"""Render six inspection views of an STL using Blender.

Usage:
    blender --background --python tools/render_stl_previews.py -- \
        input.stl output-directory basename [comma-separated-views]
"""

import os
import sys

import bpy
from mathutils import Vector


def arguments():
    args = sys.argv[sys.argv.index("--") + 1 :]
    if len(args) not in (3, 4):
        raise SystemExit(
            "expected: input.stl output-directory basename [comma-separated-views]"
        )
    requested_views = args[3].split(",") if len(args) == 4 else None
    return args[0], args[1], args[2], requested_views


def look_at(camera, target):
    direction = Vector(target) - camera.location
    camera.rotation_euler = direction.to_track_quat("-Z", "Y").to_euler()


def render_view(camera, center, span, name, direction, output_dir, basename):
    distance = span * 2.2
    camera.location = Vector(center) + Vector(direction).normalized() * distance
    look_at(camera, center)
    camera.data.type = "ORTHO"
    camera.data.ortho_scale = span * 1.35
    bpy.context.scene.render.filepath = os.path.join(
        output_dir, f"{basename}_{name}.png"
    )
    bpy.ops.render.render(write_still=True)


def main():
    input_path, output_dir, basename, requested_views = arguments()
    os.makedirs(output_dir, exist_ok=True)

    bpy.ops.wm.read_factory_settings(use_empty=True)
    bpy.ops.wm.stl_import(filepath=os.path.abspath(input_path))
    model = bpy.context.selected_objects[0]
    model.name = "Feather case"

    material = bpy.data.materials.new("Case material")
    material.diffuse_color = (0.16, 0.42, 0.72, 1.0)
    material.metallic = 0.0
    material.roughness = 0.45
    model.data.materials.append(material)

    corners = [model.matrix_world @ Vector(corner) for corner in model.bound_box]
    mins = Vector([min(v[i] for v in corners) for i in range(3)])
    maxs = Vector([max(v[i] for v in corners) for i in range(3)])
    center = (mins + maxs) / 2
    span = max(maxs - mins)

    world = bpy.data.worlds.new("Inspection world")
    world.use_nodes = True
    world.node_tree.nodes["Background"].inputs["Color"].default_value = (
        0.035,
        0.04,
        0.05,
        1,
    )
    world.node_tree.nodes["Background"].inputs["Strength"].default_value = 0.5
    bpy.context.scene.world = world

    camera_data = bpy.data.cameras.new("Camera")
    camera = bpy.data.objects.new("Camera", camera_data)
    bpy.context.collection.objects.link(camera)
    bpy.context.scene.camera = camera

    key_data = bpy.data.lights.new("Key", type="AREA")
    key_data.energy = 900
    key_data.shape = "DISK"
    key_data.size = span
    key = bpy.data.objects.new("Key", key_data)
    key.location = center + Vector((span, -span, span * 1.5))
    bpy.context.collection.objects.link(key)

    fill_data = bpy.data.lights.new("Fill", type="AREA")
    fill_data.energy = 500
    fill_data.size = span
    fill = bpy.data.objects.new("Fill", fill_data)
    fill.location = center + Vector((-span, span, span))
    bpy.context.collection.objects.link(fill)

    scene = bpy.context.scene
    scene.render.engine = "BLENDER_WORKBENCH"
    scene.render.resolution_x = 800
    scene.render.resolution_y = 600
    scene.render.resolution_percentage = 100
    scene.render.image_settings.file_format = "PNG"
    scene.render.film_transparent = False
    scene.display.shading.light = "STUDIO"
    scene.display.shading.color_type = "MATERIAL"
    scene.display.shading.show_shadows = True
    scene.display.shading.show_cavity = True
    scene.display.shading.cavity_type = "BOTH"
    scene.display.shading.curvature_ridge_factor = 1.5
    scene.display.shading.curvature_valley_factor = 1.2

    views = {
        "iso": (1, -1, 0.8),
        "front": (-1, 0, 0),
        "back": (1, 0, 0),
        "left": (0, -1, 0),
        "right": (0, 1, 0),
        "top": (0, 0, 1),
    }
    selected = requested_views or list(views)
    unknown = sorted(set(selected) - set(views))
    if unknown:
        raise SystemExit(f"unknown views: {', '.join(unknown)}")
    for name in selected:
        direction = views[name]
        render_view(camera, center, span, name, direction, output_dir, basename)


if __name__ == "__main__":
    main()