"""The feeder's one motion, exec'd by nf_build.py after the meshes exist (needs bpy, NOZZLE_TRAVEL, NEEDLE_TRAVEL).

NutritionFeeder_Root["inject"]: 0 = needle away (nozzle up inside the collar, needle inside the nozzle), 1 = as in the
picture (nozzle out, needle down to the palm). The nozzle runs 0 .. 0.55, the needle 0.55 .. 1, each eased.
The meshes are built in the picture's pose; each moving part keeps ["closed_location"] (inject 0).
Drivers are simple expressions (the user's Blender runs with Python auto-run off).
Timeline, 30 fps: away at frame 1, out at 60, held to 120, away again at 180.
"""
root = bpy.data.objects["NutritionFeeder_Root"]
nozzle = bpy.data.objects["SM_NutritionFeeder_Nozzle"]
needle = bpy.data.objects["SM_NutritionFeeder_Needle"]
root["inject"] = 0.0
ui = root.id_properties_ui("inject")
ui.update(min=0.0, max=1.0, soft_min=0.0, soft_max=1.0, description="0 needle away, 1 needle out (as in the picture)")

RIG = {}
for ob, travel, a, b in ((nozzle, NOZZLE_TRAVEL, 0.0, 0.55), (needle, NEEDLE_TRAVEL, 0.55, 1.0)):
    z_out = ob.location.z
    z_closed = z_out + travel
    ob["closed_location"] = (ob.location.x, ob.location.y, z_closed)
    ob["open_location"] = (ob.location.x, ob.location.y, z_out)
    ob.location.z = z_closed
    ob.driver_remove("location", 2)
    fc = ob.driver_add("location", 2)
    d = fc.driver
    d.type = 'SCRIPTED'
    var = d.variables.new()
    var.name = "v"
    var.type = 'SINGLE_PROP'
    var.targets[0].id_type = 'OBJECT'
    var.targets[0].id = root
    var.targets[0].data_path = '["inject"]'
    d.expression = "%.6f - %.6f*smoothstep(%.2f, %.2f, v)" % (z_closed, travel, a, b)
    if not d.is_simple_expression:
        t = "min(max((v-%.2f)/%.2f,0.0),1.0)" % (a, b - a)
        d.expression = "%.6f - %.6f*%s*%s*(3-2*%s)" % (z_closed, travel, t, t, t)
    for m in list(fc.modifiers):
        fc.modifiers.remove(m)
    RIG[ob.name] = dict(expression=d.expression, simple=d.is_simple_expression, closed_z=z_closed, open_z=z_out)

sc = bpy.context.scene
sc.render.fps = 30
sc.frame_start, sc.frame_end = 1, 180
for fr, val in ((1, 0.0), (60, 1.0), (120, 1.0), (180, 0.0)):
    root["inject"] = val
    root.keyframe_insert('["inject"]', frame=fr)
if root.animation_data and root.animation_data.action:
    root.animation_data.action.name = "NutritionFeeder | INJECT"
sc.frame_set(1)
root["rig"] = str(RIG)