from ctypes import c_uint, byref

from django.contrib.gis.geos.error import GEOSIndexError

from django.contrib.gis.geos.geometry import GEOSGeometry

from django.contrib.gis.geos.libgeos import get_pointer_arr, GEOM_PTR

from django.contrib.gis.geos.linestring import LinearRing

from django.contrib.gis.geos import prototypes as capi

class Polygon(GEOSGeometry):

    def __init__(self, *args, **kwargs):

        """

        Initializes on an exterior ring and a sequence of holes (both

        instances may be either LinearRing instances, or a tuple/list

        that may be constructed into a LinearRing).

        Examples of initialization, where shell, hole1, and hole2 are 

        valid LinearRing geometries:

        >>> poly = Polygon(shell, hole1, hole2)

        >>> poly = Polygon(shell, (hole1, hole2))

        Example where a tuple parameters are used:

        >>> poly = Polygon(((0, 0), (0, 10), (10, 10), (0, 10), (0, 0)), 

                           ((4, 4), (4, 6), (6, 6), (6, 4), (4, 4)))

        """

        if not args:

            raise TypeError('Must provide at least one LinearRing, or a tuple, to initialize a Polygon.')

        # Getting the ext_ring and init_holes parameters from the argument list

        ext_ring = args[0]

        init_holes = args[1:]

        n_holes = len(init_holes)

        # If initialized as Polygon(shell, (LinearRing, LinearRing)) [for backward-compatibility]

        if n_holes == 1 and isinstance(init_holes[0], (tuple, list)) and \

                (len(init_holes[0]) == 0 or isinstance(init_holes[0][0], LinearRing)): 

            init_holes = init_holes[0]

            n_holes = len(init_holes)

        # Ensuring the exterior ring and holes parameters are LinearRing objects

        # or may be instantiated into LinearRings.

        ext_ring = self._construct_ring(ext_ring, 'Exterior parameter must be a LinearRing or an object that can initialize a LinearRing.')

        holes_list = [] # Create new list, cause init_holes is a tuple.

        for i in xrange(n_holes):

            holes_list.append(self._construct_ring(init_holes[i], 'Holes parameter must be a sequence of LinearRings or objects that can initialize to LinearRings'))

        # Why another loop?  Because if a TypeError is raised, cloned pointers will

        # be around that can't be cleaned up.

        holes = get_pointer_arr(n_holes)

        for i in xrange(n_holes): holes[i] = capi.geom_clone(holes_list[i].ptr)

        # Getting the shell pointer address.

        shell = capi.geom_clone(ext_ring.ptr)

        # Calling with the GEOS createPolygon factory.

        super(Polygon, self).__init__(capi.create_polygon(shell, byref(holes), c_uint(n_holes)), **kwargs)

    def __getitem__(self, index):

        """

        Returns the ring at the specified index.  The first index, 0, will 

        always return the exterior ring.  Indices > 0 will return the 

        interior ring at the given index (e.g., poly[1] and poly[2] would

        return the first and second interior ring, respectively).

        """

        if index == 0:

            return self.exterior_ring

        else:

            # Getting the interior ring, have to subtract 1 from the index.

            return self.get_interior_ring(index-1) 

    def __setitem__(self, index, ring):

        "Sets the ring at the specified index with the given ring."

        # Checking the index and ring parameters.

        self._checkindex(index)

        if not isinstance(ring, LinearRing):

            raise TypeError('must set Polygon index with a LinearRing object')

        # Getting the shell

        if index == 0:

            shell = capi.geom_clone(ring.ptr)

        else:

            shell = capi.geom_clone(capi.get_extring(self.ptr))

        # Getting the interior rings (holes)

        nholes = len(self)-1

        if nholes > 0:

            holes = get_pointer_arr(nholes)

            for i in xrange(nholes):

                if i == (index-1):

                    holes[i] = capi.geom_clone(ring.ptr)

                else:

                    holes[i] = capi.geom_clone(capi.get_intring(self.ptr, i))

            holes_param = byref(holes)

        else:

            holes_param = None

        # Getting the current pointer, replacing with the newly constructed

        # geometry, and destroying the old geometry.

        prev_ptr = self.ptr

        srid = self.srid

        self.ptr = capi.create_polygon(shell, holes_param, c_uint(nholes))

        if srid: self.srid = srid

        capi.destroy_geom(prev_ptr)

    def __iter__(self):

        "Iterates over each ring in the polygon."

        for i in xrange(len(self)):

            yield self[i]

    def __len__(self):

        "Returns the number of rings in this Polygon."

        return self.num_interior_rings + 1

    def _construct_ring(self, param, msg=''):

        "Helper routine for trying to construct a ring from the given parameter."

        if isinstance(param, LinearRing): return param

        try:

            ring = LinearRing(param)

            return ring

        except TypeError:

            raise TypeError(msg)

    @classmethod

    def from_bbox(cls, bbox):

        "Constructs a Polygon from a bounding box (4-tuple)."

        x0, y0, x1, y1 = bbox

        return GEOSGeometry( 'POLYGON((%s %s, %s %s, %s %s, %s %s, %s %s))' %  (

                x0, y0, x0, y1, x1, y1, x1, y0, x0, y0) )

    def get_interior_ring(self, ring_i):

        """

        Gets the interior ring at the specified index, 0 is for the first 

        interior ring, not the exterior ring.

        """

        self._checkindex(ring_i+1)

        return GEOSGeometry(capi.geom_clone(capi.get_intring(self.ptr, ring_i)), srid=self.srid)

    #### Polygon Properties ####

    @property

    def num_interior_rings(self):

        "Returns the number of interior rings."

        # Getting the number of rings

        return capi.get_nrings(self.ptr)

    def get_ext_ring(self):

        "Gets the exterior ring of the Polygon."

        return GEOSGeometry(capi.geom_clone(capi.get_extring(self.ptr)), srid=self.srid)

    def set_ext_ring(self, ring):

        "Sets the exterior ring of the Polygon."

        self[0] = ring

    # properties for the exterior ring/shell

    exterior_ring = property(get_ext_ring, set_ext_ring)

    shell = exterior_ring

    @property

    def tuple(self):

        "Gets the tuple for each ring in this Polygon."

        return tuple([self[i].tuple for i in xrange(len(self))])

    coords = tuple

    @property

    def kml(self):

        "Returns the KML representation of this Polygon."

        inner_kml = ''.join(["<innerBoundaryIs>%s</innerBoundaryIs>" % self[i+1].kml 

                             for i in xrange(self.num_interior_rings)])

        return "<Polygon><outerBoundaryIs>%s</outerBoundaryIs>%s</Polygon>" % (self[0].kml, inner_kml)