"""Self-contained PyG loader for the GNN Disassembly dataset.

Two loader variants:
  - load_pyg_frame_products_only(ep, frame)  → constraint graph only, no robot
  - load_pyg_frame_with_robot(ep, frame)     → constraint graph + robot agent node

Both return torch_geometric.data.Data with:
  x            (N, 268)      node features
  edge_index   (2, N*(N-1))  fully connected directed message-passing edges
  edge_attr    (N*(N-1), 3)  [has_constraint, is_locked, src_blocks_dst]
  num_nodes    N

Notes on the edge feature design:
- The graph is FULLY CONNECTED and structurally symmetric.
  Both (i, j) and (j, i) exist in edge_index for every node pair i != j.
- Direction is NOT encoded in the graph structure. It is encoded as
  a feature: `src_blocks_dst`.
- `has_constraint` and `is_locked` are symmetric per pair (same value
  for both (i, j) and (j, i)).
- `src_blocks_dst` is asymmetric: it is 1 if the edge's src node
  physically blocks its dst node, 0 otherwise.
"""

import json
from dataclasses import dataclass
from pathlib import Path
from typing import Dict, List, Optional, Tuple

import numpy as np
import torch
from torch_geometric.data import Data


# ─────────────────────────────────────────────────────────────────────────────
# Helpers
# ─────────────────────────────────────────────────────────────────────────────

def list_labeled_frames(episode_dir: Path) -> List[int]:
    """Return sorted list of frame indices that have saved annotations."""
    mask_dir = episode_dir / "annotations" / "side_masks"
    if not mask_dir.exists():
        return []
    frames = []
    for p in mask_dir.glob("frame_*.npz"):
        try:
            frames.append(int(p.stem.split("_")[1]))
        except (ValueError, IndexError):
            continue
    return sorted(frames)


def resolve_frame_state(graph_json: dict, frame_idx: int) -> Tuple[Dict[str, bool], Dict[str, bool]]:
    """Resolve delta-encoded constraints + visibility at a frame.

    Walks frame_states from frame 0 to frame_idx, accumulating deltas.
    Returns (constraints_dict, visibility_dict).
    """
    constraints: Dict[str, bool] = {}
    visibility: Dict[str, bool] = {}
    # Defaults: every component visible, every edge locked
    for c in graph_json["components"]:
        visibility[c["id"]] = True
    for e in graph_json["edges"]:
        constraints[f"{e['src']}->{e['dst']}"] = True
    # Walk deltas up to frame_idx
    fs_dict = graph_json.get("frame_states", {})
    for f in sorted([int(k) for k in fs_dict]):
        if f > frame_idx:
            break
        fs = fs_dict[str(f)]
        for k, v in fs.get("constraints", {}).items():
            constraints[k] = v
        for k, v in fs.get("visibility", {}).items():
            visibility[k] = v
    return constraints, visibility


def type_one_hot(comp_type: str, type_vocab: List[str]) -> List[float]:
    """9-dim one-hot encoding of component type based on type_vocab."""
    return [1.0 if t == comp_type else 0.0 for t in type_vocab]


# ─────────────────────────────────────────────────────────────────────────────
# Raw data loader (NumPy only, no torch)
# ─────────────────────────────────────────────────────────────────────────────

@dataclass
class FrameData:
    graph: dict
    masks: Dict[str, np.ndarray]
    embeddings: Dict[str, np.ndarray]
    depth_info: dict
    robot: Optional[dict]
    constraints: Dict[str, bool]
    visibility: Dict[str, bool]


def load_frame_data(episode_dir: Path, frame_idx: int) -> FrameData:
    """Load all v3 annotation files for one frame."""
    anno = episode_dir / "annotations"

    with open(anno / "side_graph.json") as f:
        graph = json.load(f)

    def _load_npz_dict(path: Path) -> Dict[str, np.ndarray]:
        if not path.exists():
            return {}
        d = np.load(path)
        return {k: d[k] for k in d.files}

    masks = _load_npz_dict(anno / "side_masks" / f"frame_{frame_idx:06d}.npz")
    embeddings = _load_npz_dict(anno / "side_embeddings" / f"frame_{frame_idx:06d}.npz")
    depth_info = _load_npz_dict(anno / "side_depth_info" / f"frame_{frame_idx:06d}.npz")

    robot: Optional[dict] = None
    robot_path = anno / "side_robot" / f"frame_{frame_idx:06d}.npz"
    if robot_path.exists():
        r = np.load(robot_path)
        if r["visible"][0] == 1:
            robot = {k: r[k] for k in r.files}

    constraints, visibility = resolve_frame_state(graph, frame_idx)
    return FrameData(graph, masks, embeddings, depth_info, robot, constraints, visibility)


# ─────────────────────────────────────────────────────────────────────────────
# PyG loader — products only
# ─────────────────────────────────────────────────────────────────────────────

def load_pyg_frame_products_only(episode_dir: Path, frame_idx: int) -> Data:
    """Fully connected PyG graph WITHOUT robot.

    Returns Data(
        x=[N, 268],
        edge_index=[2, N*(N-1)],
        edge_attr=[N*(N-1), 3],   # [has_constraint, is_locked, src_blocks_dst]
        num_nodes=N,
    )
    where N = number of product components (robot excluded).
    """
    fd = load_frame_data(episode_dir, frame_idx)
    graph = fd.graph
    type_vocab = graph["type_vocab"]  # 9 entries incl. robot
    nodes = graph["components"]       # robot already excluded per spec
    N = len(nodes)

    # ── Node features ──
    # [256D SAM2 embedding, 3D position, 9D type one-hot, 1D visibility] = 269
    # NOTE: 256 + 3 + 9 + 1 = 269 (not 268). Adjust if you need a different layout.
    x_list = []
    for node in nodes:
        cid = node["id"]
        emb = fd.embeddings.get(cid, np.zeros(256, dtype=np.float32))

        depth_valid_key = f"{cid}_depth_valid"
        centroid_key = f"{cid}_centroid"
        if (depth_valid_key in fd.depth_info
                and int(fd.depth_info[depth_valid_key][0]) == 1):
            pos = fd.depth_info[centroid_key].astype(np.float32)
        else:
            pos = np.zeros(3, dtype=np.float32)

        type_oh = type_one_hot(node["type"], type_vocab)  # 9D
        vis = 1.0 if fd.visibility.get(cid, True) else 0.0

        feat = np.concatenate([
            emb.astype(np.float32),
            pos,
            np.array(type_oh, dtype=np.float32),
            np.array([vis], dtype=np.float32),
        ])
        x_list.append(feat)
    x = torch.tensor(np.stack(x_list), dtype=torch.float32) if x_list else torch.empty((0, 269))

    # ── Fully connected edges with 3D features ──
    # Edge feature: [has_constraint, is_locked, src_blocks_dst]
    # - has_constraint & is_locked are SYMMETRIC for the pair (A, B)
    # - src_blocks_dst is ASYMMETRIC: 1 if edge's src physically blocks dst
    constraint_set = {(e["src"], e["dst"]) for e in graph["edges"]}
    pair_forward = {}  # frozenset({a, b}) -> (blocker, blocked)
    for (s, d) in constraint_set:
        pair_forward[frozenset([s, d])] = (s, d)

    src_idx, dst_idx, edge_attr = [], [], []
    for i in range(N):
        for j in range(N):
            if i == j:
                continue
            src_id = nodes[i]["id"]
            dst_id = nodes[j]["id"]
            src_idx.append(i)
            dst_idx.append(j)

            pair_key = frozenset([src_id, dst_id])
            if pair_key in pair_forward:
                forward = pair_forward[pair_key]
                constraint_key = f"{forward[0]}->{forward[1]}"
                is_locked = fd.constraints.get(constraint_key, True)
                src_blocks_dst = 1.0 if src_id == forward[0] else 0.0
                edge_attr.append([
                    1.0,
                    1.0 if is_locked else 0.0,
                    src_blocks_dst,
                ])
            else:
                edge_attr.append([0.0, 0.0, 0.0])  # message passing only

    return Data(
        x=x,
        edge_index=torch.tensor([src_idx, dst_idx], dtype=torch.long),
        edge_attr=torch.tensor(edge_attr, dtype=torch.float32),
        y=torch.tensor([frame_idx], dtype=torch.long),
        num_nodes=N,
    )


# ─────────────────────────────────────────────────────────────────────────────
# PyG loader — with robot agent node
# ─────────────────────────────────────────────────────────────────────────────

def load_pyg_frame_with_robot(episode_dir: Path, frame_idx: int) -> Data:
    """Fully connected PyG graph WITH robot appended as agent node.

    Robot is node N (the last node). All edges involving the robot have
    features [0, 0, 0] because the robot has no physical constraints.

    If the robot is not visible at this frame, returns the products-only graph.
    Additional attached tensors when robot is visible:
        data.robot_point_cloud  (M, 3) float32
        data.robot_pixel_coords (M, 2) int32
        data.robot_mask         (H, W) uint8
    """
    data = load_pyg_frame_products_only(episode_dir, frame_idx)
    fd = load_frame_data(episode_dir, frame_idx)
    if fd.robot is None:
        return data

    graph = fd.graph
    type_vocab = graph["type_vocab"]
    products = graph["components"]
    N_prod = len(products)
    N = N_prod + 1

    # ── Build robot node features ──
    robot_emb = fd.robot["embedding"].astype(np.float32)
    robot_pos = (fd.robot["centroid"].astype(np.float32)
                 if int(fd.robot["depth_valid"][0]) == 1
                 else np.zeros(3, dtype=np.float32))
    robot_type_oh = type_one_hot("robot", type_vocab)
    robot_feat = np.concatenate([
        robot_emb, robot_pos,
        np.array(robot_type_oh, dtype=np.float32),
        np.array([1.0], dtype=np.float32),
    ])
    x = torch.cat([data.x, torch.tensor(robot_feat, dtype=torch.float32).unsqueeze(0)], dim=0)

    # ── Rebuild edges with 3D features ──
    constraint_set = {(e["src"], e["dst"]) for e in graph["edges"]}
    pair_forward = {}
    for (s, d) in constraint_set:
        pair_forward[frozenset([s, d])] = (s, d)

    src_idx, dst_idx, edge_attr = [], [], []

    # Products × Products
    for i in range(N_prod):
        for j in range(N_prod):
            if i == j:
                continue
            src_id = products[i]["id"]
            dst_id = products[j]["id"]
            src_idx.append(i)
            dst_idx.append(j)
            pair_key = frozenset([src_id, dst_id])
            if pair_key in pair_forward:
                forward = pair_forward[pair_key]
                is_locked = fd.constraints.get(f"{forward[0]}->{forward[1]}", True)
                src_blocks_dst = 1.0 if src_id == forward[0] else 0.0
                edge_attr.append([1.0, 1.0 if is_locked else 0.0, src_blocks_dst])
            else:
                edge_attr.append([0.0, 0.0, 0.0])

    # Robot ↔ Products (both directions, message-passing only)
    robot_idx = N_prod
    for i in range(N_prod):
        src_idx.append(robot_idx); dst_idx.append(i); edge_attr.append([0.0, 0.0, 0.0])
        src_idx.append(i); dst_idx.append(robot_idx); edge_attr.append([0.0, 0.0, 0.0])

    data = Data(
        x=x,
        edge_index=torch.tensor([src_idx, dst_idx], dtype=torch.long),
        edge_attr=torch.tensor(edge_attr, dtype=torch.float32),
        y=torch.tensor([frame_idx], dtype=torch.long),
        num_nodes=N,
    )
    data.robot_point_cloud = torch.tensor(fd.robot["point_cloud"], dtype=torch.float32)
    data.robot_pixel_coords = torch.tensor(fd.robot["pixel_coords"], dtype=torch.int32)
    data.robot_mask = torch.tensor(fd.robot["mask"], dtype=torch.uint8)
    return data


# ─────────────────────────────────────────────────────────────────────────────
# Episode iterator
# ─────────────────────────────────────────────────────────────────────────────

def iterate_episode(episode_dir: Path, with_robot: bool = True):
    """Yield (frame_idx, Data) pairs for all labeled frames in an episode."""
    loader = load_pyg_frame_with_robot if with_robot else load_pyg_frame_products_only
    for frame_idx in list_labeled_frames(episode_dir):
        yield frame_idx, loader(episode_dir, frame_idx)