# Copyright 2025 the Cohere Inc. 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.
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#     http://www.apache.org/licenses/LICENSE-2.0
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# distributed under the License is distributed on an "AS IS" BASIS,
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"""PyTorch AyaVision model."""

from functools import lru_cache

import numpy as np
import torch
from torch import nn

from transformers.models.aya_vision.modeling_aya_vision import (
    AyaVisionCausalLMOutputWithPast,
    AyaVisionForConditionalGeneration,
    AyaVisionModel,
    AyaVisionModelOutputWithPast,
    AyaVisionPreTrainedModel,
)
from transformers.models.got_ocr2.image_processing_got_ocr2_fast import GotOcr2ImageProcessorFast

from ...cache_utils import Cache
from ...image_processing_utils import BatchFeature
from ...image_utils import ImageInput
from ...modeling_flash_attention_utils import FlashAttentionKwargs
from ...processing_utils import ImagesKwargs, Unpack
from ...utils import TransformersKwargs, auto_docstring, logging
from ...utils.generic import check_model_inputs
from .configuration_cohere2_vision import Cohere2VisionConfig


logger = logging.get_logger(__name__)


class Cohere2VisionMultiModalProjector(nn.Module):
    def __init__(self, config: Cohere2VisionConfig):
        super().__init__()
        self.config = config
        self.downsample_factor = config.downsample_factor
        self.intermediate_size = config.alignment_intermediate_size
        self.linear_1 = nn.Linear(
            config.vision_config.hidden_size * (config.downsample_factor**2), self.intermediate_size, bias=True
        )
        self.act = nn.SiLU()
        self.linear_2 = nn.Linear(self.intermediate_size // 2, config.text_config.hidden_size, bias=True)

    def pixel_shuffle(self, image_features):  # B, S, D
        batch_size, seq_length, feature_dim = image_features.shape
        height = width = int(seq_length**0.5)
        image_features = image_features.reshape(image_features.shape[0], width, height, -1)
        channels = image_features.shape[-1]
        image_features = image_features.reshape(
            batch_size, width, int(height / self.downsample_factor), int(channels * self.downsample_factor)
        )
        image_features = image_features.permute(0, 2, 1, 3)
        image_features = image_features.reshape(
            batch_size, int(height / self.downsample_factor), int(width / self.downsample_factor), -1
        )
        image_features = image_features.permute(0, 2, 1, 3)
        return image_features

    def forward(self, image_features):
        image_features = self.pixel_shuffle(image_features)
        hidden_states = self.linear_1(image_features)

        # Split along last dimension and apply SwiGLU
        x, gate = hidden_states.chunk(2, dim=-1)
        hidden_states = self.act(gate) * x

        hidden_states = self.linear_2(hidden_states)
        return hidden_states


class Cohere2VisionModelOutputWithPast(AyaVisionModelOutputWithPast):
    pass


class Cohere2VisionCausalLMOutputWithPast(AyaVisionCausalLMOutputWithPast):
    pass


class Cohere2VisionPreTrainedModel(AyaVisionPreTrainedModel):
    base_model_prefix = "model"


class Cohere2VisionModel(AyaVisionModel):
    _checkpoint_conversion_mapping = {}

    def get_image_features(self, pixel_values: torch.FloatTensor):
        """
        Obtains image last hidden states from the vision tower and apply multimodal projection.

        Args:
            pixel_values (`torch.FloatTensor]` of shape `(batch_size, num_patches, channels, height, width)`)
               The tensors corresponding to the input images.
        Returns:
            image_features (List[`torch.Tensor`]): List of image feature tensor, each contains all the visual feature of all patches
            and are of shape `(num_patches, image_length, embed_dim)`).
        """

        image_features = self.vision_tower(pixel_values, output_hidden_states=True)
        selected_image_feature = image_features.last_hidden_state
        image_features = self.multi_modal_projector(selected_image_feature)
        return image_features

    @check_model_inputs
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        pixel_values: torch.FloatTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        use_cache: bool | None = None,
        cache_position: torch.LongTensor | None = None,
        **kwargs: Unpack[FlashAttentionKwargs],
    ) -> tuple | Cohere2VisionModelOutputWithPast:
        if (input_ids is None) ^ (inputs_embeds is not None):
            raise ValueError("You must specify exactly one of input_ids or inputs_embeds")

        if inputs_embeds is None:
            inputs_embeds = self.get_input_embeddings()(input_ids)

        if pixel_values is not None:
            image_features = self.get_image_features(pixel_values)
            image_features = image_features.to(inputs_embeds.device, inputs_embeds.dtype)
            special_image_mask = self.get_placeholder_mask(
                input_ids, inputs_embeds=inputs_embeds, image_features=image_features
            )
            inputs_embeds = inputs_embeds.masked_scatter(special_image_mask, image_features)

        outputs = self.language_model(
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            cache_position=cache_position,
            **kwargs,
        )

        return Cohere2VisionModelOutputWithPast(
            last_hidden_state=outputs.last_hidden_state,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
            image_hidden_states=image_features if pixel_values is not None else None,
        )


class Cohere2VisionForConditionalGeneration(AyaVisionForConditionalGeneration):
    _checkpoint_conversion_mapping = {}

    def get_image_features(self, pixel_values: torch.FloatTensor):
        return self.model.get_image_features(pixel_values=pixel_values)

    @check_model_inputs
    @auto_docstring
    def forward(
        self,
        input_ids: torch.LongTensor | None = None,
        pixel_values: torch.FloatTensor | None = None,
        attention_mask: torch.Tensor | None = None,
        position_ids: torch.LongTensor | None = None,
        past_key_values: Cache | None = None,
        inputs_embeds: torch.FloatTensor | None = None,
        labels: torch.LongTensor | None = None,
        use_cache: bool | None = None,
        cache_position: torch.LongTensor | None = None,
        logits_to_keep: int | torch.Tensor = 0,
        image_sizes: torch.Tensor | None = None,
        **kwargs: Unpack[TransformersKwargs],
    ) -> tuple | Cohere2VisionCausalLMOutputWithPast:
        r"""
        labels (`torch.LongTensor` of shape `(batch_size, sequence_length)`, *optional*):
            Labels for computing the masked language modeling loss. Indices should either be in `[0, ...,
            config.vocab_size]` or -100 (see `input_ids` docstring). Tokens with indices set to `-100` are ignored
            (masked), the loss is only computed for the tokens with labels in `[0, ..., config.vocab_size]`.

        Example:

        ```python
        >>> from transformers import AutoProcessor, Cohere2VisionForConditionalGeneration
        >>> import torch

        >>> processor = AutoProcessor.from_pretrained("CohereLabs/command-a-vision-07-2025", use_fast=True)
        >>> model = Cohere2VisionForConditionalGeneration.from_pretrained("CohereLabs/command-a-vision-07-2025", device_map="auto")

        >>> messages = [
        ...     {
        ...         "role": "user",
        ...         "content": [
        ...             {
        ...                 "type": "image",
        ...                 "url": "https://images.pexels.com/photos/1108099/pexels-photo-1108099.jpeg",
        ...             },
        ...             {"type": "text", "text": "what is in this image?"},
        ...         ],
        ...     },
        ... ]

        >>> inputs = processor.apply_chat_template(
        ...     messages, padding=True, add_generation_prompt=True, tokenize=True, return_dict=True, return_tensors="pt",
        ... ).to(model.device)

        >>> gen_tokens = model.generate(**inputs, max_new_tokens=300, do_sample=True, temperature=0.3)
        >>> processor.tokenizer.decode(gen_tokens[0][inputs.input_ids.shape[1]:], skip_special_tokens=True)
        ```"""
        outputs = self.model(
            input_ids=input_ids,
            pixel_values=pixel_values,
            attention_mask=attention_mask,
            position_ids=position_ids,
            past_key_values=past_key_values,
            inputs_embeds=inputs_embeds,
            use_cache=use_cache,
            cache_position=cache_position,
            image_sizes=image_sizes,
            **kwargs,
        )

        hidden_states = outputs[0]
        # Only compute necessary logits, and do not upcast them to float if we are not computing the loss
        slice_indices = slice(-logits_to_keep, None) if isinstance(logits_to_keep, int) else logits_to_keep
        logits = self.lm_head(hidden_states[:, slice_indices, :])

        loss = None
        if labels is not None:
            loss = self.loss_function(
                logits=logits, labels=labels, vocab_size=self.config.text_config.vocab_size, **kwargs
            )

        return Cohere2VisionCausalLMOutputWithPast(
            loss=loss,
            logits=logits,
            past_key_values=outputs.past_key_values,
            hidden_states=outputs.hidden_states,
            attentions=outputs.attentions,
            image_hidden_states=outputs.image_hidden_states,
        )


@lru_cache(maxsize=10)
def get_all_supported_aspect_ratios(max_image_tiles: int) -> list[tuple[int, int]]:
    """
    Computes all allowed aspect ratios for a given maximum number of input tiles.

    This function calculates all possible arrangements of tiles that can be formed
    within the constraint of the maximum number of tiles. Each arrangement is
    represented by its aspect ratio (width/height) and the corresponding tile configuration.

    Args:
        max_image_tiles (`int`):
            The maximum number of tiles allowed.

    Returns:
        `list[tuple[int, int]]`: A list of tuples, each tuple representing a valid (width, height)
        configuration in terms of number of tiles.

    Example:
        >>> get_all_supported_aspect_ratios(4)
        [(1, 1), (1, 2), (1, 3), (1, 4), (2, 1), (2, 2), (3, 1), (4, 1)]

    """
    aspect_ratios = []
    for width in range(1, max_image_tiles + 1):
        for height in range(1, max_image_tiles + 1):
            if width * height <= max_image_tiles:
                aspect_ratios.append((width, height))
    return aspect_ratios


def get_optimal_tiled_canvas(
    original_image_size: tuple[int, int],
    target_tile_size: tuple[int, int],
    min_image_tiles: int,
    max_image_tiles: int,
) -> tuple[int, int]:
    possible_resolutions = get_all_supported_aspect_ratios(max_image_tiles)
    possible_resolutions = sorted(possible_resolutions, key=lambda x: x[0] * x[1])
    image_height, image_width = original_image_size
    patch_size_height, patch_size_width = target_tile_size  # (height == width)

    candidate_resolutions = np.array(possible_resolutions) * patch_size_height
    # tiles following (width, height) order to align with aspect ratio convention
    tile_size = np.stack([image_width, image_height])
    required_scales = candidate_resolutions / tile_size
    required_scale = np.min(required_scales, axis=-1, keepdims=True)  # [n_resolutions, 1]
    if np.all(required_scale < 1):
        # We are forced to downscale, so try to minimize the amount of downscaling
        best_grid = possible_resolutions[np.argmax(required_scale)]
    else:
        # Pick the resolution that required the least upscaling so that it most closely fits the image
        required_scale = np.where(required_scale < 1.0, 10e9, required_scale)
        best_grid = possible_resolutions[np.argmin(required_scale)]
    return best_grid  # (width, height)


class Cohere2VisionFastImageProcessorKwargs(ImagesKwargs, total=False):
    """
    crop_to_patches (`bool`, *optional*, defaults to `False`):
        Whether to crop the image to patches. Can be overridden by the `crop_to_patches` parameter in the
        `preprocess` method.
    min_patches (`int`, *optional*, defaults to 1):
        The minimum number of patches to be extracted from the image. Only has an effect if `crop_to_patches` is
        set to `True`. Can be overridden by the `min_patches` parameter in the `preprocess` method.
    max_patches (`int`, *optional*, defaults to 12):
        The maximum number of patches to be extracted from the image. Only has an effect if `crop_to_patches` is
        set to `True`. Can be overridden by the `max_patches` parameter in the `preprocess` method.
    """

    crop_to_patches: bool
    min_patches: int
    max_patches: int


@auto_docstring
class Cohere2VisionImageProcessorFast(GotOcr2ImageProcessorFast):
    size = {"height": 512, "width": 512}
    min_patches = 1
    max_patches = 12
    crop_to_patches = True
    patch_size = 16
    valid_kwargs = Cohere2VisionFastImageProcessorKwargs

    def __init__(self, **kwargs: Unpack[Cohere2VisionFastImageProcessorKwargs]):
        super().__init__(**kwargs)

    @auto_docstring
    def preprocess(self, images: ImageInput, **kwargs: Unpack[Cohere2VisionFastImageProcessorKwargs]) -> BatchFeature:
        return super().preprocess(images, **kwargs)


__all__ = [
    "Cohere2VisionForConditionalGeneration",
    "Cohere2VisionPreTrainedModel",
    "Cohere2VisionModel",
    "Cohere2VisionImageProcessorFast",
]
