# Copyright 2023 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.

from typing import Callable, List, Optional, Union

import numpy as np
import torch
from transformers import CLIPTextModel, CLIPTokenizer

from ...schedulers import DDPMWuerstchenScheduler
from ...utils import logging, replace_example_docstring
from ...utils.torch_utils import randn_tensor
from ..pipeline_utils import DiffusionPipeline, ImagePipelineOutput
from .modeling_paella_vq_model import PaellaVQModel
from .modeling_wuerstchen_diffnext import WuerstchenDiffNeXt


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

EXAMPLE_DOC_STRING = """
    Examples:
        ```py
        >>> import torch
        >>> from diffusers import WuerstchenPriorPipeline, WuerstchenDecoderPipeline

        >>> prior_pipe = WuerstchenPriorPipeline.from_pretrained(
        ...     "warp-ai/wuerstchen-prior", torch_dtype=torch.float16
        ... ).to("cuda")
        >>> gen_pipe = WuerstchenDecoderPipeline.from_pretrain("warp-ai/wuerstchen", torch_dtype=torch.float16).to(
        ...     "cuda"
        ... )

        >>> prompt = "an image of a shiba inu, donning a spacesuit and helmet"
        >>> prior_output = pipe(prompt)
        >>> images = gen_pipe(prior_output.image_embeddings, prompt=prompt)
        ```
"""


class WuerstchenDecoderPipeline(DiffusionPipeline):
    """
    Pipeline for generating images from the Wuerstchen model.

    This model inherits from [`DiffusionPipeline`]. Check the superclass documentation for the generic methods the
    library implements for all the pipelines (such as downloading or saving, running on a particular device, etc.)

    Args:
        tokenizer (`CLIPTokenizer`):
            The CLIP tokenizer.
        text_encoder (`CLIPTextModel`):
            The CLIP text encoder.
        decoder ([`WuerstchenDiffNeXt`]):
            The WuerstchenDiffNeXt unet decoder.
        vqgan ([`PaellaVQModel`]):
            The VQGAN model.
        scheduler ([`DDPMWuerstchenScheduler`]):
            A scheduler to be used in combination with `prior` to generate image embedding.
        latent_dim_scale (float, `optional`, defaults to 10.67):
            Multiplier to determine the VQ latent space size from the image embeddings. If the image embeddings are
            height=24 and width=24, the VQ latent shape needs to be height=int(24*10.67)=256 and
            width=int(24*10.67)=256 in order to match the training conditions.
    """

    model_cpu_offload_seq = "text_encoder->decoder->vqgan"

    def __init__(
        self,
        tokenizer: CLIPTokenizer,
        text_encoder: CLIPTextModel,
        decoder: WuerstchenDiffNeXt,
        scheduler: DDPMWuerstchenScheduler,
        vqgan: PaellaVQModel,
        latent_dim_scale: float = 10.67,
    ) -> None:
        super().__init__()
        self.register_modules(
            tokenizer=tokenizer,
            text_encoder=text_encoder,
            decoder=decoder,
            scheduler=scheduler,
            vqgan=vqgan,
        )
        self.register_to_config(latent_dim_scale=latent_dim_scale)

    # Copied from diffusers.pipelines.unclip.pipeline_unclip.UnCLIPPipeline.prepare_latents
    def prepare_latents(self, shape, dtype, device, generator, latents, scheduler):
        if latents is None:
            latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
        else:
            if latents.shape != shape:
                raise ValueError(f"Unexpected latents shape, got {latents.shape}, expected {shape}")
            latents = latents.to(device)

        latents = latents * scheduler.init_noise_sigma
        return latents

    def encode_prompt(
        self,
        prompt,
        device,
        num_images_per_prompt,
        do_classifier_free_guidance,
        negative_prompt=None,
    ):
        batch_size = len(prompt) if isinstance(prompt, list) else 1
        # get prompt text embeddings
        text_inputs = self.tokenizer(
            prompt,
            padding="max_length",
            max_length=self.tokenizer.model_max_length,
            truncation=True,
            return_tensors="pt",
        )
        text_input_ids = text_inputs.input_ids
        attention_mask = text_inputs.attention_mask

        untruncated_ids = self.tokenizer(prompt, padding="longest", return_tensors="pt").input_ids

        if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(text_input_ids, untruncated_ids):
            removed_text = self.tokenizer.batch_decode(untruncated_ids[:, self.tokenizer.model_max_length - 1 : -1])
            logger.warning(
                "The following part of your input was truncated because CLIP can only handle sequences up to"
                f" {self.tokenizer.model_max_length} tokens: {removed_text}"
            )
            text_input_ids = text_input_ids[:, : self.tokenizer.model_max_length]
            attention_mask = attention_mask[:, : self.tokenizer.model_max_length]

        text_encoder_output = self.text_encoder(text_input_ids.to(device), attention_mask=attention_mask.to(device))
        text_encoder_hidden_states = text_encoder_output.last_hidden_state
        text_encoder_hidden_states = text_encoder_hidden_states.repeat_interleave(num_images_per_prompt, dim=0)

        uncond_text_encoder_hidden_states = None
        if do_classifier_free_guidance:
            uncond_tokens: List[str]
            if negative_prompt is None:
                uncond_tokens = [""] * batch_size
            elif type(prompt) is not type(negative_prompt):
                raise TypeError(
                    f"`negative_prompt` should be the same type to `prompt`, but got {type(negative_prompt)} !="
                    f" {type(prompt)}."
                )
            elif isinstance(negative_prompt, str):
                uncond_tokens = [negative_prompt]
            elif batch_size != len(negative_prompt):
                raise ValueError(
                    f"`negative_prompt`: {negative_prompt} has batch size {len(negative_prompt)}, but `prompt`:"
                    f" {prompt} has batch size {batch_size}. Please make sure that passed `negative_prompt` matches"
                    " the batch size of `prompt`."
                )
            else:
                uncond_tokens = negative_prompt

            uncond_input = self.tokenizer(
                uncond_tokens,
                padding="max_length",
                max_length=self.tokenizer.model_max_length,
                truncation=True,
                return_tensors="pt",
            )
            negative_prompt_embeds_text_encoder_output = self.text_encoder(
                uncond_input.input_ids.to(device), attention_mask=uncond_input.attention_mask.to(device)
            )

            uncond_text_encoder_hidden_states = negative_prompt_embeds_text_encoder_output.last_hidden_state

            # duplicate unconditional embeddings for each generation per prompt, using mps friendly method
            seq_len = uncond_text_encoder_hidden_states.shape[1]
            uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.repeat(1, num_images_per_prompt, 1)
            uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.view(
                batch_size * num_images_per_prompt, seq_len, -1
            )
            # done duplicates

            # For classifier free guidance, we need to do two forward passes.
            # Here we concatenate the unconditional and text embeddings into a single batch
            # to avoid doing two forward passes
        return text_encoder_hidden_states, uncond_text_encoder_hidden_states

    @torch.no_grad()
    @replace_example_docstring(EXAMPLE_DOC_STRING)
    def __call__(
        self,
        image_embeddings: Union[torch.FloatTensor, List[torch.FloatTensor]],
        prompt: Union[str, List[str]] = None,
        num_inference_steps: int = 12,
        timesteps: Optional[List[float]] = None,
        guidance_scale: float = 0.0,
        negative_prompt: Optional[Union[str, List[str]]] = None,
        num_images_per_prompt: int = 1,
        generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
        latents: Optional[torch.FloatTensor] = None,
        output_type: Optional[str] = "pil",
        return_dict: bool = True,
        callback: Optional[Callable[[int, int, torch.FloatTensor], None]] = None,
        callback_steps: int = 1,
    ):
        """
        Function invoked when calling the pipeline for generation.

        Args:
            image_embedding (`torch.FloatTensor` or `List[torch.FloatTensor]`):
                Image Embeddings either extracted from an image or generated by a Prior Model.
            prompt (`str` or `List[str]`):
                The prompt or prompts to guide the image generation.
            num_inference_steps (`int`, *optional*, defaults to 30):
                The number of denoising steps. More denoising steps usually lead to a higher quality image at the
                expense of slower inference.
            timesteps (`List[int]`, *optional*):
                Custom timesteps to use for the denoising process. If not defined, equal spaced `num_inference_steps`
                timesteps are used. Must be in descending order.
            guidance_scale (`float`, *optional*, defaults to 4.0):
                Guidance scale as defined in [Classifier-Free Diffusion Guidance](https://arxiv.org/abs/2207.12598).
                `decoder_guidance_scale` is defined as `w` of equation 2. of [Imagen
                Paper](https://arxiv.org/pdf/2205.11487.pdf). Guidance scale is enabled by setting
                `decoder_guidance_scale > 1`. Higher guidance scale encourages to generate images that are closely
                linked to the text `prompt`, usually at the expense of lower image quality.
            negative_prompt (`str` or `List[str]`, *optional*):
                The prompt or prompts not to guide the image generation. Ignored when not using guidance (i.e., ignored
                if `decoder_guidance_scale` is less than `1`).
            num_images_per_prompt (`int`, *optional*, defaults to 1):
                The number of images to generate per prompt.
            generator (`torch.Generator` or `List[torch.Generator]`, *optional*):
                One or a list of [torch generator(s)](https://pytorch.org/docs/stable/generated/torch.Generator.html)
                to make generation deterministic.
            latents (`torch.FloatTensor`, *optional*):
                Pre-generated noisy latents, sampled from a Gaussian distribution, to be used as inputs for image
                generation. Can be used to tweak the same generation with different prompts. If not provided, a latents
                tensor will ge generated by sampling using the supplied random `generator`.
            output_type (`str`, *optional*, defaults to `"pil"`):
                The output format of the generate image. Choose between: `"pil"` (`PIL.Image.Image`), `"np"`
                (`np.array`) or `"pt"` (`torch.Tensor`).
            return_dict (`bool`, *optional*, defaults to `True`):
                Whether or not to return a [`~pipelines.ImagePipelineOutput`] instead of a plain tuple.
            callback (`Callable`, *optional*):
                A function that will be called every `callback_steps` steps during inference. The function will be
                called with the following arguments: `callback(step: int, timestep: int, latents: torch.FloatTensor)`.
            callback_steps (`int`, *optional*, defaults to 1):
                The frequency at which the `callback` function will be called. If not specified, the callback will be
                called at every step.

        Examples:

        Returns:
            [`~pipelines.ImagePipelineOutput`] or `tuple` [`~pipelines.ImagePipelineOutput`] if `return_dict` is True,
            otherwise a `tuple`. When returning a tuple, the first element is a list with the generated image
            embeddings.
        """

        # 0. Define commonly used variables
        device = self._execution_device
        dtype = self.decoder.dtype
        do_classifier_free_guidance = guidance_scale > 1.0

        # 1. Check inputs. Raise error if not correct
        if not isinstance(prompt, list):
            if isinstance(prompt, str):
                prompt = [prompt]
            else:
                raise TypeError(f"'prompt' must be of type 'list' or 'str', but got {type(prompt)}.")

        if do_classifier_free_guidance:
            if negative_prompt is not None and not isinstance(negative_prompt, list):
                if isinstance(negative_prompt, str):
                    negative_prompt = [negative_prompt]
                else:
                    raise TypeError(
                        f"'negative_prompt' must be of type 'list' or 'str', but got {type(negative_prompt)}."
                    )

        if isinstance(image_embeddings, list):
            image_embeddings = torch.cat(image_embeddings, dim=0)
        if isinstance(image_embeddings, np.ndarray):
            image_embeddings = torch.Tensor(image_embeddings, device=device).to(dtype=dtype)
        if not isinstance(image_embeddings, torch.Tensor):
            raise TypeError(
                f"'image_embeddings' must be of type 'torch.Tensor' or 'np.array', but got {type(image_embeddings)}."
            )

        if not isinstance(num_inference_steps, int):
            raise TypeError(
                f"'num_inference_steps' must be of type 'int', but got {type(num_inference_steps)}\
                           In Case you want to provide explicit timesteps, please use the 'timesteps' argument."
            )

        # 2. Encode caption
        prompt_embeds, negative_prompt_embeds = self.encode_prompt(
            prompt,
            device,
            image_embeddings.size(0) * num_images_per_prompt,
            do_classifier_free_guidance,
            negative_prompt,
        )
        text_encoder_hidden_states = (
            torch.cat([prompt_embeds, negative_prompt_embeds]) if negative_prompt_embeds is not None else prompt_embeds
        )

        # 3. Determine latent shape of latents
        latent_height = int(image_embeddings.size(2) * self.config.latent_dim_scale)
        latent_width = int(image_embeddings.size(3) * self.config.latent_dim_scale)
        latent_features_shape = (image_embeddings.size(0) * num_images_per_prompt, 4, latent_height, latent_width)

        # 4. Prepare and set timesteps
        if timesteps is not None:
            self.scheduler.set_timesteps(timesteps=timesteps, device=device)
            timesteps = self.scheduler.timesteps
            num_inference_steps = len(timesteps)
        else:
            self.scheduler.set_timesteps(num_inference_steps, device=device)
            timesteps = self.scheduler.timesteps

        # 5. Prepare latents
        latents = self.prepare_latents(latent_features_shape, dtype, device, generator, latents, self.scheduler)

        # 6. Run denoising loop
        for i, t in enumerate(self.progress_bar(timesteps[:-1])):
            ratio = t.expand(latents.size(0)).to(dtype)
            effnet = (
                torch.cat([image_embeddings, torch.zeros_like(image_embeddings)])
                if do_classifier_free_guidance
                else image_embeddings
            )
            # 7. Denoise latents
            predicted_latents = self.decoder(
                torch.cat([latents] * 2) if do_classifier_free_guidance else latents,
                r=torch.cat([ratio] * 2) if do_classifier_free_guidance else ratio,
                effnet=effnet,
                clip=text_encoder_hidden_states,
            )

            # 8. Check for classifier free guidance and apply it
            if do_classifier_free_guidance:
                predicted_latents_text, predicted_latents_uncond = predicted_latents.chunk(2)
                predicted_latents = torch.lerp(predicted_latents_uncond, predicted_latents_text, guidance_scale)

            # 9. Renoise latents to next timestep
            latents = self.scheduler.step(
                model_output=predicted_latents,
                timestep=ratio,
                sample=latents,
                generator=generator,
            ).prev_sample

            if callback is not None and i % callback_steps == 0:
                callback(i, t, latents)

        # 10. Scale and decode the image latents with vq-vae
        latents = self.vqgan.config.scale_factor * latents
        images = self.vqgan.decode(latents).sample.clamp(0, 1)

        # Offload all models
        self.maybe_free_model_hooks()

        if output_type not in ["pt", "np", "pil"]:
            raise ValueError(f"Only the output types `pt`, `np` and `pil` are supported not output_type={output_type}")

        if output_type == "np":
            images = images.permute(0, 2, 3, 1).cpu().numpy()
        elif output_type == "pil":
            images = images.permute(0, 2, 3, 1).cpu().numpy()
            images = self.numpy_to_pil(images)

        if not return_dict:
            return images
        return ImagePipelineOutput(images)
