# Copyright (c) 2023-2024, NVIDIA CORPORATION.  All rights reserved.
#
# NVIDIA CORPORATION and its licensors retain all intellectual property
# and proprietary rights in and to this software, related documentation
# and any modifications thereto.  Any use, reproduction, disclosure or
# distribution of this software and related documentation without an express
# license agreement from NVIDIA CORPORATION is strictly prohibited.

from typing import List, Optional, Set, Tuple, Union
from types import MethodType

import torch
from torch import nn

from timm.models import VisionTransformer, checkpoint_seq

from .feature_normalizer import IntermediateFeatureNormalizerBase, NullIntermediateFeatureNormalizer

from .extra_models import DinoWrapper
from .vit_patch_generator import ViTPatchGenerator
from .forward_intermediates import forward_intermediates


def _forward_cpe(self: VisionTransformer, x: torch.Tensor) -> torch.Tensor:
    x = self.patch_generator(x)
    if getattr(self, 'grad_checkpointing', False) and not torch.jit.is_scripting():
        x = checkpoint_seq(self.blocks, x)
    else:
        x = self.blocks(x)
    x = self.norm(x)
    return x


def _take_indices(
        num_blocks: int,
        n: Optional[Union[int, List[int], Tuple[int]]],
) -> Tuple[Set[int], int]:
    if isinstance(n, int):
        assert n >= 0
        take_indices = {x for x in range(num_blocks - n, num_blocks)}
    else:
        take_indices = {num_blocks + idx if idx < 0 else idx for idx in n}
    return take_indices, max(take_indices)


def _forward_intermediates_cpe(
        self,
        x: torch.Tensor,
        norm: bool = False,
        **kwargs,
) -> Union[List[torch.Tensor], Tuple[torch.Tensor, List[torch.Tensor]]]:
    return forward_intermediates(
        self,
        patch_extractor=self.patch_generator,
        num_summary_tokens=self.patch_generator.num_skip,
        num_cls_tokens=self.patch_generator.num_cls_tokens,
        norm=self.norm if norm else lambda y: y,
        x=x,
        **kwargs,
    )


def _forward_cpe_dinov2(self: DinoWrapper, x: torch.Tensor) -> torch.Tensor:
    y = _forward_cpe(self.inner, x)

    return y[:, 0], y[:, self.num_summary_tokens:]


def _forward_intermediates_cpe_dinov2(self: DinoWrapper, *args, **kwargs):
    return _forward_intermediates_cpe(self.inner, *args, **kwargs)


def _enable_cpe_for_timm_vit(model: VisionTransformer,
                             max_img_size: Union[int, Tuple[int, int]] = 1024,
                             num_cls_tokens: int = 1,
                             pos_dropout: float = 0.1,
                             register_multiple: int = Optional[None],
                             num_registers: int = Optional[None],
):
    if not isinstance(model, VisionTransformer):
        raise ValueError("CPE only support for VisionTransformer models!")

    patch_size = model.patch_embed.patch_size[0]
    embed_dim = model.embed_dim
    input_dims = model.patch_embed.img_size
    normalize_patches = not isinstance(model.patch_embed.norm, nn.Identity)
    cls_token = model.cls_token is not None

    max_img_size = int(round(max_img_size / patch_size) * patch_size)

    patch_generator = ViTPatchGenerator(
        patch_size=patch_size,
        embed_dim=embed_dim,
        input_dims=input_dims,
        normalize_patches=normalize_patches,
        cls_token=cls_token,
        max_input_dims=max_img_size,
        pos_dropout=pos_dropout,
        num_cls_tokens=num_cls_tokens,
        register_multiple=register_multiple,
        num_registers=num_registers,
    )

    model.patch_generator = patch_generator
    model.patch_embed = None
    model.cls_token = None
    model.pos_embed = None
    model.pos_drop = None
    model.patch_size = patch_size
    model.num_cls_tokens = num_cls_tokens
    model.num_registers = patch_generator.num_registers

    model.forward_features = MethodType(_forward_cpe, model)
    model.forward_intermediates = MethodType(_forward_intermediates_cpe, model)


def _enable_cpe_for_dv2_reg_vit(model: DinoWrapper,
                                max_img_size: Union[int, Tuple[int, int]] = 1024,
                                num_cls_tokens: int = 1,
                                pos_dropout: float = 0.1,
                                register_multiple: int = Optional[None],
                                num_registers: int = Optional[None],
):
    patch_size = model.patch_size
    embed_dim = model.embed_dim
    input_dims = model.inner.patch_embed.patches_resolution
    normalize_patches = not isinstance(model.inner.patch_embed.norm, nn.Identity)
    cls_token = True

    max_img_size = int(round(max_img_size / patch_size) * patch_size)

    patch_generator = ViTPatchGenerator(
        patch_size=patch_size,
        embed_dim=embed_dim,
        input_dims=input_dims,
        normalize_patches=normalize_patches,
        cls_token=cls_token,
        max_input_dims=max_img_size,
        pos_dropout=pos_dropout,
        num_cls_tokens=num_cls_tokens,
        register_multiple=register_multiple,
        num_registers=num_registers,
        patch_bias=True,
    )

    inner = model.inner
    inner.patch_generator = patch_generator
    inner.patch_embed = None
    inner.cls_token = None
    inner.pos_embed = None
    inner.register_tokens = None
    inner.patch_size = patch_size

    model.forward_features = MethodType(_forward_cpe_dinov2, model)
    model.forward_intermediates = MethodType(_forward_intermediates_cpe_dinov2, model)


def enable_cpe(model: nn.Module,
               *args,
               **kwargs,
):
    if isinstance(model, VisionTransformer):
        _enable_cpe_for_timm_vit(model, *args, **kwargs)
    elif isinstance(model, DinoWrapper):
        _enable_cpe_for_dv2_reg_vit(model, *args, **kwargs)
    else:
        raise ValueError(f'CPE not supported for this model type: {type(model)}')