"""Build the Shadeless shader node group."""

import bpy


SHADELESS_GROUP_NAME = "O Shadeless"


def build_shadeless_group():
    group = bpy.data.node_groups.new(SHADELESS_GROUP_NAME, "ShaderNodeTree")
    group.interface.new_socket(
        name="Shader", in_out="OUTPUT", socket_type="NodeSocketShader"
    )
    group.interface.new_socket(
        name="Color", in_out="INPUT", socket_type="NodeSocketColor"
    )
    nodes = group.nodes
    links = group.links
    group_input = nodes.new("NodeGroupInput")
    group_input.location = (-900.0, -350.0)
    group_output = nodes.new("NodeGroupOutput")
    group_output.location = (850.0, 100.0)

    diffuse = nodes.new("ShaderNodeBsdfDiffuse")
    diffuse.location = (250.0, -150.0)
    emission = nodes.new("ShaderNodeEmission")
    emission.location = (250.0, -400.0)
    links.new(group_input.outputs["Color"], diffuse.inputs["Color"])
    links.new(group_input.outputs["Color"], emission.inputs["Color"])

    light_path = nodes.new("ShaderNodeLightPath")
    light_path.location = (-900.0, 150.0)
    bounce_count = nodes.new("ShaderNodeMath")
    bounce_count.operation = "SUBTRACT"
    bounce_count.location = (-500.0, -50.0)
    links.new(light_path.outputs["Ray Depth"], bounce_count.inputs[0])
    links.new(light_path.outputs["Transmission Depth"], bounce_count.inputs[1])
    refracted = nodes.new("ShaderNodeMath")
    refracted.operation = "SUBTRACT"
    refracted.inputs[0].default_value = 1.0
    refracted.location = (-250.0, -50.0)
    links.new(bounce_count.outputs[0], refracted.inputs[1])

    reflection_limit = nodes.new("ShaderNodeMath")
    reflection_limit.operation = "SUBTRACT"
    reflection_limit.inputs[0].default_value = 2.0
    reflection_limit.location = (-650.0, 450.0)
    links.new(light_path.outputs["Ray Depth"], reflection_limit.inputs[1])
    camera_reflected = nodes.new("ShaderNodeMath")
    camera_reflected.operation = "MULTIPLY"
    camera_reflected.location = (-400.0, 400.0)
    links.new(reflection_limit.outputs[0], camera_reflected.inputs[0])
    links.new(light_path.outputs["Is Glossy Ray"], camera_reflected.inputs[1])
    shadow_or_reflect = nodes.new("ShaderNodeMath")
    shadow_or_reflect.operation = "MAXIMUM"
    shadow_or_reflect.location = (-100.0, 350.0)
    links.new(camera_reflected.outputs[0], shadow_or_reflect.inputs[0])
    links.new(light_path.outputs["Is Shadow Ray"], shadow_or_reflect.inputs[1])
    shader_factor = nodes.new("ShaderNodeMath")
    shader_factor.operation = "MAXIMUM"
    shader_factor.location = (150.0, 300.0)
    links.new(shadow_or_reflect.outputs[0], shader_factor.inputs[0])
    links.new(refracted.outputs[0], shader_factor.inputs[1])

    mix = nodes.new("ShaderNodeMixShader")
    mix.location = (550.0, 100.0)
    links.new(shader_factor.outputs[0], mix.inputs["Fac"])
    links.new(diffuse.outputs["BSDF"], mix.inputs[1])
    links.new(emission.outputs["Emission"], mix.inputs[2])
    links.new(mix.outputs["Shader"], group_output.inputs["Shader"])
    group.color_tag = "SHADER"
    group.description = (
        "Display color without scene lighting while preserving shadows "
        "and reflections."
    )
    group.use_fake_user = True
    return group