# GPL # "author": "Phil Cote, cotejrp1, (http://www.blenderaddons.com)"

import bpy
import bmesh
from bpy.types import Operator
from bpy.props import (
        FloatProperty,
        IntProperty,
        )
from math import pi
from mathutils import (
        Quaternion,
        Vector,
        )
from bpy_extras.object_utils import (
        AddObjectHelper,
        object_data_add,
        )


def create_step(width, base_level, step_height, num_sides):

    axis = [0, 0, -1]
    PI2 = pi * 2
    rad = width / 2

    quat_angles = [(cur_side / num_sides) * PI2
                        for cur_side in range(num_sides)]

    quaternions = [Quaternion(axis, quat_angle)
                        for quat_angle in quat_angles]

    init_vectors = [Vector([rad, 0, base_level])] * len(quaternions)

    quat_vector_pairs = list(zip(quaternions, init_vectors))
    vectors = [quaternion @ vec for quaternion, vec in quat_vector_pairs]
    bottom_list = [(vec.x, vec.y, vec.z) for vec in vectors]
    top_list = [(vec.x, vec.y, vec.z + step_height) for vec in vectors]
    full_list = bottom_list + top_list

    return full_list


def split_list(l, n):
    """
    split the blocks up.  Credit to oremj for this one.
    http://stackoverflow.com/questions/312443/how-do-you-split-a-list-into-evenly-sized-chunks-in-python
    """
    n *= 2
    returned_list = [l[i: i + n] for i in range(0, len(l), n)]
    return returned_list


def get_connector_pairs(lst, n_sides):
    # chop off the verts that get used for the base and top
    lst = lst[n_sides:]
    lst = lst[:-n_sides]
    lst = split_list(lst, n_sides)
    return lst


def add_pyramid_object(self, context):
    all_verts = []

    height_offset = 0
    cur_width = self.width

    for i in range(self.num_steps):
        verts_loc = create_step(cur_width, height_offset, self.height,
                                self.num_sides)
        height_offset += self.height
        cur_width -= self.reduce_by
        all_verts.extend(verts_loc)

    mesh = bpy.data.meshes.new("Pyramid")
    bm = bmesh.new()

    for v_co in all_verts:
        bm.verts.new(v_co)

    def add_faces(n, block_vert_sets):
        for bvs in block_vert_sets:
            for i in range(self.num_sides - 1):
                bm.faces.new([bvs[i], bvs[i + n], bvs[i + n + 1], bvs[i + 1]])
            bm.faces.new([bvs[n - 1], bvs[(n * 2) - 1], bvs[n], bvs[0]])

    # get the base and cap faces done.
    bm.faces.new(bm.verts[0:self.num_sides])
    bm.faces.new(reversed(bm.verts[-self.num_sides:]))  # otherwise normal faces intern... T44619.

    # side faces
    block_vert_sets = split_list(bm.verts, self.num_sides)
    add_faces(self.num_sides, block_vert_sets)

    # connector faces between faces and faces of the block above it.
    connector_pairs = get_connector_pairs(bm.verts, self.num_sides)
    add_faces(self.num_sides, connector_pairs)

    bm.to_mesh(mesh)
    mesh.update()
    res = object_data_add(context, mesh, operator=self)


class AddPyramid(Operator, AddObjectHelper):
    bl_idname = "mesh.primitive_steppyramid_add"
    bl_label = "Pyramid"
    bl_description = "Construct a step pyramid mesh"
    bl_options = {'REGISTER', 'UNDO', 'PRESET'}

    num_sides: IntProperty(
            name="Number Sides",
            description="How many sides each step will have",
            min=3,
            default=4
            )
    num_steps: IntProperty(
            name="Number of Steps",
            description="How many steps for the overall pyramid",
            min=1,
            default=10
            )
    width: FloatProperty(
            name="Initial Width",
            description="Initial base step width",
            min=0.01,
            default=2
            )
    height: FloatProperty(
            name="Height",
            description="How tall each step will be",
            min=0.01,
            default=0.1
            )
    reduce_by: FloatProperty(
            name="Reduce Step By",
            description="How much to reduce each succeeding step by",
            min=.01,
            default=.20
            )

    def execute(self, context):
        add_pyramid_object(self, context)

        return {'FINISHED'}
