#!/usr/bin/env python3
"""Replay a duck-state-rec.py jsonl through MuJoCo offscreen: exact sim qpos per frame -> mp4.

Uses the body server's own World/Body mapping (joint names -> qpos addresses), so the render is the
simulated robot's real state, not a re-simulation. Tracking camera on the trunk.
usage (in microduck_rl, MUJOCO_GL=egl): uv run python duck-replay-render.py <in.jsonl> <out.mp4>
       [--fps 30] [--w 1280] [--h 720] [--dist 0.9] [--elev -15] [--azim 135] [--label TEXT]
"""
import argparse, json
import imageio
import mujoco
import numpy as np
from mjlab_microduck.sim.body_server import DEFAULT_SCENE, World, Body

ap = argparse.ArgumentParser()
ap.add_argument("inp"); ap.add_argument("out")
ap.add_argument("--fps", type=int, default=30)
ap.add_argument("--w", type=int, default=1280); ap.add_argument("--h", type=int, default=720)
ap.add_argument("--dist", type=float, default=0.9)
ap.add_argument("--elev", type=float, default=-15.0)
ap.add_argument("--azim", type=float, default=135.0)
ap.add_argument("--fixed", type=str, default=None, help="x,y,z fixed lookat (world camera, no tracking)")
a = ap.parse_args()

rows = [json.loads(l) for l in open(a.inp)]
world = World(DEFAULT_SCENE, 1)
body = Body(world, 0)
m, d = world.model, world.data
m.vis.global_.offwidth = max(m.vis.global_.offwidth, a.w)
m.vis.global_.offheight = max(m.vis.global_.offheight, a.h)
r = mujoco.Renderer(m, height=a.h, width=a.w)
cam = mujoco.MjvCamera()
cam.type = mujoco.mjtCamera.mjCAMERA_FREE
cam.distance, cam.elevation, cam.azimuth = a.dist, a.elev, a.azim

# resample the recording onto a fixed frame clock (wall time), nearest earlier sample
t = np.array([row["wall"] for row in rows]); t -= t[0]
n_frames = int(t[-1] * a.fps) + 1
w = imageio.get_writer(a.out, fps=a.fps, codec="libx264", quality=8, pixelformat="yuv420p",
                       macro_block_size=8)
j = 0
look = None
for k in range(n_frames):
    tk = k / a.fps
    while j + 1 < len(rows) and t[j + 1] <= tk:
        j += 1
    row = rows[j]
    d.qpos[body.trunk:body.trunk + 3] = row["trunk"]
    d.qpos[body.trunk + 3:body.trunk + 7] = row["quat"]
    for slot, wire in enumerate(body.to_wire):
        d.qpos[body.qpos_adr[slot]] = row["positions"][wire]
    mujoco.mj_forward(m, d)
    p = np.array(row["trunk"], dtype=float)
    # smooth the camera target so walking bob does not shake the frame
    look = p if look is None else 0.9 * look + 0.1 * p
    cam.lookat[:] = [float(v) for v in a.fixed.split(",")] if a.fixed else [look[0], look[1], 0.08]
    r.update_scene(d, camera=cam)
    w.append_data(r.render())
w.close()
print(f"{n_frames} frames, {t[-1]:.1f} s -> {a.out}")