# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

"""
Wan2.2 TI2V (Text-Image-to-Video) Pipeline.

This pipeline supports the unified TI2V-5B model that can generate videos from:
- Text only (T2V mode)
- Text + Image (I2V mode)

The key difference from the MoE-based I2V pipeline is:
- Single transformer (not MoE with two transformers)
- Uses expand_timesteps mode for image conditioning
- No CLIP image encoder - only VAE encoding for image condition
"""

from __future__ import annotations

import logging
import os
from collections.abc import Iterable
from typing import Any, cast

import numpy as np
import PIL.Image
import torch
from diffusers import AutoencoderKLWan
from diffusers.utils.torch_utils import randn_tensor
from torch import nn
from transformers import AutoTokenizer, UMT5EncoderModel
from vllm.model_executor.models.utils import AutoWeightsLoader

from vllm_omni.diffusion.data import DiffusionOutput, OmniDiffusionConfig
from vllm_omni.diffusion.distributed.cfg_parallel import CFGParallelMixin
from vllm_omni.diffusion.distributed.utils import get_local_device
from vllm_omni.diffusion.model_loader.diffusers_loader import DiffusersPipelineLoader
from vllm_omni.diffusion.models.interface import SupportImageInput
from vllm_omni.diffusion.models.schedulers import FlowUniPCMultistepScheduler
from vllm_omni.diffusion.models.wan2_2.pipeline_wan2_2 import (
    create_transformer_from_config,
    load_transformer_config,
    retrieve_latents,
)
from vllm_omni.diffusion.request import OmniDiffusionRequest
from vllm_omni.inputs.data import OmniTextPrompt
from vllm_omni.platforms import current_omni_platform

logger = logging.getLogger(__name__)


def get_wan22_ti2v_post_process_func(
    od_config: OmniDiffusionConfig,
):
    from diffusers.video_processor import VideoProcessor

    video_processor = VideoProcessor(vae_scale_factor=8)

    def post_process_func(
        video: torch.Tensor,
        output_type: str = "np",
    ):
        if output_type == "latent":
            return video
        return video_processor.postprocess_video(video, output_type=output_type)

    return post_process_func


def get_wan22_ti2v_pre_process_func(
    od_config: OmniDiffusionConfig,
):
    """Pre-process function for TI2V: optionally load and resize input image."""
    from diffusers.video_processor import VideoProcessor

    video_processor = VideoProcessor(vae_scale_factor=8)

    def pre_process_func(request: OmniDiffusionRequest) -> OmniDiffusionRequest:
        for i, prompt in enumerate(request.prompts):
            multi_modal_data = prompt.get("multi_modal_data", {}) if not isinstance(prompt, str) else None
            raw_image = multi_modal_data.get("image", None) if multi_modal_data is not None else None
            if isinstance(prompt, str):
                prompt = OmniTextPrompt(prompt=prompt)
            if "additional_information" not in prompt:
                prompt["additional_information"] = {}

            if raw_image is None:
                raise ValueError(
                    """No image is provided. This model requires an image to run.""",
                    """Please correctly set `"multi_modal_data": {"image": <an image object or file path>, …}`""",
                )
            if not isinstance(raw_image, (str, PIL.Image.Image)):
                raise TypeError(
                    f"""Unsupported image format {raw_image.__class__}.""",
                    """Please correctly set `"multi_modal_data": {"image": <an image object or file path>, …}`""",
                )
            image = PIL.Image.open(raw_image).convert("RGB") if isinstance(raw_image, str) else raw_image

            # Calculate dimensions based on aspect ratio if not provided
            if request.sampling_params.height is None or request.sampling_params.width is None:
                # Default max area for 720P (TI2V-5B default)
                max_area = 720 * 1280
                aspect_ratio = image.height / image.width

                # Calculate dimensions maintaining aspect ratio
                mod_value = 16  # Must be divisible by 16
                height = round(np.sqrt(max_area * aspect_ratio)) // mod_value * mod_value
                width = round(np.sqrt(max_area / aspect_ratio)) // mod_value * mod_value

                if request.sampling_params.height is None:
                    request.sampling_params.height = height
                if request.sampling_params.width is None:
                    request.sampling_params.width = width

            # Resize image to target dimensions
            image = image.resize(
                (request.sampling_params.width, request.sampling_params.height),  # type: ignore # Above has ensured that width & height are not None
                PIL.Image.Resampling.LANCZOS,
            )
            prompt["multi_modal_data"]["image"] = image  # type: ignore # key existence already checked above

            # Preprocess for VAE
            prompt["additional_information"]["preprocessed_image"] = video_processor.preprocess(
                image, height=request.sampling_params.height, width=request.sampling_params.width
            )
            request.prompts[i] = prompt
        return request

    return pre_process_func


class Wan22TI2VPipeline(nn.Module, SupportImageInput, CFGParallelMixin):
    """
    Wan2.2 Text-Image-to-Video (TI2V) Pipeline.

    This is a unified pipeline that supports both:
    - Text-to-Video (T2V): when no image is provided
    - Image-to-Video (I2V): when an image is provided

    Uses expand_timesteps mode for I2V conditioning where the first frame
    is conditioned on the input image latent.
    """

    def __init__(
        self,
        *,
        od_config: OmniDiffusionConfig,
        prefix: str = "",
    ):
        super().__init__()
        self.od_config = od_config

        self.device = get_local_device()
        dtype = getattr(od_config, "dtype", torch.bfloat16)

        model = od_config.model
        local_files_only = os.path.exists(model)

        # Set up weights sources for single transformer
        self.weights_sources = [
            DiffusersPipelineLoader.ComponentSource(
                model_or_path=od_config.model,
                subfolder="transformer",
                revision=None,
                prefix="transformer.",
                fall_back_to_pt=True,
            ),
        ]

        # Text encoder
        self.tokenizer = AutoTokenizer.from_pretrained(model, subfolder="tokenizer", local_files_only=local_files_only)
        self.text_encoder = UMT5EncoderModel.from_pretrained(
            model, subfolder="text_encoder", torch_dtype=dtype, local_files_only=local_files_only
        ).to(self.device)

        # VAE
        self.vae = AutoencoderKLWan.from_pretrained(
            model, subfolder="vae", torch_dtype=torch.float32, local_files_only=local_files_only
        ).to(self.device)

        # Single transformer (TI2V uses dense 5B model, not MoE)
        # Load config from model to get correct dimensions
        transformer_config = load_transformer_config(model, "transformer", local_files_only)
        self.transformer = create_transformer_from_config(transformer_config)

        # Initialize UniPC scheduler
        flow_shift = od_config.flow_shift if od_config.flow_shift is not None else 5.0  # default for 720p
        self.scheduler = FlowUniPCMultistepScheduler(
            num_train_timesteps=1000,
            shift=flow_shift,
            prediction_type="flow_prediction",
        )

        # VAE scale factors
        self.vae_scale_factor_temporal = self.vae.config.scale_factor_temporal if hasattr(self.vae, "config") else 4
        self.vae_scale_factor_spatial = self.vae.config.scale_factor_spatial if hasattr(self.vae, "config") else 8

        # TI2V always uses expand_timesteps mode
        self.expand_timesteps = True

        self._guidance_scale = None
        self._num_timesteps = None
        self._current_timestep = None

    @property
    def guidance_scale(self):
        return self._guidance_scale

    @property
    def do_classifier_free_guidance(self):
        return self._guidance_scale is not None and self._guidance_scale > 1.0

    @property
    def num_timesteps(self):
        return self._num_timesteps

    @property
    def current_timestep(self):
        return self._current_timestep

    def forward(
        self,
        req: OmniDiffusionRequest,
        prompt: str | None = None,
        negative_prompt: str | None = None,
        image: PIL.Image.Image | torch.Tensor | None = None,
        height: int = 704,
        width: int = 1280,
        num_inference_steps: int = 40,
        guidance_scale: float = 5.0,
        frame_num: int = 81,
        output_type: str | None = "np",
        generator: torch.Generator | list[torch.Generator] | None = None,
        prompt_embeds: torch.Tensor | None = None,
        negative_prompt_embeds: torch.Tensor | None = None,
        attention_kwargs: dict | None = None,
        **kwargs,
    ) -> DiffusionOutput:
        # Get parameters from request or arguments
        if len(req.prompts) > 1:
            raise ValueError(
                """This model only supports a single prompt, not a batched request.""",
                """Please pass in a single prompt object or string, or a single-item list.""",
            )
        if len(req.prompts) == 1:  # If req.prompt is empty, default to prompt & neg_prompt in param list
            prompt = req.prompts[0] if isinstance(req.prompts[0], str) else req.prompts[0].get("prompt")
            negative_prompt = None if isinstance(req.prompts[0], str) else req.prompts[0].get("negative_prompt")
        if prompt is None and prompt_embeds is None:
            raise ValueError("Prompt or prompt_embeds is required for Wan2.2 generation.")

        # Get image from request (optional for TI2V)
        if image is None:
            multi_modal_data = (
                req.prompts[0].get("multi_modal_data", {}) if not isinstance(req.prompts[0], str) else None
            )
            raw_image = multi_modal_data.get("image", None) if multi_modal_data is not None else None
            if isinstance(raw_image, list):
                if len(raw_image) > 1:
                    logger.warning(
                        """Received a list of image. Only a single image is supported by this model."""
                        """Taking only the first image for now."""
                    )
                raw_image = raw_image[0]
            if raw_image is None:
                image = None
            elif isinstance(raw_image, str):
                image = PIL.Image.open(raw_image)
            else:
                image = cast(PIL.Image.Image | torch.Tensor, raw_image)

        # Default dimensions for TI2V-5B (720P)
        height = req.sampling_params.height or height
        width = req.sampling_params.width or width
        num_frames = req.sampling_params.num_frames if req.sampling_params.num_frames else frame_num
        num_steps = req.sampling_params.num_inference_steps or num_inference_steps

        # Respect per-request guidance_scale when explicitly provided.
        if req.sampling_params.guidance_scale_provided:
            guidance_scale = req.sampling_params.guidance_scale

        self._guidance_scale = guidance_scale

        # Validate inputs
        self.check_inputs(
            prompt=prompt,
            negative_prompt=negative_prompt,
            image=image,
            height=height,
            width=width,
            prompt_embeds=prompt_embeds,
            negative_prompt_embeds=negative_prompt_embeds,
        )

        # Adjust num_frames to be compatible with VAE temporal scaling
        if num_frames % self.vae_scale_factor_temporal != 1:
            num_frames = num_frames // self.vae_scale_factor_temporal * self.vae_scale_factor_temporal + 1
        num_frames = max(num_frames, 1)

        device = self.device
        dtype = self.transformer.dtype

        # Generator setup
        if generator is None:
            generator = req.sampling_params.generator
        if generator is None and req.sampling_params.seed is not None:
            generator = torch.Generator(device=device).manual_seed(req.sampling_params.seed)

        # Encode prompts
        if prompt_embeds is None:
            prompt_embeds, negative_prompt_embeds = self.encode_prompt(
                prompt=prompt,
                negative_prompt=negative_prompt,
                do_classifier_free_guidance=guidance_scale > 1.0,
                num_videos_per_prompt=req.sampling_params.num_outputs_per_prompt or 1,
                max_sequence_length=req.sampling_params.max_sequence_length or 512,
                device=device,
                dtype=dtype,
            )
        else:
            prompt_embeds = prompt_embeds.to(device=device, dtype=dtype)
            if negative_prompt_embeds is not None:
                negative_prompt_embeds = negative_prompt_embeds.to(device=device, dtype=dtype)

        batch_size = prompt_embeds.shape[0]

        # Timesteps
        self.scheduler.set_timesteps(num_steps, device=device)
        timesteps = self.scheduler.timesteps
        self._num_timesteps = len(timesteps)

        # Prepare latents
        num_channels_latents = self.transformer.config.in_channels
        num_latent_frames = (num_frames - 1) // self.vae_scale_factor_temporal + 1
        latent_height = height // self.vae_scale_factor_spatial
        latent_width = width // self.vae_scale_factor_spatial

        # Check if we have an image (I2V mode) or not (T2V mode)
        if image is not None:
            # I2V mode: prepare latents with image condition
            from diffusers.video_processor import VideoProcessor

            video_processor = VideoProcessor(vae_scale_factor=self.vae_scale_factor_spatial)

            if isinstance(image, PIL.Image.Image):
                image_tensor = video_processor.preprocess(image, height=height, width=width)
            else:
                image_tensor = image
            image_tensor = image_tensor.to(device=device, dtype=torch.float32)

            latents, latent_condition, first_frame_mask = self.prepare_i2v_latents(
                image=image_tensor,
                batch_size=batch_size,
                num_channels_latents=num_channels_latents,
                height=height,
                width=width,
                num_frames=num_frames,
                dtype=torch.float32,
                device=device,
                generator=generator,
                latents=req.sampling_params.latents,
            )
        else:
            # T2V mode: prepare random latents
            latents = self.prepare_latents(
                batch_size=batch_size,
                num_channels_latents=num_channels_latents,
                height=height,
                width=width,
                num_frames=num_frames,
                dtype=torch.float32,
                device=device,
                generator=generator,
                latents=req.sampling_params.latents,
            )
            latent_condition = None
            first_frame_mask = torch.ones(
                1, 1, num_latent_frames, latent_height, latent_width, dtype=torch.float32, device=device
            )

        if attention_kwargs is None:
            attention_kwargs = {}

        # Denoising loop
        for t in timesteps:
            self._current_timestep = t

            # Prepare latent input
            if latent_condition is not None:
                # I2V mode: blend condition with latents using mask
                latent_model_input = (1 - first_frame_mask) * latent_condition + first_frame_mask * latents
                latent_model_input = latent_model_input.to(dtype)

                # Expand timesteps for each patch (TI2V style)
                temp_ts = (first_frame_mask[0][0][:, ::2, ::2] * t).flatten()
                timestep = temp_ts.unsqueeze(0).expand(latents.shape[0], -1)
            else:
                # T2V mode: use latents directly
                latent_model_input = latents.to(dtype)

                # Expand timesteps for TI2V model architecture
                mask = torch.ones(1, 1, num_latent_frames, latent_height, latent_width, device=device)
                temp_ts = (mask[0][0][:, ::2, ::2] * t).flatten()
                timestep = temp_ts.unsqueeze(0).expand(latents.shape[0], -1)

            do_true_cfg = guidance_scale > 1.0 and negative_prompt_embeds is not None
            # Prepare kwargs for positive and negative predictions
            positive_kwargs = {
                "hidden_states": latent_model_input,
                "timestep": timestep,
                "encoder_hidden_states": prompt_embeds,
                "attention_kwargs": attention_kwargs,
                "return_dict": False,
                "current_model": self.transformer,
            }
            if do_true_cfg:
                negative_kwargs = {
                    "hidden_states": latent_model_input,
                    "timestep": timestep,
                    "encoder_hidden_states": negative_prompt_embeds,
                    "attention_kwargs": attention_kwargs,
                    "return_dict": False,
                    "current_model": self.transformer,
                }
            else:
                negative_kwargs = None

            # Predict noise with automatic CFG parallel handling
            noise_pred = self.predict_noise_maybe_with_cfg(
                do_true_cfg=do_true_cfg,
                true_cfg_scale=guidance_scale,
                positive_kwargs=positive_kwargs,
                negative_kwargs=negative_kwargs,
                cfg_normalize=False,
            )

            # Compute the previous noisy sample x_t -> x_t-1 with automatic CFG sync
            latents = self.scheduler_step_maybe_with_cfg(noise_pred, t, latents, do_true_cfg)

        # Wan2.2 is prone to out of memory errors when predicting large videos
        # so we empty the cache here to avoid OOM before vae decoding.
        if current_omni_platform.is_available():
            current_omni_platform.empty_cache()
        self._current_timestep = None

        # For I2V mode, blend final latents with condition
        if latent_condition is not None:
            latents = (1 - first_frame_mask) * latent_condition + first_frame_mask * latents

        # Decode
        if output_type == "latent":
            output = latents
        else:
            latents = latents.to(self.vae.dtype)
            latents_mean = (
                torch.tensor(self.vae.config.latents_mean)
                .view(1, self.vae.config.z_dim, 1, 1, 1)
                .to(latents.device, latents.dtype)
            )
            latents_std = 1.0 / torch.tensor(self.vae.config.latents_std).view(1, self.vae.config.z_dim, 1, 1, 1).to(
                latents.device, latents.dtype
            )
            latents = latents / latents_std + latents_mean
            output = self.vae.decode(latents, return_dict=False)[0]

        return DiffusionOutput(output=output)

    def predict_noise(self, current_model: nn.Module | None = None, **kwargs: Any) -> torch.Tensor:
        """
        Forward pass through transformer to predict noise.

        Args:
            current_model: The transformer model to use
            **kwargs: Arguments to pass to the transformer

        Returns:
            Predicted noise tensor
        """
        if current_model is None:
            current_model = self.transformer
        return current_model(**kwargs)[0]

    def encode_prompt(
        self,
        prompt: str | list[str],
        negative_prompt: str | list[str] | None = None,
        do_classifier_free_guidance: bool = True,
        num_videos_per_prompt: int = 1,
        max_sequence_length: int = 512,
        device: torch.device | None = None,
        dtype: torch.dtype | None = None,
    ):
        """Encode text prompts using T5 text encoder."""
        device = device or self.device
        dtype = dtype or self.text_encoder.dtype

        prompt = [prompt] if isinstance(prompt, str) else prompt
        prompt_clean = [self._prompt_clean(p) for p in prompt]
        batch_size = len(prompt_clean)

        text_inputs = self.tokenizer(
            prompt_clean,
            padding="max_length",
            max_length=max_sequence_length,
            truncation=True,
            add_special_tokens=True,
            return_attention_mask=True,
            return_tensors="pt",
        )
        ids, mask = text_inputs.input_ids, text_inputs.attention_mask
        seq_lens = mask.gt(0).sum(dim=1).long()

        prompt_embeds = self.text_encoder(ids.to(device), mask.to(device)).last_hidden_state
        prompt_embeds = prompt_embeds.to(dtype=dtype, device=device)
        prompt_embeds = [u[:v] for u, v in zip(prompt_embeds, seq_lens)]
        prompt_embeds = torch.stack(
            [torch.cat([u, u.new_zeros(max_sequence_length - u.size(0), u.size(1))]) for u in prompt_embeds], dim=0
        )

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

        negative_prompt_embeds = None
        if do_classifier_free_guidance:
            negative_prompt = negative_prompt or ""
            negative_prompt = batch_size * [negative_prompt] if isinstance(negative_prompt, str) else negative_prompt
            neg_text_inputs = self.tokenizer(
                [self._prompt_clean(p) for p in negative_prompt],
                padding="max_length",
                max_length=max_sequence_length,
                truncation=True,
                add_special_tokens=True,
                return_attention_mask=True,
                return_tensors="pt",
            )
            ids_neg, mask_neg = neg_text_inputs.input_ids, neg_text_inputs.attention_mask
            seq_lens_neg = mask_neg.gt(0).sum(dim=1).long()
            negative_prompt_embeds = self.text_encoder(ids_neg.to(device), mask_neg.to(device)).last_hidden_state
            negative_prompt_embeds = negative_prompt_embeds.to(dtype=dtype, device=device)
            negative_prompt_embeds = [u[:v] for u, v in zip(negative_prompt_embeds, seq_lens_neg)]
            negative_prompt_embeds = torch.stack(
                [
                    torch.cat([u, u.new_zeros(max_sequence_length - u.size(0), u.size(1))])
                    for u in negative_prompt_embeds
                ],
                dim=0,
            )
            negative_prompt_embeds = negative_prompt_embeds.repeat(1, num_videos_per_prompt, 1)
            negative_prompt_embeds = negative_prompt_embeds.view(batch_size * num_videos_per_prompt, seq_len, -1)

        return prompt_embeds, negative_prompt_embeds

    @staticmethod
    def _prompt_clean(text: str) -> str:
        return " ".join(text.strip().split())

    def prepare_latents(
        self,
        batch_size: int,
        num_channels_latents: int,
        height: int,
        width: int,
        num_frames: int,
        dtype: torch.dtype | None,
        device: torch.device | None,
        generator: torch.Generator | list[torch.Generator] | None,
        latents: torch.Tensor | None = None,
    ) -> torch.Tensor:
        """Prepare random latents for T2V mode."""
        if latents is not None:
            return latents.to(device=device, dtype=dtype)

        num_latent_frames = (num_frames - 1) // self.vae_scale_factor_temporal + 1
        shape = (
            batch_size,
            num_channels_latents,
            num_latent_frames,
            int(height) // self.vae_scale_factor_spatial,
            int(width) // self.vae_scale_factor_spatial,
        )
        if isinstance(generator, list) and len(generator) != batch_size:
            raise ValueError(f"Generator list length {len(generator)} does not match batch size {batch_size}.")
        latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
        return latents

    def prepare_i2v_latents(
        self,
        image: torch.Tensor,
        batch_size: int,
        num_channels_latents: int,
        height: int,
        width: int,
        num_frames: int,
        dtype: torch.dtype | None,
        device: torch.device | None,
        generator: torch.Generator | list[torch.Generator] | None,
        latents: torch.Tensor | None = None,
    ) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:
        """
        Prepare latents for I2V mode with image conditioning.

        Returns:
            latents: Initial noise latents
            latent_condition: Encoded first frame condition
            first_frame_mask: Mask (0 for first frame, 1 for rest)
        """
        num_latent_frames = (num_frames - 1) // self.vae_scale_factor_temporal + 1
        latent_height = height // self.vae_scale_factor_spatial
        latent_width = width // self.vae_scale_factor_spatial

        shape = (batch_size, num_channels_latents, num_latent_frames, latent_height, latent_width)

        if latents is None:
            latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
        else:
            latents = latents.to(device=device, dtype=dtype)

        # Prepare first frame condition
        image = image.unsqueeze(2)  # [batch, channels, 1, height, width]
        image = image.to(device=device, dtype=self.vae.dtype)

        # Encode through VAE
        latent_condition = retrieve_latents(self.vae.encode(image), sample_mode="argmax")
        latent_condition = latent_condition.repeat(batch_size, 1, 1, 1, 1)

        # Normalize latents
        latents_mean = (
            torch.tensor(self.vae.config.latents_mean)
            .view(1, self.vae.config.z_dim, 1, 1, 1)
            .to(latent_condition.device, latent_condition.dtype)
        )
        latents_std = 1.0 / torch.tensor(self.vae.config.latents_std).view(1, self.vae.config.z_dim, 1, 1, 1).to(
            latent_condition.device, latent_condition.dtype
        )
        latent_condition = (latent_condition - latents_mean) * latents_std
        latent_condition = latent_condition.to(dtype)

        # Create mask: 0 for first frame (condition), 1 for rest (to denoise)
        first_frame_mask = torch.ones(1, 1, num_latent_frames, latent_height, latent_width, dtype=dtype, device=device)
        first_frame_mask[:, :, 0] = 0

        return latents, latent_condition, first_frame_mask

    def check_inputs(
        self,
        prompt,
        negative_prompt,
        image,
        height,
        width,
        prompt_embeds=None,
        negative_prompt_embeds=None,
    ):
        if height % 16 != 0 or width % 16 != 0:
            raise ValueError(f"`height` and `width` have to be divisible by 16 but are {height} and {width}.")

        if prompt is not None and prompt_embeds is not None:
            raise ValueError("Cannot forward both `prompt` and `prompt_embeds`. Please provide only one.")

        if negative_prompt is not None and negative_prompt_embeds is not None:
            raise ValueError(
                "Cannot forward both `negative_prompt` and `negative_prompt_embeds`. Please provide only one."
            )

        if prompt is None and prompt_embeds is None:
            raise ValueError("Provide either `prompt` or `prompt_embeds`.")

    def load_weights(self, weights: Iterable[tuple[str, torch.Tensor]]) -> set[str]:
        """Load weights using AutoWeightsLoader for vLLM integration."""
        loader = AutoWeightsLoader(self)
        return loader.load_weights(weights)