import Rhino 
import scriptcontext as sc

# Points needed to create the NURBS surface
point_A = Rhino.Geometry.Point3d(0, 0, 20)
point_B = Rhino.Geometry.Point3d(0, 20, 0)
point_C = Rhino.Geometry.Point3d(20, 0, 0)
point_D = Rhino.Geometry.Point3d(20, 20, 20)

# Will create a NURBS surface from 4 corner points
my_surface = Rhino.Geometry.NurbsSurface.CreateFromCorners(point_A, 
                                                           point_B, 
                                                           point_C, 
                                                           point_D, 
                                                           tolerance = sc.doc.ModelAbsoluteTolerance)
sc.doc.Objects.AddSurface(my_surface)

import Rhino 
import scriptcontext as sc

# Curves in the u and v directions needed to create the NURBS surface
crvs = [curve_u_1, curve_u_2, curve_v_1, curve_v_2]

# Will create a NURBS surface passing through a network of curves in two directions
my_surface = Rhino.Geometry.NurbsSurface.CreateNetworkSurface(crvs, 
                                                              continuity=0, 
                                                              edgeTolerance= sc.doc.ModelAbsoluteTolerance, 
                                                              interiorTolerance= sc.doc.ModelAbsoluteTolerance,
                                                              angleTolerance= sc.doc.ModelAngleToleranceRadians)[0]

sc.doc.Objects.AddSurface(my_surface)

import rhinoscriptsyntax as rs

# getting the curves needed to create the NURBS surface
crvs = rs.GetObjects("Select the curves in u and v directions",
                     filter=4, 
                     select=True, 
                     maximum_count = 50)

# Will create a NURBS surface passing through a network of curves in two directions
rs.AddNetworkSrf(crvs)

# Will evaluate the point on the surface at local coordinates u,v.
u = 1
v = 2
my_surface.PointAt(u, v)

# Will evaluate the normal on the surface at local coordinates u,v.
u = 1
v = 2
my_surface.NormalAt(u, v)

test_point = Rhino.Geometry.Point3d(0, 0, 0)

# Will evaluate the u, v local coordinates on the surface that are the closest to the test_point
res, u, v = my_surface.ClosestPoint(test_point)

print(u, v)

# Will return the list of control points of the NURBS surface:

my_surface.Points

# Can be used to modify the control points:

control_point = my_surface.Points.GetControlPoint(1, 1)

control_point.X = 100
control_point.Y = 100
control_point.Z = 100

my_surface.Points.SetControlPoint(1, 1, control_point)