import math
from contextlib import nullcontext
from functools import partial
from typing import Dict, List, Optional, Tuple, Union

import kornia
import numpy as np
import open_clip
import torch
import torch.nn as nn
from einops import rearrange, repeat
from omegaconf import ListConfig
from torch.utils.checkpoint import checkpoint
from transformers import (ByT5Tokenizer, CLIPTextModel, CLIPTokenizer,
                          T5EncoderModel, T5Tokenizer)

from ...modules.autoencoding.regularizers import DiagonalGaussianRegularizer
from ...modules.diffusionmodules.model import Encoder
from ...modules.diffusionmodules.openaimodel import Timestep
from ...modules.diffusionmodules.util import (extract_into_tensor,
                                              make_beta_schedule)
from ...modules.distributions.distributions import DiagonalGaussianDistribution
from ...util import (append_dims, autocast, count_params, default,
                     disabled_train, expand_dims_like, instantiate_from_config)


class AbstractEmbModel(nn.Module):
    def __init__(self):
        super().__init__()
        self._is_trainable = None
        self._ucg_rate = None
        self._input_key = None

    @property
    def is_trainable(self) -> bool:
        return self._is_trainable

    @property
    def ucg_rate(self) -> Union[float, torch.Tensor]:
        return self._ucg_rate

    @property
    def input_key(self) -> str:
        return self._input_key

    @is_trainable.setter
    def is_trainable(self, value: bool):
        self._is_trainable = value

    @ucg_rate.setter
    def ucg_rate(self, value: Union[float, torch.Tensor]):
        self._ucg_rate = value

    @input_key.setter
    def input_key(self, value: str):
        self._input_key = value

    @is_trainable.deleter
    def is_trainable(self):
        del self._is_trainable

    @ucg_rate.deleter
    def ucg_rate(self):
        del self._ucg_rate

    @input_key.deleter
    def input_key(self):
        del self._input_key


class GeneralConditioner(nn.Module):
    OUTPUT_DIM2KEYS = {2: "vector", 3: "crossattn", 4: "concat", 5: "concat"}
    KEY2CATDIM = {"vector": 1, "crossattn": 2, "concat": 1}

    def __init__(self, emb_models: Union[List, ListConfig]):
        super().__init__()
        embedders = []
        for n, embconfig in enumerate(emb_models):
            embedder = instantiate_from_config(embconfig)
            assert isinstance(
                embedder, AbstractEmbModel
            ), f"embedder model {embedder.__class__.__name__} has to inherit from AbstractEmbModel"
            embedder.is_trainable = embconfig.get("is_trainable", False)
            embedder.ucg_rate = embconfig.get("ucg_rate", 0.0)
            if not embedder.is_trainable:
                embedder.train = disabled_train
                for param in embedder.parameters():
                    param.requires_grad = False
                embedder.eval()
            print(
                f"Initialized embedder #{n}: {embedder.__class__.__name__} "
                f"with {count_params(embedder, False)} params. Trainable: {embedder.is_trainable}"
            )

            if "input_key" in embconfig:
                embedder.input_key = embconfig["input_key"]
            elif "input_keys" in embconfig:
                embedder.input_keys = embconfig["input_keys"]
            else:
                raise KeyError(
                    f"need either 'input_key' or 'input_keys' for embedder {embedder.__class__.__name__}"
                )

            embedder.legacy_ucg_val = embconfig.get("legacy_ucg_value", None)
            if embedder.legacy_ucg_val is not None:
                embedder.ucg_prng = np.random.RandomState()

            embedders.append(embedder)
        self.embedders = nn.ModuleList(embedders)

    def possibly_get_ucg_val(self, embedder: AbstractEmbModel, batch: Dict) -> Dict:
        assert embedder.legacy_ucg_val is not None
        p = embedder.ucg_rate
        val = embedder.legacy_ucg_val
        for i in range(len(batch[embedder.input_key])):
            if embedder.ucg_prng.choice(2, p=[1 - p, p]):
                batch[embedder.input_key][i] = val
        return batch

    def forward(
        self, batch: Dict, force_zero_embeddings: Optional[List] = None
    ) -> Dict:
        output = dict()
        if force_zero_embeddings is None:
            force_zero_embeddings = []
        for embedder in self.embedders:
            embedding_context = nullcontext if embedder.is_trainable else torch.no_grad
            with embedding_context():
                if hasattr(embedder, "input_key") and (embedder.input_key is not None):
                    if embedder.legacy_ucg_val is not None:
                        batch = self.possibly_get_ucg_val(embedder, batch)
                    emb_out = embedder(batch[embedder.input_key])
                elif hasattr(embedder, "input_keys"):
                    emb_out = embedder(*[batch[k] for k in embedder.input_keys])
            assert isinstance(
                emb_out, (torch.Tensor, list, tuple)
            ), f"encoder outputs must be tensors or a sequence, but got {type(emb_out)}"
            if not isinstance(emb_out, (list, tuple)):
                emb_out = [emb_out]
            for emb in emb_out:
                out_key = self.OUTPUT_DIM2KEYS[emb.dim()]
                if embedder.ucg_rate > 0.0 and embedder.legacy_ucg_val is None:
                    emb = (
                        expand_dims_like(
                            torch.bernoulli(
                                (1.0 - embedder.ucg_rate)
                                * torch.ones(emb.shape[0], device=emb.device)
                            ),
                            emb,
                        )
                        * emb
                    )
                if (
                    hasattr(embedder, "input_key")
                    and embedder.input_key in force_zero_embeddings
                ):
                    emb = torch.zeros_like(emb)
                if out_key in output:
                    output[out_key] = torch.cat(
                        (output[out_key], emb), self.KEY2CATDIM[out_key]
                    )
                else:
                    output[out_key] = emb
        return output

    def get_unconditional_conditioning(
        self,
        batch_c: Dict,
        batch_uc: Optional[Dict] = None,
        force_uc_zero_embeddings: Optional[List[str]] = None,
        force_cond_zero_embeddings: Optional[List[str]] = None,
    ):
        if force_uc_zero_embeddings is None:
            force_uc_zero_embeddings = []
        ucg_rates = list()
        for embedder in self.embedders:
            ucg_rates.append(embedder.ucg_rate)
            embedder.ucg_rate = 0.0
        c = self(batch_c, force_cond_zero_embeddings)
        uc = self(batch_c if batch_uc is None else batch_uc, force_uc_zero_embeddings)

        for embedder, rate in zip(self.embedders, ucg_rates):
            embedder.ucg_rate = rate
        return c, uc


class InceptionV3(nn.Module):
    """Wrapper around the https://github.com/mseitzer/pytorch-fid inception
    port with an additional squeeze at the end"""

    def __init__(self, normalize_input=False, **kwargs):
        super().__init__()
        from pytorch_fid import inception

        kwargs["resize_input"] = True
        self.model = inception.InceptionV3(normalize_input=normalize_input, **kwargs)

    def forward(self, inp):
        outp = self.model(inp)

        if len(outp) == 1:
            return outp[0].squeeze()

        return outp


class IdentityEncoder(AbstractEmbModel):
    def encode(self, x):
        return x

    def forward(self, x):
        return x


class ClassEmbedder(AbstractEmbModel):
    def __init__(self, embed_dim, n_classes=1000, add_sequence_dim=False):
        super().__init__()
        self.embedding = nn.Embedding(n_classes, embed_dim)
        self.n_classes = n_classes
        self.add_sequence_dim = add_sequence_dim

    def forward(self, c):
        c = self.embedding(c)
        if self.add_sequence_dim:
            c = c[:, None, :]
        return c

    def get_unconditional_conditioning(self, bs, device="cuda"):
        uc_class = (
            self.n_classes - 1
        )  # 1000 classes --> 0 ... 999, one extra class for ucg (class 1000)
        uc = torch.ones((bs,), device=device) * uc_class
        uc = {self.key: uc.long()}
        return uc


class ClassEmbedderForMultiCond(ClassEmbedder):
    def forward(self, batch, key=None, disable_dropout=False):
        out = batch
        key = default(key, self.key)
        islist = isinstance(batch[key], list)
        if islist:
            batch[key] = batch[key][0]
        c_out = super().forward(batch, key, disable_dropout)
        out[key] = [c_out] if islist else c_out
        return out


class FrozenT5Embedder(AbstractEmbModel):
    """Uses the T5 transformer encoder for text"""

    def __init__(
        self, version="google/t5-v1_1-xxl", device="cuda", max_length=77, freeze=True
    ):  # others are google/t5-v1_1-xl and google/t5-v1_1-xxl
        super().__init__()
        self.tokenizer = T5Tokenizer.from_pretrained(version)
        self.transformer = T5EncoderModel.from_pretrained(version)
        self.device = device
        self.max_length = max_length
        if freeze:
            self.freeze()

    def freeze(self):
        self.transformer = self.transformer.eval()

        for param in self.parameters():
            param.requires_grad = False

    def forward(self, text):
        batch_encoding = self.tokenizer(
            text,
            truncation=True,
            max_length=self.max_length,
            return_length=True,
            return_overflowing_tokens=False,
            padding="max_length",
            return_tensors="pt",
        )
        tokens = batch_encoding["input_ids"].to(self.device)
        with torch.autocast("cuda", enabled=False):
            outputs = self.transformer(input_ids=tokens)
        z = outputs.last_hidden_state
        return z

    def encode(self, text):
        return self(text)


class FrozenByT5Embedder(AbstractEmbModel):
    """
    Uses the ByT5 transformer encoder for text. Is character-aware.
    """

    def __init__(
        self, version="google/byt5-base", device="cuda", max_length=77, freeze=True
    ):  # others are google/t5-v1_1-xl and google/t5-v1_1-xxl
        super().__init__()
        self.tokenizer = ByT5Tokenizer.from_pretrained(version)
        self.transformer = T5EncoderModel.from_pretrained(version)
        self.device = device
        self.max_length = max_length
        if freeze:
            self.freeze()

    def freeze(self):
        self.transformer = self.transformer.eval()

        for param in self.parameters():
            param.requires_grad = False

    def forward(self, text):
        batch_encoding = self.tokenizer(
            text,
            truncation=True,
            max_length=self.max_length,
            return_length=True,
            return_overflowing_tokens=False,
            padding="max_length",
            return_tensors="pt",
        )
        tokens = batch_encoding["input_ids"].to(self.device)
        with torch.autocast("cuda", enabled=False):
            outputs = self.transformer(input_ids=tokens)
        z = outputs.last_hidden_state
        return z

    def encode(self, text):
        return self(text)


class FrozenCLIPEmbedder(AbstractEmbModel):
    """Uses the CLIP transformer encoder for text (from huggingface)"""

    LAYERS = ["last", "pooled", "hidden"]

    def __init__(
        self,
        version="openai/clip-vit-large-patch14",
        device="cuda",
        max_length=77,
        freeze=True,
        layer="last",
        layer_idx=None,
        always_return_pooled=False,
    ):  # clip-vit-base-patch32
        super().__init__()
        assert layer in self.LAYERS
        self.tokenizer = CLIPTokenizer.from_pretrained(version)
        self.transformer = CLIPTextModel.from_pretrained(version)
        self.device = device
        self.max_length = max_length
        if freeze:
            self.freeze()
        self.layer = layer
        self.layer_idx = layer_idx
        self.return_pooled = always_return_pooled
        if layer == "hidden":
            assert layer_idx is not None
            assert 0 <= abs(layer_idx) <= 12

    def freeze(self):
        self.transformer = self.transformer.eval()

        for param in self.parameters():
            param.requires_grad = False

    @autocast
    def forward(self, text):
        batch_encoding = self.tokenizer(
            text,
            truncation=True,
            max_length=self.max_length,
            return_length=True,
            return_overflowing_tokens=False,
            padding="max_length",
            return_tensors="pt",
        )
        tokens = batch_encoding["input_ids"].to(self.device)
        outputs = self.transformer(
            input_ids=tokens, output_hidden_states=self.layer == "hidden"
        )
        if self.layer == "last":
            z = outputs.last_hidden_state
        elif self.layer == "pooled":
            z = outputs.pooler_output[:, None, :]
        else:
            z = outputs.hidden_states[self.layer_idx]
        if self.return_pooled:
            return z, outputs.pooler_output
        return z

    def encode(self, text):
        return self(text)


class FrozenOpenCLIPEmbedder2(AbstractEmbModel):
    """
    Uses the OpenCLIP transformer encoder for text
    """

    LAYERS = ["pooled", "last", "penultimate"]

    def __init__(
        self,
        arch="ViT-H-14",
        version="laion2b_s32b_b79k",
        device="cuda",
        max_length=77,
        freeze=True,
        layer="last",
        always_return_pooled=False,
        legacy=True,
    ):
        super().__init__()
        assert layer in self.LAYERS
        model, _, _ = open_clip.create_model_and_transforms(
            arch,
            device=torch.device("cpu"),
            pretrained=version,
        )
        del model.visual
        self.model = model

        self.device = device
        self.max_length = max_length
        self.return_pooled = always_return_pooled
        if freeze:
            self.freeze()
        self.layer = layer
        if self.layer == "last":
            self.layer_idx = 0
        elif self.layer == "penultimate":
            self.layer_idx = 1
        else:
            raise NotImplementedError()
        self.legacy = legacy

    def freeze(self):
        self.model = self.model.eval()
        for param in self.parameters():
            param.requires_grad = False

    @autocast
    def forward(self, text):
        tokens = open_clip.tokenize(text)
        z = self.encode_with_transformer(tokens.to(self.device))
        if not self.return_pooled and self.legacy:
            return z
        if self.return_pooled:
            assert not self.legacy
            return z[self.layer], z["pooled"]
        return z[self.layer]

    def encode_with_transformer(self, text):
        x = self.model.token_embedding(text)  # [batch_size, n_ctx, d_model]
        x = x + self.model.positional_embedding
        x = x.permute(1, 0, 2)  # NLD -> LND
        x = self.text_transformer_forward(x, attn_mask=self.model.attn_mask)
        if self.legacy:
            x = x[self.layer]
            x = self.model.ln_final(x)
            return x
        else:
            # x is a dict and will stay a dict
            o = x["last"]
            o = self.model.ln_final(o)
            pooled = self.pool(o, text)
            x["pooled"] = pooled
            return x

    def pool(self, x, text):
        # take features from the eot embedding (eot_token is the highest number in each sequence)
        x = (
            x[torch.arange(x.shape[0]), text.argmax(dim=-1)]
            @ self.model.text_projection
        )
        return x

    def text_transformer_forward(self, x: torch.Tensor, attn_mask=None):
        outputs = {}
        for i, r in enumerate(self.model.transformer.resblocks):
            if i == len(self.model.transformer.resblocks) - 1:
                outputs["penultimate"] = x.permute(1, 0, 2)  # LND -> NLD
            if (
                self.model.transformer.grad_checkpointing
                and not torch.jit.is_scripting()
            ):
                x = checkpoint(r, x, attn_mask)
            else:
                x = r(x, attn_mask=attn_mask)
        outputs["last"] = x.permute(1, 0, 2)  # LND -> NLD
        return outputs

    def encode(self, text):
        return self(text)


class FrozenOpenCLIPEmbedder(AbstractEmbModel):
    LAYERS = [
        # "pooled",
        "last",
        "penultimate",
    ]

    def __init__(
        self,
        arch="ViT-H-14",
        version="laion2b_s32b_b79k",
        device="cuda",
        max_length=77,
        freeze=True,
        layer="last",
    ):
        super().__init__()
        assert layer in self.LAYERS
        model, _, _ = open_clip.create_model_and_transforms(
            arch, device=torch.device("cpu"), pretrained=version
        )
        del model.visual
        self.model = model

        self.device = device
        self.max_length = max_length
        if freeze:
            self.freeze()
        self.layer = layer
        if self.layer == "last":
            self.layer_idx = 0
        elif self.layer == "penultimate":
            self.layer_idx = 1
        else:
            raise NotImplementedError()

    def freeze(self):
        self.model = self.model.eval()
        for param in self.parameters():
            param.requires_grad = False

    def forward(self, text):
        tokens = open_clip.tokenize(text)
        z = self.encode_with_transformer(tokens.to(self.device))
        return z

    def encode_with_transformer(self, text):
        x = self.model.token_embedding(text)  # [batch_size, n_ctx, d_model]
        x = x + self.model.positional_embedding
        x = x.permute(1, 0, 2)  # NLD -> LND
        x = self.text_transformer_forward(x, attn_mask=self.model.attn_mask)
        x = x.permute(1, 0, 2)  # LND -> NLD
        x = self.model.ln_final(x)
        return x

    def text_transformer_forward(self, x: torch.Tensor, attn_mask=None):
        for i, r in enumerate(self.model.transformer.resblocks):
            if i == len(self.model.transformer.resblocks) - self.layer_idx:
                break
            if (
                self.model.transformer.grad_checkpointing
                and not torch.jit.is_scripting()
            ):
                x = checkpoint(r, x, attn_mask)
            else:
                x = r(x, attn_mask=attn_mask)
        return x

    def encode(self, text):
        return self(text)


class FrozenOpenCLIPImageEmbedder(AbstractEmbModel):
    """
    Uses the OpenCLIP vision transformer encoder for images
    """

    def __init__(
        self,
        arch="ViT-H-14",
        version="laion2b_s32b_b79k",
        device="cuda",
        max_length=77,
        freeze=True,
        antialias=True,
        ucg_rate=0.0,
        unsqueeze_dim=False,
        repeat_to_max_len=False,
        num_image_crops=0,
        output_tokens=False,
        init_device=None,
    ):
        super().__init__()
        model, _, _ = open_clip.create_model_and_transforms(
            arch,
            device=torch.device(default(init_device, "cpu")),
            pretrained=version,
        )
        del model.transformer
        self.model = model
        self.max_crops = num_image_crops
        self.pad_to_max_len = self.max_crops > 0
        self.repeat_to_max_len = repeat_to_max_len and (not self.pad_to_max_len)
        self.device = device
        self.max_length = max_length
        if freeze:
            self.freeze()

        self.antialias = antialias

        self.register_buffer(
            "mean", torch.Tensor([0.48145466, 0.4578275, 0.40821073]), persistent=False
        )
        self.register_buffer(
            "std", torch.Tensor([0.26862954, 0.26130258, 0.27577711]), persistent=False
        )
        self.ucg_rate = ucg_rate
        self.unsqueeze_dim = unsqueeze_dim
        self.stored_batch = None
        self.model.visual.output_tokens = output_tokens
        self.output_tokens = output_tokens

    def preprocess(self, x):
        # normalize to [0,1]
        x = kornia.geometry.resize(
            x,
            (224, 224),
            interpolation="bicubic",
            align_corners=True,
            antialias=self.antialias,
        )
        x = (x + 1.0) / 2.0
        # renormalize according to clip
        x = kornia.enhance.normalize(x, self.mean, self.std)
        return x

    def freeze(self):
        self.model = self.model.eval()
        for param in self.parameters():
            param.requires_grad = False

    @autocast
    def forward(self, image, no_dropout=False):
        z = self.encode_with_vision_transformer(image)
        tokens = None
        if self.output_tokens:
            z, tokens = z[0], z[1]
        z = z.to(image.dtype)
        if self.ucg_rate > 0.0 and not no_dropout and not (self.max_crops > 0):
            z = (
                torch.bernoulli(
                    (1.0 - self.ucg_rate) * torch.ones(z.shape[0], device=z.device)
                )[:, None]
                * z
            )
            if tokens is not None:
                tokens = (
                    expand_dims_like(
                        torch.bernoulli(
                            (1.0 - self.ucg_rate)
                            * torch.ones(tokens.shape[0], device=tokens.device)
                        ),
                        tokens,
                    )
                    * tokens
                )
        if self.unsqueeze_dim:
            z = z[:, None, :]
        if self.output_tokens:
            assert not self.repeat_to_max_len
            assert not self.pad_to_max_len
            return tokens, z
        if self.repeat_to_max_len:
            if z.dim() == 2:
                z_ = z[:, None, :]
            else:
                z_ = z
            return repeat(z_, "b 1 d -> b n d", n=self.max_length), z
        elif self.pad_to_max_len:
            assert z.dim() == 3
            z_pad = torch.cat(
                (
                    z,
                    torch.zeros(
                        z.shape[0],
                        self.max_length - z.shape[1],
                        z.shape[2],
                        device=z.device,
                    ),
                ),
                1,
            )
            return z_pad, z_pad[:, 0, ...]
        return z

    def encode_with_vision_transformer(self, img):
        # if self.max_crops > 0:
        #    img = self.preprocess_by_cropping(img)
        if img.dim() == 5:
            assert self.max_crops == img.shape[1]
            img = rearrange(img, "b n c h w -> (b n) c h w")
        img = self.preprocess(img)
        if not self.output_tokens:
            assert not self.model.visual.output_tokens
            x = self.model.visual(img)
            tokens = None
        else:
            assert self.model.visual.output_tokens
            x, tokens = self.model.visual(img)
        if self.max_crops > 0:
            x = rearrange(x, "(b n) d -> b n d", n=self.max_crops)
            # drop out between 0 and all along the sequence axis
            x = (
                torch.bernoulli(
                    (1.0 - self.ucg_rate)
                    * torch.ones(x.shape[0], x.shape[1], 1, device=x.device)
                )
                * x
            )
            if tokens is not None:
                tokens = rearrange(tokens, "(b n) t d -> b t (n d)", n=self.max_crops)
                print(
                    f"You are running very experimental token-concat in {self.__class__.__name__}. "
                    f"Check what you are doing, and then remove this message."
                )
        if self.output_tokens:
            return x, tokens
        return x

    def encode(self, text):
        return self(text)


class FrozenCLIPT5Encoder(AbstractEmbModel):
    def __init__(
        self,
        clip_version="openai/clip-vit-large-patch14",
        t5_version="google/t5-v1_1-xl",
        device="cuda",
        clip_max_length=77,
        t5_max_length=77,
    ):
        super().__init__()
        self.clip_encoder = FrozenCLIPEmbedder(
            clip_version, device, max_length=clip_max_length
        )
        self.t5_encoder = FrozenT5Embedder(t5_version, device, max_length=t5_max_length)
        print(
            f"{self.clip_encoder.__class__.__name__} has {count_params(self.clip_encoder) * 1.e-6:.2f} M parameters, "
            f"{self.t5_encoder.__class__.__name__} comes with {count_params(self.t5_encoder) * 1.e-6:.2f} M params."
        )

    def encode(self, text):
        return self(text)

    def forward(self, text):
        clip_z = self.clip_encoder.encode(text)
        t5_z = self.t5_encoder.encode(text)
        return [clip_z, t5_z]


class SpatialRescaler(nn.Module):
    def __init__(
        self,
        n_stages=1,
        method="bilinear",
        multiplier=0.5,
        in_channels=3,
        out_channels=None,
        bias=False,
        wrap_video=False,
        kernel_size=1,
        remap_output=False,
    ):
        super().__init__()
        self.n_stages = n_stages
        assert self.n_stages >= 0
        assert method in [
            "nearest",
            "linear",
            "bilinear",
            "trilinear",
            "bicubic",
            "area",
        ]
        self.multiplier = multiplier
        self.interpolator = partial(torch.nn.functional.interpolate, mode=method)
        self.remap_output = out_channels is not None or remap_output
        if self.remap_output:
            print(
                f"Spatial Rescaler mapping from {in_channels} to {out_channels} channels after resizing."
            )
            self.channel_mapper = nn.Conv2d(
                in_channels,
                out_channels,
                kernel_size=kernel_size,
                bias=bias,
                padding=kernel_size // 2,
            )
        self.wrap_video = wrap_video

    def forward(self, x):
        if self.wrap_video and x.ndim == 5:
            B, C, T, H, W = x.shape
            x = rearrange(x, "b c t h w -> b t c h w")
            x = rearrange(x, "b t c h w -> (b t) c h w")

        for stage in range(self.n_stages):
            x = self.interpolator(x, scale_factor=self.multiplier)

        if self.wrap_video:
            x = rearrange(x, "(b t) c h w -> b t c h w", b=B, t=T, c=C)
            x = rearrange(x, "b t c h w -> b c t h w")
        if self.remap_output:
            x = self.channel_mapper(x)
        return x

    def encode(self, x):
        return self(x)


class LowScaleEncoder(nn.Module):
    def __init__(
        self,
        model_config,
        linear_start,
        linear_end,
        timesteps=1000,
        max_noise_level=250,
        output_size=64,
        scale_factor=1.0,
    ):
        super().__init__()
        self.max_noise_level = max_noise_level
        self.model = instantiate_from_config(model_config)
        self.augmentation_schedule = self.register_schedule(
            timesteps=timesteps, linear_start=linear_start, linear_end=linear_end
        )
        self.out_size = output_size
        self.scale_factor = scale_factor

    def register_schedule(
        self,
        beta_schedule="linear",
        timesteps=1000,
        linear_start=1e-4,
        linear_end=2e-2,
        cosine_s=8e-3,
    ):
        betas = make_beta_schedule(
            beta_schedule,
            timesteps,
            linear_start=linear_start,
            linear_end=linear_end,
            cosine_s=cosine_s,
        )
        alphas = 1.0 - betas
        alphas_cumprod = np.cumprod(alphas, axis=0)
        alphas_cumprod_prev = np.append(1.0, alphas_cumprod[:-1])

        (timesteps,) = betas.shape
        self.num_timesteps = int(timesteps)
        self.linear_start = linear_start
        self.linear_end = linear_end
        assert (
            alphas_cumprod.shape[0] == self.num_timesteps
        ), "alphas have to be defined for each timestep"

        to_torch = partial(torch.tensor, dtype=torch.float32)

        self.register_buffer("betas", to_torch(betas))
        self.register_buffer("alphas_cumprod", to_torch(alphas_cumprod))
        self.register_buffer("alphas_cumprod_prev", to_torch(alphas_cumprod_prev))

        # calculations for diffusion q(x_t | x_{t-1}) and others
        self.register_buffer("sqrt_alphas_cumprod", to_torch(np.sqrt(alphas_cumprod)))
        self.register_buffer(
            "sqrt_one_minus_alphas_cumprod", to_torch(np.sqrt(1.0 - alphas_cumprod))
        )
        self.register_buffer(
            "log_one_minus_alphas_cumprod", to_torch(np.log(1.0 - alphas_cumprod))
        )
        self.register_buffer(
            "sqrt_recip_alphas_cumprod", to_torch(np.sqrt(1.0 / alphas_cumprod))
        )
        self.register_buffer(
            "sqrt_recipm1_alphas_cumprod", to_torch(np.sqrt(1.0 / alphas_cumprod - 1))
        )

    def q_sample(self, x_start, t, noise=None):
        noise = default(noise, lambda: torch.randn_like(x_start))
        return (
            extract_into_tensor(self.sqrt_alphas_cumprod, t, x_start.shape) * x_start
            + extract_into_tensor(self.sqrt_one_minus_alphas_cumprod, t, x_start.shape)
            * noise
        )

    def forward(self, x):
        z = self.model.encode(x)
        if isinstance(z, DiagonalGaussianDistribution):
            z = z.sample()
        z = z * self.scale_factor
        noise_level = torch.randint(
            0, self.max_noise_level, (x.shape[0],), device=x.device
        ).long()
        z = self.q_sample(z, noise_level)
        if self.out_size is not None:
            z = torch.nn.functional.interpolate(z, size=self.out_size, mode="nearest")
        return z, noise_level

    def decode(self, z):
        z = z / self.scale_factor
        return self.model.decode(z)


class ConcatTimestepEmbedderND(AbstractEmbModel):
    """embeds each dimension independently and concatenates them"""

    def __init__(self, outdim):
        super().__init__()
        self.timestep = Timestep(outdim)
        self.outdim = outdim

    def forward(self, x):
        if x.ndim == 1:
            x = x[:, None]
        assert len(x.shape) == 2
        b, dims = x.shape[0], x.shape[1]
        x = rearrange(x, "b d -> (b d)")
        emb = self.timestep(x)
        emb = rearrange(emb, "(b d) d2 -> b (d d2)", b=b, d=dims, d2=self.outdim)
        return emb


class GaussianEncoder(Encoder, AbstractEmbModel):
    def __init__(
        self, weight: float = 1.0, flatten_output: bool = True, *args, **kwargs
    ):
        super().__init__(*args, **kwargs)
        self.posterior = DiagonalGaussianRegularizer()
        self.weight = weight
        self.flatten_output = flatten_output

    def forward(self, x) -> Tuple[Dict, torch.Tensor]:
        z = super().forward(x)
        z, log = self.posterior(z)
        log["loss"] = log["kl_loss"]
        log["weight"] = self.weight
        if self.flatten_output:
            z = rearrange(z, "b c h w -> b (h w ) c")
        return log, z


class VideoPredictionEmbedderWithEncoder(AbstractEmbModel):
    def __init__(
        self,
        n_cond_frames: int,
        n_copies: int,
        encoder_config: dict,
        sigma_sampler_config: Optional[dict] = None,
        sigma_cond_config: Optional[dict] = None,
        is_ae: bool = False,
        scale_factor: float = 1.0,
        disable_encoder_autocast: bool = False,
        en_and_decode_n_samples_a_time: Optional[int] = None,
    ):
        super().__init__()

        self.n_cond_frames = n_cond_frames
        self.n_copies = n_copies
        self.encoder = instantiate_from_config(encoder_config)
        self.sigma_sampler = (
            instantiate_from_config(sigma_sampler_config)
            if sigma_sampler_config is not None
            else None
        )
        self.sigma_cond = (
            instantiate_from_config(sigma_cond_config)
            if sigma_cond_config is not None
            else None
        )
        self.is_ae = is_ae
        self.scale_factor = scale_factor
        self.disable_encoder_autocast = disable_encoder_autocast
        self.en_and_decode_n_samples_a_time = en_and_decode_n_samples_a_time

    def forward(
        self, vid: torch.Tensor
    ) -> Union[
        torch.Tensor,
        Tuple[torch.Tensor, torch.Tensor],
        Tuple[torch.Tensor, dict],
        Tuple[Tuple[torch.Tensor, torch.Tensor], dict],
    ]:
        if self.sigma_sampler is not None:
            b = vid.shape[0] // self.n_cond_frames
            sigmas = self.sigma_sampler(b).to(vid.device)
            if self.sigma_cond is not None:
                sigma_cond = self.sigma_cond(sigmas)
                sigma_cond = repeat(sigma_cond, "b d -> (b t) d", t=self.n_copies)
            sigmas = repeat(sigmas, "b -> (b t)", t=self.n_cond_frames)
            noise = torch.randn_like(vid)
            vid = vid + noise * append_dims(sigmas, vid.ndim)

        with torch.autocast("cuda", enabled=not self.disable_encoder_autocast):
            n_samples = (
                self.en_and_decode_n_samples_a_time
                if self.en_and_decode_n_samples_a_time is not None
                else vid.shape[0]
            )
            n_rounds = math.ceil(vid.shape[0] / n_samples)
            all_out = []
            for n in range(n_rounds):
                if self.is_ae:
                    out = self.encoder.encode(vid[n * n_samples : (n + 1) * n_samples])
                else:
                    out = self.encoder(vid[n * n_samples : (n + 1) * n_samples])
                all_out.append(out)

        vid = torch.cat(all_out, dim=0)
        vid *= self.scale_factor

        vid = rearrange(vid, "(b t) c h w -> b () (t c) h w", t=self.n_cond_frames)
        vid = repeat(vid, "b 1 c h w -> (b t) c h w", t=self.n_copies)

        return_val = (vid, sigma_cond) if self.sigma_cond is not None else vid

        return return_val


class FrozenOpenCLIPImagePredictionEmbedder(AbstractEmbModel):
    def __init__(
        self,
        open_clip_embedding_config: Dict,
        n_cond_frames: int,
        n_copies: int,
    ):
        super().__init__()

        self.n_cond_frames = n_cond_frames
        self.n_copies = n_copies
        self.open_clip = instantiate_from_config(open_clip_embedding_config)

    def forward(self, vid):
        vid = self.open_clip(vid)
        vid = rearrange(vid, "(b t) d -> b t d", t=self.n_cond_frames)
        vid = repeat(vid, "b t d -> (b s) t d", s=self.n_copies)

        return vid