import PIL.Image
import torch
from transformers import CLIPImageProcessor, CLIPTextModelWithProjection, CLIPTokenizer, CLIPVisionModelWithProjection

from ...models import PriorTransformer
from ...schedulers import UnCLIPScheduler
from ...utils import is_torch_xla_available, logging, replace_example_docstring
from ...utils.torch_utils import randn_tensor
from ..kandinsky import KandinskyPriorPipelineOutput
from ..pipeline_utils import DiffusionPipeline


if is_torch_xla_available():
    import torch_xla.core.xla_model as xm

    XLA_AVAILABLE = True
else:
    XLA_AVAILABLE = False

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


EXAMPLE_DOC_STRING = """
    Examples:
        ```py
        >>> from diffusers import KandinskyV22Pipeline, KandinskyV22PriorEmb2EmbPipeline
        >>> import torch

        >>> pipe_prior = KandinskyPriorPipeline.from_pretrained(
        ...     "kandinsky-community/kandinsky-2-2-prior", torch_dtype=torch.float16
        ... )
        >>> pipe_prior.to("cuda")

        >>> prompt = "red cat, 4k photo"
        >>> img = load_image(
        ...     "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main"
        ...     "/kandinsky/cat.png"
        ... )
        >>> image_emb, nagative_image_emb = pipe_prior(prompt, image=img, strength=0.2).to_tuple()

        >>> pipe = KandinskyPipeline.from_pretrained(
        ...     "kandinsky-community/kandinsky-2-2-decoder, torch_dtype=torch.float16"
        ... )
        >>> pipe.to("cuda")

        >>> image = pipe(
        ...     image_embeds=image_emb,
        ...     negative_image_embeds=negative_image_emb,
        ...     height=768,
        ...     width=768,
        ...     num_inference_steps=100,
        ... ).images

        >>> image[0].save("cat.png")
        ```
"""

EXAMPLE_INTERPOLATE_DOC_STRING = """
    Examples:
        ```py
        >>> from diffusers import KandinskyV22PriorEmb2EmbPipeline, KandinskyV22Pipeline
        >>> from diffusers.utils import load_image
        >>> import PIL

        >>> import torch
        >>> from torchvision import transforms

        >>> pipe_prior = KandinskyV22PriorPipeline.from_pretrained(
        ...     "kandinsky-community/kandinsky-2-2-prior", torch_dtype=torch.float16
        ... )
        >>> pipe_prior.to("cuda")

        >>> img1 = load_image(
        ...     "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main"
        ...     "/kandinsky/cat.png"
        ... )

        >>> img2 = load_image(
        ...     "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main"
        ...     "/kandinsky/starry_night.jpeg"
        ... )

        >>> images_texts = ["a cat", img1, img2]
        >>> weights = [0.3, 0.3, 0.4]
        >>> image_emb, zero_image_emb = pipe_prior.interpolate(images_texts, weights)

        >>> pipe = KandinskyV22Pipeline.from_pretrained(
        ...     "kandinsky-community/kandinsky-2-2-decoder", torch_dtype=torch.float16
        ... )
        >>> pipe.to("cuda")

        >>> image = pipe(
        ...     image_embeds=image_emb,
        ...     negative_image_embeds=zero_image_emb,
        ...     height=768,
        ...     width=768,
        ...     num_inference_steps=150,
        ... ).images[0]

        >>> image.save("starry_cat.png")
        ```
"""


class KandinskyV22PriorEmb2EmbPipeline(DiffusionPipeline):
    """
    Pipeline for generating image prior for Kandinsky

    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:
        prior ([`PriorTransformer`]):
            The canonical unCLIP prior to approximate the image embedding from the text embedding.
        image_encoder ([`CLIPVisionModelWithProjection`]):
            Frozen image-encoder.
        text_encoder ([`CLIPTextModelWithProjection`]):
            Frozen text-encoder.
        tokenizer (`CLIPTokenizer`):
            Tokenizer of class
            [CLIPTokenizer](https://huggingface.co/docs/transformers/v4.21.0/en/model_doc/clip#transformers.CLIPTokenizer).
        scheduler ([`UnCLIPScheduler`]):
            A scheduler to be used in combination with `prior` to generate image embedding.
    """

    model_cpu_offload_seq = "text_encoder->image_encoder->prior"
    _exclude_from_cpu_offload = ["prior"]

    def __init__(
        self,
        prior: PriorTransformer,
        image_encoder: CLIPVisionModelWithProjection,
        text_encoder: CLIPTextModelWithProjection,
        tokenizer: CLIPTokenizer,
        scheduler: UnCLIPScheduler,
        image_processor: CLIPImageProcessor,
    ):
        super().__init__()

        self.register_modules(
            prior=prior,
            text_encoder=text_encoder,
            tokenizer=tokenizer,
            scheduler=scheduler,
            image_encoder=image_encoder,
            image_processor=image_processor,
        )

    def get_timesteps(self, num_inference_steps, strength, device):
        # get the original timestep using init_timestep
        init_timestep = min(int(num_inference_steps * strength), num_inference_steps)

        t_start = max(num_inference_steps - init_timestep, 0)
        timesteps = self.scheduler.timesteps[t_start:]

        return timesteps, num_inference_steps - t_start

    @torch.no_grad()
    @replace_example_docstring(EXAMPLE_INTERPOLATE_DOC_STRING)
    def interpolate(
        self,
        images_and_prompts: list[str | PIL.Image.Image | torch.Tensor],
        weights: list[float],
        num_images_per_prompt: int = 1,
        num_inference_steps: int = 25,
        generator: torch.Generator | list[torch.Generator] | None = None,
        latents: torch.Tensor | None = None,
        negative_prior_prompt: str | None = None,
        negative_prompt: str = "",
        guidance_scale: float = 4.0,
        device=None,
    ):
        """
        Function invoked when using the prior pipeline for interpolation.

        Args:
            images_and_prompts (`list[str | PIL.Image.Image | torch.Tensor]`):
                list of prompts and images to guide the image generation.
            weights: (`list[float]`):
                list of weights for each condition in `images_and_prompts`
            num_images_per_prompt (`int`, *optional*, defaults to 1):
                The number of images to generate per prompt.
            num_inference_steps (`int`, *optional*, defaults to 100):
                The number of denoising steps. More denoising steps usually lead to a higher quality image at the
                expense of slower inference.
            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.Tensor`, *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 be generated by sampling using the supplied random `generator`.
            negative_prior_prompt (`str`, *optional*):
                The prompt not to guide the prior diffusion process. Ignored when not using guidance (i.e., ignored if
                `guidance_scale` is less than `1`).
            negative_prompt (`str` or `list[str]`, *optional*):
                The prompt not to guide the image generation. Ignored when not using guidance (i.e., ignored if
                `guidance_scale` is less than `1`).
            guidance_scale (`float`, *optional*, defaults to 4.0):
                Guidance scale as defined in [Classifier-Free Diffusion
                Guidance](https://huggingface.co/papers/2207.12598). `guidance_scale` is defined as `w` of equation 2.
                of [Imagen Paper](https://huggingface.co/papers/2205.11487). Guidance scale is enabled by setting
                `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.

        Examples:

        Returns:
            [`KandinskyPriorPipelineOutput`] or `tuple`
        """

        device = device or self.device

        if len(images_and_prompts) != len(weights):
            raise ValueError(
                f"`images_and_prompts` contains {len(images_and_prompts)} items and `weights` contains {len(weights)} items - they should be lists of same length"
            )

        image_embeddings = []
        for cond, weight in zip(images_and_prompts, weights):
            if isinstance(cond, str):
                image_emb = self(
                    cond,
                    num_inference_steps=num_inference_steps,
                    num_images_per_prompt=num_images_per_prompt,
                    generator=generator,
                    latents=latents,
                    negative_prompt=negative_prior_prompt,
                    guidance_scale=guidance_scale,
                ).image_embeds.unsqueeze(0)

            elif isinstance(cond, (PIL.Image.Image, torch.Tensor)):
                image_emb = self._encode_image(
                    cond, device=device, num_images_per_prompt=num_images_per_prompt
                ).unsqueeze(0)

            else:
                raise ValueError(
                    f"`images_and_prompts` can only contains elements to be of type `str`, `PIL.Image.Image` or `torch.Tensor`  but is {type(cond)}"
                )

            image_embeddings.append(image_emb * weight)

        image_emb = torch.cat(image_embeddings).sum(dim=0)

        return KandinskyPriorPipelineOutput(image_embeds=image_emb, negative_image_embeds=torch.randn_like(image_emb))

    def _encode_image(
        self,
        image: torch.Tensor | list[PIL.Image.Image],
        device,
        num_images_per_prompt,
    ):
        if not isinstance(image, torch.Tensor):
            image = self.image_processor(image, return_tensors="pt").pixel_values.to(
                dtype=self.image_encoder.dtype, device=device
            )

        image_emb = self.image_encoder(image)["image_embeds"]  # B, D
        image_emb = image_emb.repeat_interleave(num_images_per_prompt, dim=0)
        image_emb.to(device=device)

        return image_emb

    def prepare_latents(self, emb, timestep, batch_size, num_images_per_prompt, dtype, device, generator=None):
        emb = emb.to(device=device, dtype=dtype)

        batch_size = batch_size * num_images_per_prompt

        init_latents = emb

        if batch_size > init_latents.shape[0] and batch_size % init_latents.shape[0] == 0:
            additional_image_per_prompt = batch_size // init_latents.shape[0]
            init_latents = torch.cat([init_latents] * additional_image_per_prompt, dim=0)
        elif batch_size > init_latents.shape[0] and batch_size % init_latents.shape[0] != 0:
            raise ValueError(
                f"Cannot duplicate `image` of batch size {init_latents.shape[0]} to {batch_size} text prompts."
            )
        else:
            init_latents = torch.cat([init_latents], dim=0)

        shape = init_latents.shape
        noise = randn_tensor(shape, generator=generator, device=device, dtype=dtype)

        # get latents
        init_latents = self.scheduler.add_noise(init_latents, noise, timestep)
        latents = init_latents

        return latents

    # Copied from diffusers.pipelines.kandinsky.pipeline_kandinsky_prior.KandinskyPriorPipeline.get_zero_embed
    def get_zero_embed(self, batch_size=1, device=None):
        device = device or self.device
        zero_img = torch.zeros(1, 3, self.image_encoder.config.image_size, self.image_encoder.config.image_size).to(
            device=device, dtype=self.image_encoder.dtype
        )
        zero_image_emb = self.image_encoder(zero_img)["image_embeds"]
        zero_image_emb = zero_image_emb.repeat(batch_size, 1)
        return zero_image_emb

    # Copied from diffusers.pipelines.kandinsky.pipeline_kandinsky_prior.KandinskyPriorPipeline._encode_prompt
    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
        text_mask = text_inputs.attention_mask.bool().to(device)

        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]

        text_encoder_output = self.text_encoder(text_input_ids.to(device))

        prompt_embeds = text_encoder_output.text_embeds
        text_encoder_hidden_states = text_encoder_output.last_hidden_state

        prompt_embeds = prompt_embeds.repeat_interleave(num_images_per_prompt, dim=0)
        text_encoder_hidden_states = text_encoder_hidden_states.repeat_interleave(num_images_per_prompt, dim=0)
        text_mask = text_mask.repeat_interleave(num_images_per_prompt, dim=0)

        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",
            )
            uncond_text_mask = uncond_input.attention_mask.bool().to(device)
            negative_prompt_embeds_text_encoder_output = self.text_encoder(uncond_input.input_ids.to(device))

            negative_prompt_embeds = negative_prompt_embeds_text_encoder_output.text_embeds
            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 = negative_prompt_embeds.shape[1]
            negative_prompt_embeds = negative_prompt_embeds.repeat(1, num_images_per_prompt)
            negative_prompt_embeds = negative_prompt_embeds.view(batch_size * num_images_per_prompt, seq_len)

            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
            )
            uncond_text_mask = uncond_text_mask.repeat_interleave(num_images_per_prompt, dim=0)

            # 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
            prompt_embeds = torch.cat([negative_prompt_embeds, prompt_embeds])
            text_encoder_hidden_states = torch.cat([uncond_text_encoder_hidden_states, text_encoder_hidden_states])

            text_mask = torch.cat([uncond_text_mask, text_mask])

        return prompt_embeds, text_encoder_hidden_states, text_mask

    @torch.no_grad()
    @replace_example_docstring(EXAMPLE_DOC_STRING)
    def __call__(
        self,
        prompt: str | list[str],
        image: torch.Tensor | list[torch.Tensor] | PIL.Image.Image | list[PIL.Image.Image],
        strength: float = 0.3,
        negative_prompt: str | list[str] | None = None,
        num_images_per_prompt: int = 1,
        num_inference_steps: int = 25,
        generator: torch.Generator | list[torch.Generator] | None = None,
        guidance_scale: float = 4.0,
        output_type: str | None = "pt",  # pt only
        return_dict: bool = True,
    ):
        """
        Function invoked when calling the pipeline for generation.

        Args:
            prompt (`str` or `list[str]`):
                The prompt or prompts to guide the image generation.
            strength (`float`, *optional*, defaults to 0.8):
                Conceptually, indicates how much to transform the reference `emb`. Must be between 0 and 1. `image`
                will be used as a starting point, adding more noise to it the larger the `strength`. The number of
                denoising steps depends on the amount of noise initially added.
            emb (`torch.Tensor`):
                The image embedding.
            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 `guidance_scale` is less than `1`).
            num_images_per_prompt (`int`, *optional*, defaults to 1):
                The number of images to generate per prompt.
            num_inference_steps (`int`, *optional*, defaults to 100):
                The number of denoising steps. More denoising steps usually lead to a higher quality image at the
                expense of slower inference.
            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.
            guidance_scale (`float`, *optional*, defaults to 4.0):
                Guidance scale as defined in [Classifier-Free Diffusion
                Guidance](https://huggingface.co/papers/2207.12598). `guidance_scale` is defined as `w` of equation 2.
                of [Imagen Paper](https://huggingface.co/papers/2205.11487). Guidance scale is enabled by setting
                `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.
            output_type (`str`, *optional*, defaults to `"pt"`):
                The output format of the generate image. Choose between: `"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.

        Examples:

        Returns:
            [`KandinskyPriorPipelineOutput`] or `tuple`
        """

        if isinstance(prompt, str):
            prompt = [prompt]
        elif not isinstance(prompt, list):
            raise ValueError(f"`prompt` has to be of type `str` or `list` but is {type(prompt)}")

        if isinstance(negative_prompt, str):
            negative_prompt = [negative_prompt]
        elif not isinstance(negative_prompt, list) and negative_prompt is not None:
            raise ValueError(f"`negative_prompt` has to be of type `str` or `list` but is {type(negative_prompt)}")

        # if the negative prompt is defined we double the batch size to
        # directly retrieve the negative prompt embedding
        if negative_prompt is not None:
            prompt = prompt + negative_prompt
            negative_prompt = 2 * negative_prompt

        device = self._execution_device

        batch_size = len(prompt)
        batch_size = batch_size * num_images_per_prompt

        do_classifier_free_guidance = guidance_scale > 1.0
        prompt_embeds, text_encoder_hidden_states, text_mask = self._encode_prompt(
            prompt, device, num_images_per_prompt, do_classifier_free_guidance, negative_prompt
        )

        if not isinstance(image, list):
            image = [image]

        if isinstance(image[0], torch.Tensor):
            image = torch.cat(image, dim=0)

        if isinstance(image, torch.Tensor) and image.ndim == 2:
            # allow user to pass image_embeds directly
            image_embeds = image.repeat_interleave(num_images_per_prompt, dim=0)
        elif isinstance(image, torch.Tensor) and image.ndim != 4:
            raise ValueError(
                f" if pass `image` as pytorch tensor, or a list of pytorch tensor, please make sure each tensor has shape [batch_size, channels, height, width], currently {image[0].unsqueeze(0).shape}"
            )
        else:
            image_embeds = self._encode_image(image, device, num_images_per_prompt)

        # prior
        self.scheduler.set_timesteps(num_inference_steps, device=device)

        latents = image_embeds
        timesteps, num_inference_steps = self.get_timesteps(num_inference_steps, strength, device)
        latent_timestep = timesteps[:1].repeat(batch_size)
        latents = self.prepare_latents(
            latents,
            latent_timestep,
            batch_size // num_images_per_prompt,
            num_images_per_prompt,
            prompt_embeds.dtype,
            device,
            generator,
        )

        for i, t in enumerate(self.progress_bar(timesteps)):
            # expand the latents if we are doing classifier free guidance
            latent_model_input = torch.cat([latents] * 2) if do_classifier_free_guidance else latents

            predicted_image_embedding = self.prior(
                latent_model_input,
                timestep=t,
                proj_embedding=prompt_embeds,
                encoder_hidden_states=text_encoder_hidden_states,
                attention_mask=text_mask,
            ).predicted_image_embedding

            if do_classifier_free_guidance:
                predicted_image_embedding_uncond, predicted_image_embedding_text = predicted_image_embedding.chunk(2)
                predicted_image_embedding = predicted_image_embedding_uncond + guidance_scale * (
                    predicted_image_embedding_text - predicted_image_embedding_uncond
                )

            if i + 1 == timesteps.shape[0]:
                prev_timestep = None
            else:
                prev_timestep = timesteps[i + 1]

            latents = self.scheduler.step(
                predicted_image_embedding,
                timestep=t,
                sample=latents,
                generator=generator,
                prev_timestep=prev_timestep,
            ).prev_sample

            if XLA_AVAILABLE:
                xm.mark_step()

        latents = self.prior.post_process_latents(latents)

        image_embeddings = latents

        # if negative prompt has been defined, we retrieve split the image embedding into two
        if negative_prompt is None:
            zero_embeds = self.get_zero_embed(latents.shape[0], device=latents.device)
        else:
            image_embeddings, zero_embeds = image_embeddings.chunk(2)

        self.maybe_free_model_hooks()

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

        if output_type == "np":
            image_embeddings = image_embeddings.cpu().numpy()
            zero_embeds = zero_embeds.cpu().numpy()

        if not return_dict:
            return (image_embeddings, zero_embeds)

        return KandinskyPriorPipelineOutput(image_embeds=image_embeddings, negative_image_embeds=zero_embeds)
