import re
from typing import Optional

import mlx.core as mx
import mlx.nn as nn
import numpy as np

from ..base import InputEmbeddingsFeatures
from . import processing_idefics3  # noqa: F401
from .config import ModelConfig
from .language import LanguageModel
from .vision import VisionModel


def masked_scatter(
    final_embedding: mx.array,
    image_mask_expanded: mx.array,
    scaled_image_features: mx.array,
):
    # Reshape the tensors to 1D
    final_embedding_shape = final_embedding.shape
    scaled_image_features_flattened = mx.flatten(scaled_image_features)
    final_embedding_flattened = mx.flatten(final_embedding)
    image_mask_expanded_flattened = mx.flatten(image_mask_expanded)

    # Scatter the scaled image features into the special image token positions
    image_positions = mx.array(np.where(image_mask_expanded_flattened)[0], mx.uint32)
    final_embedding_flattened[image_positions] = scaled_image_features_flattened

    # Reshape back to the original shape
    final_embedding = mx.reshape(final_embedding_flattened, final_embedding_shape)

    return final_embedding


class MLP(nn.Module):
    def __init__(self, config: ModelConfig):
        super().__init__()
        input_size = config.vision_config.hidden_size * (config.scale_factor**2)
        output_size = config.text_config.hidden_size
        self.proj = nn.Linear(input_size, output_size, bias=False)

    def __call__(self, x):
        return self.proj(x)


class Idefics3Connector(nn.Module):
    def __init__(self, config: ModelConfig):
        super().__init__()
        self.scale_factor = config.scale_factor
        self.modality_projection = MLP(config)

    def pixel_shuffle(self, x, scale_factor=2):
        bsz, seq, embed_dim = x.shape
        height = width = int(seq**0.5)
        x = x.reshape(bsz, height, width, embed_dim)
        x = x.reshape(bsz, height, int(width / scale_factor), embed_dim * scale_factor)
        x = x.transpose(0, 2, 1, 3)
        x = x.reshape(
            bsz,
            int(width / scale_factor),
            int(height / scale_factor),
            embed_dim * (scale_factor**2),
        )
        x = x.transpose(0, 2, 1, 3)
        x = x.reshape(bsz, int(seq / (scale_factor**2)), embed_dim * (scale_factor**2))
        return x

    def __call__(self, image_hidden_states):
        image_hidden_states = self.pixel_shuffle(image_hidden_states, self.scale_factor)
        image_hidden_states = self.modality_projection(image_hidden_states)
        return image_hidden_states


class Model(nn.Module):
    def __init__(self, config: ModelConfig):
        super().__init__()
        self.model_type = config.model_type
        self.config = config

        self.vision_model = VisionModel(config.vision_config)
        self.language_model = LanguageModel(config.text_config)
        self.connector = Idefics3Connector(config)

    def get_input_embeddings(
        self,
        input_ids: Optional[mx.array] = None,
        pixel_values: Optional[mx.array] = None,
        **kwargs,
    ):
        pixel_attention_mask = kwargs.get("pixel_attention_mask", None)

        if pixel_values is None:
            return InputEmbeddingsFeatures(
                inputs_embeds=self.language_model.embed_tokens(input_ids)
            )

        inputs_embeds = self.language_model.embed_tokens(input_ids)

        batch_size, num_images, num_channels, height, width = pixel_values.shape
        pixel_values = pixel_values.reshape(
            batch_size * num_images, num_channels, height, width
        )

        # Remove padding images - padding image are full 0.
        nb_values_per_image = np.prod(pixel_values.shape[1:])
        real_images_mask = (pixel_values == 0.0).sum(
            axis=(-1, -2, -3)
        ) != nb_values_per_image
        real_images_inds = np.where(real_images_mask)[0].tolist()
        pixel_values = pixel_values[real_images_inds, ...]

        if pixel_attention_mask is None:
            pixel_attention_mask = mx.ones(
                (pixel_values.size(0), pixel_values.size(2), pixel_values.size(3)),
                dtype=mx.bool,
            )
        else:
            # Remove padding images from the mask
            pixel_attention_mask = pixel_attention_mask.reshape(
                batch_size * num_images, height, width
            )
            pixel_attention_mask = pixel_attention_mask[real_images_inds]

        patch_size = self.config.vision_config.patch_size
        batch_size, height, width = pixel_attention_mask.shape

        # Calculate number of patches
        patches_h = height // patch_size
        patches_w = width // patch_size

        # Reshape to extract patches
        reshaped = pixel_attention_mask[
            :, : patches_h * patch_size, : patches_w * patch_size
        ]
        reshaped = reshaped.reshape(
            batch_size, patches_h, patch_size, patches_w, patch_size
        )
        reshaped = reshaped.transpose(
            0, 1, 3, 2, 4
        )  # (batch, patches_h, patches_w, patch_size, patch_size)

        # Sum over patch dimensions and check if any pixels are active
        patch_attention_mask = reshaped.sum(axis=(-1, -2)) > 0

        pooler_output, *_ = self.vision_model(
            pixel_values.transpose(0, 2, 3, 1),
            patch_attention_mask=patch_attention_mask,
            output_hidden_states=True,
        )

        image_features = pooler_output.astype(pixel_values.dtype)
        image_features = self.connector(image_features)

        final_inputs_embeds = self._prepare_inputs_for_multimodal(
            image_features, inputs_embeds, input_ids
        )
        return InputEmbeddingsFeatures(inputs_embeds=final_inputs_embeds)

    def _prepare_inputs_for_multimodal(self, image_features, inputs_embeds, input_ids):
        special_image_mask = input_ids == self.config.image_token_index
        n_image_tokens = special_image_mask.sum()
        special_image_mask = special_image_mask[..., None]
        special_image_mask = mx.broadcast_to(special_image_mask, inputs_embeds.shape)

        n_image_features = image_features.shape[0]
        n_image_mask_elements = special_image_mask.sum()
        if n_image_mask_elements != image_features.size:
            raise ValueError(
                f"Image features and image tokens do not match: tokens: {n_image_tokens}, features {n_image_features}"
            )

        inputs_embeds = masked_scatter(
            inputs_embeds, special_image_mask, image_features
        )

        return inputs_embeds

    @property
    def layers(self):
        return self.language_model.layers

    def __call__(
        self,
        input_ids: mx.array,
        pixel_values: mx.array,
        cache=None,
        **kwargs,
    ):
        input_embeddings_features = self.get_input_embeddings(
            input_ids, pixel_values, **kwargs
        )
        logits = self.language_model(
            inputs=input_ids,
            cache=cache,
            inputs_embeds=input_embeddings_features.inputs_embeds,
        )
        return logits

    def sanitize(self, weights):
        weights = {
            (
                f"{k.split('.', 1)[1]}"
                if re.match(r"^model\.", k)
                else (f"language_model.{k}" if re.match(r"^lm_head\.", k) else k)
            ): v
            for k, v in weights.items()
        }

        weights = {
            (
                f"language_model.{k.split('.', 1)[1]}"
                if re.match(
                    r"^text_model\.",
                    k,
                )
                else k
            ): v
            for k, v in weights.items()
        }

        return weights
