"""
Postprocess 可见体素投影结果。

Usage 示例：
    # 后处理并可视化生成视频
    python postprocess.py \
        --data-dir "blender_projects/Hip Hop Dancing/voxel_export_data" \
        --visualize

常用参数：
    --data-dir       包含 metadata.json 和 rendered/visible_voxel_ids.npz 的目录（必填）
    --visible-npz    可见体素 npz 路径（默认：<data-dir>/rendered/visible_voxel_ids.npz）
    --output         输出的 postprocess 结果 .npy 路径（默认：<data-dir>/processed/visible_voxels.npy）
    --visualize      是否根据 .npy 渲染视频
    --output-video   输出视频路径（默认：<data-dir>/processed/visible_voxels.mp4）
    --fps            视频帧率（默认：24）
"""

import argparse
import json
import math
from pathlib import Path

import imageio.v3 as iio
import numpy as np


WORLD_RADIUS_MODE = "half_size"  # or "half_diagonal"
USE_DEPTH_OCCLUSION = True
MIN_DRAW_RADIUS = 1
MAX_DRAW_RADIUS = 100
FIRST_FRAME_COLOR_VALID_DEPTH_EPS = 1e-6


def parse_args():
    p = argparse.ArgumentParser(description="Postprocess visible voxel data into screen-space representation")
    p.add_argument("--data-dir", type=str, required=True,
                   help="Directory containing metadata.json and voxel data")
    p.add_argument("--visible-npz", type=str, default=None,
                   help="Path to visible_voxel_ids .npz (default: <data-dir>/rendered/visible_voxel_ids.npz)")
    p.add_argument("--output", type=str, default=None,
                   help="Output .npy path (default: <data-dir>/rendered/visible_voxels.npy)")
    p.add_argument("--visualize", action="store_true",
                   help="Render visualization video after postprocessing")
    p.add_argument("--output-video", type=str, default=None,
                   help="Output video path (default: <data-dir>/rendered/visible_voxels.mp4)")
    p.add_argument("--fps", type=int, default=24, help="Video frame rate (default: 24)")
    return p.parse_args()


# --------------------------- camera / metadata ---------------------------
def compute_intrinsics(intr: dict):
    focal = intr["focal_length"]
    sw, sh = intr["sensor_width"], intr["sensor_height"]
    res_x, res_y = intr["resolution_x"], intr["resolution_y"]
    fit = intr.get("sensor_fit", "AUTO")

    if fit == "VERTICAL":
        fpx = focal / sh * res_y
    elif fit == "HORIZONTAL":
        fpx = focal / sw * res_x
    else:
        fpx = focal / sw * res_x if res_x >= res_y else focal / sh * res_y

    fx = fy = float(fpx)
    cx = float(res_x) / 2.0
    cy = float(res_y) / 2.0
    return fx, fy, cx, cy


def normalize_camera_extrinsics(cam_extrinsics):
    cam_mat = np.array(cam_extrinsics, dtype=np.float32)
    scale = np.linalg.norm(cam_mat[:3, 0])
    if abs(scale - 1.0) > 1e-6:
        cam_mat[:3, :3] /= scale
    return cam_mat


def load_metadata(data_dir: Path):
    with open(data_dir / "metadata.json", "r", encoding="utf-8") as f:
        return json.load(f)


def load_camera_list(metadata):
    cams = []
    for fr in metadata["frames"]:
        intr = fr["camera_intrinsics"]
        fx, fy, cx, cy = compute_intrinsics(intr)
        cam_mat = normalize_camera_extrinsics(fr["camera_extrinsics"])
        cams.append((cam_mat, fx, fy, cx, cy))
    return cams


# --------------------------- id / radius helpers ---------------------------
def build_object_id_ranges(metadata, data_dir: Path):
    obj_info = metadata["objects_info"]
    obj_names = list(obj_info.keys())

    static_path = data_dir / metadata.get("static_data_file", "static.npz")
    static_npz = np.load(static_path) if static_path.exists() else None

    frame0_path = data_dir / metadata["frames"][0]["data_file"]
    frame0_npz = np.load(frame0_path)

    object_ranges = {}
    next_id = 1

    for name in obj_names:
        if static_npz is not None and name in static_npz:
            n = int(static_npz[name].shape[0])
        elif name in frame0_npz:
            n = int(frame0_npz[name].shape[0])
        else:
            n = 0

        start_id = next_id
        end_id = next_id + n - 1
        object_ranges[name] = {
            "start_id": start_id,
            "end_id": end_id,
            "count": n,
            "voxel_size": float(obj_info[name]["voxel_size"]),
        }
        next_id += n

    if static_npz is not None:
        static_npz.close()
    frame0_npz.close()
    return object_ranges, next_id - 1


def build_id_to_radius_world(object_ranges, max_id):
    id_to_radius = np.zeros(max_id + 1, dtype=np.float32)
    for _, info in object_ranges.items():
        s = int(info["start_id"])
        e = int(info["end_id"])
        if e < s:
            continue

        voxel_size = float(info["voxel_size"])
        if WORLD_RADIUS_MODE == "half_diagonal":
            r_world = 0.5 * math.sqrt(3.0) * voxel_size
        else:
            r_world = 0.5 * voxel_size
        id_to_radius[s:e + 1] = r_world
    return id_to_radius


# --------------------------- geometry / projection ---------------------------
def world_to_camera(points_world, cam_extrinsics):
    view_mat = np.linalg.inv(cam_extrinsics)
    pts_h = np.concatenate(
        [points_world.astype(np.float32), np.ones((len(points_world), 1), dtype=np.float32)],
        axis=1,
    )
    pos_view = (view_mat @ pts_h.T).T[:, :3]
    return pos_view


def project_frame(points_world, cam_extrinsics, fx, fy, cx, cy):
    pos_view = world_to_camera(points_world, cam_extrinsics)
    z = -pos_view[:, 2]
    px_x = fx * pos_view[:, 0] / z + cx
    px_y = cy - fy * pos_view[:, 1] / z
    return px_x, px_y, z


# --------------------------- color helpers ---------------------------
def hsv_to_bgr_uint8(h, s=0.85, v=0.95):
    h = float(h % 1.0)
    s = float(np.clip(s, 0.0, 1.0))
    v = float(np.clip(v, 0.0, 1.0))
    i = int(h * 6.0)
    f = h * 6.0 - i
    p = v * (1.0 - s)
    q = v * (1.0 - f * s)
    t = v * (1.0 - (1.0 - f) * s)
    i = i % 6
    if i == 0:
        r, g, b = v, t, p
    elif i == 1:
        r, g, b = q, v, p
    elif i == 2:
        r, g, b = p, v, t
    elif i == 3:
        r, g, b = p, q, v
    elif i == 4:
        r, g, b = t, p, v
    else:
        r, g, b = v, p, q
    return np.array([b, g, r], dtype=np.float32) * 255.0


def build_colors_from_first_frame(voxels, visibility):
    """
    Assign a fixed BGR color to every compact voxel index based on its first-frame (x, y, z).
    The first frame here means t=0. If a voxel is not visible in frame 0, keep it black.
    """
    T, N, _ = voxels.shape
    colors = np.zeros((N, 3), dtype=np.uint8)

    base_pts = voxels[0].copy()
    valid = visibility[0] > 0
    if not np.any(valid):
        return colors

    pts = base_pts[valid]
    x = pts[:, 0]
    y = pts[:, 1]
    z = pts[:, 2]

    def normalize(arr):
        amin = float(arr.min())
        amax = float(arr.max())
        if amax - amin < 1e-8:
            return np.zeros_like(arr, dtype=np.float32)
        return ((arr - amin) / (amax - amin)).astype(np.float32)

    xn = normalize(x)
    yn = normalize(y)
    zn = normalize(z)

    hue = (0.55 * xn + 0.30 * yn + 0.15 * zn) % 1.0
    sat = 0.65 + 0.30 * (1.0 - zn)
    val = 0.75 + 0.20 * yn

    valid_idx = np.where(valid)[0]
    for local_i, global_i in enumerate(valid_idx):
        bgr = hsv_to_bgr_uint8(hue[local_i], sat[local_i], val[local_i])
        colors[global_i] = np.clip(np.round(bgr), 0, 255).astype(np.uint8)

    return colors

def build_colors_from_seg(voxels_segIDs):
    """
    Assign one stable random BGR color per segment id.
    seg id 0 is reserved as unknown/background and stays black.
    """
    seg_ids = np.asarray(voxels_segIDs, dtype=np.uint32).reshape(-1)
    colors = np.zeros((len(seg_ids), 3), dtype=np.uint8)
    if len(seg_ids) == 0:
        return colors

    unique_seg = np.unique(seg_ids)
    for seg in unique_seg:
        # Stable random per segment id, independent of global RNG state.
        rng = np.random.default_rng(int(seg))
        colors[seg_ids == seg] = rng.integers(0, 256, size=3, dtype=np.uint8)
    return colors
    
# --------------------------- postprocess ---------------------------
def postprocess_visible_voxels(data_dir, visible_npz_path, out_path, verbose=False):
    data_dir = Path(data_dir)
    visible_npz_path = Path(visible_npz_path)
    out_path = Path(out_path)

    metadata = load_metadata(data_dir)
    cams = load_camera_list(metadata)
    T = len(cams)

    vis_npz = np.load(visible_npz_path, allow_pickle=False)
    frame_ids_keys = sorted(k for k in vis_npz.files if k.endswith("_ids"))
    frame_pos_keys = sorted(k for k in vis_npz.files if k.endswith("_pos"))

    if len(frame_ids_keys) != T or len(frame_pos_keys) != T:
        raise RuntimeError(
            f"Mismatch: metadata has {T} frames, but npz has {len(frame_ids_keys)} id frames and {len(frame_pos_keys)} pos frames."
        )

    all_ids = np.unique(np.concatenate([vis_npz[k].astype(np.uint32) for k in frame_ids_keys], axis=0)).astype(np.uint32)
    N = len(all_ids)
    id_to_compact = {int(raw_id): i for i, raw_id in enumerate(all_ids.tolist())}

    object_ranges, max_id = build_object_id_ranges(metadata, data_dir)
    id_to_radius_world = build_id_to_radius_world(object_ranges, max_id)

    # voxels stores screen coordinates (x, y, z_depth), not world coordinates.
    voxels = np.zeros((T, N, 3), dtype=np.float32)
    visibility = np.zeros((T, N), dtype=np.float32)
    voxels_radius = np.zeros((T, N), dtype=np.float32)
    voxels_segIDs = np.zeros(N, dtype=np.uint32)

    for t in range(T):
        frame_tag = f"frame_{t+1:04d}"
        ids = vis_npz[f"{frame_tag}_ids"].astype(np.uint32)
        pos_world = vis_npz[f"{frame_tag}_pos"].astype(np.float32)
        seg_key = f"{frame_tag}_segment"
        seg_ids = vis_npz[seg_key].astype(np.uint32) if seg_key in vis_npz.files else None

        if len(ids) != len(pos_world):
            raise RuntimeError(f"{frame_tag}: ids len {len(ids)} != pos len {len(pos_world)}")
        if seg_ids is not None and len(seg_ids) != len(ids):
            raise RuntimeError(f"{frame_tag}: segment len {len(seg_ids)} != ids len {len(ids)}")
        if len(ids) == 0:
            continue

        compact_idx = np.array([id_to_compact[int(i)] for i in ids], dtype=np.int64)
        visibility[t, compact_idx] = 1.0
        if seg_ids is not None:
            prev = voxels_segIDs[compact_idx]
            # Keep a stable per-voxel segment id across frames; fill unknown slots first.
            voxels_segIDs[compact_idx] = np.where(prev == 0, seg_ids, prev).astype(np.uint32)

        cam_mat, fx, fy, cx, cy = cams[t]
        px_x, px_y, z = project_frame(pos_world, cam_mat, fx, fy, cx, cy)
        z = np.maximum(z, FIRST_FRAME_COLOR_VALID_DEPTH_EPS)

        voxels[t, compact_idx, 0] = px_x.astype(np.float32)
        voxels[t, compact_idx, 1] = px_y.astype(np.float32)
        voxels[t, compact_idx, 2] = z.astype(np.float32)

        r_world = id_to_radius_world[ids]
        r_px = fy * r_world / z
        voxels_radius[t, compact_idx] = np.maximum(r_px, 0.0).astype(np.float32)

        if verbose:
            print(f"[frame {t+1:04d}] visible={len(ids)}")

    point_colors_bgr = build_colors_from_first_frame(voxels, visibility)

    result = {
        "voxels": voxels,
        "visibility": visibility,
        "voxels_radius": voxels_radius,
        "voxels_segIDs": voxels_segIDs,
    }

    out_path.parent.mkdir(parents=True, exist_ok=True)
    np.save(out_path, result)

    vis_per_frame = visibility.sum(axis=1)
    r_vis = voxels_radius[visibility > 0]
    if verbose:
        print(f"[done] saved -> {out_path}")
        print(f"  voxels           : {voxels.shape}  (screen x, y, z)")
        print(f"  visibility       : {visibility.shape}")
        print(f"  voxels_radius    : {voxels_radius.shape}")
        print(f"  voxels_segIDs    : {voxels_segIDs.shape}")
        print(f"  point_colors_bgr : {point_colors_bgr.shape}")
        print(f"  all_ids          : {all_ids.shape}, min={all_ids.min()}, max={all_ids.max()}")
        print(f"  visible/frame    : min={vis_per_frame.min():.0f}  max={vis_per_frame.max():.0f}  mean={vis_per_frame.mean():.1f}")
        if r_vis.size:
            print(f"  radius px        : min={r_vis.min():.2f}  max={r_vis.max():.2f}  mean={r_vis.mean():.2f}")

    vis_npz.close()
    return result


# --------------------------- visualization ---------------------------
def rasterize_disks(xs, ys, depths, radii, colors_bgr, W, H, use_depth=USE_DEPTH_OCCLUSION):
    canvas = np.zeros((H, W, 3), dtype=np.uint8)
    if len(xs) == 0:
        return canvas

    if use_depth:
        occ = np.full((H, W), np.inf, dtype=np.float32)
        order = np.argsort(depths)[::-1]  # far -> near
    else:
        occ = None
        order = range(len(xs))

    yy_grid_cache = {}
    xx_grid_cache = {}

    for idx in order:
        x = int(round(float(xs[idx])))
        y = int(round(float(ys[idx])))
        d = float(depths[idx])
        r = int(max(MIN_DRAW_RADIUS, min(MAX_DRAW_RADIUS, round(float(radii[idx])))))

        if d <= 0:
            continue

        x0 = max(x - r, 0)
        x1 = min(x + r + 1, W)
        y0 = max(y - r, 0)
        y1 = min(y + r + 1, H)
        if x0 >= x1 or y0 >= y1:
            continue

        h = y1 - y0
        w = x1 - x0
        key = (h, w)
        if key not in yy_grid_cache:
            yy, xx = np.ogrid[:h, :w]
            yy_grid_cache[key] = yy
            xx_grid_cache[key] = xx
        yy = yy_grid_cache[key]
        xx = xx_grid_cache[key]
        mask = (xx + x0 - x) ** 2 + (yy + y0 - y) ** 2 <= r * r

        if use_depth:
            sub_occ = occ[y0:y1, x0:x1]
            update = mask & (d < sub_occ)
            if not np.any(update):
                continue
            sub_canvas = canvas[y0:y1, x0:x1]
            sub_canvas[update] = colors_bgr[idx]
            sub_occ[update] = d
        else:
            sub_canvas = canvas[y0:y1, x0:x1]
            sub_canvas[mask] = colors_bgr[idx]

    return canvas


def render_video_from_postprocessed(
    postprocessed,
    metadata_path,
    out_video,
    fps=24,
    mode="first_color",
    use_depth=USE_DEPTH_OCCLUSION,
):
    if isinstance(postprocessed, (str, Path)):
        pp = np.load(postprocessed, allow_pickle=True).item()
    else:
        pp = postprocessed

    voxels = pp["voxels"]
    visibility = pp["visibility"]
    voxels_radius = pp["voxels_radius"]
    voxels_segIDs = pp["voxels_segIDs"]
    if mode == "first_color":
        point_colors_bgr = build_colors_from_first_frame(voxels, visibility)
    else:
        point_colors_bgr = build_colors_from_seg(voxels_segIDs)

    with open(metadata_path, "r", encoding="utf-8") as f:
        metadata = json.load(f)

    frames = metadata["frames"]
    W = int(frames[0]["camera_intrinsics"]["resolution_x"])
    H = int(frames[0]["camera_intrinsics"]["resolution_y"])
    T = len(frames)

    if voxels.shape[0] != T:
        raise RuntimeError(f"postprocessed T={voxels.shape[0]} but metadata T={T}")

    out_video = Path(out_video)
    out_video.parent.mkdir(parents=True, exist_ok=True)

    frames_list = []

    for t in range(T):
        vis_mask = visibility[t] > 0
        pts = voxels[t, vis_mask]  # already screen x,y,z
        rad = voxels_radius[t, vis_mask]
        cols = point_colors_bgr[vis_mask]

        if len(pts) == 0:
            canvas = np.zeros((H, W, 3), dtype=np.uint8)
            frames_list.append(canvas)
            print(f"[frame {t+1:04d}] 0 visible voxels")
            continue

        px_x = pts[:, 0]
        px_y = pts[:, 1]
        depth = pts[:, 2]
        valid = (
            (depth > 0)
            & (px_x >= 0)
            & (px_x < W)
            & (px_y >= 0)
            & (px_y < H)
            & (rad > 0)
        )

        canvas = rasterize_disks(
            px_x[valid],
            px_y[valid],
            depth[valid].astype(np.float32),
            rad[valid].astype(np.float32),
            cols[valid],
            W,
            H,
            use_depth=use_depth,
        )
        frames_list.append(canvas)
        print(f"[frame {t+1:04d}] plotted={int(valid.sum())}")

    if frames_list:
        stack = np.stack(frames_list, axis=0)
        iio.imwrite(str(out_video), stack, fps=fps)
    print(f"[done] saved video -> {out_video}")


# --------------------------- CLI ---------------------------
def main():
    args = parse_args()
    data_dir = Path(args.data_dir)
    rendered_dir = data_dir / "rendered"
    processed_dir = data_dir / "processed"

    visible_npz = Path(args.visible_npz) if args.visible_npz else rendered_dir / "visible_voxel_ids.npz"
    out_npy = Path(args.output) if args.output else processed_dir / "visible_voxels.npy"
    out_video = Path(args.output_video) if args.output_video else processed_dir / "visible_voxels.mp4"

    result = postprocess_visible_voxels(data_dir, visible_npz, out_npy)

    if args.visualize:
        render_video_from_postprocessed(
            result,
            metadata_path=data_dir / "metadata.json",
            out_video=out_video,
            fps=args.fps,
            # mode="seg"
        )


if __name__ == "__main__":
    main()