Example on how to generate gloss diffuse shader via pyhon #Blender #BSE

blender-generate-mix-shader-example.py

# for https://blender.stackexchange.com/q/143599/3710

import bpy

mat_name = "Material_Name"

# check whether the material already exists
if bpy.data.materials.get(mat_name):
    mat = bpy.data.materials[mat_name]
else:
    # create the material
    mat = bpy.data.materials.new(mat_name)
    mat.diffuse_color = (0.1,0.0,0.7) # viewport color
    mat.use_nodes = True

# get the material nodes
nodes = mat.node_tree.nodes

# clear all nodes to start clean
for node in nodes:
    nodes.remove(node)

# create glossy node
node_glossy = nodes.new(type='ShaderNodeBsdfGlossy')
node_glossy.location = -200,100

# create diffuse node
node_diffuse = nodes.new(type='ShaderNodeBsdfDiffuse')
node_diffuse.inputs[0].default_value = (0,1,0,1)  # green RGBA
node_diffuse.inputs[1].default_value = 5.0 # strength
node_diffuse.location = -200,-100

# create mix shader node
node_mix = nodes.new(type='ShaderNodeMixShader')
node_mix.location = 0,0

# create output node
node_output = nodes.new(type='ShaderNodeOutputMaterial')   
node_output.location = 200,0

# link nodes
links = mat.node_tree.links
link_diff_mix = links.new(node_diffuse.outputs[0], node_mix.inputs[2])
link_gloss_mix = links.new(node_glossy.outputs[0], node_mix.inputs[1])

# link mix to output node
link_mix_out = links.new(node_mix.outputs[0], node_output.inputs[0])


# Assign it to the context object
obj = bpy.context.object

if obj.data.materials:
    # assign to 1st material slot
    obj.data.materials[0] = mat
else:
    # no slots
    obj.data.materials.append(mat)