# Copyright 2026 The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Tests for TOPReward's pre-processing helpers and encoder step."""

from __future__ import annotations

import pytest
import torch

from lerobot.configs import FeatureType, PipelineFeatureType, PolicyFeature
from lerobot.rewards.topreward.processor_topreward import (
    TOPREWARD_FEATURE_PREFIX,
    TOPREWARD_INPUT_KEYS,
    _expand_tasks,
    _prepare_video_batch,
)
from lerobot.types import TransitionKey
from tests.utils import skip_if_package_missing

# ---------------------------------------------------------------------------
# _prepare_video_batch — raw image/video batch -> (B, T, C, H, W) uint8
# ---------------------------------------------------------------------------


def test_prepare_video_batch_batched_chw_float_is_converted_to_uint8():
    video = torch.rand(2, 4, 3, 8, 8)
    tensor = _prepare_video_batch(video, max_frames=None)

    assert tensor.shape == (2, 4, 3, 8, 8)
    assert tensor.dtype == torch.uint8
    assert tensor.min() >= 0 and tensor.max() <= 255


def test_prepare_video_batch_batched_thwc_uint8_is_permuted_to_channel_first():
    video = torch.randint(0, 256, (2, 3, 8, 8, 3), dtype=torch.uint8)
    tensor = _prepare_video_batch(video, max_frames=None)

    assert tensor.shape == (2, 3, 3, 8, 8)
    assert tensor.dtype == torch.uint8


def test_prepare_video_batch_max_frames_tail_crops_recent_frames():
    video = torch.zeros(1, 10, 3, 4, 4)
    for t in range(10):
        video[:, t] = t / 9.0

    tensor = _prepare_video_batch(video, max_frames=3)

    assert tensor.shape == (1, 3, 3, 4, 4)
    assert int(tensor[0, 0, 0, 0, 0]) == int(7 / 9 * 255)
    assert int(tensor[0, -1, 0, 0, 0]) == 255


def test_prepare_video_batch_rejects_3d_input():
    with pytest.raises(ValueError, match="Expected TOPReward frames"):
        _prepare_video_batch(torch.zeros(4, 8, 8), max_frames=None)


def test_prepare_video_batch_floats_above_one_are_rescaled_and_clipped():
    video = torch.full((1, 1, 3, 2, 2), 5.0)
    tensor = _prepare_video_batch(video, max_frames=None)

    assert tensor.shape == (1, 1, 3, 2, 2)
    assert int(tensor.max()) == 255


def test_prepare_video_batch_clips_very_large_floats_to_uint8_max():
    video = torch.full((1, 1, 3, 2, 2), 300.0)
    tensor = _prepare_video_batch(video, max_frames=None)

    assert int(tensor.max()) == 255


# ---------------------------------------------------------------------------
# _expand_tasks — string / list / tuple broadcasting to batch size
# ---------------------------------------------------------------------------


def test_expand_tasks_string_is_broadcast_to_batch_size():
    assert _expand_tasks("pick up", batch_size=3, default=None) == ["pick up", "pick up", "pick up"]


def test_expand_tasks_list_of_matching_size_passes_through():
    assert _expand_tasks(["a", "b", "c"], batch_size=3, default=None) == ["a", "b", "c"]


def test_expand_tasks_tuple_is_normalised_to_list():
    assert _expand_tasks(("a", "b"), batch_size=2, default=None) == ["a", "b"]


def test_expand_tasks_single_element_list_is_broadcast():
    assert _expand_tasks(["only one"], batch_size=3, default=None) == ["only one"] * 3


def test_expand_tasks_size_mismatch_raises():
    with pytest.raises(ValueError, match="Expected 3 tasks"):
        _expand_tasks(["a", "b"], batch_size=3, default=None)


def test_expand_tasks_missing_uses_default():
    assert _expand_tasks(None, batch_size=2, default="fallback") == ["fallback", "fallback"]


def test_expand_tasks_missing_without_default_raises():
    with pytest.raises(KeyError, match="task description"):
        _expand_tasks(None, batch_size=1, default=None)


def test_expand_tasks_wrong_type_raises():
    with pytest.raises(TypeError, match="must be a string or list"):
        _expand_tasks(42, batch_size=1, default=None)


# ---------------------------------------------------------------------------
# Encoder step — stubbed AutoProcessor
# ---------------------------------------------------------------------------


def _skip_if_topreward_extras_missing(func):
    func = skip_if_package_missing("transformers")(func)
    return func


class _FakeTokenizer:
    eos_token = "<|endoftext|>"
    pad_token = "<|endoftext|>"

    def __call__(self, *args, **kwargs):
        return {"input_ids": torch.zeros(1, 10, dtype=torch.long)}


class _FakeAutoProcessor:
    def __init__(self) -> None:
        self.tokenizer = _FakeTokenizer()

    @classmethod
    def from_pretrained(cls, *args, **kwargs):  # noqa: ARG003
        return cls()

    def apply_chat_template(self, messages, **kwargs):  # noqa: ARG002
        return "fake_prompt_text"

    def __call__(self, text=None, images=None, videos=None, **kwargs):  # noqa: ARG002
        seq_len = 10
        batch_size = len(text) if isinstance(text, list) else 1
        return {
            "input_ids": torch.randint(0, 100, (batch_size, seq_len)),
            "attention_mask": torch.ones(batch_size, seq_len, dtype=torch.long),
            "pixel_values_videos": torch.zeros(batch_size, 1536, dtype=torch.float32),
            "video_grid_thw": torch.ones(batch_size, 3, dtype=torch.long),
            "mm_token_type_ids": torch.zeros(batch_size, seq_len, dtype=torch.long),
        }


def _build_step(monkeypatch, **overrides):
    from lerobot.rewards.topreward import processor_topreward

    monkeypatch.setattr(processor_topreward, "AutoProcessor", _FakeAutoProcessor)
    return processor_topreward.TOPRewardEncoderProcessorStep(**overrides)


def _make_transition(observation: dict, complementary: dict | None = None) -> dict:
    transition: dict = {TransitionKey.OBSERVATION: observation}
    if complementary is not None:
        transition[TransitionKey.COMPLEMENTARY_DATA] = complementary
    return transition


@_skip_if_topreward_extras_missing
def test_encoder_step_emits_input_ids_and_labels(monkeypatch):
    """The processor must emit Qwen-VL tensors including ``input_ids`` and
    ``labels`` under the ``observation.topreward.*`` namespace."""
    step = _build_step(monkeypatch)

    frames_batch = torch.zeros(2, 4, 3, 8, 8)
    out = step(
        _make_transition(
            observation={"observation.images.top": frames_batch},
            complementary={"task": ["pick", "place"]},
        )
    )

    obs_out = out[TransitionKey.OBSERVATION]
    for key in TOPREWARD_INPUT_KEYS:
        assert f"{TOPREWARD_FEATURE_PREFIX}{key}" in obs_out

    input_ids = obs_out[f"{TOPREWARD_FEATURE_PREFIX}input_ids"]
    labels = obs_out[f"{TOPREWARD_FEATURE_PREFIX}labels"]
    assert labels.dtype == torch.long
    assert labels.shape == (2, 10)
    assert labels[:, :-1].eq(-100).all()
    assert labels[:, -1].equal(input_ids[:, -1])


@_skip_if_topreward_extras_missing
def test_encoder_step_get_config_roundtrips_user_fields(monkeypatch):
    step = _build_step(
        monkeypatch,
        vlm_name="Qwen/Qwen3-VL-8B-Instruct",
        image_key="observation.images.cam_top",
        task_key="task",
        default_task="do the thing",
        max_frames=8,
        fps=4.0,
        add_chat_template=True,
        max_length=2048,
    )

    cfg = step.get_config()
    assert cfg["vlm_name"] == "Qwen/Qwen3-VL-8B-Instruct"
    assert cfg["image_key"] == "observation.images.cam_top"
    assert cfg["default_task"] == "do the thing"
    assert cfg["max_frames"] == 8
    assert cfg["fps"] == 4.0
    assert cfg["add_chat_template"] is True
    assert cfg["max_length"] == 2048


@_skip_if_topreward_extras_missing
def test_encoder_step_transform_features_is_identity(monkeypatch):
    step = _build_step(monkeypatch)
    features = {
        PipelineFeatureType.OBSERVATION: {
            "observation.images.top": PolicyFeature(shape=(3, 224, 224), type=FeatureType.VISUAL),
        }
    }
    assert step.transform_features(features) == features


@_skip_if_topreward_extras_missing
def test_encoder_step_rejects_missing_image_key(monkeypatch):
    step = _build_step(monkeypatch, image_key="observation.images.top")
    with pytest.raises(KeyError, match="image key"):
        step(_make_transition(observation={}, complementary={"task": "pick"}))