from itertools import chain
from typing import Optional

import numpy as np

from c3nav.mapdata.render.data import HybridGeometry
from c3nav.mapdata.render.engines.base import FillAttribs, RenderEngine, StrokeAttribs


# noinspection PyAbstractClass
class Base3DEngine(RenderEngine):
    is_3d = True

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

        self.vertices = []

        self.np_scale = np.array((self.scale, self.scale, self.scale))
        self.np_offset = np.array((-self.minx * self.scale, -self.maxy * self.scale, 0))

    def _add_geometry(self, geometry, fill: Optional[FillAttribs], stroke: Optional[StrokeAttribs], **kwargs):
        if fill is not None:
            self.vertices.append(self._place_geometry(geometry))

    @staticmethod
    def _append_to_vertices(vertices, append=None):
        if append is not None:
            append = np.array(append, dtype=np.float32).flatten()
            vertices = np.dstack((
                vertices,
                append.reshape(1, append.size).repeat(vertices.shape[0]*3, 0).reshape((-1, 3, append.size))
            ))
        return vertices

    def _place_geometry(self, geometry: HybridGeometry, append=None, offset=True):
        vertices = np.vstack(tuple(chain(*(
            mesh.tolist() for mesh in chain(geometry.faces, *geometry.add_faces.values())
        ))))
        if offset:
            vertices = vertices * self.np_scale + self.np_offset
        return self._append_to_vertices(vertices, append)