# Stage 44: save a blend that ALREADY contains the turntable, so viewing her needs no scripting.
#
#   blender --background --python 44_make_spin_blend.py -- <in.blend> <out.blend> [seconds_per_turn]
#
# 43_spin.py has to run inside a live GUI session, and a GUI Blender launched from this agent gets
# reaped when the launching command finishes. Baking the animation into the file instead means it
# survives: open the file, press spacebar.
import bpy, sys, math

argv = sys.argv[sys.argv.index("--") + 1:]
SRC, OUT = argv[0], argv[1]
SEC = float(argv[2]) if len(argv) > 2 else 50.0
FPS = 24

bpy.ops.wm.open_mainfile(filepath=SRC)
ob = max([o for o in bpy.data.objects if o.type == 'MESH'], key=lambda o: len(o.data.vertices))
scn = bpy.context.scene
scn.render.fps = FPS
scn.sync_mode = 'FRAME_DROP'          # honour real time, or playback is a blur
n = int(round(SEC * FPS))
scn.frame_start = 1
scn.frame_end = n                     # frame n+1 repeats frame 1, so the loop is seamless
scn.frame_set(1)

bpy.context.preferences.edit.keyframe_new_interpolation_type = 'LINEAR'
ob.animation_data_clear()
ob.rotation_mode = 'XYZ'
ob.rotation_euler = (0.0, 0.0, 0.0)
ob.keyframe_insert("rotation_euler", index=2, frame=1)
ob.rotation_euler = (0.0, 0.0, 2.0 * math.pi)
ob.keyframe_insert("rotation_euler", index=2, frame=n + 1)
ob.rotation_euler = (0.0, 0.0, 0.0)

bpy.ops.wm.save_as_mainfile(filepath=OUT)
print(f"SPINBLEND_DONE {n} frames @ {FPS}fps = {SEC:.0f}s per turn -> {OUT}")