"""Schema for BF16 joint-window Context pre-KV features."""

from __future__ import annotations

from typing import Mapping

import torch

from .schema import HIDDEN_SIZE
from .v2_schema import (
    CONTEXT_BLOCK_IDS,
    TOKENS_PER_FRAME,
    validate_case_tensors_v2,
    validate_step_tensors_v2,
)


SCHEMA_VERSION_PREFEATURE = "predictor_context_prefeature_bf16_v1"
SUPERVISION_PAIRS = ((0, 1), (1, 2), (2, 3))
DEFAULT_ACTIONS = (
    ("w_s", "w-15,s-16"),
    ("a_d", "a-15,d-16"),
    ("up_down", "up-15,down-16"),
    ("left_right", "left-15,right-16"),
)


def validate_case_tensors(tensors: Mapping[str, torch.Tensor]) -> int:
    return validate_case_tensors_v2(tensors)


def validate_step_tensors(tensors: Mapping[str, torch.Tensor]) -> None:
    validate_step_tensors_v2(tensors)


def validate_context_prefeature(
    block_id: int,
    tensors: Mapping[str, torch.Tensor],
) -> int:
    if block_id not in CONTEXT_BLOCK_IDS:
        raise ValueError(f"Unsupported context block: {block_id}")
    required = {
        "img_modulated",
        "context_valid_mask",
        "selected_frame_indices",
        "context_viewmats",
        "context_Ks",
        "rope_temporal_size",
        "start_rope_start_idx",
    }
    missing = required.difference(tensors)
    if missing:
        raise ValueError(f"Block {block_id} missing prefeature keys: {sorted(missing)}")

    feature = tensors["img_modulated"]
    if feature.ndim != 3 or feature.shape[0] != 1 or feature.shape[2] != HIDDEN_SIZE:
        raise ValueError(f"Unexpected block {block_id} feature shape: {tuple(feature.shape)}")
    if feature.dtype != torch.bfloat16:
        raise ValueError(f"Block {block_id} img_modulated must be BF16")
    if not torch.isfinite(feature).all():
        raise ValueError(f"Block {block_id} img_modulated contains non-finite values")
    tokens = int(feature.shape[1])
    if tokens % TOKENS_PER_FRAME:
        raise ValueError(f"Block {block_id} token count {tokens} is not frame-aligned")
    frames = tokens // TOKENS_PER_FRAME

    mask = tensors["context_valid_mask"]
    if tuple(mask.shape) != (1, tokens) or mask.dtype != torch.bool or not bool(mask.all()):
        raise ValueError("On-disk context_valid_mask must be all-True and unpadded")
    indices = tensors["selected_frame_indices"]
    if tuple(indices.shape) != (frames,) or indices.dtype != torch.int64:
        raise ValueError("selected_frame_indices must be int64 [context_frames]")
    if frames and (int(indices.min()) < 0 or not bool(torch.all(indices[1:] > indices[:-1]))):
        raise ValueError("selected_frame_indices must be non-negative and strictly increasing")
    if tuple(tensors["context_viewmats"].shape) != (1, frames, 4, 4):
        raise ValueError("Unexpected context_viewmats shape")
    if tuple(tensors["context_Ks"].shape) != (1, frames, 3, 3):
        raise ValueError("Unexpected context_Ks shape")
    for name in ("context_viewmats", "context_Ks"):
        value = tensors[name]
        if value.dtype != torch.bfloat16 or not torch.isfinite(value).all():
            raise ValueError(f"{name} must contain finite BF16 values")
    for name in ("rope_temporal_size", "start_rope_start_idx"):
        value = tensors[name]
        if value.dtype != torch.int64 or value.numel() != 1:
            raise ValueError(f"{name} must be one int64 scalar")
    if int(tensors["rope_temporal_size"].item()) != frames:
        raise ValueError("rope_temporal_size must equal the compact context frame count")
    if int(tensors["start_rope_start_idx"].item()) != 0:
        raise ValueError("Context prefill must start RoPE at zero")
    return frames