ),
                (1, 0, 0.5),
                (0, 1, 0.5))
            scalar_data0 = (0, 1, 2)
            conn0 = ((0, 1, 2),)
            neighbors0 = ((None, 0, None),)
            neighbor_zones0 = ((None, 1, None),)

            # Triangle 1
            nodes1 = (
                (1, 0, 0.5),
                (0, 1, 0.5),
                (1, 1, 1  ))
            scalar_data1 = (1, 2, 3)
            conn1 = ((0, 1, 2),)
            neighbors1 = ((0, None, None),)
            neighbor_zones1 = ((0, None, None),)

            # Create the dataset and zones
            ds = tp.active_frame().create_dataset('Data', ['x','y','z','s'])
            z0 = ds.add_fe_zone(ZoneType.FETriangle,
                                name='FE Triangle Float (3,1) Nodal 0',
                                num_points=len(nodes0), num_elements=len(conn0),
                                face_neighbor_mode=FaceNeighborMode.GlobalOneToOne)
            z1 = ds.add_fe_zone(ZoneType.FETriangle,
                                name='FE Triangle Float (3,1) Nodal 1',
                                num_points=len(nodes1), num_elements=len(conn1),
                                face_neighbor_mode=FaceNeighborMode.GlobalOneToOne)

            # Fill in and connect first triangle
            z0.values('x')[:] = [n[0] for n in nodes0]
            z0.values('y')[:] = [n[1] for n in nodes0]
            z0.values('z')[:] = [n[2] for n in nodes0]
            z0.nodemap[:] = conn0
            z0.values('s')[:] = scalar_data0

            # Fill in and connect second triangle
            z1.values('x')[:] = [n[0] for n in nodes1]
            z1.values('y')[:] = [n[1] for n in nodes1]
            z1.values('z')[:] = [n[2] for n in nodes1]
            z1.nodemap[:] = conn1
            z1.values('s')[:] = scalar_data1

            # Set face neighbors
            z0.face_neighbors.set_neighbors(neighbors0, neighbor_zones0, obscures=True)
            z1.face_neighbors.set_neighbors(neighbors1, neighbor_zones1, obscures=True)

            ### Setup a view of the data
            plot = tp.active_frame().plot(PlotType.Cartesian3D)
            plot.activate()

            plot.contour(0).colormap_name = 'Sequential - Yellow/Green/Blue'
            plot.contour(0).colormap_filter.distribution = ColorMapDistribution.Continuous

            for ax in plot.axes:
                ax.show = True

            plot.show_mesh = False
            plot.show_contour = True
            plot.show_edge = True
            plot.use_translucency = True

            # View parameters obtained interactively from Tecplot 360
            plot.view.distance = 10
            plot.view.width = 2
            plot.view.psi = 80
            plot.view.theta = 30
            plot.view.alpha = 0
            plot.view.position = (-4.2, -8.0, 2.3)

            fmaps = plot.fieldmaps()
            fmaps.surfaces.surfaces_to_plot = SurfacesToPlot.All
            fmaps.effects.surface_translucency = 40

            # Turning on mesh, we can see all the individual triangles
            plot.show_mesh = True
            fmaps.mesh.line_pattern = LinePattern.Dashed

            plot.contour(0).levels.reset_to_nice()
            tp.export.save_png('fe_triangles1.png', 600, supersample=3)

        ..  figure:: /_static/images/fe_triangles1.png
            :width: 300px
            :figwidth: 300px

            Two triangles in two separate zones, stitched together using global
            face neighbors, showing the edge and mesh.
        """
        def __init__(self, zone):
            self.zone = zone
            super().__init__(self._native_reference())

        @lock()
        def _native_reference(self):
            return _tecutil.DataFaceNbrGetReadableRef(self.zone.index + 1)

        def __eq__(self, other):
            self_addr  = addressof(cast(self , POINTER(c_int64)).contents)
            other_addr = addressof(cast(other, POINTER(c_int64)).contents)
            return self_addr == other_addr

        def __ne__(self, other):
            return not (self == other)

        @property
        def c_type(self):
            """Underlying storage type used by the Tecplot Engine.

            Possible values: `ctypes.c_int32`, ctypes.c_int64`.

            .. note:: This property is read-only.
            """
            _ctypes = {
                OffsetDataType.OffsetDataType_32Bit: c_int32,
                OffsetDataType.OffsetDataType_64Bit: c_int64}
            data_type = _tecutil.DataFaceNbrRawItemType(self)
            return _ctypes[data_type]

        @property
        def mode(self):
            """`FaceNeighborMode`: Relative locality of the face neighbors.

            Possible values: `FaceNeighborMode.LocalOneToOne`,
                `FaceNeighborMode.LocalOneToMany`,
                `FaceNeighborMode.GlobalOneToOne`,
                `FaceNeighborMode.GlobalOneToMany`.

            .. note:: This property is read-only.

            Face neighbors are used when the face of an element overlaps with
            another face from another element. The neighbors can be completely
            "local", within a single zone, or "global" conntecting two or more
            zones together. Furthermore, the connections made can be one-to-one
            meaning there any given face can only neighbor one other face, or
            one-to-many where a single face can neighbor several other faces. The
            face neighbor mode is set on zone creation and can not be changed
            afterwards::

                >>> zone = dataset.add_fe_zone(ZoneType.FETriangle, 'Zone', 4, 2,
                ...    face_neighbor_mode=FaceNeighborMode.LocalOneToMany)
                >>> print(zone.face_neighbors.mode)
                FaceNeighborMode.LocalOneToMany
            """
            return _tecutil.DataFaceNbrGetModeByRef(self)

        def set_neighbors(self, neighbors, zones=None, obscures=False):
            """Clear and set face neighbors from the given array.

            Parameters:
                neighbors (array of `integers <int>`): Zero-based Element indices
                    of the neighbors for each face in the zone. A value of
                    :math:`-1` or `None` indicates no neighbor.
                zones (array of `Zones <data_access>`, optional): This parameter is
                    only used when the face neighbor mode is global one-to-one or
                    global one-to-many. (default: `None`)
                obscures (array of `booleans <bool>`, optional): Indicates that the
                    neighbors completely obscure the face. (default: `False`)

            This method uses the `FaceNeighbors.assignment()` context internally to
            ensure the proper book keeping is done. See the example code for
            `FaceNeighbors` class object for details on how to use this method.
            """
            with self.assignment():
                for elem, faces in enumerate(neighbors):
                    for face, face_neighbors in enumerate(faces):
                        if face_neighbors is None:
                            continue
                        elif face_neighbors == -1:
                            continue

                        if not hasattr(face_neighbors, '__iter__'):
                            face_neighbors = [face_neighbors]
                        if zones is None:
                            neighbor_zones = None
                        else:
                            z = zones[elem][face]
                            if not hasattr(z, '__iter__'):
                                z = [z]
                            neighbor_zones = z
                        if hasattr(obscures, '__iter__'):
                            if hasattr(obscures[elem], '__iter__'):
                                obscure = obscures[elem][face]
                            else:
                                obscure = obscures[elem]
                        else:
                            obscure = obscures
                        self.add_neighbors(elem, face, face_neighbors,
                                           neighbor_zones, obscure)

        def add_neighbors(self, element, face, neighbors, zones=None,
                          obscure=False):
            """Connect boundary of an element's face to a neighboring face.

            This sets the boundary connection face neighbors within an open face
            neighbor assignment sequence for the specified element and face.

            Parameters:
                element (`int`): The element number (zero-based).
                face (`int`): The face number on the element (zero-based).
                neighbors (`list` of `integers <int>` or `None`): List of
                    zero-based indices of the neighboring faces.
                zones (`list` of zone objects, optional): List of zones for
                    global neighbors. This must be the same length as
                    ``neighbors``. Use `None` to indicate these are local
                    neighbors. (default: `None`)
                obscure (`bool`, optional): Indicates that the neighbors
                    completely obscure the face. (default: `False`)

            This method must be called from within a `FaceNeighbors.assignment()`
            context which will clear any previously existing face neighbor data::

                >>> with zone.face_neighbors.assigment():
                ...     for elem, face, neighbors, zn in face_neighbor_data:
                ...         zone.face_neighbors.add_neighbors(elem, face,
                ...                                           neighbors, zn)

            See the example code for `FaceNeighbors` class object for more details
            on how to set up user-defined face neighbors.
            """
            if __debug__:
                if zones is not None:
                    if len(neighbors) != len(zones):
                        msg = 'neighbors and zones must be the same length'
                        raise TecplotLogicError(msg)

            _dispatch = {
                c_int32: _tecutil.DataFaceNbrAssignByRef,
                c_int64: _tecutil.DataFaceNbrAssignByRef64}
            int_type = self.c_type

            def _add_one(arr):
                def _f(x):
                    return x + 1 if x is not None else 0
                return list(map(_f, arr))

            def _add_one_index(arr):
                def _f(x):
                    return getattr(x, 'index', x) + 1 if x is not None else 0
                return list(map(_f, arr))

            n = len(neighbors)
            neighbors = (int_type * n)(*_add_one(neighbors))
            if zones is not None:
                zones = (c_int32 * n)(*_add_one_index(zones))
            args = (element + 1, face + 1, obscure, n, neighbors, zones)

            if __debug__:
                if min(neighbors) < 1 or self.zone.num_faces < max(neighbors):
                    raise TecplotIndexError
                if zones:
                    if min(zones) < 1 or self.zone.dataset.num_zones < max(zones):
                        raise TecplotIndexError
                log.debug(dedent('''\
                    Face Neighbor Assign:
                        elem: {},
                        face: {},
                        obs: {},
                        n: {},
                        nbrs: {},
                        zns: {}''').format(
                            element + 1, face + 1, obscure, n,
                            array_to_str(neighbors), array_to_str(zones)))

            if not _dispatch[int_type](self, *args):
                raise TecplotSystemError()

        def add_local_neighbors(self, neighbors, offset=0):
            """Assign all local one-to-one face neighbors at once.

            Parameters:
                neighbors (2D array of `integers <int>`): :math:`(E,F)` Array of
                    the face neighbors where :math:`E` is the number of elements
                    and :math:`F` is the number of faces per element.
                offset (`int`, optional): Offset in Tecplot's face
                    neighbor array to begin assigning the supplied neighbor
                    elements. (default: 0)

            This method must be called from within a `FaceNeighbors.assignment()`
            context which will clear any previously existing face neighbor data::

                >>> with zone.face_neighbors.assigment():
                ...     zone.face_neighbors.add_local_neighbors(neighbors)

            See the example code for `FaceNeighbors` class object for more details
            on how to set up user-defined face neighbors.
            """
            _dispatch = {
                c_int32: _tecutil.DataFaceNbrAssignArrayByRef,
                c_int64: _tecutil.DataFaceNbrAssignArrayByRef64}
            int_type = self.c_type

            def _flatten_add_one(arr):
                def _add_one(x):
                    return x + 1 if x is not None else 0
                return list(map(_add_one, it.chain(*arr)))

            neighbors = _flatten_add_one(neighbors)
            n = len(neighbors)
            neighbors = (int_type * n)(*neighbors)

            if __debug__:
                if min(neighbors) < 0 or self.zone.num_faces < max(neighbors):
                    raise TecplotIndexError
                log.debug(dedent('''\
                    Face Neighbor Assign Array:
                        offset: {},
                        nbrs({}): {}''').format(offset + 1, n,
                                                array_to_str(neighbors)))

            _dispatch[int_type](self, offset + 1, n, neighbors)

        @contextmanager
        def assignment(self):
            """Context manager for assigning face neighbors.

            This context ensures the proper book keeping is done when setting face
            neighbors. After the face neighbors are specified, this context will
            valid the connections and make appropriate changes to the zone
            metadata. It must be used with the
            `FaceNeighbors.add_local_neighbors()` and/or
            `FaceNeighbors.add_neighbors()` methods. See the `FaceNeighbors`
            example code for more details on how to set up user-defined face
            neighbors.

            """
            with lock():
                if not _tecutil.DataFaceNbrBeginAssign(self.zone.index + 1):
                    raise TecplotSystemError()
                try:
                    yield
                finally:
                    _tecutil.DataFaceNbrEndAssign()
            c_void_p.__init__(self, self._native_reference())

        _Neighbor = namedtuple('Neighbor', ['element', 'zone'])

        def neighbors(self, element, face):
            """Get the neighboring elements and zones of a specific face.

            Parameters:
                element (`int`): The zero-based index of the element.
                face (`int`): The zero-based index of the face on this
                    element.

            Returns:
                `list` of `namedtuples <collections.namedtuple>`:
                ``(element, zone)``:
                    ``element``:
                        The zero-based index of the neighboring element.
                    ``zone``:
                        The zone holding the neighboring element. A value of `None`
                        indicates this is a local (intra-zone) neighbor connection.

            Example getting the neighboring faces of a zone's first element, second
            face::

                >>> neighbors = zone.face_neighbors.neighbors(element=0, face=1)
                >>> for neighbor in neighbors:
                ...     elem, zn = neighbor
                ...     print(elem, zn.index)
                21 2
            """
            element = element + 1
            face = face + 1
            n, user_spec = _tecutil.DataFaceNbrGetNumNByRef(self, element, face)
            neighbors = []
            for i in range(1, n + 1):
                res = _tecutil.DataFaceNbrGetNbrByRef(self, element, face, i)
                neighbor_elem, neighbor_zone = res
                neighbor_elem -= 1
                if neighbor_zone == 0:
                    neighbor_zone = None
                else:
                    neighbor_zone =  self.zone.dataset.zone(neighbor_zone - 1)
                neighbor = FaceNeighbors._Neighbor(neighbor_elem, neighbor_zone)
                neighbors.append(neighbor)
            return neighbors

        def is_obscured(self, element, face, active_zones=None):
            """Obscuration of the specified face.

            Parameters:
                element (`int`): The zero-based index of the element.
                face (`int`): The zero-based index of the face on the
                    element.
                active_zones (`list` of `Zones <data_access>`): List of zones to
                    consider when global face neighbors are present. If `None`,
                    the active zones of the dataset's parent frame will be used.

            Returns:
                `bool`

            .. note::

                Because datasets can be shared between frames, the default frame
                used to identify the active zones may not be the one you want. In
                this case, you can use the `Frame.active_zones()` method to provide
                the active zones for a specific frame. Furthermore, the plot type
                of the frame must have the concept of active zones - i.e. it must
                not be in "sketch" mode.

            Example usage::

                >>> zone.face_neighbors.is_obscured(element=0, face=1)
                True
            """
            if active_zones is None:
                frame = self.zone.dataset.frame
                active_zones = frame.active_zones()
            with IndexSet(*active_zones) as active_zones:
                return _tecutil.DataFaceNbrFaceIsObscured(self, element + 1,
                                                          face + 1, active_zones)