"""
Copyright (c) Contributors to the Open 3D Engine Project.
For complete copyright and license terms please see the LICENSE at the root of this distribution.

SPDX-License-Identifier: Apache-2.0 OR MIT
"""

import WhiteBoxMath as whiteBoxMath
import WhiteBoxInit as init 

import argparse
import azlmbr.legacy.general as general
import azlmbr.bus as bus
import azlmbr.whitebox.api as api

# usage: pyRunFile path/to/file/staircase.py <steps> <depth> <height> <width>

# formula to determine the new amount of faces added with each polygon translation
def faces_added(step):
    return (step + 2) * 4


# returns the face handles used to make the top back block, used for extruding upward
def top_back_face_handle(num_faces):
    return api.FaceHandle(num_faces - 4)


# determines the edge that needs to be hidden at the back of the staircase
# next edge seems to related to prev edge by the recursive sequence e(n+1) = e(n)+20+6*n
def edge_to_hide(prev_edge, step):
    if step == 0:
        return 20
    return prev_edge + 20 + 6 * step
    

def create_staircase_from_white_box_mesh(whiteBoxMesh, num_steps, depth, height, width):
    # number of faces the mesh starts with
    curr_faces = 12
    # backmost face of the white box mesh, this will be extruded to add new steps for the staircase
    back_face = api.FaceHandle(10)
    # backmost face of the white box mesh, this will be extruded to add width to the staircase
    side_face = api.FaceHandle(5)

    # change the default whiteBoxMesh which will act as the first step to the staircase
    if height != 1.0 and height > 0.0:
        offset = height - 1.0
        top_polygon = whiteBoxMesh.FacePolygonHandle(azlmbr.object.construct('FaceHandle', 0))
        whiteBoxMesh.TranslatePolygon(top_polygon, offset)
    if depth != 1.0 and depth > 0.0:
        offset = depth - 1.0
        back_polygon = whiteBoxMesh.FacePolygonHandle(back_face)
        whiteBoxMesh.TranslatePolygon(back_polygon, offset)
    if width != 1.0 and width > 0.0:
        offset = width - 1.0
        side_polygon = whiteBoxMesh.FacePolygonHandle(side_face)
        whiteBoxMesh.TranslatePolygon(side_polygon, offset)
    

    prev_edge = 0
    # create rest of the staircase steps
    for step in range(0, num_steps):
        # extrude the back to create room for a new step
        back_polygon = whiteBoxMesh.TranslatePolygonAppend(whiteBoxMesh.FacePolygonHandle(back_face), depth)
        curr_faces += faces_added(step)
        back_faces = back_polygon.FaceHandles
        back_face = back_faces[-1]
        # extrude upward to create the new step
        top_back_polygon = whiteBoxMesh.FacePolygonHandle(top_back_face_handle(curr_faces))
        whiteBoxMesh.TranslatePolygonAppend(top_back_polygon, height)
        curr_faces += 8
        # hide any edge created in the backside from extruding upward
        prev_edge = edge_to_hide(prev_edge, step)
        whiteBoxMesh.HideEdge(api.EdgeHandle(prev_edge))


def create_staircase(whiteBoxMesh, num_steps=2, depth=1.0, height=1.0, width=1.0):
    # if calling create_staircase directly, we need to start with a unit cube
    whiteBoxMesh.InitializeAsUnitCube()
    create_staircase_from_white_box_mesh(whiteBoxMesh, num_steps, depth, height, width)

    
if __name__ == "__main__":
    # cmdline arguments
    parser = argparse.ArgumentParser(description='Creates a staircase shaped white box mesh.')
    parser.add_argument('num_steps', nargs='?', default=4, type=int, help='number of steps in the staircase')
    parser.add_argument('depth', nargs='?', default=1.0, type=float, help='depth of each step in the staircase')
    parser.add_argument('height', nargs='?', default=1.0, type=float, help='height of each step in the staircase')
    parser.add_argument('width', nargs='?', default=1.0, type=float, help='width of each step in the staircase')
    args = parser.parse_args()

    # initialize whiteBoxMesh
    whiteBoxEntity = init.create_white_box_entity("WhiteBox-Staircase")
    whiteBoxMeshComponent = init.create_white_box_component(whiteBoxEntity)
    whiteBoxMesh = init.create_white_box_handle(whiteBoxMeshComponent)

    create_staircase_from_white_box_mesh(whiteBoxMesh, args.num_steps, args.depth, args.height, args.width)

    # update whiteBoxMesh
    init.update_white_box(whiteBoxMesh, whiteBoxMeshComponent)