# Copyright 2025 The HuggingFace 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.

import inspect
from typing import List, Optional, Union

import torch

from ...schedulers import UniPCMultistepScheduler
from ...utils import logging
from ...utils.torch_utils import randn_tensor
from ..modular_pipeline import PipelineBlock, PipelineState
from ..modular_pipeline_utils import ComponentSpec, InputParam, OutputParam
from .modular_pipeline import WanModularPipeline


logger = logging.get_logger(__name__)  # pylint: disable=invalid-name


# TODO(yiyi, aryan): We need another step before text encoder to set the `num_inference_steps` attribute for guider so that
# things like when to do guidance and how many conditions to be prepared can be determined. Currently, this is done by
# always assuming you want to do guidance in the Guiders. So, negative embeddings are prepared regardless of what the
# configuration of guider is.


# Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.retrieve_timesteps
def retrieve_timesteps(
    scheduler,
    num_inference_steps: Optional[int] = None,
    device: Optional[Union[str, torch.device]] = None,
    timesteps: Optional[List[int]] = None,
    sigmas: Optional[List[float]] = None,
    **kwargs,
):
    r"""
    Calls the scheduler's `set_timesteps` method and retrieves timesteps from the scheduler after the call. Handles
    custom timesteps. Any kwargs will be supplied to `scheduler.set_timesteps`.

    Args:
        scheduler (`SchedulerMixin`):
            The scheduler to get timesteps from.
        num_inference_steps (`int`):
            The number of diffusion steps used when generating samples with a pre-trained model. If used, `timesteps`
            must be `None`.
        device (`str` or `torch.device`, *optional*):
            The device to which the timesteps should be moved to. If `None`, the timesteps are not moved.
        timesteps (`List[int]`, *optional*):
            Custom timesteps used to override the timestep spacing strategy of the scheduler. If `timesteps` is passed,
            `num_inference_steps` and `sigmas` must be `None`.
        sigmas (`List[float]`, *optional*):
            Custom sigmas used to override the timestep spacing strategy of the scheduler. If `sigmas` is passed,
            `num_inference_steps` and `timesteps` must be `None`.

    Returns:
        `Tuple[torch.Tensor, int]`: A tuple where the first element is the timestep schedule from the scheduler and the
        second element is the number of inference steps.
    """
    if timesteps is not None and sigmas is not None:
        raise ValueError("Only one of `timesteps` or `sigmas` can be passed. Please choose one to set custom values")
    if timesteps is not None:
        accepts_timesteps = "timesteps" in set(inspect.signature(scheduler.set_timesteps).parameters.keys())
        if not accepts_timesteps:
            raise ValueError(
                f"The current scheduler class {scheduler.__class__}'s `set_timesteps` does not support custom"
                f" timestep schedules. Please check whether you are using the correct scheduler."
            )
        scheduler.set_timesteps(timesteps=timesteps, device=device, **kwargs)
        timesteps = scheduler.timesteps
        num_inference_steps = len(timesteps)
    elif sigmas is not None:
        accept_sigmas = "sigmas" in set(inspect.signature(scheduler.set_timesteps).parameters.keys())
        if not accept_sigmas:
            raise ValueError(
                f"The current scheduler class {scheduler.__class__}'s `set_timesteps` does not support custom"
                f" sigmas schedules. Please check whether you are using the correct scheduler."
            )
        scheduler.set_timesteps(sigmas=sigmas, device=device, **kwargs)
        timesteps = scheduler.timesteps
        num_inference_steps = len(timesteps)
    else:
        scheduler.set_timesteps(num_inference_steps, device=device, **kwargs)
        timesteps = scheduler.timesteps
    return timesteps, num_inference_steps


class WanInputStep(PipelineBlock):
    model_name = "wan"

    @property
    def description(self) -> str:
        return (
            "Input processing step that:\n"
            "  1. Determines `batch_size` and `dtype` based on `prompt_embeds`\n"
            "  2. Adjusts input tensor shapes based on `batch_size` (number of prompts) and `num_videos_per_prompt`\n\n"
            "All input tensors are expected to have either batch_size=1 or match the batch_size\n"
            "of prompt_embeds. The tensors will be duplicated across the batch dimension to\n"
            "have a final batch_size of batch_size * num_videos_per_prompt."
        )

    @property
    def inputs(self) -> List[InputParam]:
        return [
            InputParam("num_videos_per_prompt", default=1),
        ]

    @property
    def intermediate_inputs(self) -> List[str]:
        return [
            InputParam(
                "prompt_embeds",
                required=True,
                type_hint=torch.Tensor,
                description="Pre-generated text embeddings. Can be generated from text_encoder step.",
            ),
            InputParam(
                "negative_prompt_embeds",
                type_hint=torch.Tensor,
                description="Pre-generated negative text embeddings. Can be generated from text_encoder step.",
            ),
        ]

    @property
    def intermediate_outputs(self) -> List[str]:
        return [
            OutputParam(
                "batch_size",
                type_hint=int,
                description="Number of prompts, the final batch size of model inputs should be batch_size * num_videos_per_prompt",
            ),
            OutputParam(
                "dtype",
                type_hint=torch.dtype,
                description="Data type of model tensor inputs (determined by `prompt_embeds`)",
            ),
            OutputParam(
                "prompt_embeds",
                type_hint=torch.Tensor,
                kwargs_type="guider_input_fields",  # already in intermedites state but declare here again for guider_input_fields
                description="text embeddings used to guide the image generation",
            ),
            OutputParam(
                "negative_prompt_embeds",
                type_hint=torch.Tensor,
                kwargs_type="guider_input_fields",  # already in intermedites state but declare here again for guider_input_fields
                description="negative text embeddings used to guide the image generation",
            ),
        ]

    def check_inputs(self, components, block_state):
        if block_state.prompt_embeds is not None and block_state.negative_prompt_embeds is not None:
            if block_state.prompt_embeds.shape != block_state.negative_prompt_embeds.shape:
                raise ValueError(
                    "`prompt_embeds` and `negative_prompt_embeds` must have the same shape when passed directly, but"
                    f" got: `prompt_embeds` {block_state.prompt_embeds.shape} != `negative_prompt_embeds`"
                    f" {block_state.negative_prompt_embeds.shape}."
                )

    @torch.no_grad()
    def __call__(self, components: WanModularPipeline, state: PipelineState) -> PipelineState:
        block_state = self.get_block_state(state)
        self.check_inputs(components, block_state)

        block_state.batch_size = block_state.prompt_embeds.shape[0]
        block_state.dtype = block_state.prompt_embeds.dtype

        _, seq_len, _ = block_state.prompt_embeds.shape
        block_state.prompt_embeds = block_state.prompt_embeds.repeat(1, block_state.num_videos_per_prompt, 1)
        block_state.prompt_embeds = block_state.prompt_embeds.view(
            block_state.batch_size * block_state.num_videos_per_prompt, seq_len, -1
        )

        if block_state.negative_prompt_embeds is not None:
            _, seq_len, _ = block_state.negative_prompt_embeds.shape
            block_state.negative_prompt_embeds = block_state.negative_prompt_embeds.repeat(
                1, block_state.num_videos_per_prompt, 1
            )
            block_state.negative_prompt_embeds = block_state.negative_prompt_embeds.view(
                block_state.batch_size * block_state.num_videos_per_prompt, seq_len, -1
            )

        self.set_block_state(state, block_state)

        return components, state


class WanSetTimestepsStep(PipelineBlock):
    model_name = "wan"

    @property
    def expected_components(self) -> List[ComponentSpec]:
        return [
            ComponentSpec("scheduler", UniPCMultistepScheduler),
        ]

    @property
    def description(self) -> str:
        return "Step that sets the scheduler's timesteps for inference"

    @property
    def inputs(self) -> List[InputParam]:
        return [
            InputParam("num_inference_steps", default=50),
            InputParam("timesteps"),
            InputParam("sigmas"),
        ]

    @property
    def intermediate_outputs(self) -> List[OutputParam]:
        return [
            OutputParam("timesteps", type_hint=torch.Tensor, description="The timesteps to use for inference"),
            OutputParam(
                "num_inference_steps",
                type_hint=int,
                description="The number of denoising steps to perform at inference time",
            ),
        ]

    @torch.no_grad()
    def __call__(self, components: WanModularPipeline, state: PipelineState) -> PipelineState:
        block_state = self.get_block_state(state)
        block_state.device = components._execution_device

        block_state.timesteps, block_state.num_inference_steps = retrieve_timesteps(
            components.scheduler,
            block_state.num_inference_steps,
            block_state.device,
            block_state.timesteps,
            block_state.sigmas,
        )

        self.set_block_state(state, block_state)
        return components, state


class WanPrepareLatentsStep(PipelineBlock):
    model_name = "wan"

    @property
    def expected_components(self) -> List[ComponentSpec]:
        return []

    @property
    def description(self) -> str:
        return "Prepare latents step that prepares the latents for the text-to-video generation process"

    @property
    def inputs(self) -> List[InputParam]:
        return [
            InputParam("height", type_hint=int),
            InputParam("width", type_hint=int),
            InputParam("num_frames", type_hint=int),
            InputParam("latents", type_hint=Optional[torch.Tensor]),
            InputParam("num_videos_per_prompt", type_hint=int, default=1),
        ]

    @property
    def intermediate_inputs(self) -> List[InputParam]:
        return [
            InputParam("generator"),
            InputParam(
                "batch_size",
                required=True,
                type_hint=int,
                description="Number of prompts, the final batch size of model inputs should be `batch_size * num_videos_per_prompt`. Can be generated in input step.",
            ),
            InputParam("dtype", type_hint=torch.dtype, description="The dtype of the model inputs"),
        ]

    @property
    def intermediate_outputs(self) -> List[OutputParam]:
        return [
            OutputParam(
                "latents", type_hint=torch.Tensor, description="The initial latents to use for the denoising process"
            )
        ]

    @staticmethod
    def check_inputs(components, block_state):
        if (block_state.height is not None and block_state.height % components.vae_scale_factor_spatial != 0) or (
            block_state.width is not None and block_state.width % components.vae_scale_factor_spatial != 0
        ):
            raise ValueError(
                f"`height` and `width` have to be divisible by {components.vae_scale_factor_spatial} but are {block_state.height} and {block_state.width}."
            )
        if block_state.num_frames is not None and (
            block_state.num_frames < 1 or (block_state.num_frames - 1) % components.vae_scale_factor_temporal != 0
        ):
            raise ValueError(
                f"`num_frames` has to be greater than 0, and (num_frames - 1) must be divisible by {components.vae_scale_factor_temporal}, but got {block_state.num_frames}."
            )

    @staticmethod
    # Copied from diffusers.pipelines.wan.pipeline_wan.WanPipeline.prepare_latents with self->comp
    def prepare_latents(
        comp,
        batch_size: int,
        num_channels_latents: int = 16,
        height: int = 480,
        width: int = 832,
        num_frames: int = 81,
        dtype: Optional[torch.dtype] = None,
        device: Optional[torch.device] = None,
        generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
        latents: Optional[torch.Tensor] = None,
    ) -> torch.Tensor:
        if latents is not None:
            return latents.to(device=device, dtype=dtype)

        num_latent_frames = (num_frames - 1) // comp.vae_scale_factor_temporal + 1
        shape = (
            batch_size,
            num_channels_latents,
            num_latent_frames,
            int(height) // comp.vae_scale_factor_spatial,
            int(width) // comp.vae_scale_factor_spatial,
        )
        if isinstance(generator, list) and len(generator) != batch_size:
            raise ValueError(
                f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"
                f" size of {batch_size}. Make sure the batch size matches the length of the generators."
            )

        latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
        return latents

    @torch.no_grad()
    def __call__(self, components: WanModularPipeline, state: PipelineState) -> PipelineState:
        block_state = self.get_block_state(state)

        block_state.height = block_state.height or components.default_height
        block_state.width = block_state.width or components.default_width
        block_state.num_frames = block_state.num_frames or components.default_num_frames
        block_state.device = components._execution_device
        block_state.dtype = torch.float32  # Wan latents should be torch.float32 for best quality
        block_state.num_channels_latents = components.num_channels_latents

        self.check_inputs(components, block_state)

        block_state.latents = self.prepare_latents(
            components,
            block_state.batch_size * block_state.num_videos_per_prompt,
            block_state.num_channels_latents,
            block_state.height,
            block_state.width,
            block_state.num_frames,
            block_state.dtype,
            block_state.device,
            block_state.generator,
            block_state.latents,
        )

        self.set_block_state(state, block_state)

        return components, state
