import pymol
from pymol import cmd, util

def style_peptide():
    object_list = cmd.get_object_list()
    if not object_list:
        print("Error: No molecular structure is currently loaded.")
        return
        
    original_name = object_list[0]
    new_name = "peptide"
    cmd.set_name(original_name, new_name)
    
    cmd.h_add(new_name)

    cmd.show('sticks', new_name)
    cmd.show('spheres', new_name)
    cmd.show('cartoon', new_name)
    
    # Global stick radius for non-H bonds (Heavy-Heavy atom bonds)
    cmd.set('stick_radius', '0.25', new_name)
    cmd.set('valence_mode', '3') 
    
    # Sphere sizing
    cmd.set('sphere_scale', '0.15', f'({new_name} and elem H)')
    cmd.set('sphere_scale', '0.25', f'({new_name} and not elem H)')

    # Use cmd.set_bond to set the radius for bonds involving Hydrogens
    # The selection syntax 'neighbor' is used to find bonds connected to Hydrogens.
    cmd.set_bond('radius', 0.1, f'({new_name} and elem H)', 'neighbor')

    # Cartoon transparency
    cmd.set('cartoon_transparency', '0.5', new_name)

    # Color by element
    try:
        cmd.util.cif_color(new_name)
    except:
        cmd.color('byelement', new_name)

cmd.extend('style_peptide', style_peptide)

print("PyMOL command 'style_peptide' has been updated and should now correctly apply H-bond radius.")