AutoAsing | Python Fiddle

import bpy
import os
import os.path

class AutoAsignTex(bpy.types.Operator):
   bl_idname = "object.auto_asign_tex"
   bl_label = "Auto Asign Textures"
   bl_options = {'REGISTER', 'UNDO'}

#context.os.system('cls')
   bpy.context.scene.render.engine = 'CYCLES'
   print("\n\nObjects")
      
   bpy.context.scene.render.engine = 'CYCLES'
   mat_names = []
   def execute(self, context):
      for ob in context.selected_objects:
         print(ob.name)
         print(ob.name)
         for mat_slot in ob.material_slots:
            for mtex_slot in mat_slot.material.texture_slots:
               if mtex_slot:
                  if hasattr(mtex_slot.texture , 'image'):
                     mat_name = "{}".format(mtex_slot.name)
                     for img in bpy.data.images:
                        #print(img.name)
                        mat = mat_slot.material
                        if img.name == (mat_name or mat_n):
                           if not mat.use_nodes:
                              print("{} - {}".format(img.name, mat_name))
                              mat.use_nodes = True
                              tex_node = mat.node_tree.nodes.new('TEX_IMAGE')
                              mixShad_node = mat.node_tree.nodes.new('MIX_SHADER')
                              trns_node = mat.node_tree.nodes.new('BSDF_TRANSPARENT')
                              diff_node = mat.node_tree.nodes['Diffuse BSDF']
                              matOut_node = mat.node_tree.nodes['Material Output']
                              mat.node_tree.links.new(tex_node.outputs['Color'], diff_node.inputs['Color'])
                              mat.node_tree.links.new(tex_node.outputs['Alpha'], mixShad_node.inputs['Fac'])
                              mat.node_tree.links.new(diff_node.outputs['BSDF'], mixShad_node.inputs[2])
                              mat.node_tree.links.new(trns_node.outputs['BSDF'], mixShad_node.inputs['Shader'])
                              mat.node_tree.links.new(mixShad_node.outputs['Shader'], matOut_node.inputs['Surface'])
                              tex_node.image = img
      return {'FINISHED'} 
                        #self.dewit()
                                
def register():
   #unregister()
   bpy.utils.register_class(AutoAsignTex)
   #bpy.types.VIEW3D_MT_object.prepend(OBJECT_MT_hello.draw)  # << add menu above
   #bpy.types.VIEW3D_MT_object.append(OBJECT_MT_hello.draw)  # << add menu below
   
def unregister():
   #if hasattr(bpy.types, "AutoAsignTex"):
   #bpy.types.VIEW3D_MT_object.remove(bpy.types.OBJECT_MT_hello.draw)
   bpy.utils.unregister_class(AutoAsignTex)
   
if __name__ == "__main__":
   register()
         
                     #mat.node_tree.nodes['Image Texture'].translate_attach(TRANSFORM_OT_translate={"value":(0, 0, 0), "constraint_axis":(False, False, False), "constraint_orientation":'GLOBAL', "mirror":False, "proportional":'DISABLED', "proportional_edit_falloff":'SMOOTH', "proportional_size":1, "snap":False, "snap_target":'CLOSEST', "snap_point":(0, 0, 0), "snap_align":False, "snap_normal":(0, 0, 0), "texture_space":False, "release_confirm":False}, NODE_OT_attach={})
                     
            #tex_node.location = Vector((200.0, 400.0))
            
         #else:
            #print("{} - {}".format(img.name, mat_name))
            
            
            #print("\n\nObjects")                
            #tex_name_list = []
            #mat_names = []
            #for ob in bpy.data.objects:
               #print(ob.name)
               #for mat_slot in ob.material_slots:
                  #mat_names.append(mat_slot.material.name)
                  #print("mat_names: {}".format(mat_slot.material.name))
                  #for mtex_slot in mat_slot.material.texture_slots:
                     #if mtex_slot:
                        #print("\t%s" % mtex_slot)
                        #if hasattr(mtex_slot.texture , 'image'):
                           #tex_name_list.append(mtex_slot.texture.image.name)

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